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Strange (Undefined?) Behavior of Free in C

- by Chris Cirefice

This is really strange... and I can't debug it (tried for about two hours, debugger starts going haywire after a while...). Anyway, I'm trying to do something really simple: Free an array of strings. The array is in the form: char **myStrings. The array elements are initialized as: myString[index] = malloc(strlen(word)); myString[index] = word; and I'm calling a function like this: free_memory(myStrings, size); where size is the length of the array (I know this is not the problem, I tested it extensively and everything except this function is working). free_memory looks like this: void free_memory(char **list, int size) { for (int i = 0; i < size; i ++) { free(list[i]); } free(list); } Now here comes the weird part. if (size> strlen(list[i])) then the program crashes. For example, imagine that I have a list of strings that looks something like this: myStrings[0] = "Some"; myStrings[1] = "random"; myStrings[2] = "strings"; And thus the length of this array is 3. If I pass this to my free_memory function, strlen(myStrings[0]) > 3 (4 3), and the program crashes. However, if I change myStrings[0] to be "So" instead, then strlen(myStrings[0]) < 3 (2 < 3) and the program does not crash. So it seems to me that free(list[i]) is actually going through the char[] that is at that location and trying to free each character, which I imagine is undefined behavior. The only reason I say this is because I can play around with the size of the first element of myStrings and make the program crash whenever I feel like it, so I'm assuming that this is the problem area. Note: I did try to debug this by stepping through the function that calls free_memory, noting any weird values and such, but the moment I step into the free_memory function, the debugger crashes, so I'm not really sure what is going on. Nothing is out of the ordinary until I enter the function, then the world explodes. Another note: I also posted the shortened version of the source for this program (not too long; Pastebin) here. I am compiling on MinGW with the c99 flag on. PS - I just thought of this. I am indeed passing numUniqueWords to the free function, and I know that this does not actually free the entire piece of memory that I allocated. I've called it both ways, that's not the issue. And I left it how I did because that is the way that I will be calling it after I get it to work in the first place, I need to revise some of my logic in that function. Source, as per request (on-site): #include <stdio.h> #include <string.h> #include <ctype.h> #include <stdlib.h> #include "words.h" int getNumUniqueWords(char text[], int size); int main(int argc, char* argv[]) { setvbuf(stdout, NULL, 4, _IONBF); // For Eclipse... stupid bug. --> does NOT affect the program, just the output to console! int nbr_words; char text[] = "Some - \"text, a stdin\". We'll have! also repeat? We'll also have a repeat!"; int length = sizeof(text); nbr_words = getNumUniqueWords(text, length); return 0; } void free_memory(char **list, int size) { for (int i = 0; i < size; i ++) { // You can see that printing the values is fine, as long as free is not called. // When free is called, the program will crash if (size > strlen(list[i])) //printf("Wanna free value %d w/len of %d: %s\n", i, strlen(list[i]), list[i]); free(list[i]); } free(list); } int getNumUniqueWords(char text[], int length) { int numTotalWords = 0; char *word; printf("Length: %d characters\n", length); char totalWords[length]; strcpy(totalWords, text); word = strtok(totalWords, " ,.-!?()\"0123456789"); while (word != NULL) { numTotalWords ++; printf("%s\n", word); word = strtok(NULL, " ,.-!?()\"0123456789"); } printf("Looks like we counted %d total words\n\n", numTotalWords); char *uniqueWords[numTotalWords]; char *tempWord; int wordAlreadyExists = 0; int numUniqueWords = 0; char totalWordsCopy[length]; strcpy(totalWordsCopy, text); for (int i = 0; i < numTotalWords; i++) { uniqueWords[i] = NULL; } // Tokenize until all the text is consumed. word = strtok(totalWordsCopy, " ,.-!?()\"0123456789"); while (word != NULL) { // Look through the word list for the current token. for (int j = 0; j < numTotalWords; j ++) { // Just for clarity, no real meaning. tempWord = uniqueWords[j]; // The word list is either empty or the current token is not in the list. if (tempWord == NULL) { break; } //printf("Comparing (%s) with (%s)\n", tempWord, word); // If the current token is the same as the current element in the word list, mark and break if (strcmp(tempWord, word) == 0) { printf("\nDuplicate: (%s)\n\n", word); wordAlreadyExists = 1; break; } } // Word does not exist, add it to the array. if (!wordAlreadyExists) { uniqueWords[numUniqueWords] = malloc(strlen(word)); uniqueWords[numUniqueWords] = word; numUniqueWords ++; printf("Unique: %s\n", word); } // Reset flags and continue. wordAlreadyExists = 0; word = strtok(NULL, " ,.-!?()\"0123456789"); } // Print out the array just for funsies - make sure it's working properly. for (int x = 0; x <numUniqueWords; x++) { printf("Unique list %d: %s\n", x, uniqueWords[x]); } printf("\nNumber of unique words: %d\n\n", numUniqueWords); // Right below is where things start to suck. free_memory(uniqueWords, numUniqueWords); return numUniqueWords; }

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Capturing and Transforming ASP.NET Output with Response.Filter

- by Rick Strahl

During one of my Handlers and Modules session at DevConnections this week one of the attendees asked a question that I didn’t have an immediate answer for. Basically he wanted to capture response output completely and then apply some filtering to the output – effectively injecting some additional content into the page AFTER the page had completely rendered. Specifically the output should be captured from anywhere – not just a page and have this code injected into the page. Some time ago I posted some code that allows you to capture ASP.NET Page output by overriding the Render() method, capturing the HtmlTextWriter() and reading its content, modifying the rendered data as text then writing it back out. I’ve actually used this approach on a few occasions and it works fine for ASP.NET pages. But this obviously won’t work outside of the Page class environment and it’s not really generic – you have to create a custom page class in order to handle the output capture. [updated 11/16/2009 – updated ResponseFilterStream implementation and a few additional notes based on comments] Enter Response.Filter However, ASP.NET includes a Response.Filter which can be used – well to filter output. Basically Response.Filter is a stream through which the OutputStream is piped back to the Web Server (indirectly). As content is written into the Response object, the filter stream receives the appropriate Stream commands like Write, Flush and Close as well as read operations although for a Response.Filter that’s uncommon to be hit. The Response.Filter can be programmatically replaced at runtime which allows you to effectively intercept all output generation that runs through ASP.NET. A common Example: Dynamic GZip Encoding A rather common use of Response.Filter hooking up code based, dynamic GZip compression for requests which is dead simple by applying a GZipStream (or DeflateStream) to Response.Filter. The following generic routines can be used very easily to detect GZip capability of the client and compress response output with a single line of code and a couple of library helper routines: WebUtils.GZipEncodePage(); which is handled with a few lines of reusable code and a couple of static helper methods: /// <summary> ///Sets up the current page or handler to use GZip through a Response.Filter ///IMPORTANT: ///You have to call this method before any output is generated! /// </summary> public static void GZipEncodePage() { HttpResponse Response = HttpContext.Current.Response; if(IsGZipSupported()) { stringAcceptEncoding = HttpContext.Current.Request.Headers["Accept-Encoding"]; if(AcceptEncoding.Contains("deflate")) { Response.Filter = newSystem.IO.Compression.DeflateStream(Response.Filter, System.IO.Compression.CompressionMode.Compress); Response.AppendHeader("Content-Encoding", "deflate"); } else { Response.Filter = newSystem.IO.Compression.GZipStream(Response.Filter, System.IO.Compression.CompressionMode.Compress); Response.AppendHeader("Content-Encoding", "gzip"); } } // Allow proxy servers to cache encoded and unencoded versions separately Response.AppendHeader("Vary", "Content-Encoding"); } /// <summary> /// Determines if GZip is supported /// </summary> /// <returns></returns> public static bool IsGZipSupported() { string AcceptEncoding = HttpContext.Current.Request.Headers["Accept-Encoding"]; if (!string.IsNullOrEmpty(AcceptEncoding) && (AcceptEncoding.Contains("gzip") || AcceptEncoding.Contains("deflate"))) return true; return false; } GZipStream and DeflateStream are streams that are assigned to Response.Filter and by doing so apply the appropriate compression on the active Response. Response.Filter content is chunked So to implement a Response.Filter effectively requires only that you implement a custom stream and handle the Write() method to capture Response output as it’s written. At first blush this seems very simple – you capture the output in Write, transform it and write out the transformed content in one pass. And that indeed works for small amounts of content. But you see, the problem is that output is written in small buffer chunks (a little less than 16k it appears) rather than just a single Write() statement into the stream, which makes perfect sense for ASP.NET to stream data back to IIS in smaller chunks to minimize memory usage en route. Unfortunately this also makes it a more difficult to implement any filtering routines since you don’t directly get access to all of the response content which is problematic especially if those filtering routines require you to look at the ENTIRE response in order to transform or capture the output as is needed for the solution the gentleman in my session asked for. So in order to address this a slightly different approach is required that basically captures all the Write() buffers passed into a cached stream and then making the stream available only when it’s complete and ready to be flushed. As I was thinking about the implementation I also started thinking about the few instances when I’ve used Response.Filter implementations. Each time I had to create a new Stream subclass and create my custom functionality but in the end each implementation did the same thing – capturing output and transforming it. I thought there should be an easier way to do this by creating a re-usable Stream class that can handle stream transformations that are common to Response.Filter implementations. Creating a semi-generic Response Filter Stream Class What I ended up with is a ResponseFilterStream class that provides a handful of Events that allow you to capture and/or transform Response content. The class implements a subclass of Stream and then overrides Write() and Flush() to handle capturing and transformation operations. By exposing events it’s easy to hook up capture or transformation operations via single focused methods. ResponseFilterStream exposes the following events: CaptureStream, CaptureString Captures the output only and provides either a MemoryStream or String with the final page output. Capture is hooked to the Flush() operation of the stream. TransformStream, TransformString Allows you to transform the complete response output with events that receive a MemoryStream or String respectively and can you modify the output then return it back as a return value. The transformed output is then written back out in a single chunk to the response output stream. These events capture all output internally first then write the entire buffer into the response. TransformWrite, TransformWriteString Allows you to transform the Response data as it is written in its original chunk size in the Stream’s Write() method. Unlike TransformStream/TransformString which operate on the complete output, these events only see the current chunk of data written. This is more efficient as there’s no caching involved, but can cause problems due to searched content splitting over multiple chunks. Using this implementation, creating a custom Response.Filter transformation becomes as simple as the following code. To hook up the Response.Filter using the MemoryStream version event: ResponseFilterStream filter = new ResponseFilterStream(Response.Filter); filter.TransformStream += filter_TransformStream; Response.Filter = filter; and the event handler to do the transformation: MemoryStream filter_TransformStream(MemoryStream ms) { Encoding encoding = HttpContext.Current.Response.ContentEncoding; string output = encoding.GetString(ms.ToArray()); output = FixPaths(output); ms = new MemoryStream(output.Length); byte[] buffer = encoding.GetBytes(output); ms.Write(buffer,0,buffer.Length); return ms; } private string FixPaths(string output) { string path = HttpContext.Current.Request.ApplicationPath; // override root path wonkiness if (path == "/") path = ""; output = output.Replace("\"~/", "\"" + path + "/").Replace("'~/", "'" + path + "/"); return output; } The idea of the event handler is that you can do whatever you want to the stream and return back a stream – either the same one that’s been modified or a brand new one – which is then sent back to as the final response. The above code can be simplified even more by using the string version events which handle the stream to string conversions for you: ResponseFilterStream filter = new ResponseFilterStream(Response.Filter); filter.TransformString += filter_TransformString; Response.Filter = filter; and the event handler to do the transformation calling the same FixPaths method shown above: string filter_TransformString(string output) { return FixPaths(output); } The events for capturing output and capturing and transforming chunks work in a very similar way. By using events to handle the transformations ResponseFilterStream becomes a reusable component and we don’t have to create a new stream class or subclass an existing Stream based classed. By the way, the example used here is kind of a cool trick which transforms “~/” expressions inside of the final generated HTML output – even in plain HTML controls not HTML controls – and transforms them into the appropriate application relative path in the same way that ResolveUrl would do. So you can write plain old HTML like this: <a href=”~/default.aspx”>Home</a> and have it turned into: <a href=”/myVirtual/default.aspx”>Home</a> without having to use an ASP.NET control like Hyperlink or Image or having to constantly use: <img src=”<%= ResolveUrl(“~/images/home.gif”) %>” /> in MVC applications (which frankly is one of the most annoying things about MVC especially given the path hell that extension-less and endpoint-less URLs impose). I can’t take credit for this idea. While discussing the Response.Filter issues on Twitter a hint from Dylan Beattie who pointed me at one of his examples which does something similar. I thought the idea was cool enough to use an example for future demos of Response.Filter functionality in ASP.NET next I time I do the Modules and Handlers talk (which was great fun BTW). How practical this is is debatable however since there’s definitely some overhead to using a Response.Filter in general and especially on one that caches the output and the re-writes it later. Make sure to test for performance anytime you use Response.Filter hookup and make sure it' doesn’t end up killing perf on you. You’ve been warned :-}. How does ResponseFilterStream work? The big win of this implementation IMHO is that it’s a reusable component – so for implementation there’s no new class, no subclassing – you simply attach to an event to implement an event handler method with a straight forward signature to retrieve the stream or string you’re interested in. The implementation is based on a subclass of Stream as is required in order to handle the Response.Filter requirements. What’s different than other implementations I’ve seen in various places is that it supports capturing output as a whole to allow retrieving the full response output for capture or modification. The exception are the TransformWrite and TransformWrite events which operate only active chunk of data written by the Response. For captured output, the Write() method captures output into an internal MemoryStream that is cached until writing is complete. So Write() is called when ASP.NET writes to the Response stream, but the filter doesn’t pass on the Write immediately to the filter’s internal stream. The data is cached and only when the Flush() method is called to finalize the Stream’s output do we actually send the cached stream off for transformation (if the events are hooked up) and THEN finally write out the returned content in one big chunk. Here’s the implementation of ResponseFilterStream: /// <summary> /// A semi-generic Stream implementation for Response.Filter with /// an event interface for handling Content transformations via /// Stream or String. /// <remarks> /// Use with care for large output as this implementation copies /// the output into a memory stream and so increases memory usage. /// </remarks> /// </summary> public class ResponseFilterStream : Stream { /// <summary> /// The original stream /// </summary> Stream _stream; /// <summary> /// Current position in the original stream /// </summary> long _position; /// <summary> /// Stream that original content is read into /// and then passed to TransformStream function /// </summary> MemoryStream _cacheStream = new MemoryStream(5000); /// <summary> /// Internal pointer that that keeps track of the size /// of the cacheStream /// </summary> int _cachePointer = 0; /// <summary> /// /// </summary> /// <param name="responseStream"></param> public ResponseFilterStream(Stream responseStream) { _stream = responseStream; } /// <summary> /// Determines whether the stream is captured /// </summary> private bool IsCaptured { get { if (CaptureStream != null || CaptureString != null || TransformStream != null || TransformString != null) return true; return false; } } /// <summary> /// Determines whether the Write method is outputting data immediately /// or delaying output until Flush() is fired. /// </summary> private bool IsOutputDelayed { get { if (TransformStream != null || TransformString != null) return true; return false; } } /// <summary> /// Event that captures Response output and makes it available /// as a MemoryStream instance. Output is captured but won't /// affect Response output. /// </summary> public event Action<MemoryStream> CaptureStream; /// <summary> /// Event that captures Response output and makes it available /// as a string. Output is captured but won't affect Response output. /// </summary> public event Action<string> CaptureString; /// <summary> /// Event that allows you transform the stream as each chunk of /// the output is written in the Write() operation of the stream. /// This means that that it's possible/likely that the input /// buffer will not contain the full response output but only /// one of potentially many chunks. /// /// This event is called as part of the filter stream's Write() /// operation. /// </summary> public event Func<byte[], byte[]> TransformWrite; /// <summary> /// Event that allows you to transform the response stream as /// each chunk of bytep[] output is written during the stream's write /// operation. This means it's possibly/likely that the string /// passed to the handler only contains a portion of the full /// output. Typical buffer chunks are around 16k a piece. /// /// This event is called as part of the stream's Write operation. /// </summary> public event Func<string, string> TransformWriteString; /// <summary> /// This event allows capturing and transformation of the entire /// output stream by caching all write operations and delaying final /// response output until Flush() is called on the stream. /// </summary> public event Func<MemoryStream, MemoryStream> TransformStream; /// <summary> /// Event that can be hooked up to handle Response.Filter /// Transformation. Passed a string that you can modify and /// return back as a return value. The modified content /// will become the final output. /// </summary> public event Func<string, string> TransformString; protected virtual void OnCaptureStream(MemoryStream ms) { if (CaptureStream != null) CaptureStream(ms); } private void OnCaptureStringInternal(MemoryStream ms) { if (CaptureString != null) { string content = HttpContext.Current.Response.ContentEncoding.GetString(ms.ToArray()); OnCaptureString(content); } } protected virtual void OnCaptureString(string output) { if (CaptureString != null) CaptureString(output); } protected virtual byte[] OnTransformWrite(byte[] buffer) { if (TransformWrite != null) return TransformWrite(buffer); return buffer; } private byte[] OnTransformWriteStringInternal(byte[] buffer) { Encoding encoding = HttpContext.Current.Response.ContentEncoding; string output = OnTransformWriteString(encoding.GetString(buffer)); return encoding.GetBytes(output); } private string OnTransformWriteString(string value) { if (TransformWriteString != null) return TransformWriteString(value); return value; } protected virtual MemoryStream OnTransformCompleteStream(MemoryStream ms) { if (TransformStream != null) return TransformStream(ms); return ms; } /// <summary> /// Allows transforming of strings /// /// Note this handler is internal and not meant to be overridden /// as the TransformString Event has to be hooked up in order /// for this handler to even fire to avoid the overhead of string /// conversion on every pass through. /// </summary> /// <param name="responseText"></param> /// <returns></returns> private string OnTransformCompleteString(string responseText) { if (TransformString != null) TransformString(responseText); return responseText; } /// <summary> /// Wrapper method form OnTransformString that handles /// stream to string and vice versa conversions /// </summary> /// <param name="ms"></param> /// <returns></returns> internal MemoryStream OnTransformCompleteStringInternal(MemoryStream ms) { if (TransformString == null) return ms; //string content = ms.GetAsString(); string content = HttpContext.Current.Response.ContentEncoding.GetString(ms.ToArray()); content = TransformString(content); byte[] buffer = HttpContext.Current.Response.ContentEncoding.GetBytes(content); ms = new MemoryStream(); ms.Write(buffer, 0, buffer.Length); //ms.WriteString(content); return ms; } /// <summary> /// /// </summary> public override bool CanRead { get { return true; } } public override bool CanSeek { get { return true; } } /// <summary> /// /// </summary> public override bool CanWrite { get { return true; } } /// <summary> /// /// </summary> public override long Length { get { return 0; } } /// <summary> /// /// </summary> public override long Position { get { return _position; } set { _position = value; } } /// <summary> /// /// </summary> /// <param name="offset"></param> /// <param name="direction"></param> /// <returns></returns> public override long Seek(long offset, System.IO.SeekOrigin direction) { return _stream.Seek(offset, direction); } /// <summary> /// /// </summary> /// <param name="length"></param> public override void SetLength(long length) { _stream.SetLength(length); } /// <summary> /// /// </summary> public override void Close() { _stream.Close(); } /// <summary> /// Override flush by writing out the cached stream data /// </summary> public override void Flush() { if (IsCaptured && _cacheStream.Length > 0) { // Check for transform implementations _cacheStream = OnTransformCompleteStream(_cacheStream); _cacheStream = OnTransformCompleteStringInternal(_cacheStream); OnCaptureStream(_cacheStream); OnCaptureStringInternal(_cacheStream); // write the stream back out if output was delayed if (IsOutputDelayed) _stream.Write(_cacheStream.ToArray(), 0, (int)_cacheStream.Length); // Clear the cache once we've written it out _cacheStream.SetLength(0); } // default flush behavior _stream.Flush(); } /// <summary> /// /// </summary> /// <param name="buffer"></param> /// <param name="offset"></param> /// <param name="count"></param> /// <returns></returns> public override int Read(byte[] buffer, int offset, int count) { return _stream.Read(buffer, offset, count); } /// <summary> /// Overriden to capture output written by ASP.NET and captured /// into a cached stream that is written out later when Flush() /// is called. /// </summary> /// <param name="buffer"></param> /// <param name="offset"></param> /// <param name="count"></param> public override void Write(byte[] buffer, int offset, int count) { if ( IsCaptured ) { // copy to holding buffer only - we'll write out later _cacheStream.Write(buffer, 0, count); _cachePointer += count; } // just transform this buffer if (TransformWrite != null) buffer = OnTransformWrite(buffer); if (TransformWriteString != null) buffer = OnTransformWriteStringInternal(buffer); if (!IsOutputDelayed) _stream.Write(buffer, offset, buffer.Length); } } The key features are the events and corresponding OnXXX methods that handle the event hookups, and the Write() and Flush() methods of the stream implementation. All the rest of the members tend to be plain jane passthrough stream implementation code without much consequence. I do love the way Action<t> and Func<T> make it so easy to create the event signatures for the various events – sweet. A few Things to consider Performance Response.Filter is not great for performance in general as it adds another layer of indirection to the ASP.NET output pipeline, and this implementation in particular adds a memory hit as it basically duplicates the response output into the cached memory stream which is necessary since you may have to look at the entire response. If you have large pages in particular this can cause potentially serious memory pressure in your server application. So be careful of wholesale adoption of this (or other) Response.Filters. Make sure to do some performance testing to ensure it’s not killing your app’s performance. Response.Filter works everywhere A few questions came up in comments and discussion as to capturing ALL output hitting the site and – yes you can definitely do that by assigning a Response.Filter inside of a module. If you do this however you’ll want to be very careful and decide which content you actually want to capture especially in IIS 7 which passes ALL content – including static images/CSS etc. through the ASP.NET pipeline. So it is important to filter only on what you’re looking for – like the page extension or maybe more effectively the Response.ContentType. Response.Filter Chaining Originally I thought that filter chaining doesn’t work at all due to a bug in the stream implementation code. But it’s quite possible to assign multiple filters to the Response.Filter property. So the following actually works to both compress the output and apply the transformed content: WebUtils.GZipEncodePage(); ResponseFilterStream filter = new ResponseFilterStream(Response.Filter); filter.TransformString += filter_TransformString; Response.Filter = filter; However the following does not work resulting in invalid content encoding errors: ResponseFilterStream filter = new ResponseFilterStream(Response.Filter); filter.TransformString += filter_TransformString; Response.Filter = filter; WebUtils.GZipEncodePage(); In other words multiple Response filters can work together but it depends entirely on the implementation whether they can be chained or in which order they can be chained. In this case running the GZip/Deflate stream filters apparently relies on the original content length of the output and chokes when the content is modified. But if attaching the compression first it works fine as unintuitive as that may seem. Resources Download example code Capture Output from ASP.NET Pages © Rick Strahl, West Wind Technologies, 2005-2010Posted in ASP.NET

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MySQL Syslog Audit Plugin

- by jonathonc

This post shows the construction process of the Syslog Audit plugin that was presented at MySQL Connect 2012. It is based on an environment that has the appropriate development tools enabled including gcc,g++ and cmake. It also assumes you have downloaded the MySQL source code (5.5.16 or higher) and have compiled and installed the system into the /usr/local/mysql directory ready for use. The information provided below is designed to show the different components that make up a plugin, and specifically an audit type plugin, and how it comes together to be used within the MySQL service. The MySQL Reference Manual contains information regarding the plugin API and how it can be used, so please refer there for more detailed information. The code in this post is designed to give the simplest information necessary, so handling every return code, managing race conditions etc is not part of this example code. Let's start by looking at the most basic implementation of our plugin code as seen below: /* Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved. Author: Jonathon Coombes Licence: GPL Description: An auditing plugin that logs to syslog and can adjust the loglevel via the system variables. */ #include <stdio.h> #include <string.h> #include <mysql/plugin_audit.h> #include <syslog.h> There is a commented header detailing copyright/licencing and meta-data information and then the include headers. The two important include statements for our plugin are the syslog.h plugin, which gives us the structures for syslog, and the plugin_audit.h include which has details regarding the audit specific plugin api. Note that we do not need to include the general plugin header plugin.h, as this is done within the plugin_audit.h file already. To implement our plugin within the current implementation we need to add it into our source code and compile. > cd /usr/local/src/mysql-5.5.28/plugin > mkdir audit_syslog > cd audit_syslog A simple CMakeLists.txt file is created to manage the plugin compilation: MYSQL_ADD_PLUGIN(audit_syslog audit_syslog.cc MODULE_ONLY) Run the cmake command at the top level of the source and then you can compile the plugin using the 'make' command. This results in a compiled audit_syslog.so library, but currently it is not much use to MySQL as there is no level of api defined to communicate with the MySQL service. Now we need to define the general plugin structure that enables MySQL to recognise the library as a plugin and be able to install/uninstall it and have it show up in the system. The structure is defined in the plugin.h file in the MySQL source code. /* Plugin library descriptor */ mysql_declare_plugin(audit_syslog) { MYSQL_AUDIT_PLUGIN, /* plugin type */ &audit_syslog_descriptor, /* descriptor handle */ "audit_syslog", /* plugin name */ "Author Name", /* author */ "Simple Syslog Audit", /* description */ PLUGIN_LICENSE_GPL, /* licence */ audit_syslog_init, /* init function */ audit_syslog_deinit, /* deinit function */ 0x0001, /* plugin version */ NULL, /* status variables */ NULL, /* system variables */ NULL, /* no reserves */ 0, /* no flags */ } mysql_declare_plugin_end; The general plugin descriptor above is standard for all plugin types in MySQL. The plugin type is defined along with the init/deinit functions and interface methods into the system for sharing information, and various other metadata information. The descriptors have an internally recognised version number so that plugins can be matched against the api on the running server. The other details are usually related to the type-specific methods and structures to implement the plugin. Each plugin has a type-specific descriptor as well which details how the plugin is implemented for the specific purpose of that plugin type. /* Plugin type-specific descriptor */ static struct st_mysql_audit audit_syslog_descriptor= { MYSQL_AUDIT_INTERFACE_VERSION, /* interface version */ NULL, /* release_thd function */ audit_syslog_notify, /* notify function */ { (unsigned long) MYSQL_AUDIT_GENERAL_CLASSMASK | MYSQL_AUDIT_CONNECTION_CLASSMASK } /* class mask */ }; In this particular case, the release_thd function has not been defined as it is not required. The important method for auditing is the notify function which is activated when an event occurs on the system. The notify function is designed to activate on an event and the implementation will determine how it is handled. For the audit_syslog plugin, the use of the syslog feature sends all events to the syslog for recording. The class mask allows us to determine what type of events are being seen by the notify function. There are currently two major types of event: 1. General Events: This includes general logging, errors, status and result type events. This is the main one for tracking the queries and operations on the database. 2. Connection Events: This group is based around user logins. It monitors connections and disconnections, but also if somebody changes user while connected. With most audit plugins, the principle behind the plugin is to track changes to the system over time and counters can be an important part of this process. The next step is to define and initialise the counters that are used to track the events in the service. There are 3 counters defined in total for our plugin - the # of general events, the # of connection events and the total number of events. static volatile int total_number_of_calls; /* Count MYSQL_AUDIT_GENERAL_CLASS event instances */ static volatile int number_of_calls_general; /* Count MYSQL_AUDIT_CONNECTION_CLASS event instances */ static volatile int number_of_calls_connection; The init and deinit functions for the plugin are there to be called when the plugin is activated and when it is terminated. These offer the best option to initialise the counters for our plugin: /* Initialize the plugin at server start or plugin installation. */ static int audit_syslog_init(void *arg __attribute__((unused))) { openlog("mysql_audit:",LOG_PID|LOG_PERROR|LOG_CONS,LOG_USER); total_number_of_calls= 0; number_of_calls_general= 0; number_of_calls_connection= 0; return(0); } The init function does a call to openlog to initialise the syslog functionality. The parameters are the service to log under ("mysql_audit" in this case), the syslog flags and the facility for the logging. Then each of the counters are initialised to zero and a success is returned. If the init function is not defined, it will return success by default. /* Terminate the plugin at server shutdown or plugin deinstallation. */ static int audit_syslog_deinit(void *arg __attribute__((unused))) { closelog(); return(0); } The deinit function will simply close our syslog connection and return success. Note that the syslog functionality is part of the glibc libraries and does not require any external factors. The function names are what we define in the general plugin structure, so these have to match otherwise there will be errors. The next step is to implement the event notifier function that was defined in the type specific descriptor (audit_syslog_descriptor) which is audit_syslog_notify. /* Event notifier function */ static void audit_syslog_notify(MYSQL_THD thd __attribute__((unused)), unsigned int event_class, const void *event) { total_number_of_calls++; if (event_class == MYSQL_AUDIT_GENERAL_CLASS) { const struct mysql_event_general *event_general= (const struct mysql_event_general *) event; number_of_calls_general++; syslog(audit_loglevel,"%lu: User: %s Command: %s Query: %s\n", event_general->general_thread_id, event_general->general_user, event_general->general_command, event_general->general_query ); } else if (event_class == MYSQL_AUDIT_CONNECTION_CLASS) { const struct mysql_event_connection *event_connection= (const struct mysql_event_connection *) event; number_of_calls_connection++; syslog(audit_loglevel,"%lu: User: %s@%s[%s] Event: %d Status: %d\n", event_connection->thread_id, event_connection->user, event_connection->host, event_connection->ip, event_connection->event_subclass, event_connection->status ); } } In the case of an event, the notifier function is called. The first step is to increment the total number of events that have occurred in our database.The event argument is then cast into the appropriate event structure depending on the class type, of general event or connection event. The event type counters are incremented and details are sent via the syslog() function out to the system log. There are going to be different line formats and information returned since the general events have different data compared to the connection events, even though some of the details overlap, for example, user, thread id, host etc. On compiling the code now, there should be no errors and the resulting audit_syslog.so can be loaded into the server and ready to use. Log into the server and type: mysql> INSTALL PLUGIN audit_syslog SONAME 'audit_syslog.so'; This will install the plugin and will start updating the syslog immediately. Note that the audit plugin attaches to the immediate thread and cannot be uninstalled while that thread is active. This means that you cannot run the UNISTALL command until you log into a different connection (thread) on the server. Once the plugin is loaded, the system log will show output such as the following: Oct 8 15:33:21 machine mysql_audit:[8337]: 87: User: root[root] @ localhost [] Command: (null) Query: INSTALL PLUGIN audit_syslog SONAME 'audit_syslog.so' Oct 8 15:33:21 machine mysql_audit:[8337]: 87: User: root[root] @ localhost [] Command: Query Query: INSTALL PLUGIN audit_syslog SONAME 'audit_syslog.so' Oct 8 15:33:40 machine mysql_audit:[8337]: 87: User: root[root] @ localhost [] Command: (null) Query: show tables Oct 8 15:33:40 machine mysql_audit:[8337]: 87: User: root[root] @ localhost [] Command: Query Query: show tables Oct 8 15:33:43 machine mysql_audit:[8337]: 87: User: root[root] @ localhost [] Command: (null) Query: select * from t1 Oct 8 15:33:43 machine mysql_audit:[8337]: 87: User: root[root] @ localhost [] Command: Query Query: select * from t1 It appears that two of each event is being shown, but in actuality, these are two separate event types - the result event and the status event. This could be refined further by changing the audit_syslog_notify function to handle the different event sub-types in a different manner. So far, it seems that the logging is working with events showing up in the syslog output. The issue now is that the counters created earlier to track the number of events by type are not accessible when the plugin is being run. Instead there needs to be a way to expose the plugin specific information to the service and vice versa. This could be done via the information_schema plugin api, but for something as simple as counters, the obvious choice is the system status variables. This is done using the standard structure and the declaration: /* Plugin status variables for SHOW STATUS */ static struct st_mysql_show_var audit_syslog_status[]= { { "Audit_syslog_total_calls", (char *) &total_number_of_calls, SHOW_INT }, { "Audit_syslog_general_events", (char *) &number_of_calls_general, SHOW_INT }, { "Audit_syslog_connection_events", (char *) &number_of_calls_connection, SHOW_INT }, { 0, 0, SHOW_INT } }; The structure is simply the name that will be displaying in the mysql service, the address of the associated variables, and the data type being used for the counter. It is finished with a blank structure to show that there are no more variables. Remember that status variables may have the same name for variables from other plugin, so it is considered appropriate to add the plugin name at the start of the status variable name to avoid confusion. Looking at the status variables in the mysql client shows something like the following: mysql> show global status like "audit%"; +--------------------------------+-------+ | Variable_name | Value | +--------------------------------+-------+ | Audit_syslog_connection_events | 1 | | Audit_syslog_general_events | 2 | | Audit_syslog_total_calls | 3 | +--------------------------------+-------+ 3 rows in set (0.00 sec) The final connectivity piece for the plugin is to allow the interactive change of the logging level between the plugin and the system. This requires the ability to send changes via the mysql service through to the plugin. This is done using the system variables interface and defining a single variable to keep track of the active logging level for the facility. /* Plugin system variables for SHOW VARIABLES */ static MYSQL_SYSVAR_STR(loglevel, audit_loglevel, PLUGIN_VAR_RQCMDARG, "User can specify the log level for auditing", audit_loglevel_check, audit_loglevel_update, "LOG_NOTICE"); static struct st_mysql_sys_var* audit_syslog_sysvars[] = { MYSQL_SYSVAR(loglevel), NULL }; So now the system variable 'loglevel' is defined for the plugin and associated to the global variable 'audit_loglevel'. The check or validation function is defined to make sure that no garbage values are attempted in the update of the variable. The update function is used to save the new value to the variable. Note that the audit_syslog_sysvars structure is defined in the general plugin descriptor to associate the link between the plugin and the system and how much they interact. Next comes the implementation of the validation function and the update function for the system variable. It is worth noting that if you have a simple numeric such as integers for the variable types, the validate function is often not required as MySQL will handle the automatic check and validation of simple types. /* longest valid value */ #define MAX_LOGLEVEL_SIZE 100 /* hold the valid values */ static const char *possible_modes[]= { "LOG_ERROR", "LOG_WARNING", "LOG_NOTICE", NULL }; static int audit_loglevel_check( THD* thd, /*!< in: thread handle */ struct st_mysql_sys_var* var, /*!< in: pointer to system variable */ void* save, /*!< out: immediate result for update function */ struct st_mysql_value* value) /*!< in: incoming string */ { char buff[MAX_LOGLEVEL_SIZE]; const char *str; const char **found; int length; length= sizeof(buff); if (!(str= value->val_str(value, buff, &length))) return 1; /* We need to return a pointer to a locally allocated value in "save". Here we pick to search for the supplied value in an global array of constant strings and return a pointer to one of them. The other possiblity is to use the thd_alloc() function to allocate a thread local buffer instead of the global constants. */ for (found= possible_modes; *found; found++) { if (!strcmp(*found, str)) { *(const char**)save= *found; return 0; } } return 1; } The validation function is simply to take the value being passed in via the SET GLOBAL VARIABLE command and check if it is one of the pre-defined values allowed in our possible_values array. If it is found to be valid, then the value is assigned to the save variable ready for passing through to the update function. static void audit_loglevel_update( THD* thd, /*!< in: thread handle */ struct st_mysql_sys_var* var, /*!< in: system variable being altered */ void* var_ptr, /*!< out: pointer to dynamic variable */ const void* save) /*!< in: pointer to temporary storage */ { /* assign the new value so that the server can read it */ *(char **) var_ptr= *(char **) save; /* assign the new value to the internal variable */ audit_loglevel= *(char **) save; } Since all the validation has been done already, the update function is quite simple for this plugin. The first part is to update the system variable pointer so that the server can read the value. The second part is to update our own global plugin variable for tracking the value. Notice that the save variable is passed in as a void type to allow handling of various data types, so it must be cast to the appropriate data type when assigning it to the variables. Looking at how the latest changes affect the usage of the plugin and the interaction within the server shows: mysql> show global variables like "audit%"; +-----------------------+------------+ | Variable_name | Value | +-----------------------+------------+ | audit_syslog_loglevel | LOG_NOTICE | +-----------------------+------------+ 1 row in set (0.00 sec) mysql> set global audit_syslog_loglevel="LOG_ERROR"; Query OK, 0 rows affected (0.00 sec) mysql> show global status like "audit%"; +--------------------------------+-------+ | Variable_name | Value | +--------------------------------+-------+ | Audit_syslog_connection_events | 1 | | Audit_syslog_general_events | 11 | | Audit_syslog_total_calls | 12 | +--------------------------------+-------+ 3 rows in set (0.00 sec) mysql> show global variables like "audit%"; +-----------------------+-----------+ | Variable_name | Value | +-----------------------+-----------+ | audit_syslog_loglevel | LOG_ERROR | +-----------------------+-----------+ 1 row in set (0.00 sec) So now we have a plugin that will audit the events on the system and log the details to the system log. It allows for interaction to see the number of different events within the server details and provides a mechanism to change the logging level interactively via the standard system methods of the SET command. A more complex auditing plugin may have more detailed code, but each of the above areas is what will be involved and simply expanded on to add more functionality. With the above skeleton code, it is now possible to create your own audit plugins to implement your own auditing requirements. If, however, you are not of the coding persuasion, then you could always consider the option of the MySQL Enterprise Audit plugin that is available to purchase.

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How John Got 15x Improvement Without Really Trying

- by rchrd

The following article was published on a Sun Microsystems website a number of years ago by John Feo. It is still useful and worth preserving. So I'm republishing it here. How I Got 15x Improvement Without Really Trying John Feo, Sun Microsystems Taking ten "personal" program codes used in scientific and engineering research, the author was able to get from 2 to 15 times performance improvement easily by applying some simple general optimization techniques. Introduction Scientific research based on computer simulation depends on the simulation for advancement. The research can advance only as fast as the computational codes can execute. The codes' efficiency determines both the rate and quality of results. In the same amount of time, a faster program can generate more results and can carry out a more detailed simulation of physical phenomena than a slower program. Highly optimized programs help science advance quickly and insure that monies supporting scientific research are used as effectively as possible. Scientific computer codes divide into three broad categories: ISV, community, and personal. ISV codes are large, mature production codes developed and sold commercially. The codes improve slowly over time both in methods and capabilities, and they are well tuned for most vendor platforms. Since the codes are mature and complex, there are few opportunities to improve their performance solely through code optimization. Improvements of 10% to 15% are typical. Examples of ISV codes are DYNA3D, Gaussian, and Nastran. Community codes are non-commercial production codes used by a particular research field. Generally, they are developed and distributed by a single academic or research institution with assistance from the community. Most users just run the codes, but some develop new methods and extensions that feed back into the general release. The codes are available on most vendor platforms. Since these codes are younger than ISV codes, there are more opportunities to optimize the source code. Improvements of 50% are not unusual. Examples of community codes are AMBER, CHARM, BLAST, and FASTA. Personal codes are those written by single users or small research groups for their own use. These codes are not distributed, but may be passed from professor-to-student or student-to-student over several years. They form the primordial ocean of applications from which community and ISV codes emerge. Government research grants pay for the development of most personal codes. This paper reports on the nature and performance of this class of codes. Over the last year, I have looked at over two dozen personal codes from more than a dozen research institutions. The codes cover a variety of scientific fields, including astronomy, atmospheric sciences, bioinformatics, biology, chemistry, geology, and physics. The sources range from a few hundred lines to more than ten thousand lines, and are written in Fortran, Fortran 90, C, and C++. For the most part, the codes are modular, documented, and written in a clear, straightforward manner. They do not use complex language features, advanced data structures, programming tricks, or libraries. I had little trouble understanding what the codes did or how data structures were used. Most came with a makefile. Surprisingly, only one of the applications is parallel. All developers have access to parallel machines, so availability is not an issue. Several tried to parallelize their applications, but stopped after encountering difficulties. Lack of education and a perception that parallelism is difficult prevented most from trying. I parallelized several of the codes using OpenMP, and did not judge any of the codes as difficult to parallelize. Even more surprising than the lack of parallelism is the inefficiency of the codes. I was able to get large improvements in performance in a matter of a few days applying simple optimization techniques. Table 1 lists ten representative codes [names and affiliation are omitted to preserve anonymity]. Improvements on one processor range from 2x to 15.5x with a simple average of 4.75x. I did not use sophisticated performance tools or drill deep into the program's execution character as one would do when tuning ISV or community codes. Using only a profiler and source line timers, I identified inefficient sections of code and improved their performance by inspection. The changes were at a high level. I am sure there is another factor of 2 or 3 in each code, and more if the codes are parallelized. The study’s results show that personal scientific codes are running many times slower than they should and that the problem is pervasive. Computational scientists are not sloppy programmers; however, few are trained in the art of computer programming or code optimization. I found that most have a working knowledge of some programming language and standard software engineering practices; but they do not know, or think about, how to make their programs run faster. They simply do not know the standard techniques used to make codes run faster. In fact, they do not even perceive that such techniques exist. The case studies described in this paper show that applying simple, well known techniques can significantly increase the performance of personal codes. It is important that the scientific community and the Government agencies that support scientific research find ways to better educate academic scientific programmers. The inefficiency of their codes is so bad that it is retarding both the quality and progress of scientific research. # cacheperformance redundantoperations loopstructures performanceimprovement 1 x x 15.5 2 x 2.8 3 x x 2.5 4 x 2.1 5 x x 2.0 6 x 5.0 7 x 5.8 8 x 6.3 9 2.2 10 x x 3.3 Table 1 — Area of improvement and performance gains of 10 codes The remainder of the paper is organized as follows: sections 2, 3, and 4 discuss the three most common sources of inefficiencies in the codes studied. These are cache performance, redundant operations, and loop structures. Each section includes several examples. The last section summaries the work and suggests a possible solution to the issues raised. Optimizing cache performance Commodity microprocessor systems use caches to increase memory bandwidth and reduce memory latencies. Typical latencies from processor to L1, L2, local, and remote memory are 3, 10, 50, and 200 cycles, respectively. Moreover, bandwidth falls off dramatically as memory distances increase. Programs that do not use cache effectively run many times slower than programs that do. When optimizing for cache, the biggest performance gains are achieved by accessing data in cache order and reusing data to amortize the overhead of cache misses. Secondary considerations are prefetching, associativity, and replacement; however, the understanding and analysis required to optimize for the latter are probably beyond the capabilities of the non-expert. Much can be gained simply by accessing data in the correct order and maximizing data reuse. 6 out of the 10 codes studied here benefited from such high level optimizations. Array Accesses The most important cache optimization is the most basic: accessing Fortran array elements in column order and C array elements in row order. Four of the ten codes—1, 2, 4, and 10—got it wrong. Compilers will restructure nested loops to optimize cache performance, but may not do so if the loop structure is too complex, or the loop body includes conditionals, complex addressing, or function calls. In code 1, the compiler failed to invert a key loop because of complex addressing do I = 0, 1010, delta_x IM = I - delta_x IP = I + delta_x do J = 5, 995, delta_x JM = J - delta_x JP = J + delta_x T1 = CA1(IP, J) + CA1(I, JP) T2 = CA1(IM, J) + CA1(I, JM) S1 = T1 + T2 - 4 * CA1(I, J) CA(I, J) = CA1(I, J) + D * S1 end do end do In code 2, the culprit is conditionals do I = 1, N do J = 1, N If (IFLAG(I,J) .EQ. 0) then T1 = Value(I, J-1) T2 = Value(I-1, J) T3 = Value(I, J) T4 = Value(I+1, J) T5 = Value(I, J+1) Value(I,J) = 0.25 * (T1 + T2 + T5 + T4) Delta = ABS(T3 - Value(I,J)) If (Delta .GT. MaxDelta) MaxDelta = Delta endif enddo enddo I fixed both programs by inverting the loops by hand. Code 10 has three-dimensional arrays and triply nested loops. The structure of the most computationally intensive loops is too complex to invert automatically or by hand. The only practical solution is to transpose the arrays so that the dimension accessed by the innermost loop is in cache order. The arrays can be transposed at construction or prior to entering a computationally intensive section of code. The former requires all array references to be modified, while the latter is cost effective only if the cost of the transpose is amortized over many accesses. I used the second approach to optimize code 10. Code 5 has four-dimensional arrays and loops are nested four deep. For all of the reasons cited above the compiler is not able to restructure three key loops. Assume C arrays and let the four dimensions of the arrays be i, j, k, and l. In the original code, the index structure of the three loops is L1: for i L2: for i L3: for i for l for l for j for k for j for k for j for k for l So only L3 accesses array elements in cache order. L1 is a very complex loop—much too complex to invert. I brought the loop into cache alignment by transposing the second and fourth dimensions of the arrays. Since the code uses a macro to compute all array indexes, I effected the transpose at construction and changed the macro appropriately. The dimensions of the new arrays are now: i, l, k, and j. L3 is a simple loop and easily inverted. L2 has a loop-carried scalar dependence in k. By promoting the scalar name that carries the dependence to an array, I was able to invert the third and fourth subloops aligning the loop with cache. Code 5 is by far the most difficult of the four codes to optimize for array accesses; but the knowledge required to fix the problems is no more than that required for the other codes. I would judge this code at the limits of, but not beyond, the capabilities of appropriately trained computational scientists. Array Strides When a cache miss occurs, a line (64 bytes) rather than just one word is loaded into the cache. If data is accessed stride 1, than the cost of the miss is amortized over 8 words. Any stride other than one reduces the cost savings. Two of the ten codes studied suffered from non-unit strides. The codes represent two important classes of "strided" codes. Code 1 employs a multi-grid algorithm to reduce time to convergence. The grids are every tenth, fifth, second, and unit element. Since time to convergence is inversely proportional to the distance between elements, coarse grids converge quickly providing good starting values for finer grids. The better starting values further reduce the time to convergence. The downside is that grids of every nth element, n > 1, introduce non-unit strides into the computation. In the original code, much of the savings of the multi-grid algorithm were lost due to this problem. I eliminated the problem by compressing (copying) coarse grids into continuous memory, and rewriting the computation as a function of the compressed grid. On convergence, I copied the final values of the compressed grid back to the original grid. The savings gained from unit stride access of the compressed grid more than paid for the cost of copying. Using compressed grids, the loop from code 1 included in the previous section becomes do j = 1, GZ do i = 1, GZ T1 = CA(i+0, j-1) + CA(i-1, j+0) T4 = CA1(i+1, j+0) + CA1(i+0, j+1) S1 = T1 + T4 - 4 * CA1(i+0, j+0) CA(i+0, j+0) = CA1(i+0, j+0) + DD * S1 enddo enddo where CA and CA1 are compressed arrays of size GZ. Code 7 traverses a list of objects selecting objects for later processing. The labels of the selected objects are stored in an array. The selection step has unit stride, but the processing steps have irregular stride. A fix is to save the parameters of the selected objects in temporary arrays as they are selected, and pass the temporary arrays to the processing functions. The fix is practical if the same parameters are used in selection as in processing, or if processing comprises a series of distinct steps which use overlapping subsets of the parameters. Both conditions are true for code 7, so I achieved significant improvement by copying parameters to temporary arrays during selection. Data reuse In the previous sections, we optimized for spatial locality. It is also important to optimize for temporal locality. Once read, a datum should be used as much as possible before it is forced from cache. Loop fusion and loop unrolling are two techniques that increase temporal locality. Unfortunately, both techniques increase register pressure—as loop bodies become larger, the number of registers required to hold temporary values grows. Once register spilling occurs, any gains evaporate quickly. For multiprocessors with small register sets or small caches, the sweet spot can be very small. In the ten codes presented here, I found no opportunities for loop fusion and only two opportunities for loop unrolling (codes 1 and 3). In code 1, unrolling the outer and inner loop one iteration increases the number of result values computed by the loop body from 1 to 4, do J = 1, GZ-2, 2 do I = 1, GZ-2, 2 T1 = CA1(i+0, j-1) + CA1(i-1, j+0) T2 = CA1(i+1, j-1) + CA1(i+0, j+0) T3 = CA1(i+0, j+0) + CA1(i-1, j+1) T4 = CA1(i+1, j+0) + CA1(i+0, j+1) T5 = CA1(i+2, j+0) + CA1(i+1, j+1) T6 = CA1(i+1, j+1) + CA1(i+0, j+2) T7 = CA1(i+2, j+1) + CA1(i+1, j+2) S1 = T1 + T4 - 4 * CA1(i+0, j+0) S2 = T2 + T5 - 4 * CA1(i+1, j+0) S3 = T3 + T6 - 4 * CA1(i+0, j+1) S4 = T4 + T7 - 4 * CA1(i+1, j+1) CA(i+0, j+0) = CA1(i+0, j+0) + DD * S1 CA(i+1, j+0) = CA1(i+1, j+0) + DD * S2 CA(i+0, j+1) = CA1(i+0, j+1) + DD * S3 CA(i+1, j+1) = CA1(i+1, j+1) + DD * S4 enddo enddo The loop body executes 12 reads, whereas as the rolled loop shown in the previous section executes 20 reads to compute the same four values. In code 3, two loops are unrolled 8 times and one loop is unrolled 4 times. Here is the before for (k = 0; k < NK[u]; k++) { sum = 0.0; for (y = 0; y < NY; y++) { sum += W[y][u][k] * delta[y]; } backprop[i++]=sum; } and after code for (k = 0; k < KK - 8; k+=8) { sum0 = 0.0; sum1 = 0.0; sum2 = 0.0; sum3 = 0.0; sum4 = 0.0; sum5 = 0.0; sum6 = 0.0; sum7 = 0.0; for (y = 0; y < NY; y++) { sum0 += W[y][0][k+0] * delta[y]; sum1 += W[y][0][k+1] * delta[y]; sum2 += W[y][0][k+2] * delta[y]; sum3 += W[y][0][k+3] * delta[y]; sum4 += W[y][0][k+4] * delta[y]; sum5 += W[y][0][k+5] * delta[y]; sum6 += W[y][0][k+6] * delta[y]; sum7 += W[y][0][k+7] * delta[y]; } backprop[k+0] = sum0; backprop[k+1] = sum1; backprop[k+2] = sum2; backprop[k+3] = sum3; backprop[k+4] = sum4; backprop[k+5] = sum5; backprop[k+6] = sum6; backprop[k+7] = sum7; } for one of the loops unrolled 8 times. Optimizing for temporal locality is the most difficult optimization considered in this paper. The concepts are not difficult, but the sweet spot is small. Identifying where the program can benefit from loop unrolling or loop fusion is not trivial. Moreover, it takes some effort to get it right. Still, educating scientific programmers about temporal locality and teaching them how to optimize for it will pay dividends. Reducing instruction count Execution time is a function of instruction count. Reduce the count and you usually reduce the time. The best solution is to use a more efficient algorithm; that is, an algorithm whose order of complexity is smaller, that converges quicker, or is more accurate. Optimizing source code without changing the algorithm yields smaller, but still significant, gains. This paper considers only the latter because the intent is to study how much better codes can run if written by programmers schooled in basic code optimization techniques. The ten codes studied benefited from three types of "instruction reducing" optimizations. The two most prevalent were hoisting invariant memory and data operations out of inner loops. The third was eliminating unnecessary data copying. The nature of these inefficiencies is language dependent. Memory operations The semantics of C make it difficult for the compiler to determine all the invariant memory operations in a loop. The problem is particularly acute for loops in functions since the compiler may not know the values of the function's parameters at every call site when compiling the function. Most compilers support pragmas to help resolve ambiguities; however, these pragmas are not comprehensive and there is no standard syntax. To guarantee that invariant memory operations are not executed repetitively, the user has little choice but to hoist the operations by hand. The problem is not as severe in Fortran programs because in the absence of equivalence statements, it is a violation of the language's semantics for two names to share memory. Codes 3 and 5 are C programs. In both cases, the compiler did not hoist all invariant memory operations from inner loops. Consider the following loop from code 3 for (y = 0; y < NY; y++) { i = 0; for (u = 0; u < NU; u++) { for (k = 0; k < NK[u]; k++) { dW[y][u][k] += delta[y] * I1[i++]; } } } Since dW[y][u] can point to the same memory space as delta for one or more values of y and u, assignment to dW[y][u][k] may change the value of delta[y]. In reality, dW and delta do not overlap in memory, so I rewrote the loop as for (y = 0; y < NY; y++) { i = 0; Dy = delta[y]; for (u = 0; u < NU; u++) { for (k = 0; k < NK[u]; k++) { dW[y][u][k] += Dy * I1[i++]; } } } Failure to hoist invariant memory operations may be due to complex address calculations. If the compiler can not determine that the address calculation is invariant, then it can hoist neither the calculation nor the associated memory operations. As noted above, code 5 uses a macro to address four-dimensional arrays #define MAT4D(a,q,i,j,k) (double *)((a)->data + (q)*(a)->strides[0] + (i)*(a)->strides[3] + (j)*(a)->strides[2] + (k)*(a)->strides[1]) The macro is too complex for the compiler to understand and so, it does not identify any subexpressions as loop invariant. The simplest way to eliminate the address calculation from the innermost loop (over i) is to define a0 = MAT4D(a,q,0,j,k) before the loop and then replace all instances of *MAT4D(a,q,i,j,k) in the loop with a0[i] A similar problem appears in code 6, a Fortran program. The key loop in this program is do n1 = 1, nh nx1 = (n1 - 1) / nz + 1 nz1 = n1 - nz * (nx1 - 1) do n2 = 1, nh nx2 = (n2 - 1) / nz + 1 nz2 = n2 - nz * (nx2 - 1) ndx = nx2 - nx1 ndy = nz2 - nz1 gxx = grn(1,ndx,ndy) gyy = grn(2,ndx,ndy) gxy = grn(3,ndx,ndy) balance(n1,1) = balance(n1,1) + (force(n2,1) * gxx + force(n2,2) * gxy) * h1 balance(n1,2) = balance(n1,2) + (force(n2,1) * gxy + force(n2,2) * gyy)*h1 end do end do The programmer has written this loop well—there are no loop invariant operations with respect to n1 and n2. However, the loop resides within an iterative loop over time and the index calculations are independent with respect to time. Trading space for time, I precomputed the index values prior to the entering the time loop and stored the values in two arrays. I then replaced the index calculations with reads of the arrays. Data operations Ways to reduce data operations can appear in many forms. Implementing a more efficient algorithm produces the biggest gains. The closest I came to an algorithm change was in code 4. This code computes the inner product of K-vectors A(i) and B(j), 0 = i < N, 0 = j < M, for most values of i and j. Since the program computes most of the NM possible inner products, it is more efficient to compute all the inner products in one triply-nested loop rather than one at a time when needed. The savings accrue from reading A(i) once for all B(j) vectors and from loop unrolling. for (i = 0; i < N; i+=8) { for (j = 0; j < M; j++) { sum0 = 0.0; sum1 = 0.0; sum2 = 0.0; sum3 = 0.0; sum4 = 0.0; sum5 = 0.0; sum6 = 0.0; sum7 = 0.0; for (k = 0; k < K; k++) { sum0 += A[i+0][k] * B[j][k]; sum1 += A[i+1][k] * B[j][k]; sum2 += A[i+2][k] * B[j][k]; sum3 += A[i+3][k] * B[j][k]; sum4 += A[i+4][k] * B[j][k]; sum5 += A[i+5][k] * B[j][k]; sum6 += A[i+6][k] * B[j][k]; sum7 += A[i+7][k] * B[j][k]; } C[i+0][j] = sum0; C[i+1][j] = sum1; C[i+2][j] = sum2; C[i+3][j] = sum3; C[i+4][j] = sum4; C[i+5][j] = sum5; C[i+6][j] = sum6; C[i+7][j] = sum7; }} This change requires knowledge of a typical run; i.e., that most inner products are computed. The reasons for the change, however, derive from basic optimization concepts. It is the type of change easily made at development time by a knowledgeable programmer. In code 5, we have the data version of the index optimization in code 6. Here a very expensive computation is a function of the loop indices and so cannot be hoisted out of the loop; however, the computation is invariant with respect to an outer iterative loop over time. We can compute its value for each iteration of the computation loop prior to entering the time loop and save the values in an array. The increase in memory required to store the values is small in comparison to the large savings in time. The main loop in Code 8 is doubly nested. The inner loop includes a series of guarded computations; some are a function of the inner loop index but not the outer loop index while others are a function of the outer loop index but not the inner loop index for (j = 0; j < N; j++) { for (i = 0; i < M; i++) { r = i * hrmax; R = A[j]; temp = (PRM[3] == 0.0) ? 1.0 : pow(r, PRM[3]); high = temp * kcoeff * B[j] * PRM[2] * PRM[4]; low = high * PRM[6] * PRM[6] / (1.0 + pow(PRM[4] * PRM[6], 2.0)); kap = (R > PRM[6]) ? high * R * R / (1.0 + pow(PRM[4]*r, 2.0) : low * pow(R/PRM[6], PRM[5]); < rest of loop omitted > }} Note that the value of temp is invariant to j. Thus, we can hoist the computation for temp out of the loop and save its values in an array. for (i = 0; i < M; i++) { r = i * hrmax; TEMP[i] = pow(r, PRM[3]); } [N.B. – the case for PRM[3] = 0 is omitted and will be reintroduced later.] We now hoist out of the inner loop the computations invariant to i. Since the conditional guarding the value of kap is invariant to i, it behooves us to hoist the computation out of the inner loop, thereby executing the guard once rather than M times. The final version of the code is for (j = 0; j < N; j++) { R = rig[j] / 1000.; tmp1 = kcoeff * par[2] * beta[j] * par[4]; tmp2 = 1.0 + (par[4] * par[4] * par[6] * par[6]); tmp3 = 1.0 + (par[4] * par[4] * R * R); tmp4 = par[6] * par[6] / tmp2; tmp5 = R * R / tmp3; tmp6 = pow(R / par[6], par[5]); if ((par[3] == 0.0) && (R > par[6])) { for (i = 1; i <= imax1; i++) KAP[i] = tmp1 * tmp5; } else if ((par[3] == 0.0) && (R <= par[6])) { for (i = 1; i <= imax1; i++) KAP[i] = tmp1 * tmp4 * tmp6; } else if ((par[3] != 0.0) && (R > par[6])) { for (i = 1; i <= imax1; i++) KAP[i] = tmp1 * TEMP[i] * tmp5; } else if ((par[3] != 0.0) && (R <= par[6])) { for (i = 1; i <= imax1; i++) KAP[i] = tmp1 * TEMP[i] * tmp4 * tmp6; } for (i = 0; i < M; i++) { kap = KAP[i]; r = i * hrmax; < rest of loop omitted > } } Maybe not the prettiest piece of code, but certainly much more efficient than the original loop, Copy operations Several programs unnecessarily copy data from one data structure to another. This problem occurs in both Fortran and C programs, although it manifests itself differently in the two languages. Code 1 declares two arrays—one for old values and one for new values. At the end of each iteration, the array of new values is copied to the array of old values to reset the data structures for the next iteration. This problem occurs in Fortran programs not included in this study and in both Fortran 77 and Fortran 90 code. Introducing pointers to the arrays and swapping pointer values is an obvious way to eliminate the copying; but pointers is not a feature that many Fortran programmers know well or are comfortable using. An easy solution not involving pointers is to extend the dimension of the value array by 1 and use the last dimension to differentiate between arrays at different times. For example, if the data space is N x N, declare the array (N, N, 2). Then store the problem’s initial values in (_, _, 2) and define the scalar names new = 2 and old = 1. At the start of each iteration, swap old and new to reset the arrays. The old–new copy problem did not appear in any C program. In programs that had new and old values, the code swapped pointers to reset data structures. Where unnecessary coping did occur is in structure assignment and parameter passing. Structures in C are handled much like scalars. Assignment causes the data space of the right-hand name to be copied to the data space of the left-hand name. Similarly, when a structure is passed to a function, the data space of the actual parameter is copied to the data space of the formal parameter. If the structure is large and the assignment or function call is in an inner loop, then copying costs can grow quite large. While none of the ten programs considered here manifested this problem, it did occur in programs not included in the study. A simple fix is always to refer to structures via pointers. Optimizing loop structures Since scientific programs spend almost all their time in loops, efficient loops are the key to good performance. Conditionals, function calls, little instruction level parallelism, and large numbers of temporary values make it difficult for the compiler to generate tightly packed, highly efficient code. Conditionals and function calls introduce jumps that disrupt code flow. Users should eliminate or isolate conditionls to their own loops as much as possible. Often logical expressions can be substituted for if-then-else statements. For example, code 2 includes the following snippet MaxDelta = 0.0 do J = 1, N do I = 1, M < code omitted > Delta = abs(OldValue ? NewValue) if (Delta > MaxDelta) MaxDelta = Delta enddo enddo if (MaxDelta .gt. 0.001) goto 200 Since the only use of MaxDelta is to control the jump to 200 and all that matters is whether or not it is greater than 0.001, I made MaxDelta a boolean and rewrote the snippet as MaxDelta = .false. do J = 1, N do I = 1, M < code omitted > Delta = abs(OldValue ? NewValue) MaxDelta = MaxDelta .or. (Delta .gt. 0.001) enddo enddo if (MaxDelta) goto 200 thereby, eliminating the conditional expression from the inner loop. A microprocessor can execute many instructions per instruction cycle. Typically, it can execute one or more memory, floating point, integer, and jump operations. To be executed simultaneously, the operations must be independent. Thick loops tend to have more instruction level parallelism than thin loops. Moreover, they reduce memory traffice by maximizing data reuse. Loop unrolling and loop fusion are two techniques to increase the size of loop bodies. Several of the codes studied benefitted from loop unrolling, but none benefitted from loop fusion. This observation is not too surpising since it is the general tendency of programmers to write thick loops. As loops become thicker, the number of temporary values grows, increasing register pressure. If registers spill, then memory traffic increases and code flow is disrupted. A thick loop with many temporary values may execute slower than an equivalent series of thin loops. The biggest gain will be achieved if the thick loop can be split into a series of independent loops eliminating the need to write and read temporary arrays. I found such an occasion in code 10 where I split the loop do i = 1, n do j = 1, m A24(j,i)= S24(j,i) * T24(j,i) + S25(j,i) * U25(j,i) B24(j,i)= S24(j,i) * T25(j,i) + S25(j,i) * U24(j,i) A25(j,i)= S24(j,i) * C24(j,i) + S25(j,i) * V24(j,i) B25(j,i)= S24(j,i) * U25(j,i) + S25(j,i) * V25(j,i) C24(j,i)= S26(j,i) * T26(j,i) + S27(j,i) * U26(j,i) D24(j,i)= S26(j,i) * T27(j,i) + S27(j,i) * V26(j,i) C25(j,i)= S27(j,i) * S28(j,i) + S26(j,i) * U28(j,i) D25(j,i)= S27(j,i) * T28(j,i) + S26(j,i) * V28(j,i) end do end do into two disjoint loops do i = 1, n do j = 1, m A24(j,i)= S24(j,i) * T24(j,i) + S25(j,i) * U25(j,i) B24(j,i)= S24(j,i) * T25(j,i) + S25(j,i) * U24(j,i) A25(j,i)= S24(j,i) * C24(j,i) + S25(j,i) * V24(j,i) B25(j,i)= S24(j,i) * U25(j,i) + S25(j,i) * V25(j,i) end do end do do i = 1, n do j = 1, m C24(j,i)= S26(j,i) * T26(j,i) + S27(j,i) * U26(j,i) D24(j,i)= S26(j,i) * T27(j,i) + S27(j,i) * V26(j,i) C25(j,i)= S27(j,i) * S28(j,i) + S26(j,i) * U28(j,i) D25(j,i)= S27(j,i) * T28(j,i) + S26(j,i) * V28(j,i) end do end do Conclusions Over the course of the last year, I have had the opportunity to work with over two dozen academic scientific programmers at leading research universities. Their research interests span a broad range of scientific fields. Except for two programs that relied almost exclusively on library routines (matrix multiply and fast Fourier transform), I was able to improve significantly the single processor performance of all codes. Improvements range from 2x to 15.5x with a simple average of 4.75x. Changes to the source code were at a very high level. I did not use sophisticated techniques or programming tools to discover inefficiencies or effect the changes. Only one code was parallel despite the availability of parallel systems to all developers. Clearly, we have a problem—personal scientific research codes are highly inefficient and not running parallel. The developers are unaware of simple optimization techniques to make programs run faster. They lack education in the art of code optimization and parallel programming. I do not believe we can fix the problem by publishing additional books or training manuals. To date, the developers in questions have not studied the books or manual available, and are unlikely to do so in the future. Short courses are a possible solution, but I believe they are too concentrated to be much use. The general concepts can be taught in a three or four day course, but that is not enough time for students to practice what they learn and acquire the experience to apply and extend the concepts to their codes. Practice is the key to becoming proficient at optimization. I recommend that graduate students be required to take a semester length course in optimization and parallel programming. We would never give someone access to state-of-the-art scientific equipment costing hundreds of thousands of dollars without first requiring them to demonstrate that they know how to use the equipment. Yet the criterion for time on state-of-the-art supercomputers is at most an interesting project. Requestors are never asked to demonstrate that they know how to use the system, or can use the system effectively. A semester course would teach them the required skills. Government agencies that fund academic scientific research pay for most of the computer systems supporting scientific research as well as the development of most personal scientific codes. These agencies should require graduate schools to offer a course in optimization and parallel programming as a requirement for funding. About the Author John Feo received his Ph.D. in Computer Science from The University of Texas at Austin in 1986. After graduate school, Dr. Feo worked at Lawrence Livermore National Laboratory where he was the Group Leader of the Computer Research Group and principal investigator of the Sisal Language Project. In 1997, Dr. Feo joined Tera Computer Company where he was project manager for the MTA, and oversaw the programming and evaluation of the MTA at the San Diego Supercomputer Center. In 2000, Dr. Feo joined Sun Microsystems as an HPC application specialist. He works with university research groups to optimize and parallelize scientific codes. Dr. Feo has published over two dozen research articles in the areas of parallel parallel programming, parallel programming languages, and application performance.

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jQuery Datatables throws error when dynamically created row headers

- by JM4

I am using the Datatables jquery plugin for one of my projects. For one in particular, the number of columns can vary based on how many children a consumer has (yes I realize normalization and proper technique would insert on another row but it is a client requirement). Datatables must be set up as such: <table> <thead> <tr> <th></th> </tr> </thead> <tbody> <tr> <td></td> </tr> </tbody> </table> my script starts out as: <table cellpadding="0" cellspacing="0" border="0" class="display" id="sortable"> <thead> <tr> <th>parent name</th> <th>parent phone</th> <?php try { $db->beginTransaction(); $stmt = $db->prepare("SELECT max(num_deps) FROM (SELECT count(a.id) as num_deps FROM children a INNER JOIN parents b USING(id) WHERE a.id !=0 GROUP BY a.id) x"); $stmt->execute(); $rows = $stmt->fetchAll(); for($i=1; $i<=$rows[0][0]; $i++) { echo " <th>Child Name ".$i."</th> <th>Date of Birth ".$i."</th> "; } $db->commit(); } catch (PDOException $e) { echo "<p align='center'>There was a system error. Please contact administration.<br>".$e->getMessage()."</p><br />"; } ?> </tr> </thead> In this manner, the final column headers can be 1 or 50 spots long. However, with this dynamic code in place, datatables throws the following error: ""DataTables warning (table id = 'datatable'): Cannot reinitialise DataTable. To retrieve the DataTables object for this table, please pass either no arguments to the dataTable() function, or set bRetrive to true. Alternativly, to destroy old table and create a new one...ETC."' Yes I have set "bRetrieve" : true in the javascript above and that does not do the trick. If I remove the code above, the file "works" fine but it leaves off the necessary columns for my table. Any ideas? Displaying JS <script type="text/javascript" src="//ajax.googleapis.com/ajax/libs/jqueryui/1.8.6/jquery-ui.min.js"></script> <script type="text/javascript" src="../media/js/jquery.dataTables.min.js"></script> <script type="text/javascript" src="../media/js/TableTools/TableTools.js"></script> <script type="text/javascript" src="../media/ZeroClipboard/ZeroClipboard.js"></script> <script type="text/javascript"> $(document).ready(function() { TableToolsInit.sSwfPath = "../media/swf/ZeroClipboard.swf"; oTable = $('#sortable').dataTable({ "bRetrieve": true, "bProcessing": true, "sScrollX": "100%", "sScrollXInner": "110%", "bScrollCollapse": true, "bJQueryUI": true, "sPaginationType": "full_numbers", "sDom": 'T<"clear"><"fg-toolbar ui-widget-header ui-corner-tl ui-corner-tr ui-helper-clearfix"lfr>t<"fg-toolbar ui-widget-header ui-corner-bl ui-corner-br ui-helper-clearfix"ip>' }); }); </script> </head> TOP piece of HTML <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Home</title> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> <link rel="stylesheet" type="text/css" href="style.css" /> <link rel="stylesheet" type="text/css" href="default.css" /> <script type="text/javascript" src="//ajax.googleapis.com/ajax/libs/jquery/1.4.3/jquery.min.js"></script> <style type="text/css" title="currentStyle"> @import "TableTools.css"; @import "demo_table_jui.css"; @import "jquery-ui-1.8.4.custom.css"; </style> <script type="text/javascript" src="//ajax.googleapis.com/ajax/libs/jqueryui/1.8.6/jquery-ui.min.js"></script> <script type="text/javascript" src="js/jquery.dataTables.min.js"></script> <script type="text/javascript" src="js/TableTools/TableTools.js"></script> <script type="text/javascript" src="ZeroClipboard/ZeroClipboard.js"></script> <script type="text/javascript"> $(document).ready(function() { TableToolsInit.sSwfPath = "ZeroClipboard.swf"; oTable = $('#sortable').dataTable({ "bRetrieve": true, "bProcessing": true, "sScrollX": "100%", "sScrollXInner": "110%", "bScrollCollapse": true, "bJQueryUI": true, "sPaginationType": "full_numbers", "sDom": 'T<"clear"><"fg-toolbar ui-widget-header ui-corner-tl ui-corner-tr ui-helper-clearfix"lfr>t<"fg-toolbar ui-widget-header ui-corner-bl ui-corner-br ui-helper-clearfix"ip>' }); }); </script> </head> <body bgcolor="#e0e0e0"> <div class="main"> <div class="body"> <div class="body_resize"> <div class="liquid-round"> <div class="top"><span><h2>Details</h2></span></div> <div class="center-content"> <div style="overflow-x:hidden; min-height:400px; max-height:600px; overflow-y:auto;"> <div class="demo_jui"><br /> <table cellpadding="0" cellspacing="0" border="0" class="display" width="100%" id="sortable"> <thead> <tr> <th>First Name</th> <th>MI</th> <th>Last Name</th> <th>Street Address</th> <th>City</th> <th>State</th> <th>Zip</th> <th>DOB</th> <th>Gender</th> <th>Spouse Name</th> <th>Spouse Date of Birth</th>  <th>Dependent Child Name 1</th> <th>Dependent Date of Birth 1</th> <th>Dependent Child Name 2</th> <th>Dependent Date of Birth 2</th> <th>Dependent Child Name 3</th> <th>Dependent Date of Birth 3</th> <th>Dependent Child Name 4</th> <th>Dependent Date of Birth 4</th> <th>Dependent Child Name 5</th> <th>Dependent Date of Birth 5</th> <th>Dependent Child Name 6</th> <th>Dependent Date of Birth 6</th> <th>Dependent Child Name 7</th> <th>Dependent Date of Birth 7</th> </tr> </thead> <tbody> <tr> ... UPDATE REGARDING COMMENTS/ANSWERS I have received a number of responses indicating the number of headers may not match the field count in the body. As I mention below, eliminating the php script below altogether would eliminate 5+ fields in the header and without question throw the count match off balance. This DOES NOT however cause an error and in fact "resolves" the issue in that datatables functions properly (even though there is NO header record for 5+ fields in the body.

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Setting up a pc bluetooth server for android

- by Del

Alright, I've been reading a lot of topics the past two or three days and nothing seems to have asked this. I am writing a PC side server for my andriod device, this is for exchanging some information and general debugging. Eventually I will be connecting to a SPP device to control a microcontroller. I have managed, using the following (Android to pc) to connect to rfcomm channel 11 and exchange data between my android device and my pc. Method m = device.getClass().getMethod("createRfcommSocket", new Class[] { int.class }); tmp = (BluetoothSocket) m.invoke(device, Integer.valueOf(11)); I have attempted the createRfcommSocketToServiceRecord(UUID) method, with absolutely no luck. For the PC side, I have been using the C Bluez stack for linux. I have the following code which registers the service and opens a server socket: int main(int argc, char **argv) { struct sockaddr_rc loc_addr = { 0 }, rem_addr = { 0 }; char buf[1024] = { 0 }; char str[1024] = { 0 }; int s, client, bytes_read; sdp_session_t *session; socklen_t opt = sizeof(rem_addr); session = register_service(); s = socket(AF_BLUETOOTH, SOCK_STREAM, BTPROTO_RFCOMM); loc_addr.rc_family = AF_BLUETOOTH; loc_addr.rc_bdaddr = *BDADDR_ANY; loc_addr.rc_channel = (uint8_t) 11; bind(s, (struct sockaddr *)&loc_addr, sizeof(loc_addr)); listen(s, 1); client = accept(s, (struct sockaddr *)&rem_addr, &opt); ba2str( &rem_addr.rc_bdaddr, buf ); fprintf(stderr, "accepted connection from %s\n", buf); memset(buf, 0, sizeof(buf)); bytes_read = read(client, buf, sizeof(buf)); if( bytes_read 0 ) { printf("received [%s]\n", buf); } sprintf(str,"to Android."); printf("sent [%s]\n",str); write(client, str, sizeof(str)); close(client); close(s); sdp_close( session ); return 0; } sdp_session_t *register_service() { uint32_t svc_uuid_int[] = { 0x00000000,0x00000000,0x00000000,0x00000000 }; uint8_t rfcomm_channel = 11; const char *service_name = "Remote Host"; const char *service_dsc = "What the remote should be connecting to."; const char *service_prov = "Your mother"; uuid_t root_uuid, l2cap_uuid, rfcomm_uuid, svc_uuid; sdp_list_t *l2cap_list = 0, *rfcomm_list = 0, *root_list = 0, *proto_list = 0, *access_proto_list = 0; sdp_data_t *channel = 0, *psm = 0; sdp_record_t *record = sdp_record_alloc(); // set the general service ID sdp_uuid128_create( &svc_uuid, &svc_uuid_int ); sdp_set_service_id( record, svc_uuid ); // make the service record publicly browsable sdp_uuid16_create(&root_uuid, PUBLIC_BROWSE_GROUP); root_list = sdp_list_append(0, &root_uuid); sdp_set_browse_groups( record, root_list ); // set l2cap information sdp_uuid16_create(&l2cap_uuid, L2CAP_UUID); l2cap_list = sdp_list_append( 0, &l2cap_uuid ); proto_list = sdp_list_append( 0, l2cap_list ); // set rfcomm information sdp_uuid16_create(&rfcomm_uuid, RFCOMM_UUID); channel = sdp_data_alloc(SDP_UINT8, &rfcomm_channel); rfcomm_list = sdp_list_append( 0, &rfcomm_uuid ); sdp_list_append( rfcomm_list, channel ); sdp_list_append( proto_list, rfcomm_list ); // attach protocol information to service record access_proto_list = sdp_list_append( 0, proto_list ); sdp_set_access_protos( record, access_proto_list ); // set the name, provider, and description sdp_set_info_attr(record, service_name, service_prov, service_dsc); int err = 0; sdp_session_t *session = 0; // connect to the local SDP server, register the service record, and // disconnect session = sdp_connect( BDADDR_ANY, BDADDR_LOCAL, SDP_RETRY_IF_BUSY ); err = sdp_record_register(session, record, 0); // cleanup //sdp_data_free( channel ); sdp_list_free( l2cap_list, 0 ); sdp_list_free( rfcomm_list, 0 ); sdp_list_free( root_list, 0 ); sdp_list_free( access_proto_list, 0 ); return session; } And another piece of code, in addition to 'sdptool browse local' which can verifty that the service record is running on the pc: int main(int argc, char **argv) { uuid_t svc_uuid; uint32_t svc_uuid_int[] = { 0x00000000,0x00000000,0x00000000,0x00000000 }; int err; bdaddr_t target; sdp_list_t *response_list = NULL, *search_list, *attrid_list; sdp_session_t *session = 0; str2ba( "01:23:45:67:89:AB", &target ); // connect to the SDP server running on the remote machine session = sdp_connect( BDADDR_ANY, BDADDR_LOCAL, SDP_RETRY_IF_BUSY ); // specify the UUID of the application we're searching for sdp_uuid128_create( &svc_uuid, &svc_uuid_int ); search_list = sdp_list_append( NULL, &svc_uuid ); // specify that we want a list of all the matching applications' attributes uint32_t range = 0x0000ffff; attrid_list = sdp_list_append( NULL, &range ); // get a list of service records that have UUID 0xabcd err = sdp_service_search_attr_req( session, search_list, \ SDP_ATTR_REQ_RANGE, attrid_list, &response_list); sdp_list_t *r = response_list; // go through each of the service records for (; r; r = r-next ) { sdp_record_t *rec = (sdp_record_t*) r-data; sdp_list_t *proto_list; // get a list of the protocol sequences if( sdp_get_access_protos( rec, &proto_list ) == 0 ) { sdp_list_t *p = proto_list; // go through each protocol sequence for( ; p ; p = p-next ) { sdp_list_t *pds = (sdp_list_t*)p-data; // go through each protocol list of the protocol sequence for( ; pds ; pds = pds-next ) { // check the protocol attributes sdp_data_t *d = (sdp_data_t*)pds-data; int proto = 0; for( ; d; d = d-next ) { switch( d-dtd ) { case SDP_UUID16: case SDP_UUID32: case SDP_UUID128: proto = sdp_uuid_to_proto( &d-val.uuid ); break; case SDP_UINT8: if( proto == RFCOMM_UUID ) { printf("rfcomm channel: %d\n",d-val.int8); } break; } } } sdp_list_free( (sdp_list_t*)p-data, 0 ); } sdp_list_free( proto_list, 0 ); } printf("found service record 0x%x\n", rec-handle); sdp_record_free( rec ); } sdp_close(session); } Output: $ ./search rfcomm channel: 11 found service record 0x10008 sdptool: Service Name: Remote Host Service Description: What the remote should be connecting to. Service Provider: Your mother Service RecHandle: 0x10008 Protocol Descriptor List: "L2CAP" (0x0100) "RFCOMM" (0x0003) Channel: 11 And for logcat I'm getting this: 07-22 15:57:06.087: ERROR/BTLD(215): ****************search UUID = 0000*********** 07-22 15:57:06.087: INFO//system/bin/btld(209): btapp_dm_GetRemoteServiceChannel() 07-22 15:57:06.087: INFO//system/bin/btld(209): ##### USerial_Ioctl: BT_Wake, 0x8003 #### 07-22 15:57:06.097: INFO/ActivityManager(88): Displayed activity com.example.socktest/.socktest: 79 ms (total 79 ms) 07-22 15:57:06.697: INFO//system/bin/btld(209): ##### USerial_Ioctl: BT_Sleep, 0x8004 #### 07-22 15:57:07.517: WARN/BTLD(215): ccb timer ticks: 2147483648 07-22 15:57:07.517: INFO//system/bin/btld(209): ##### USerial_Ioctl: BT_Wake, 0x8003 #### 07-22 15:57:07.547: WARN/BTLD(215): info:x10 07-22 15:57:07.547: INFO/BTL-IFS(215): send_ctrl_msg: [BTL_IFS CTRL] send BTLIF_DTUN_SIGNAL_EVT (CTRL) 10 pbytes (hdl 14) 07-22 15:57:07.547: DEBUG/DTUN_HCID_BZ4(253): dtun_dm_sig_link_up() 07-22 15:57:07.547: INFO/DTUN_HCID_BZ4(253): dtun_dm_sig_link_up: dummy_handle = 342 07-22 15:57:07.547: DEBUG/ADAPTER(253): adapter_get_device(00:02:72:AB:7C:EE) 07-22 15:57:07.547: ERROR/BluetoothEventLoop.cpp(88): pollData[0] is revented, check next one 07-22 15:57:07.547: ERROR/BluetoothEventLoop.cpp(88): event_filter: Received signal org.bluez.Device:PropertyChanged from /org/bluez/253/hci0/dev_00_02_72_AB_7C_EE 07-22 15:57:07.777: WARN/BTLD(215): process_service_search_attr_rsp 07-22 15:57:07.787: INFO/BTL-IFS(215): send_ctrl_msg: [BTL_IFS CTRL] send BTLIF_DTUN_SIGNAL_EVT (CTRL) 13 pbytes (hdl 14) 07-22 15:57:07.787: INFO/DTUN_HCID_BZ4(253): dtun_dm_sig_rmt_service_channel: success=0, service=00000000 07-22 15:57:07.787: ERROR/DTUN_HCID_BZ4(253): discovery unsuccessful! 07-22 15:57:08.497: INFO//system/bin/btld(209): ##### USerial_Ioctl: BT_Sleep, 0x8004 #### 07-22 15:57:09.507: INFO//system/bin/btld(209): ##### USerial_Ioctl: BT_Wake, 0x8003 #### 07-22 15:57:09.597: INFO/BTL-IFS(215): send_ctrl_msg: [BTL_IFS CTRL] send BTLIF_DTUN_SIGNAL_EVT (CTRL) 11 pbytes (hdl 14) 07-22 15:57:09.597: DEBUG/DTUN_HCID_BZ4(253): dtun_dm_sig_link_down() 07-22 15:57:09.597: INFO/DTUN_HCID_BZ4(253): dtun_dm_sig_link_down device = 0xf7a0 handle = 342 reason = 22 07-22 15:57:09.597: ERROR/BluetoothEventLoop.cpp(88): pollData[0] is revented, check next one 07-22 15:57:09.597: ERROR/BluetoothEventLoop.cpp(88): event_filter: Received signal org.bluez.Device:PropertyChanged from /org/bluez/253/hci0/dev_00_02_72_AB_7C_EE 07-22 15:57:09.597: DEBUG/BluetoothA2dpService(88): Received intent Intent { act=android.bluetooth.device.action.ACL_DISCONNECTED (has extras) } 07-22 15:57:10.107: INFO//system/bin/btld(209): ##### USerial_Ioctl: BT_Sleep, 0x8004 #### 07-22 15:57:12.107: DEBUG/BluetoothService(88): Cleaning up failed UUID channel lookup: 00:02:72:AB:7C:EE 00000000-0000-0000-0000-000000000000 07-22 15:57:12.107: ERROR/Socket Test(5234): connect() failed 07-22 15:57:12.107: DEBUG/ASOCKWRP(5234): asocket_abort [31,32,33] 07-22 15:57:12.107: INFO/BLZ20_WRAPPER(5234): blz20_wrp_shutdown: s 31, how 2 07-22 15:57:12.107: DEBUG/BLZ20_WRAPPER(5234): blz20_wrp_shutdown: fd (-1:31), bta -1, rc 0, wflags 0x0 07-22 15:57:12.107: INFO/BLZ20_WRAPPER(5234): __close_prot_rfcomm: fd 31 07-22 15:57:12.107: INFO/BLZ20_WRAPPER(5234): __close_prot_rfcomm: bind not completed on this socket 07-22 15:57:12.107: DEBUG/BLZ20_WRAPPER(5234): btlif_signal_event: fd (-1:31), bta -1, rc 0, wflags 0x0 07-22 15:57:12.107: DEBUG/BLZ20_WRAPPER(5234): btlif_signal_event: event BTLIF_BTS_EVT_ABORT matched 07-22 15:57:12.107: DEBUG/BTL_IFC_WRP(5234): wrp_close_s_only: wrp_close_s_only [31] (31:-1) [] 07-22 15:57:12.107: DEBUG/BTL_IFC_WRP(5234): wrp_close_s_only: data socket closed 07-22 15:57:12.107: DEBUG/BTL_IFC_WRP(5234): wsactive_del: delete wsock 31 from active list [ad3e1494] 07-22 15:57:12.107: DEBUG/BTL_IFC_WRP(5234): wrp_close_s_only: wsock fully closed, return to pool 07-22 15:57:12.107: DEBUG/BLZ20_WRAPPER(5234): btsk_free: success 07-22 15:57:12.107: DEBUG/BLZ20_WRAPPER(5234): blz20_wrp_write: wrote 1 bytes out of 1 on fd 33 07-22 15:57:12.107: DEBUG/ASOCKWRP(5234): asocket_destroy 07-22 15:57:12.107: DEBUG/ASOCKWRP(5234): asocket_abort [31,32,33] 07-22 15:57:12.107: INFO/BLZ20_WRAPPER(5234): blz20_wrp_shutdown: s 31, how 2 07-22 15:57:12.107: DEBUG/BLZ20_WRAPPER(5234): blz20_wrp_shutdown: btsk not found, normal close (31) 07-22 15:57:12.107: DEBUG/BLZ20_WRAPPER(5234): blz20_wrp_write: wrote 1 bytes out of 1 on fd 33 07-22 15:57:12.107: INFO/BLZ20_WRAPPER(5234): blz20_wrp_close: s 33 07-22 15:57:12.107: DEBUG/BLZ20_WRAPPER(5234): blz20_wrp_close: btsk not found, normal close (33) 07-22 15:57:12.107: INFO/BLZ20_WRAPPER(5234): blz20_wrp_close: s 32 07-22 15:57:12.107: DEBUG/BLZ20_WRAPPER(5234): blz20_wrp_close: btsk not found, normal close (32) 07-22 15:57:12.107: INFO/BLZ20_WRAPPER(5234): blz20_wrp_close: s 31 07-22 15:57:12.107: DEBUG/BLZ20_WRAPPER(5234): blz20_wrp_close: btsk not found, normal close (31) 07-22 15:57:12.157: DEBUG/Sensors(88): close_akm, fd=151 07-22 15:57:12.167: ERROR/CachedBluetoothDevice(477): onUuidChanged: Time since last connect14970690 07-22 15:57:12.237: DEBUG/Socket Test(5234): -On Stop- Sorry for bombarding you guys with what seems like a difficult question and a lot to read, but I've been working on this problem for a while and I've tried a lot of different things to get this working. Let me reiterate, I can get it to work, but not using service discovery protocol. I've tried a several different UUIDs and on two different computers, although I only have my HTC Incredible to test with. I've also heard some rumors that the BT stack wasn't working on the HTC Droid, but that isn't the case, at least, for PC interaction.

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Windows-1251 file inside UTF-8 site?

- by Spoonk

Hello everyone Masters Of Web Delevopment :) I have a piece of PHP script that fetches last 10 played songs from my winamp. This script is inside file (lets call it "lastplayed.php") which is included in my site with php include function inside a "div". My site is on UTF-8 encoding. The problem is that some songs titles are in Windows-1251 encoding. And in my site they displays like "??????"... Is there any known way to tell to this div with included "lastplayed.php" in it, to be with windows-1251 encoding? Or any other suggestions? P.S: The file with fetching script a.k.a. "lastplayed.php", is converted to UTF-8. But if it is ANCII it's the same result. I try to put and meta tag with windows-1251 between head tag but nothing happens again. P.P.S: Script that fetches the Winamp's data (lastplayed.php): <?php /****** * You may use and/or modify this script as long as you: * 1. Keep my name & webpage mentioned * 2. Don't use it for commercial purposes * * If you want to use this script without complying to the rules above, please contact me first at: [email protected] * * Author: Martijn Korse * Website: http://devshed.excudo.net * * Date: 08-05-2006 ***/ /** * version 2.0 */ class Radio { var $fields = array(); var $fieldsDefaults = array("Server Status", "Stream Status", "Listener Peak", "Average Listen Time", "Stream Title", "Content Type", "Stream Genre", "Stream URL", "Current Song"); var $very_first_str; var $domain, $port, $path; var $errno, $errstr; var $trackLists = array(); var $isShoutcast; var $nonShoutcastData = array( "Server Status" => "n/a", "Stream Status" => "n/a", "Listener Peak" => "n/a", "Average Listen Time" => "n/a", "Stream Title" => "n/a", "Content Type" => "n/a", "Stream Genre" => "n/a", "Stream URL" => "n/a", "Stream AIM" => "n/a", "Stream IRC" => "n/a", "Current Song" => "n/a" ); var $altServer = False; function Radio($url) { $parsed_url = parse_url($url); $this->domain = isset($parsed_url['host']) ? $parsed_url['host'] : ""; $this->port = !isset($parsed_url['port']) || empty($parsed_url['port']) ? "80" : $parsed_url['port']; $this->path = empty($parsed_url['path']) ? "/" : $parsed_url['path']; if (empty($this->domain)) { $this->domain = $this->path; $this->path = ""; } $this->setOffset("Current Stream Information"); $this->setFields(); // setting default fields $this->setTableStart("<table border=0 cellpadding=2 cellspacing=2>"); $this->setTableEnd("</table>"); } function setFields($array=False) { if (!$array) $this->fields = $this->fieldsDefaults; else $this->fields = $array; } function setOffset($string) { $this->very_first_str = $string; } function setTableStart($string) { $this->tableStart = $string; } function setTableEnd($string) { $this->tableEnd = $string; } function getHTML($page=False) { if (!$page) $page = $this->path; $contents = ""; $domain = (substr($this->domain, 0, 7) == "http://") ? substr($this->domain, 7) : $this->domain; if (@$fp = fsockopen($domain, $this->port, $this->errno, $this->errstr, 2)) { fputs($fp, "GET ".$page." HTTP/1.1\r\n". "User-Agent: Mozilla/4.0 (compatible; MSIE 5.5; Windows 98)\r\n". "Accept: */*\r\n". "Host: ".$domain."\r\n\r\n"); $c = 0; while (!feof($fp) && $c <= 20) { $contents .= fgets($fp, 4096); $c++; } fclose ($fp); preg_match("/(Content-Type:)(.*)/i", $contents, $matches); if (count($matches) > 0) { $contentType = trim($matches[2]); if ($contentType == "text/html") { $this->isShoutcast = True; return $contents; } else { $this->isShoutcast = False; $htmlContent = substr($contents, 0, strpos($contents, "\r\n\r\n")); $dataStr = str_replace("\r", "\n", str_replace("\r\n", "\n", $contents)); $lines = explode("\n", $dataStr); foreach ($lines AS $line) { if ($dp = strpos($line, ":")) { $key = substr($line, 0, $dp); $value = trim(substr($line, ($dp+1))); if (preg_match("/genre/i", $key)) $this->nonShoutcastData['Stream Genre'] = $value; if (preg_match("/name/i", $key)) $this->nonShoutcastData['Stream Title'] = $value; if (preg_match("/url/i", $key)) $this->nonShoutcastData['Stream URL'] = $value; if (preg_match("/content-type/i", $key)) $this->nonShoutcastData['Content Type'] = $value; if (preg_match("/icy-br/i", $key)) $this->nonShoutcastData['Stream Status'] = "Stream is up at ".$value."kbps"; if (preg_match("/icy-notice2/i", $key)) { $this->nonShoutcastData['Server Status'] = "This is <span style=\"color: red;\">not</span> a Shoutcast server!"; if (preg_match("/ultravox/i", $value)) $this->nonShoutcastData['Server Status'] .= " But an <a href=\"http://ultravox.aol.com/\" target=\"_blank\">Ultravox</a> Server"; $this->altServer = $value; } } } return nl2br($htmlContent); } } else return $contents; } else { return False; } } function getServerInfo($display_array=null, $very_first_str=null) { if (!isset($display_array)) $display_array = $this->fields; if (!isset($very_first_str)) $very_first_str = $this->very_first_str; if ($html = $this->getHTML()) { // parsing the contents $data = array(); foreach ($display_array AS $key => $item) { if ($this->isShoutcast) { $very_first_pos = stripos($html, $very_first_str); $first_pos = stripos($html, $item, $very_first_pos); $line_start = strpos($html, "<td>", $first_pos); $line_end = strpos($html, "</td>", $line_start) + 4; $difference = $line_end - $line_start; $line = substr($html, $line_start, $difference); $data[$key] = strip_tags($line); } else { $data[$key] = $this->nonShoutcastData[$item]; } } return $data; } else { return $this->errstr." (".$this->errno.")"; } } function createHistoryArray($page) { if (!in_array($page, $this->trackLists)) { $this->trackLists[] = $page; if ($html = $this->getHTML($page)) { $fromPos = stripos($html, $this->tableStart); $toPos = stripos($html, $this->tableEnd, $fromPos); $tableData = substr($html, $fromPos, ($toPos-$fromPos)); $lines = explode("</tr><tr>", $tableData); $tracks = array(); $c = 0; foreach ($lines AS $line) { $info = explode ("</td><td>", $line); $time = trim(strip_tags($info[0])); if (substr($time, 0, 9) != "Copyright" && !preg_match("/Tag Loomis, Tom Pepper and Justin Frankel/i", $info[1])) { $this->tracks[$c]['time'] = $time; $this->tracks[$c++]['track'] = trim(strip_tags($info[1])); } } if (count($this->tracks) > 0) { unset($this->tracks[0]); if (isset($this->tracks[1])) $this->tracks[1]['track'] = str_replace("Current Song", "", $this->tracks[1]['track']); } } else { $this->tracks[0] = array("time"=>$this->errno, "track"=>$this->errstr); } } } function getHistoryArray($page="/played.html") { if (!in_array($page, $this->trackLists)) $this->createHistoryArray($page); return $this->tracks; } function getHistoryTable($page="/played.html", $trackColText=False, $class=False) { $title_utf8 = mb_convert_encoding($trackArr ,"utf-8" ,"auto"); if (!in_array($page, $this->trackLists)) $this->createHistoryArray($page); if ($trackColText) $output .= " <div class='lastplayed_top'></div> <div".($class ? " class=\"".$class."\"" : "").">"; foreach ($this->tracks AS $title_utf8) $output .= "<div style='padding:2px 0;'>".$title_utf8['track']."</div>"; $output .= "</div><div class='lastplayed_bottom'></div> <div class='lastplayed_title'>".$trackColText."</div> \n"; return $output; } } // this is needed for those with a php version < 5 // the function is copied from the user comments @ php.net (http://nl3.php.net/stripos) if (!function_exists("stripos")) { function stripos($haystack, $needle, $offset=0) { return strpos(strtoupper($haystack), strtoupper($needle), $offset); } } ?> And the calling script outside the lastplayed.php: include "lastplayed.php"; $radio = new Radio($ip.":".$port); echo $radio->getHistoryTable("/played.html", "<b>Last played:</b>", "lastplayed_content");

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RUN FUNCTION AFTER SOMETIME IN JQUERY & AUTOMATIC SLICING OF IMAGES

- by user2697032

I am not being able to start the automatic slicing of images, it is happening only after a click, how should i modify my code so that i get to change the slicing of the images automatically. <!DOCTYPE html> <html lang="en"> <head> <title>Slicebox - 3D Image Slider</title> <meta charset="UTF-8" /> <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <meta name="description" content="Slicebox - 3D Image Slider with Fallback" /> <meta name="keywords" content="jquery, css3, 3d, webkit, fallback, slider, css3, 3d transforms, slices, rotate, box, automatic" /> <meta name="author" content="Pedro Botelho for Codrops" /> <link rel="shortcut icon" href="../favicon.ico"> <link rel="stylesheet" type="text/css" href="css/demo.css" /> <link rel="stylesheet" type="text/css" href="css/slicebox.css" /> <link rel="stylesheet" type="text/css" href="css/custom.css" /> <script type="text/javascript" src="js/modernizr.custom.46884.js"></script> </head> <body onload="funct()"> <div class="container"> <div class="codrops-top clearfix"> <a href="http://tympanus.net/Development/AutomaticImageMontage/"><span>« Previous Demo: </span>Automatic Image Montage</a> <span class="right"> <a target="_blank" href="http://www.flickr.com/photos/strupler/">Images by <strong>ND Strupler</strong></a> <a href="http://tympanus.net/codrops/?p=5657"><strong>Back to the Codrops Article</strong></a> </span> </div> <h1>Slicebox <span>A fresh 3D image slider with graceful fallback</span></h1> <div class="more"> <ul id="sb-examples"> <li>More examples:</li> <li class="selected"><a href="index.html">Example 1</a></li> <li><a href="index2.html">Example 2</a></li> <li><a href="index3.html">Example 3</a></li> <li><a href="index4.html">Example 4</a></li> </ul> </div> <div class="wrapper" id="checkthis"> <ul id="sb-slider" class="sb-slider"> <li> <a href="http://www.flickr.com/photos/strupler/2969141180" target="_blank"><img src="images/1.jpg" alt="image1"/></a> <div class="sb-description"> <h3>Creative Lifesaver</h3> </div> </li> <li> <a href="http://www.flickr.com/photos/strupler/2968268187" target="_blank"><img src="images/2.jpg" alt="image2"/></a> <div class="sb-description"> <h3>Honest Entertainer</h3> </div> </li> <li> <a href="http://www.flickr.com/photos/strupler/2968114825" target="_blank"><img src="images/3.jpg" alt="image1"/></a> <div class="sb-description"> <h3>Brave Astronaut</h3> </div> </li> <li> <a href="http://www.flickr.com/photos/strupler/2968122059" target="_blank"><img src="images/4.jpg" alt="image1"/></a> <div class="sb-description"> <h3>Affectionate Decision Maker</h3> </div> </li> <li> <a href="http://www.flickr.com/photos/strupler/2969119944" target="_blank"><img src="images/5.jpg" alt="image1"/></a> <div class="sb-description"> <h3>Faithful Investor</h3> </div> </li> <li> <a href="http://www.flickr.com/photos/strupler/2968126177" target="_blank"><img src="images/6.jpg" alt="image1"/></a> <div class="sb-description"> <h3>Groundbreaking Artist</h3> </div> </li> <li> <a href="http://www.flickr.com/photos/strupler/2968945158" target="_blank"><img src="images/7.jpg" alt="image1"/></a> <div class="sb-description"> <h3>Selfless Philantropist</h3> </div> </li> </ul> <div id="shadow" class="shadow"></div> <div id="nav-arrows" class="nav-arrows"> <a href="#x">Next</a> <a href="#y">Previous</a> </div> <div id="nav-dots" class="nav-dots"> <span class="nav-dot-current"></span> <span></span> <span></span> <span></span> <span></span> <span></span> <span></span> </div> </div> <p class="info"><strong>Example 1:</strong> Default settings</p> </div> <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.8.2/jquery.min.js"></script> <script type="text/javascript" src="js/jquery.slicebox.js"></script> <script type="text/javascript"> $(function() { var Page = (function() { var $navArrows = $( '#nav-arrows' ).hide(), $navDots = $( '#nav-dots' ).hide(), $nav = $navDots.children( 'span' ), $shadow = $( '#shadow' ).hide(), slicebox = $( '#sb-slider' ).slicebox( { onReady : function() { $navArrows.show(); $navDots.show(); $shadow.show(); }, onBeforeChange : function( pos ) { $nav.removeClass( 'nav-dot-current' ); $nav.eq( pos ).addClass( 'nav-dot-current' ); } } ), init = function() { initEvents(); }, initEvents = function() { // add navigation events $navArrows.children( ':first' ).on( 'click', function() { setInterval("callme()", 1000); return false; } ); //$(function(){ //callme(); //}); function callme(){ //$('#checkit').append("callme loaded<br />"); slicebox.next(); setInterval("callme()", 1000); } $navArrows.children( ':last' ).on( 'click', function() { slicebox.previous(); return false; } ); $nav.each( function( i ) { $( this ).on( 'click', function( event ) { var $dot = $( this ); if( !slicebox.isActive() ) { $nav.removeClass( 'nav-dot-current' ); $dot.addClass( 'nav-dot-current' ); } slicebox.jump( i + 1 ); return false; } ); } ); }; return { init : init }; })(); Page.init(); }); </script> <script> // make sure the "myContainer" id in the script is the same id of the div $(document).ready(function() { slicebox.next(); $('#nav-arrows').sbslider(); // this is the piece of code that will do the magic thing }); </script> </body> </html> I am not being able to start the automatic slicing of images, it is happening only after a click, how should i modify my code so that i get to change the slicing of the images automatically.

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How to Make a Game like Space Invaders - Ray Wenderlich (why do my space invaders scroll off screen)

- by Erv Noel

I'm following this tutorial(http://www.raywenderlich.com/51068/how-to-make-a-game-like-space-invaders-with-sprite-kit-tutorial-part-1) and I've run into a problem right after the part where I add [self determineInvaderMovementDirection]; to my GameScene.m file (specifically to my moveInvadersForUpdate method) The tutorial states that the space invaders should be moving accordingly after adding this piece of code but when I run they move to the left and they do not come back. I'm not sure what I am doing wrong as I have followed this tutorial very carefully. Any help or clarification would be greatly appreciated. Thanks in advance ! Here is the full GameScene.m #import "GameScene.h" #import <CoreMotion/CoreMotion.h> #pragma mark - Custom Type Definitions /* The type definition and constant definitions 1,2,3 take care of the following tasks: 1.Define the possible types of invader enemies. This can be used in switch statements later when things like displaying different sprites images for each enemy type. The typedef makes InvaderType a formal Obj-C type that is type checked for method arguments and variables.This is so that the wrong method argument is not used or assigned to the wrong variable. 2. Define the size of the invaders and that they'll be laid out in a grid of rows and columns on the screen. 3. Define a name that will be used to identify invaders when searching for them. */ //1 typedef enum InvaderType { InvaderTypeA, InvaderTypeB, InvaderTypeC } InvaderType; /* Invaders move in a fixed pattern: right, right, down, left, down, right right. InvaderMovementDirection tracks the invaders' progress through this pattern */ typedef enum InvaderMovementDirection { InvaderMovementDirectionRight, InvaderMovementDirectionLeft, InvaderMovementDirectionDownThenRight, InvaderMovementDirectionDownThenLeft, InvaderMovementDirectionNone } InvaderMovementDirection; //2 #define kInvaderSize CGSizeMake(24,16) #define kInvaderGridSpacing CGSizeMake(12,12) #define kInvaderRowCount 6 #define kInvaderColCount 6 //3 #define kInvaderName @"invader" #define kShipSize CGSizeMake(30, 16) //stores the size of the ship #define kShipName @"ship" // stores the name of the ship stored on the sprite node #define kScoreHudName @"scoreHud" #define kHealthHudName @"healthHud" /* this class extension allows you to add “private” properties to GameScene class, without revealing the properties to other classes or code. You still get the benefit of using Objective-C properties, but your GameScene state is stored internally and can’t be modified by other external classes. As well, it doesn’t clutter the namespace of datatypes that your other classes see. This class extension is used in the method didMoveToView */ #pragma mark - Private GameScene Properties @interface GameScene () @property BOOL contentCreated; @property InvaderMovementDirection invaderMovementDirection; @property NSTimeInterval timeOfLastMove; @property NSTimeInterval timePerMove; @end @implementation GameScene #pragma mark Object Lifecycle Management #pragma mark - Scene Setup and Content Creation /*This method simply invokes createContent using the BOOL property contentCreated to make sure you don’t create your scene’s content more than once. This property is defined in an Objective-C Class Extension found near the top of the file()*/ - (void)didMoveToView:(SKView *)view { if (!self.contentCreated) { [self createContent]; self.contentCreated = YES; } } - (void)createContent { //1 - Invaders begin by moving to the right self.invaderMovementDirection = InvaderMovementDirectionRight; //2 - Invaders take 1 sec for each move. Each step left, right or down // takes 1 second. self.timePerMove = 1.0; //3 - Invaders haven't moved yet, so set the time to zero self.timeOfLastMove = 0.0; [self setupInvaders]; [self setupShip]; [self setupHud]; } /* Creates an invade sprite of a given type 1. Use the invadeType parameterr to determine color of the invader 2. Call spriteNodeWithColor:size: of SKSpriteNode to alloc and init a sprite that renders as a rect of the given color invaderColor with size kInvaderSize */ -(SKNode*)makeInvaderOfType:(InvaderType)invaderType { //1 SKColor* invaderColor; switch (invaderType) { case InvaderTypeA: invaderColor = [SKColor redColor]; break; case InvaderTypeB: invaderColor = [SKColor greenColor]; break; case InvaderTypeC: invaderColor = [SKColor blueColor]; break; } //2 SKSpriteNode* invader = [SKSpriteNode spriteNodeWithColor:invaderColor size:kInvaderSize]; invader.name = kInvaderName; return invader; } -(void)setupInvaders { //1 - loop over the rows CGPoint baseOrigin = CGPointMake(kInvaderSize.width / 2, 180); for (NSUInteger row = 0; row < kInvaderRowCount; ++row) { //2 - Choose a single InvaderType for all invaders // in this row based on the row number InvaderType invaderType; if (row % 3 == 0) invaderType = InvaderTypeA; else if (row % 3 == 1) invaderType = InvaderTypeB; else invaderType = InvaderTypeC; //3 - Does some math to figure out where the first invader // in the row should be positioned CGPoint invaderPosition = CGPointMake(baseOrigin.x, row * (kInvaderGridSpacing.height + kInvaderSize.height) + baseOrigin.y); //4 - Loop over the columns for (NSUInteger col = 0; col < kInvaderColCount; ++col) { //5 - Create an invader for the current row and column and add it // to the scene SKNode* invader = [self makeInvaderOfType:invaderType]; invader.position = invaderPosition; [self addChild:invader]; //6 - update the invaderPosition so that it's correct for the //next invader invaderPosition.x += kInvaderSize.width + kInvaderGridSpacing.width; } } } -(void)setupShip { //1 - creates ship using makeShip. makeShip can easily be used later // to create another ship (ex. to set up more lives) SKNode* ship = [self makeShip]; //2 - Places the ship on the screen. In SpriteKit the origin is at the lower //left corner of the screen. The anchorPoint is based on a unit square with (0, 0) at the lower left of the sprite's area and (1, 1) at its top right. Since SKSpriteNode has a default anchorPoint of (0.5, 0.5), i.e., its center, the ship's position is the position of its center. Positioning the ship at kShipSize.height/2.0f means that half of the ship's height will protrude below its position and half above. If you check the math, you'll see that the ship's bottom aligns exactly with the bottom of the scene. ship.position = CGPointMake(self.size.width / 2.0f, kShipSize.height/2.0f); [self addChild:ship]; } -(SKNode*)makeShip { SKNode* ship = [SKSpriteNode spriteNodeWithColor:[SKColor greenColor] size:kShipSize]; ship.name = kShipName; return ship; } -(void)setupHud { //Sets the score label font to Courier SKLabelNode* scoreLabel = [SKLabelNode labelNodeWithFontNamed:@"Courier"]; //1 - Give the score label a name so it becomes easy to find later when // the score needs to be updated. scoreLabel.name = kScoreHudName; scoreLabel.fontSize = 15; //2 - Color the score label green scoreLabel.fontColor = [SKColor greenColor]; scoreLabel.text = [NSString stringWithFormat:@"Score: %04u", 0]; //3 - Positions the score label near the top left corner of the screen scoreLabel.position = CGPointMake(20 + scoreLabel.frame.size.width/2, self.size.height - (20 + scoreLabel.frame.size.height/2)); [self addChild:scoreLabel]; //Applies the font of the health label SKLabelNode* healthLabel = [SKLabelNode labelNodeWithFontNamed:@"Courier"]; //4 - Give the health label a name so it can be referenced later when it needs // to be updated to display the health healthLabel.name = kHealthHudName; healthLabel.fontSize = 15; //5 - Colors the health label red healthLabel.fontColor = [SKColor redColor]; healthLabel.text = [NSString stringWithFormat:@"Health: %.1f%%", 100.0f]; //6 - Positions the health Label on the upper right hand side of the screen healthLabel.position = CGPointMake(self.size.width - healthLabel.frame.size.width/2 - 20, self.size.height - (20 + healthLabel.frame.size.height/2)); [self addChild:healthLabel]; } #pragma mark - Scene Update - (void)update:(NSTimeInterval)currentTime { //Makes the invaders move [self moveInvadersForUpdate:currentTime]; } #pragma mark - Scene Update Helpers //This method will get invoked by update -(void)moveInvadersForUpdate:(NSTimeInterval)currentTime { //1 - if it's not yet time to move, exit the method. moveInvadersForUpdate: // is invoked 60 times per second, but you don't want the invaders to move // that often since the movement would be too fast to see if (currentTime - self.timeOfLastMove < self.timePerMove) return; //2 - Recall that the scene holds all the invaders as child nodes; which were // added to the scene using addChild: in setupInvaders identifying each invader // by its name property. Invoking enumerateChildNodesWithName:usingBlock only loops over the invaders because they're named kInvaderType; which makes the loop skip the ship and the HUD. The guts og the block moves the invaders 10 pixels either right, left or down depending on the value of invaderMovementDirection [self enumerateChildNodesWithName:kInvaderName usingBlock:^(SKNode *node, BOOL *stop) { switch (self.invaderMovementDirection) { case InvaderMovementDirectionRight: node.position = CGPointMake(node.position.x - 10, node.position.y); break; case InvaderMovementDirectionLeft: node.position = CGPointMake(node.position.x - 10, node.position.y); break; case InvaderMovementDirectionDownThenLeft: case InvaderMovementDirectionDownThenRight: node.position = CGPointMake(node.position.x, node.position.y - 10); break; InvaderMovementDirectionNone: default: break; } }]; //3 - Record that you just moved the invaders, so that the next time this method is invoked (1/60th of a second from when it starts), the invaders won't move again until the set time period of one second has elapsed. self.timeOfLastMove = currentTime; //Makes it so that the invader movement direction changes only when the invaders are actually moving. Invaders only move when the check on self.timeOfLastMove passes (when conditional expression is true) [self determineInvaderMovementDirection]; } #pragma mark - Invader Movement Helpers -(void)determineInvaderMovementDirection { //1 - Since local vars accessed by block are default const(means they cannot be changed), this snippet of code qualifies proposedMovementDirection with __block so that you can modify it in //2 __block InvaderMovementDirection proposedMovementDirection = self.invaderMovementDirection; //2 - Loops over the invaders in the scene and refers to the block with the invader as an argument [self enumerateChildNodesWithName:kInvaderName usingBlock:^(SKNode *node, BOOL *stop) { switch (self.invaderMovementDirection) { case InvaderMovementDirectionRight: //3 - If the invader's right edge is within 1pt of the right edge of the scene, it's about to move offscreen. Sets proposedMovementDirection so that the invaders move down then left. You compare the invader's frame(the frame that contains its content in the scene's coordinate system) with the scene width. Since the scene has an anchorPoint of (0,0) by default and is scaled to fill it's parent view, this comparison ensures you're testing against the view's edges. if (CGRectGetMaxX(node.frame) >= node.scene.size.width - 1.0f) { proposedMovementDirection = InvaderMovementDirectionDownThenLeft; *stop = YES; } break; case InvaderMovementDirectionLeft: //4 - If the invader's left edge is within 1 pt of the left edge of the scene, it's about to move offscreen. Sets the proposedMovementDirection so invaders move down then right if (CGRectGetMinX(node.frame) <= 1.0f) { proposedMovementDirection = InvaderMovementDirectionDownThenRight; *stop = YES; } break; case InvaderMovementDirectionDownThenLeft: //5 - If invaders are moving down then left, they already moved down at this point, so they should now move left. proposedMovementDirection = InvaderMovementDirectionLeft; *stop = YES; break; case InvaderMovementDirectionDownThenRight: //6 - if the invaders are moving down then right, they already moved down so they should now move right. proposedMovementDirection = InvaderMovementDirectionRight; *stop = YES; break; default: break; } }]; //7 - if the proposed invader movement direction is different than the current invader movement direction, update the current direction to the proposed direction if (proposedMovementDirection != self.invaderMovementDirection) { self.invaderMovementDirection = proposedMovementDirection; } } #pragma mark - Bullet Helpers #pragma mark - User Tap Helpers #pragma mark - HUD Helpers #pragma mark - Physics Contact Helpers #pragma mark - Game End Helpers @end

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Problems extracting information from RSS feed description field

- by Graeme

Hi, I've built an iPhone application using the parsing code from the TopSongs sample iPhone application. I've hit a problem though - the feed I'm trying to parse data from doesn't have a separate field for every piece of information (i.e. if it was for a feed about dogs, all the information such as dog type, dog age and dog price is contained in the feed. However, the TopSongs app relies on information having its own tags, so instead of using it uses and . So my question is this. How do I extract this information from the description field so that it can be parsed using the TopSongs parser? Can you somehow extract the dog age, price and type information using Yahoo Pipes and use that RSS feed for the feed? Or is there code that I can add to do it in application? Update: To view the code of my application parser (based on the TopSongs Core Data Apple provided application, see below. Here's a sample of one item from the the actual RSS feed I'm using (the description is longer, and has status,size, and a couple of other fields, but they're all formatted the same.: <item> <title>MOE, MARGRET STREET</title> <description> <b>District/Region:</b> REGION 09</br><b>Location:</b> MOE</br><b>Name:</b> MARGRET STREET</br></description> <pubDate>Thu,11 Mar 2010 05:43:03 GMT</pubDate> <guid>1266148</guid> </item> /* File: iTunesRSSImporter.m Abstract: Downloads, parses, and imports the iTunes top songs RSS feed into Core Data. Version: 1.1 Disclaimer: IMPORTANT: This Apple software is supplied to you by Apple Inc. ("Apple") in consideration of your agreement to the following terms, and your use, installation, modification or redistribution of this Apple software constitutes acceptance of these terms. If you do not agree with these terms, please do not use, install, modify or redistribute this Apple software. In consideration of your agreement to abide by the following terms, and subject to these terms, Apple grants you a personal, non-exclusive license, under Apple's copyrights in this original Apple software (the "Apple Software"), to use, reproduce, modify and redistribute the Apple Software, with or without modifications, in source and/or binary forms; provided that if you redistribute the Apple Software in its entirety and without modifications, you must retain this notice and the following text and disclaimers in all such redistributions of the Apple Software. Neither the name, trademarks, service marks or logos of Apple Inc. may be used to endorse or promote products derived from the Apple Software without specific prior written permission from Apple. Except as expressly stated in this notice, no other rights or licenses, express or implied, are granted by Apple herein, including but not limited to any patent rights that may be infringed by your derivative works or by other works in which the Apple Software may be incorporated. The Apple Software is provided by Apple on an "AS IS" basis. APPLE MAKES NO WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION THE IMPLIED WARRANTIES OF NON-INFRINGEMENT, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, REGARDING THE APPLE SOFTWARE OR ITS USE AND OPERATION ALONE OR IN COMBINATION WITH YOUR PRODUCTS. IN NO EVENT SHALL APPLE BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) ARISING IN ANY WAY OUT OF THE USE, REPRODUCTION, MODIFICATION AND/OR DISTRIBUTION OF THE APPLE SOFTWARE, HOWEVER CAUSED AND WHETHER UNDER THEORY OF CONTRACT, TORT (INCLUDING NEGLIGENCE), STRICT LIABILITY OR OTHERWISE, EVEN IF APPLE HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. Copyright (C) 2009 Apple Inc. All Rights Reserved. */ #import "iTunesRSSImporter.h" #import "Song.h" #import "Category.h" #import "CategoryCache.h" #import <libxml/tree.h> // Function prototypes for SAX callbacks. This sample implements a minimal subset of SAX callbacks. // Depending on your application's needs, you might want to implement more callbacks. static void startElementSAX(void *context, const xmlChar *localname, const xmlChar *prefix, const xmlChar *URI, int nb_namespaces, const xmlChar **namespaces, int nb_attributes, int nb_defaulted, const xmlChar **attributes); static void endElementSAX(void *context, const xmlChar *localname, const xmlChar *prefix, const xmlChar *URI); static void charactersFoundSAX(void *context, const xmlChar *characters, int length); static void errorEncounteredSAX(void *context, const char *errorMessage, ...); // Forward reference. The structure is defined in full at the end of the file. static xmlSAXHandler simpleSAXHandlerStruct; // Class extension for private properties and methods. @interface iTunesRSSImporter () @property BOOL storingCharacters; @property (nonatomic, retain) NSMutableData *characterBuffer; @property BOOL done; @property BOOL parsingASong; @property NSUInteger countForCurrentBatch; @property (nonatomic, retain) Song *currentSong; @property (nonatomic, retain) NSURLConnection *rssConnection; @property (nonatomic, retain) NSDateFormatter *dateFormatter; // The autorelease pool property is assign because autorelease pools cannot be retained. @property (nonatomic, assign) NSAutoreleasePool *importPool; @end static double lookuptime = 0; @implementation iTunesRSSImporter @synthesize iTunesURL, delegate, persistentStoreCoordinator; @synthesize rssConnection, done, parsingASong, storingCharacters, currentSong, countForCurrentBatch, characterBuffer, dateFormatter, importPool; - (void)dealloc { [iTunesURL release]; [characterBuffer release]; [currentSong release]; [rssConnection release]; [dateFormatter release]; [persistentStoreCoordinator release]; [insertionContext release]; [songEntityDescription release]; [theCache release]; [super dealloc]; } - (void)main { self.importPool = [[NSAutoreleasePool alloc] init]; if (delegate && [delegate respondsToSelector:@selector(importerDidSave:)]) { [[NSNotificationCenter defaultCenter] addObserver:delegate selector:@selector(importerDidSave:) name:NSManagedObjectContextDidSaveNotification object:self.insertionContext]; } done = NO; self.dateFormatter = [[[NSDateFormatter alloc] init] autorelease]; [dateFormatter setDateStyle:NSDateFormatterLongStyle]; [dateFormatter setTimeStyle:NSDateFormatterNoStyle]; // necessary because iTunes RSS feed is not localized, so if the device region has been set to other than US // the date formatter must be set to US locale in order to parse the dates [dateFormatter setLocale:[[[NSLocale alloc] initWithLocaleIdentifier:@"US"] autorelease]]; self.characterBuffer = [NSMutableData data]; NSURLRequest *theRequest = [NSURLRequest requestWithURL:iTunesURL]; // create the connection with the request and start loading the data rssConnection = [[NSURLConnection alloc] initWithRequest:theRequest delegate:self]; // This creates a context for "push" parsing in which chunks of data that are not "well balanced" can be passed // to the context for streaming parsing. The handler structure defined above will be used for all the parsing. // The second argument, self, will be passed as user data to each of the SAX handlers. The last three arguments // are left blank to avoid creating a tree in memory. context = xmlCreatePushParserCtxt(&simpleSAXHandlerStruct, self, NULL, 0, NULL); if (rssConnection != nil) { do { [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]]; } while (!done); } // Display the total time spent finding a specific object for a relationship NSLog(@"lookup time %f", lookuptime); // Release resources used only in this thread. xmlFreeParserCtxt(context); self.characterBuffer = nil; self.dateFormatter = nil; self.rssConnection = nil; self.currentSong = nil; [theCache release]; theCache = nil; NSError *saveError = nil; NSAssert1([insertionContext save:&saveError], @"Unhandled error saving managed object context in import thread: %@", [saveError localizedDescription]); if (delegate && [delegate respondsToSelector:@selector(importerDidSave:)]) { [[NSNotificationCenter defaultCenter] removeObserver:delegate name:NSManagedObjectContextDidSaveNotification object:self.insertionContext]; } if (self.delegate != nil && [self.delegate respondsToSelector:@selector(importerDidFinishParsingData:)]) { [self.delegate importerDidFinishParsingData:self]; } [importPool release]; self.importPool = nil; } - (NSManagedObjectContext *)insertionContext { if (insertionContext == nil) { insertionContext = [[NSManagedObjectContext alloc] init]; [insertionContext setPersistentStoreCoordinator:self.persistentStoreCoordinator]; } return insertionContext; } - (void)forwardError:(NSError *)error { if (self.delegate != nil && [self.delegate respondsToSelector:@selector(importer:didFailWithError:)]) { [self.delegate importer:self didFailWithError:error]; } } - (NSEntityDescription *)songEntityDescription { if (songEntityDescription == nil) { songEntityDescription = [[NSEntityDescription entityForName:@"Song" inManagedObjectContext:self.insertionContext] retain]; } return songEntityDescription; } - (CategoryCache *)theCache { if (theCache == nil) { theCache = [[CategoryCache alloc] init]; theCache.managedObjectContext = self.insertionContext; } return theCache; } - (Song *)currentSong { if (currentSong == nil) { currentSong = [[Song alloc] initWithEntity:self.songEntityDescription insertIntoManagedObjectContext:self.insertionContext]; } return currentSong; } #pragma mark NSURLConnection Delegate methods // Forward errors to the delegate. - (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error { [self performSelectorOnMainThread:@selector(forwardError:) withObject:error waitUntilDone:NO]; // Set the condition which ends the run loop. done = YES; } // Called when a chunk of data has been downloaded. - (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data { // Process the downloaded chunk of data. xmlParseChunk(context, (const char *)[data bytes], [data length], 0); } - (void)connectionDidFinishLoading:(NSURLConnection *)connection { // Signal the context that parsing is complete by passing "1" as the last parameter. xmlParseChunk(context, NULL, 0, 1); context = NULL; // Set the condition which ends the run loop. done = YES; } #pragma mark Parsing support methods static const NSUInteger kImportBatchSize = 20; - (void)finishedCurrentSong { parsingASong = NO; self.currentSong = nil; countForCurrentBatch++; // Periodically purge the autorelease pool and save the context. The frequency of this action may need to be tuned according to the // size of the objects being parsed. The goal is to keep the autorelease pool from growing too large, but // taking this action too frequently would be wasteful and reduce performance. if (countForCurrentBatch == kImportBatchSize) { [importPool release]; self.importPool = [[NSAutoreleasePool alloc] init]; NSError *saveError = nil; NSAssert1([insertionContext save:&saveError], @"Unhandled error saving managed object context in import thread: %@", [saveError localizedDescription]); countForCurrentBatch = 0; } } /* Character data is appended to a buffer until the current element ends. */ - (void)appendCharacters:(const char *)charactersFound length:(NSInteger)length { [characterBuffer appendBytes:charactersFound length:length]; } - (NSString *)currentString { // Create a string with the character data using UTF-8 encoding. UTF-8 is the default XML data encoding. NSString *currentString = [[[NSString alloc] initWithData:characterBuffer encoding:NSUTF8StringEncoding] autorelease]; [characterBuffer setLength:0]; return currentString; } @end #pragma mark SAX Parsing Callbacks // The following constants are the XML element names and their string lengths for parsing comparison. // The lengths include the null terminator, to ensure exact matches. static const char *kName_Item = "item"; static const NSUInteger kLength_Item = 5; static const char *kName_Title = "title"; static const NSUInteger kLength_Title = 6; static const char *kName_Category = "category"; static const NSUInteger kLength_Category = 9; static const char *kName_Itms = "itms"; static const NSUInteger kLength_Itms = 5; static const char *kName_Artist = "description"; static const NSUInteger kLength_Artist = 7; static const char *kName_Album = "description"; static const NSUInteger kLength_Album = 6; static const char *kName_ReleaseDate = "releasedate"; static const NSUInteger kLength_ReleaseDate = 12; /* This callback is invoked when the importer finds the beginning of a node in the XML. For this application, out parsing needs are relatively modest - we need only match the node name. An "item" node is a record of data about a song. In that case we create a new Song object. The other nodes of interest are several of the child nodes of the Song currently being parsed. For those nodes we want to accumulate the character data in a buffer. Some of the child nodes use a namespace prefix. */ static void startElementSAX(void *parsingContext, const xmlChar *localname, const xmlChar *prefix, const xmlChar *URI, int nb_namespaces, const xmlChar **namespaces, int nb_attributes, int nb_defaulted, const xmlChar **attributes) { iTunesRSSImporter *importer = (iTunesRSSImporter *)parsingContext; // The second parameter to strncmp is the name of the element, which we known from the XML schema of the feed. // The third parameter to strncmp is the number of characters in the element name, plus 1 for the null terminator. if (prefix == NULL && !strncmp((const char *)localname, kName_Item, kLength_Item)) { importer.parsingASong = YES; } else if (importer.parsingASong && ( (prefix == NULL && (!strncmp((const char *)localname, kName_Title, kLength_Title) || !strncmp((const char *)localname, kName_Category, kLength_Category))) || ((prefix != NULL && !strncmp((const char *)prefix, kName_Itms, kLength_Itms)) && (!strncmp((const char *)localname, kName_Artist, kLength_Artist) || !strncmp((const char *)localname, kName_Album, kLength_Album) || !strncmp((const char *)localname, kName_ReleaseDate, kLength_ReleaseDate))) )) { importer.storingCharacters = YES; } } /* This callback is invoked when the parse reaches the end of a node. At that point we finish processing that node, if it is of interest to us. For "item" nodes, that means we have completed parsing a Song object. We pass the song to a method in the superclass which will eventually deliver it to the delegate. For the other nodes we care about, this means we have all the character data. The next step is to create an NSString using the buffer contents and store that with the current Song object. */ static void endElementSAX(void *parsingContext, const xmlChar *localname, const xmlChar *prefix, const xmlChar *URI) { iTunesRSSImporter *importer = (iTunesRSSImporter *)parsingContext; if (importer.parsingASong == NO) return; if (prefix == NULL) { if (!strncmp((const char *)localname, kName_Item, kLength_Item)) { [importer finishedCurrentSong]; } else if (!strncmp((const char *)localname, kName_Title, kLength_Title)) { importer.currentSong.title = importer.currentString; } else if (!strncmp((const char *)localname, kName_Category, kLength_Category)) { double before = [NSDate timeIntervalSinceReferenceDate]; Category *category = [importer.theCache categoryWithName:importer.currentString]; double delta = [NSDate timeIntervalSinceReferenceDate] - before; lookuptime += delta; importer.currentSong.category = category; } } else if (!strncmp((const char *)prefix, kName_Itms, kLength_Itms)) { if (!strncmp((const char *)localname, kName_Artist, kLength_Artist)) { NSString *string = importer.currentSong.artist; NSArray *strings = [string componentsSeparatedByString: @", "]; //importer.currentSong.artist = importer.currentString; } else if (!strncmp((const char *)localname, kName_Album, kLength_Album)) { importer.currentSong.album = importer.currentString; } else if (!strncmp((const char *)localname, kName_ReleaseDate, kLength_ReleaseDate)) { NSString *dateString = importer.currentString; importer.currentSong.releaseDate = [importer.dateFormatter dateFromString:dateString]; } } importer.storingCharacters = NO; } /* This callback is invoked when the parser encounters character data inside a node. The importer class determines how to use the character data. */ static void charactersFoundSAX(void *parsingContext, const xmlChar *characterArray, int numberOfCharacters) { iTunesRSSImporter *importer = (iTunesRSSImporter *)parsingContext; // A state variable, "storingCharacters", is set when nodes of interest begin and end. // This determines whether character data is handled or ignored. if (importer.storingCharacters == NO) return; [importer appendCharacters:(const char *)characterArray length:numberOfCharacters]; } /* A production application should include robust error handling as part of its parsing implementation. The specifics of how errors are handled depends on the application. */ static void errorEncounteredSAX(void *parsingContext, const char *errorMessage, ...) { // Handle errors as appropriate for your application. NSCAssert(NO, @"Unhandled error encountered during SAX parse."); } // The handler struct has positions for a large number of callback functions. If NULL is supplied at a given position, // that callback functionality won't be used. Refer to libxml documentation at http://www.xmlsoft.org for more information // about the SAX callbacks. static xmlSAXHandler simpleSAXHandlerStruct = { NULL, /* internalSubset */ NULL, /* isStandalone */ NULL, /* hasInternalSubset */ NULL, /* hasExternalSubset */ NULL, /* resolveEntity */ NULL, /* getEntity */ NULL, /* entityDecl */ NULL, /* notationDecl */ NULL, /* attributeDecl */ NULL, /* elementDecl */ NULL, /* unparsedEntityDecl */ NULL, /* setDocumentLocator */ NULL, /* startDocument */ NULL, /* endDocument */ NULL, /* startElement*/ NULL, /* endElement */ NULL, /* reference */ charactersFoundSAX, /* characters */ NULL, /* ignorableWhitespace */ NULL, /* processingInstruction */ NULL, /* comment */ NULL, /* warning */ errorEncounteredSAX, /* error */ NULL, /* fatalError //: unused error() get all the errors */ NULL, /* getParameterEntity */ NULL, /* cdataBlock */ NULL, /* externalSubset */ XML_SAX2_MAGIC, // NULL, startElementSAX, /* startElementNs */ endElementSAX, /* endElementNs */ NULL, /* serror */ }; Thanks.

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Can ping device from one computer and not the other

- by Sean Duggan

I've recently been assigned to work on a diagnostic program done in C++ which communicates with a piece of electronic equipment. Our normal scenario involves communicating via an RS232 interface, but I've been asked to make our program work over ethernet, source code having been done in Visual Basic. After much thrashing about trying to get the code to work and continuing to get 10049 Winsock errors when I tried to connect, I tried pinging the switch. From the computer the VB program is running on, I can see the switch via ping, nslookup, tracert, and pathping (I was going down the list of programs) and I can do this via URI or IP address. From my laptop, sending the same commands fails every time. They're both using the same network cable and the same USB-to-Ethernet device (I've been swapping them between tests) but one can see the switch and the other cannot. I'm working on the programming end, but the ping results makes me think that there might be a network issue stymieing me. wry grin I'm not much of a network guy, so I'm appealing to expert assistance. Both computers are running Windows XP if that helps. The connection is to an "IP-RS8" device which then connects to our VCU-C units. Each unit is accessible via URI or IP address on the desktop computer we usually have connected to the units (it's running the older VB program that I was asked to lift the networking code from). The connection is made via a USB-to-Ethernet adapter so as to leave the regular Ethernet port available for connecting to the company network. Hmm... come to think of it, I've probably been confusing the issue, talking about pinging "the switch" rather than indicating that it's the devices. My apologies. Communication is generally done with a DLL that uses Winsock functions to make queries for data from the VCU and then to receive. I'm failing when connecting. I haven't found anything on the firewall which should block these commands, but I'll keep poking. I don't know if it's potentially relevant, but on the desktop, the adapter maps to Local Area Connection 3 while on the laptop, it consistently maps to Local Area Connection 2. Currently reading up on DHCP. IPConfig /all results: Desktop Host Name . . . . . . . . . . . . : AMERDAEXXXXXX Primary Dns Suffix . . . . . . . : amer.example.com Node Type . . . . . . . . . . . . : Hybrid IP Routing Enabled. . . . . . . . : No WINS Proxy Enabled. . . . . . . . : No DNS Suffix Search List. . . . . . : COMPANY.com amer.example.com atle.example.com cone.example.com apac.example.com scan.example.com bYX.example.com Ethernet adapter Local Area Connection X: Connection-specific DNS Suffix . : amer.example.com Description . . . . . . . . . . . : Broadcom NetXtreme XYxx Gigabit Controller Physical Address. . . . . . . . . : YY-XX-YB-XX-XX-XX Dhcp Enabled. . . . . . . . . . . : Yes Autoconfiguration Enabled . . . . : Yes IP Address. . . . . . . . . . . . : XYY.XXX.XY.XXX Subnet Mask . . . . . . . . . . . : XXX.XXX.XXY.Y Default Gateway . . . . . . . . . : XYY.XXX.XY.X DHCP Server . . . . . . . . . . . : XY.XXX.XXY.XX DNS Servers . . . . . . . . . . . : XY.XXX.XXY.XX XY.XXY.XXY.XX Primary WINS Server . . . . . . . : XY.XXX.XXY.X Secondary WINS Server . . . . . . : XY.XXY.XXY.X Lease Obtained. . . . . . . . . . : Thursday, July XX, XYXX XY:XX:XX AM Lease Expires . . . . . . . . . . : Sunday, July XX, XYXX XY:XX:XX AM Ethernet adapter Local Area Connection X: Connection-specific DNS Suffix . : Description . . . . . . . . . . . : ASIX axYYYYX USBX.Y to Fast Ethernet Adapter Physical Address. . . . . . . . . : YY-XY-BY-YX-XY-AY Dhcp Enabled. . . . . . . . . . . : Yes Autoconfiguration Enabled . . . . : Yes IP Address. . . . . . . . . . . . : XY.Y.Y.X Subnet Mask . . . . . . . . . . . : XXX.XXX.XXY.Y Default Gateway . . . . . . . . . : XY.Y.Y.X DHCP Server . . . . . . . . . . . : XY.Y.Y.XY DNS Servers . . . . . . . . . . . : XY.Y.Y.X Lease Obtained. . . . . . . . . . : Thursday, July XX, XYXX XY:XX:XY AM Lease Expires . . . . . . . . . . : Tuesday, August YX, XYXX XX:XY:XY AM Laptop Windows IP Configuration Host Name . . . . . . . . . . . . : AMERLAFYYXXYX Primary Dns Suffix . . . . . . . : amer.example.com Node Type . . . . . . . . . . . . : Hybrid IP Routing Enabled. . . . . . . . : No WINS Proxy Enabled. . . . . . . . : No DNS Suffix Search List. . . . . . : COMPANY.com amer.example.com atle.example.com cone.example.com apac.example.com scan.example.com bYX.example.com Ethernet adapter Local Area Connection: Connection-specific DNS Suffix . : amer.example.com Description . . . . . . . . . . . : Intel(R) 82567LM Gigabit Network Connection Physical Address. . . . . . . . . : YY-XY-BY-DY-XB-YX Dhcp Enabled. . . . . . . . . . . : Yes Autoconfiguration Enabled . . . . : Yes IP Address. . . . . . . . . . . . : XYY.XXX.XY.XY Subnet Mask . . . . . . . . . . . : XXX.XXX.XXY.Y Default Gateway . . . . . . . . . : XYY.XXX.XY.X DHCP Server . . . . . . . . . . . : XY.XXX.XXY.XX DNS Servers . . . . . . . . . . . : XY.XXX.XXY.XX XY.XXY.XXY.XX Primary WINS Server . . . . . . . : XY.XXX.XXY.X Secondary WINS Server . . . . . . : XY.XXY.XXY.X Lease Obtained. . . . . . . . . . : Thursday, July XX, XYXX XX:XX:XX AM Lease Expires . . . . . . . . . . : Sunday, July XX, XYXX XX:XX:XX AM Ethernet adapter {XYXAAYXX-YEDY-XXYX-YYEX-BYXYXXYEEYEX}: Connection-specific DNS Suffix . : Description . . . . . . . . . . . : Nortel IPSECSHM Adapter - Packet Scheduler iniport Physical Address. . . . . . . . . : XX-XX-XX-XX-XX-YY Dhcp Enabled. . . . . . . . . . . : No IP Address. . . . . . . . . . . . : Y.Y.Y.Y Subnet Mask . . . . . . . . . . . : Y.Y.Y.Y Default Gateway . . . . . . . . . : Ethernet adapter Leaf Networks Adapter: Connection-specific DNS Suffix . : Description . . . . . . . . . . . : Leaf Networks Adapter Physical Address. . . . . . . . . : YY-FF-FA-BC-YF-AY Dhcp Enabled. . . . . . . . . . . : No IP Address. . . . . . . . . . . . : X.XYY.XY.XX Subnet Mask . . . . . . . . . . . : XXX.Y.Y.Y Default Gateway . . . . . . . . . : Ethernet adapter Local Area Connection 3: Media State . . . . . . . . . . . : Media disconnected Description . . . . . . . . . . . : Bluetooth LAN Access Server Driver Physical Address. . . . . . . . . : YY-FX-AX-YA-BY-CA Ethernet adapter Wireless Network Connection 2: Media State . . . . . . . . . . . : Media disconnected Description . . . . . . . . . . . : Intel(R) WiFi Link 5300 AGN Physical Address. . . . . . . . . : YY-XX-YA-CX-FC-YE Ethernet adapter Local Area Connection 2: Connection-specific DNS Suffix . : Description . . . . . . . . . . . : ASIX ax88772 USB2.0 to Fast Ethernet Adapter Physical Address. . . . . . . . . : YY-XY-BY-YX-XY-AY Dhcp Enabled. . . . . . . . . . . : No IP Address. . . . . . . . . . . . : XYX.XYY.X.X Subnet Mask . . . . . . . . . . . : XXX.XXX.XXX.Y Default Gateway . . . . . . . . . :

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