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• vector iterator not dereferencable at runtime on a vector<vector<vector<A*>*>*>

  - by marouanebj

  Hi, I have this destructor that create error at runtime "vector iterator not dereferencable". The gridMatrix is a std::vector<std::vector<std::vector<AtomsCell< Atom<T> * > * > * > * > I added the typename and also the typedef but I still have the error. I will move for this idea of vect of vect* of vect* to use boost::multi_array I think, but still I want to understand were this is wrong. /// @brief destructor ~AtomsGrid(void) { // free all the memory for all the pointers inside gridMatrix (all except the Atom<T>* ) //typedef typename ::value_type value_type; typedef std::vector<AtomsCell< Atom<T>* >*> std_vectorOfAtomsCell; typedef std::vector<std_vectorOfAtomsCell*> std_vectorOfVectorOfAtomsCell; std_vectorOfAtomsCell* vectorOfAtomsCell; std_vectorOfVectorOfAtomsCell* vectorOfVecOfAtomsCell; typename std_vectorOfVectorOfAtomsCell::iterator itSecond; typename std_vectorOfVectorOfAtomsCell::reverse_iterator reverseItSecond; typename std::vector<std_vectorOfVectorOfAtomsCell*>::iterator itFirst; //typename std::vector<AtomsCell< Atom<T>* >*>* vectorOfAtomsCell; //typename std::vector<std::vector<AtomsCell< Atom<T>* >*>*>* vectorOfVecOfAtomsCell; //typename std::vector<std::vector<AtomsCell< Atom<T>* >*>*>::iterator itSecond; //typename std::vector<std::vector<AtomsCell< Atom<T>* >*>*>::reverse_iterator reverseItSecond; //typename std::vector<std::vector<std::vector<AtomsCell< Atom<T>* >*>*>*>::iterator itFirst; for (itFirst = gridMatrix.begin(); itFirst != gridMatrix.end(); ++itFirst) { vectorOfVecOfAtomsCell = (*itFirst); while (!vectorOfVecOfAtomsCell->empty()) { reverseItSecond = vectorOfVecOfAtomsCell->rbegin(); itSecond = vectorOfVecOfAtomsCell->rbegin().base(); vectorOfAtomsCell = (*itSecond); // ERROR during run: "vector iterator not dereferencable" // I think the ERROR is because I need some typedef typename or template ???!!! // the error seems here event at itFirst //fr_Myit_Utils::vectorElementDeleter(*vectorOfAtomsCell); //vectorOfVecOfAtomsCell->pop_back(); } } fr_Myit_Utils::vectorElementDeleter(gridMatrix); } If someone want the full code that create the error I'm happy to give it but I do not think we can attach file in the forum. BUT still its is not very big so if you want it I can copy past it here. Thanks

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• How to use SQL file streaming win32 API and support WCF streaming

  - by Mahesh

  I'm using Sql server file stream type to store large files in the backend. I'm trying to use WCf to stream the file across to the clients. I'm able to get the handle to the file using SQLFileStream (API). I then try to return this stream. I have implemenetd data chunking on the client side to retrive the data from the stream. I'm able to do it for regular filestream and memory stream. Also if i convert then sqlfilestream in to memorystream that also works. The only think that doesn't work is when I try to return sqlfilestream. What am I doing wrong. I have tried both nettcpbinding with streaming enabled and http binding with MTOM encoding. This is the error message am getting : Socket connection was aborted. This could be caused by an error processing your mesage or a receive timeout being exceeded by the remote host, or an underlying network issue.. Local socket timneout was 00:09:59.... Here is my sample code RemoteFileInfo info = new RemoteFileInfo(); info.FileName = "SampleXMLFileService.xml"; string pathName = DataAccess.GetDataSnapshotPath("DataSnapshot1"); SqlConnection connection = DataAccess.GetConnection(); SqlTransaction sqlTransaction = connection.BeginTransaction("SQLSileStreamingTrans"); SqlCommand command = new SqlCommand(); command.Connection = connection; command.Transaction = sqlTransaction; command.CommandText = "SELECT GET_FILESTREAM_TRANSACTION_CONTEXT()"; byte[] transcationContext = command.ExecuteScalar() as byte[]; SqlFileStream stream = new SqlFileStream(pathName, transcationContext, FileAccess.Read); // byte[] bytes = new byte[stream.Length]; // stream.Read(bytes, 0, (int) stream.Length); // Stream reeturnStream = stream; // MemoryStream memoryStream = new MemoryStream(bytes); info.FileByteStream = stream; info.Length = info.FileByteStream.Length; connection.Close(); return info; [MessageContract] public class RemoteFileInfo : IDisposable { [MessageHeader(MustUnderstand = true)] public string FileName; [MessageHeader(MustUnderstand = true)] public long Length; [MessageBodyMember(Order = 1)] public System.IO.Stream FileByteStream; public void Dispose() { if (FileByteStream != null) { FileByteStream.Close(); FileByteStream = null; } } } ANy help is appreciated

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• Importing CSV filte to SQL server...

  - by sam

  HI guys, I am trying to import CSV file to SQL server database, no success, I am still newbie to sql server, thanks Operation stopped... Initializing Data Flow Task (Success) Initializing Connections (Success) Setting SQL Command (Success) Setting Source Connection (Success) Setting Destination Connection (Success) Validating (Success) Messages Warning 0x80049304: Data Flow Task 1: Warning: Could not open global shared memory to communicate with performance DLL; data flow performance counters are not available. To resolve, run this package as an administrator, or on the system's console. (SQL Server Import and Export Wizard) Prepare for Execute (Success) Pre-execute (Success) Messages Information 0x402090dc: Data Flow Task 1: The processing of file "D:\test.csv" has started. (SQL Server Import and Export Wizard) Executing (Error) Messages Error 0xc002f210: Drop table(s) SQL Task 1: Executing the query "drop table [dbo].[test] " failed with the following error: "Cannot drop the table 'dbo.test', because it does not exist or you do not have permission.". Possible failure reasons: Problems with the query, "ResultSet" property not set correctly, parameters not set correctly, or connection not established correctly. (SQL Server Import and Export Wizard) Error 0xc02020a1: Data Flow Task 1: Data conversion failed. The data conversion for column ""Code"" returned status value 4 and status text "Text was truncated or one or more characters had no match in the target code page.". (SQL Server Import and Export Wizard) Error 0xc020902a: Data Flow Task 1: The "output column ""Code"" (38)" failed because truncation occurred, and the truncation row disposition on "output column ""Code"" (38)" specifies failure on truncation. A truncation error occurred on the specified object of the specified component. (SQL Server Import and Export Wizard) Error 0xc0202092: Data Flow Task 1: An error occurred while processing file "D:\test.csv" on data row 21. (SQL Server Import and Export Wizard) Error 0xc0047038: Data Flow Task 1: SSIS Error Code DTS_E_PRIMEOUTPUTFAILED. The PrimeOutput method on component "Source - test_csv" (1) returned error code 0xC0202092. The component returned a failure code when the pipeline engine called PrimeOutput(). The meaning of the failure code is defined by the component, but the error is fatal and the pipeline stopped executing. There may be error messages posted before this with more information about the failure. (SQL Server Import and Export Wizard) Copying to [dbo].[test] (Stopped) Post-execute (Success) Messages Information 0x402090dd: Data Flow Task 1: The processing of file "D:\test.csv" has ended. (SQL Server Import and Export Wizard) Information 0x402090df: Data Flow Task 1: The final commit for the data insertion in "component "Destination - test" (70)" has started. (SQL Server Import and Export Wizard) Information 0x402090e0: Data Flow Task 1: The final commit for the data insertion in "component "Destination - test" (70)" has ended. (SQL Server Import and Export Wizard) Information 0x4004300b: Data Flow Task 1: "component "Destination - test" (70)" wrote 0 rows. (SQL Server Import and Export Wizard)

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• sharepoint search is not working

  - by Nikkho

  Hi all, I have an issue with SharePoint search. The situation The server is installed with SharePoint on a farm with 2 servers. A new app pool is created and that app pool is using a domain account called moss_service. moss_service is set to be in the administrator group in both server. moss_service is also set to be the db_creator in the content database. When I checked it initially, the search's default content access account is using another different account, I changed that to be using moss_service account. I didn't do IIS reset because this is a production server, they dont want frequent iis reset. Strangely, checking the services.msc under "office sharepoint server search" the account is still using an old one. (and apparently it's only running on 1 server, the other server is not running) I then change that to the following: domain\moss_service with the password. and then I rerun the crawl. How do I diagnose the issue Basically everytime I change something I restart the crawl and then check the event viewer. Multiple things come out but the following is the major ones: The start address cannot be crawled. The password for the content access account cannot be decrypted because it was stored with different credentials. Re-type the password for the account used to crawl this content. (0x80042406) Performance monitoring cannot be initialized for the gatherer object, because the counters are not loaded or the shared memory object cannot be opened. This only affects availability of the perfmon counters. Restart the computer. Access is denied. Check that the Default Content Access Account has access to this content, or add a crawl rule to crawl this content. (0x80041205) Crawl Logs Result The crawl log is showing this: The password for the content access account cannot be decrypted because it was stored with different credentials. Re-type the password for the account used to crawl this content. I tried changing it again at service.mstsc and the rerun the full crawl again but then it doesn't work. I have tried entering it using the following way: [email protected] and domain\moss_service My Questions are: How do I fix this? Is this the right way to setup the search? Does the search account has to be using a different domain account? Seemed like one fix complicates the other, how do I set this right? Is it worth it to upgrade to sp2?

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• Unable to retrieve information form HP-UX pst_status object

  - by bogertron

  I am attempting to get process information by using the HP-UX C/C++ library. After scouring the internet, I have discovered that HP-UX has the pstat.h header file which allows programmers to retrieve the process information. After attempting to understand code from the internet hp website, I attempted to create a little test sample to comprehend what the code does. I attempted to use example 3, however, I ran into several issues. The first issue came when I attempted to execute the following line of code: (void)printf("pid is %d, command is %s\n", pst[i].pst_pid, pst[i].pst_ucomm); When I attempted to print the string, I hit a memory fault. So I decided to attempt to see what the string is and came up with the following: #include <sys/param.h> #include <sys/pstat.h> #include <sys/unistd.h> #include <string.h> int main(int argc, char** argv) { #define BURST ((size_t)10) struct pst_status pst[BURST]; int i, count; int idx = 0; /* index within the context */ int index = 0; /* loop until count == 0, will occur all have been returned */ while ((count=pstat_getproc(pst, sizeof(pst[0]),BURST,idx))>0) { index = 0; printf("index: %d", index); /* got count (max of BURST) this time. process them */ while (pst[i].pst_ucomm[index] != '\0') { printf("%c", pst[i].pst_ucomm[index]); index++; } printf("\n"); for (i = 0; i < count; i++) { printf("pid is %d, command is \n", pst[i].pst_pid); } /* * now go back and do it again, using the next index after * the current 'burst' */ idx = pst[count-1].pst_idx + 1; } if (count == -1) perror("pstat_getproc()"); #undef BURST } Unfortunately, what happens is that I get the first process printed, then pid is 2, command is pid is 2, command is pid is 2, command is... I know that I must be doing something foolish since my C/C++ skills are not that great, but I cannot figure out what the issue is since the code is largely copied from the hp website. So here's the question(s) for clarity: 1. Why can't printf("%s", pst[i].pst_ucomm); handle strings? 2. Why can't I iterate over the processes in the system? Any help is greatly appreciated.

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• What are the reasons why the CPU usage doesn’t go 100% with C# and APM?

  - by Martin

  I have an application which is CPU intensive. When the data is processed on a single thread, the CPU usage goes to 100% for many minutes. So the performance of the application appears to be bound by the CPU. I have multithreaded the logic of the application, which result in an increase of the overall performance. However, the CPU usage hardly goes above 30%-50%. I would expect the CPU (and the many cores) to go to 100% since I process many set of data at the same time. Below is a simplified example of the logic I use to start the threads. When I run this example, the CPU goes to 100% (on an 8/16 cores machine). However, my application which uses the same pattern doesn’t. public class DataExecutionContext { public int Counter { get; set; } // Arrays of data } static void Main(string[] args) { // Load data from the database into the context var contexts = new List<DataExecutionContext>(100); for (int i = 0; i < 100; i++) { contexts.Add(new DataExecutionContext()); } // Data loaded. Start to process. var latch = new CountdownEvent(contexts.Count); var processData = new Action<DataExecutionContext>(c => { // The thread doesn't access data from a DB, file, // network, etc. It reads and write data in RAM only // (in its context). for (int i = 0; i < 100000000; i++) c.Counter++; }); foreach (var context in contexts) { processData.BeginInvoke(context, new AsyncCallback(ar => { latch.Signal(); }), null); } latch.Wait(); } I have reduced the number of locks to the strict minimum (only the latch is locking). The best way I found was to create a context in which a thread can read/write in memory. Contexts are not shared among other threads. The threads can’t access the database, files or network. In other words, I profiled my application and I didn’t find any bottleneck. Why the CPU usage of my application doesn’t go about 50%? Is it the pattern I use? Should I create my own thread instead of using the .Net thread pool? Is there any gotchas? Is there any tool that you could recommend me to find my issue? Thanks!

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• 'NoneType' object has no attribute 'get' error using SQLAlchemy

  - by Az

  I've been trying to map an object to a database using SQLAlchemy but have run into a snag. Version info if handy: [OS: Mac OSX 10.5.8 | Python: 2.6.4 | SQLAlchemy: 0.5.8] The class I'm going to map: class Student(object): def __init__(self, name, id): self.id = id self.name = name self.preferences = collections.defaultdict(set) self.allocated_project = None self.allocated_rank = 0 def __repr__(self): return str(self) def __str__(self): return "%s %s" %(self.id, self.name) Background: Now, I've got a function that reads in the necessary information from a text database into these objects. The function more or less works and I can easily access the information from the objects. Before the SQLAlchemy code runs, the function will read in the necessary info and store it into the Class. There is a dictionary called students which stores this as such: students = {} students[id] = Student(<all the info from the various "reader" functions>) Afterwards, there is an "allocation" algorithm that will allocate projects to student. It does that well enough. The allocated_project remains as None if a student is unsuccessful in getting a project. SQLAlchemy bit: So after all this happens, I'd like to map my object to a database table. Using the documentation, I've used the following code to only map certain bits. I also begin to create a Session. from sqlalchemy import * from sqlalchemy.orm import * engine = create_engine('sqlite:///:memory:', echo=False) metadata = MetaData() students_table = Table('studs', metadata, Column('id', Integer, primary_key=True), Column('name', String) ) metadata.create_all(engine) mapper(Student, students_table) Session = sessionmaker(bind=engine) sesh = Session() Now after that, I was curious to see if I could print out all the students from my students dictionary. for student in students.itervalues(): print student What do I get but an error: Traceback (most recent call last): File "~/FYP_Tests/FYP_Tests.py", line 140, in <module> print student File "/~FYP_Tests/Parties.py", line 30, in __str__ return "%s %s" %(self.id, self.name) File "/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/SQLAlchemy-0.5.8-py2.6.egg/sqlalchemy/orm/attributes.py", line 158, in __get__ return self.impl.get(instance_state(instance), instance_dict(instance)) AttributeError: 'NoneType' object has no attribute 'get' I'm at a loss as to how to resolve this issue, if it is an issue. If more information is required, please ask and I will provide it.

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• When constructing a Bitmap with Bitmap.FromHbitmap(), how soon can the original bitmap handle be del

  - by GBegen

  From the documentation of Image.FromHbitmap() at http://msdn.microsoft.com/en-us/library/k061we7x%28VS.80%29.aspx : The FromHbitmap method makes a copy of the GDI bitmap; so you can release the incoming GDI bitmap using the GDIDeleteObject method immediately after creating the new Image. This pretty explicitly states that the bitmap handle can be immediately deleted with DeleteObject as soon as the Bitmap instance is created. Looking at the implementation of Image.FromHbitmap() with Reflector, however, shows that it is a pretty thin wrapper around the GDI+ function, GdipCreateBitmapFromHBITMAP(). There is pretty scant documentation on the GDI+ flat functions, but http://msdn.microsoft.com/en-us/library/ms533971%28VS.85%29.aspx says that GdipCreateBitmapFromHBITMAP() corresponds to the Bitmap::Bitmap() constructor that takes an HBITMAP and an HPALETTE as parameters. The documentation for this version of the Bitmap::Bitmap() constructor at http://msdn.microsoft.com/en-us/library/ms536314%28VS.85%29.aspx has this to say: You are responsible for deleting the GDI bitmap and the GDI palette. However, you should not delete the GDI bitmap or the GDI palette until after the GDI+ Bitmap::Bitmap object is deleted or goes out of scope. Do not pass to the GDI+ Bitmap::Bitmap constructor a GDI bitmap or a GDI palette that is currently (or was previously) selected into a device context. Furthermore, one can see the source code for the C++ portion of GDI+ in GdiPlusBitmap.h that the Bitmap::Bitmap() constructor in question is itself a wrapper for the GdipCreateBitmapFromHBITMAP() function from the flat API: inline Bitmap::Bitmap( IN HBITMAP hbm, IN HPALETTE hpal ) { GpBitmap *bitmap = NULL; lastResult = DllExports::GdipCreateBitmapFromHBITMAP(hbm, hpal, &bitmap); SetNativeImage(bitmap); } What I can't easily see is the implementation of GdipCreateBitmapFromHBITMAP() that is the core of this functionality, but the two remarks in the documentation seem to be contradictory. The .Net documentation says I can delete the bitmap handle immediately, and the GDI+ documentation says the bitmap handle must be kept until the wrapping object is deleted, but both are based on the same GDI+ function. Furthermore, the GDI+ documentation warns against using a source HBITMAP that is currently or previously selected into a device context. While I can understand why the bitmap should not be selected into a device context currently, I do not understand why there is a warning against using a bitmap that was previously selected into a device context. That would seem to prevent use of GDI+ bitmaps that had been created in memory using standard GDI. So, in summary: Does the original bitmap handle need to be kept around until the .Net Bitmap object is disposed? Does the GDI+ function, GdipCreateBitmapFromHBITMAP(), make a copy of the source bitmap or merely hold onto the handle to the original? Why should I not use an HBITMAP that was previously selected into a device context?

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• Salesforce/PHP - Bulk Outbound message (SOAP), Time out issue

  - by Phill Pafford

  Salesforce can send up to 100 requests inside 1 SOAP message. While sending this type of Bulk Ooutbound message request my PHP script finishes executing but SF fails to accept the ACK used to clear the message queue on the Salesforce side of things. Looking at the Outbound message log (monitoring) I see all the messages in a pending state with the Delivery Failure Reason "java.net.SocketTimeoutException: Read timed out". If my script has finished execution, why do I get this error? I have tried these methods to increase the execution time on my server as I have no access on the Salesforce side: set_time_limit(0); // in the script max_execution_time = 360 ; Maximum execution time of each script, in seconds max_input_time = 360 ; Maximum amount of time each script may spend parsing request data memory_limit = 32M ; Maximum amount of memory a script may consume I used the high settings just for testing. Any thoughts as to why this is failing the ACK delivery back to Salesforce? Here is some of the code: This is how I accept and send the ACK file for the imcoming SOAP request $data = 'php://input'; $content = file_get_contents($data); if($content) { respond('true'); } else { respond('false'); } The respond function function respond($tf) { $ACK = <<<ACK <?xml version = "1.0" encoding = "utf-8"?> <soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> <soapenv:Body> <notifications xmlns="http://soap.sforce.com/2005/09/outbound"> <Ack>$tf</Ack> </notifications> </soapenv:Body> </soapenv:Envelope> ACK; print trim($ACK); } These are in a generic script that I include into the script that uses the data for a specific workflow. I can process about 25 requests (That are in 1 SOAP response) but once I go over that I get the timeout error in the Salesforce queue. for 50 requests is usually takes my PHP script 86.77 seconds. Could it be Apache? PHP? I have also tested just accepting the 100 request SOAP response and just accepting and sending the ACK the queue clears out, so I know it's on my side of things. I show no errors in the apache log, the script runs fine. Thanks for any insight into this, --Phill

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• C# Monte Carlo Incremental Risk Calculation optimisation, random numbers, parallel execution

  - by m3ntat

  My current task is to optimise a Monte Carlo Simulation that calculates Capital Adequacy figures by region for a set of Obligors. It is running about 10 x too slow for where it will need to be in production and number or daily runs required. Additionally the granularity of the result figures will need to be improved down to desk possibly book level at some stage, the code I've been given is basically a prototype which is used by business units in a semi production capacity. The application is currently single threaded so I'll need to make it multi-threaded, may look at System.Threading.ThreadPool or the Microsoft Parallel Extensions library but I'm constrained to .NET 2 on the server at this bank so I may have to consider this guy's port, http://www.codeproject.com/KB/cs/aforge_parallel.aspx. I am trying my best to get them to upgrade to .NET 3.5 SP1 but it's a major exercise in an organisation of this size and might not be possible in my contract time frames. I've profiled the application using the trial of dotTrace (http://www.jetbrains.com/profiler). What other good profilers exist? Free ones? A lot of the execution time is spent generating uniform random numbers and then translating this to a normally distributed random number. They are using a C# Mersenne twister implementation. I am not sure where they got it or if it's the best way to go about this (or best implementation) to generate the uniform random numbers. Then this is translated to a normally distributed version for use in the calculation (I haven't delved into the translation code yet). Also what is the experience using the following? http://quantlib.org http://www.qlnet.org (C# port of quantlib) or http://www.boost.org Any alternatives you know of? I'm a C# developer so would prefer C#, but a wrapper to C++ shouldn't be a problem, should it? Maybe even faster leveraging the C++ implementations. I am thinking some of these libraries will have the fastest method to directly generate normally distributed random numbers, without the translation step. Also they may have some other functions that will be helpful in the subsequent calculations. Also the computer this is on is a quad core Opteron 275, 8 GB memory but Windows Server 2003 Enterprise 32 bit. Should I advise them to upgrade to a 64 bit OS? Any links to articles supporting this decision would really be appreciated. Anyway, any advice and help you may have is really appreciated.

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• XNA - Keyboard text input

  - by Sekhat

  Okay, so basically I want to be able to retrieve keyboard text. Like entering text into a text field or something. I'm only writing my game for windows. I've disregarded using Guide.BeginShowKeyboardInput because it breaks the feel of a self contained game, and the fact that the Guide always shows XBOX buttons doesn't seem right to me either. Yes it's the easiest way, but I don't like it. Next I tried using System.Windows.Forms.NativeWindow. I created a class that inherited from it, and passed it the Games window handle, implemented the WndProc function to catch WM_CHAR (or WM_KEYDOWN) though the WndProc got called for other messages, WM_CHAR and WM_KEYDOWN never did. So I had to abandon that idea, and besides, I was also referencing the whole of Windows forms, which meant unnecessary memory footprint bloat. So my last idea was to create a Thread level, low level keyboard hook. This has been the most successful so far. I get WM_KEYDOWN message, (not tried WM_CHAR yet) translate the virtual keycode with Win32 funcation MapVirtualKey to a char. And I get my text! (I'm just printing with Debug.Write at the moment) A couple problems though. It's as if I have caps lock on, and an unresponsive shift key. (Of course it's not however, it's just that there is only one Virtual Key Code per key, so translating it only has one output) and it adds overhead as it attaches itself to the Windows Hook List and isn't as fast as I'd like it to be, but the slowness could be more due to Debug.Write. Has anyone else approached this and solved it, without having to resort to an on screen keyboard? or does anyone have further ideas for me to try? thanks in advance. note: This is cross posted from the XNA Creators Forums, so if I get an answer there I'll post it here and Vice-Versa Question asked by Jimmy Maybe I'm not understanding the question, but why can't you use the XNA Keyboard and KeyboardState classes? My comment: It's because though you can read keystates, you can't get access to typed text as and how it is typed by the user. So let me further clarify. I want to implement being able to read text input from the user as if they are typing into textbox is windows. The keyboard and KeyboardState class get states of all keys, but I'd have to map each key and combination to it's character representation. This falls over when the user doesn't use the same keyboard language as I do especially with symbols (my double quotes is shift + 2, while american keyboards have theirs somewhere near the return key).

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• How to optimize my PageRank calculation?

  - by asmaier

  In the book Programming Collective Intelligence I found the following function to compute the PageRank: def calculatepagerank(self,iterations=20): # clear out the current PageRank tables self.con.execute("drop table if exists pagerank") self.con.execute("create table pagerank(urlid primary key,score)") self.con.execute("create index prankidx on pagerank(urlid)") # initialize every url with a PageRank of 1.0 self.con.execute("insert into pagerank select rowid,1.0 from urllist") self.dbcommit() for i in range(iterations): print "Iteration %d" % i for (urlid,) in self.con.execute("select rowid from urllist"): pr=0.15 # Loop through all the pages that link to this one for (linker,) in self.con.execute("select distinct fromid from link where toid=%d" % urlid): # Get the PageRank of the linker linkingpr=self.con.execute("select score from pagerank where urlid=%d" % linker).fetchone()[0] # Get the total number of links from the linker linkingcount=self.con.execute("select count(*) from link where fromid=%d" % linker).fetchone()[0] pr+=0.85*(linkingpr/linkingcount) self.con.execute("update pagerank set score=%f where urlid=%d" % (pr,urlid)) self.dbcommit() However, this function is very slow, because of all the SQL queries in every iteration >>> import cProfile >>> cProfile.run("crawler.calculatepagerank()") 2262510 function calls in 136.006 CPU seconds Ordered by: standard name ncalls tottime percall cumtime percall filename:lineno(function) 1 0.000 0.000 136.006 136.006 <string>:1(<module>) 1 20.826 20.826 136.006 136.006 searchengine.py:179(calculatepagerank) 21 0.000 0.000 0.528 0.025 searchengine.py:27(dbcommit) 21 0.528 0.025 0.528 0.025 {method 'commit' of 'sqlite3.Connecti 1 0.000 0.000 0.000 0.000 {method 'disable' of '_lsprof.Profiler 1339864 112.602 0.000 112.602 0.000 {method 'execute' of 'sqlite3.Connec 922600 2.050 0.000 2.050 0.000 {method 'fetchone' of 'sqlite3.Cursor' 1 0.000 0.000 0.000 0.000 {range} So I optimized the function and came up with this: def calculatepagerank2(self,iterations=20): # clear out the current PageRank tables self.con.execute("drop table if exists pagerank") self.con.execute("create table pagerank(urlid primary key,score)") self.con.execute("create index prankidx on pagerank(urlid)") # initialize every url with a PageRank of 1.0 self.con.execute("insert into pagerank select rowid,1.0 from urllist") self.dbcommit() inlinks={} numoutlinks={} pagerank={} for (urlid,) in self.con.execute("select rowid from urllist"): inlinks[urlid]=[] numoutlinks[urlid]=0 # Initialize pagerank vector with 1.0 pagerank[urlid]=1.0 # Loop through all the pages that link to this one for (inlink,) in self.con.execute("select distinct fromid from link where toid=%d" % urlid): inlinks[urlid].append(inlink) # get number of outgoing links from a page numoutlinks[urlid]=self.con.execute("select count(*) from link where fromid=%d" % urlid).fetchone()[0] for i in range(iterations): print "Iteration %d" % i for urlid in pagerank: pr=0.15 for link in inlinks[urlid]: linkpr=pagerank[link] linkcount=numoutlinks[link] pr+=0.85*(linkpr/linkcount) pagerank[urlid]=pr for urlid in pagerank: self.con.execute("update pagerank set score=%f where urlid=%d" % (pagerank[urlid],urlid)) self.dbcommit() This function is 20 times faster (but uses a lot more memory for all the temporary dictionaries) because it avoids the unnecessary SQL queries in every iteration: >>> cProfile.run("crawler.calculatepagerank2()") 64802 function calls in 6.950 CPU seconds Ordered by: standard name ncalls tottime percall cumtime percall filename:lineno(function) 1 0.004 0.004 6.950 6.950 <string>:1(<module>) 1 1.004 1.004 6.946 6.946 searchengine.py:207(calculatepagerank2 2 0.000 0.000 0.104 0.052 searchengine.py:27(dbcommit) 23065 0.012 0.000 0.012 0.000 {meth 'append' of 'list' objects} 2 0.104 0.052 0.104 0.052 {meth 'commit' of 'sqlite3.Connection 1 0.000 0.000 0.000 0.000 {meth 'disable' of '_lsprof.Profiler' 31298 5.809 0.000 5.809 0.000 {meth 'execute' of 'sqlite3.Connectio 10431 0.018 0.000 0.018 0.000 {method 'fetchone' of 'sqlite3.Cursor' 1 0.000 0.000 0.000 0.000 {range} But is it possible to further reduce the number of SQL queries to speed up the function even more?

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• XmlReader throws on an RSS feed, when the RSS document includes an embedded <script> block.

  - by Cheeso

  The code: using (XmlReader xmlr = XmlReader.Create(new StringReader(allXml))) { var items = from item in SyndicationFeed.Load(xmlr).Items select item; } The exception: Exception: System.Xml.XmlException: Unexpected node type Element. ReadElementString method can only be called on elements with simple or empty content. Line 11, position 25. at System.Xml.XmlReader.ReadElementString() at System.ServiceModel.Syndication.Rss20FeedFormatter.ReadXml(XmlReader reader, SyndicationFeed result) at System.ServiceModel.Syndication.Rss20FeedFormatter.ReadFeed(XmlReader reader) at System.ServiceModel.Syndication.Rss20FeedFormatter.ReadFrom(XmlReader reader) at System.ServiceModel.Syndication.SyndicationFeed.Load[TSyndicationFeed](XmlReader reader) at System.ServiceModel.Syndication.SyndicationFeed.Load(XmlReader reader) at Ionic.ToolsAndTests.ReadRss.Run() in c:\dev\dotnet\ReadRss.cs:line 90 The XML content: <?xml version="1.0" encoding="utf-8"?> <?xml-stylesheet type="text/xsl" href="https://www.ibm.com/developerworks/mydeveloperworks/blogs/roller-ui/styles/rss.xsl" media="screen"?><rss version="2.0" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:atom="http://www.w3.org/2005/Atom" > <channel> <title>Software architecture, software engineering, and Renaissance Jazz</title> <link>https://www.ibm.com/developerworks/mydeveloperworks/blogs/gradybooch</link> <atom:link rel="self" type="application/rss+xml" href="https://www.ibm.com/developerworks/mydeveloperworks/blogs/gradybooch/feed/entries/rss?lang=en" /> <description>Software architecture, software engineering, and Renaissance Jazz</description> <language>en-us</language> <copyright>Copyright <script type='text/javascript'> document.write(blogsDate.date.localize (1273534889181));</script></copyright> <lastBuildDate>Mon, 10 May 2010 19:41:29 -0400</lastBuildDate> As you can see, on line 11, at position 25, there's a script block inside the <copyright> element. Other people have reported similar errors with other XML documents. The way I worked around this was to do a StreamReader.ReadToEnd, then do Regex.Replace on the result of that to yank out the script block, before passing the modified string to XmlReader.Create(). Feels like a hack. Has anyone got a better approach? I don't like this because I have to read in a 125k string into memory. Is it valid rss to include "complex content" like that - a script block inside an element? Thanks.

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• Seeking for faster $.(':data(key)')

  - by PoltoS

  I'm writing an extension to jQuery that adds data to DOM elements using el.data('lalala', my_data); and then uses that data to upload elements dynamically. Each time I get new data from the server I need to update all elements having el.data('lalala') != null; To get all needed elements I use an extension by James Padolsey: $(':data(lalala)').each(...); Everything was great until I came to the situation where I need to run that code 50 times - it is very slow! It takes about 8 seconds to execute on my page with 3640 DOM elements var x, t = (new Date).getTime(); for (n=0; n < 50; n++) { jQuery(':data(lalala)').each(function() { x++; }); }; console.log(((new Date).getTime()-t)/1000); Since I don't need RegExp as parameter of :data selector I've tried to replace this by var x, t = (new Date).getTime(); for (n=0; n < 50; n++) { jQuery('*').each(function() { if ($(this).data('lalala')) x++; }); }; console.log(((new Date).getTime()-t)/1000); This code is faster (5 sec), but I want get more. Q Are there any faster way to get all elements with this data key? In fact, I can keep an array with all elements I need, since I execute .data('key') in my module. Checking 100 elements having the desired .data('lalala') is better then checking 3640 :) So the solution would be like for (i in elements) { el = elements[i]; .... But sometimes elements are removed from the page (using jQuery .remove()). Both solutions described above [$(':data(lalala)') solution and if ($(this).data('lalala'))] will skip removed items (as I need), while the solution with array will still point to removed element (in fact, the element would not be really deleted - it will only be deleted from the DOM tree - because my array will still have a reference). I found that .remove() also removes data from the node, so my solution will change into var toRemove = []; for (vari in elements) { var el = elements[i]; if ($(el).data('lalala')) .... else toRemove.push(i); }; for (var ii in toRemove) elements.splice(toRemove[ii], 1); // remove element from array This solution is 100 times faster! Q Will the garbage collector release memory taken by DOM elements when deleted from that array? Remember, elements have been referenced by DOM tree, we made a new reference in our array, then removed with .remove() and then removed from the array. Is there a better way to do this?

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• Which OAuth library do you find works best for Objective-C/iPhone?

  - by Brennan

  I have been looking to switch to OAuth for my Twitter integration code and now that there is a deadline in less than 7 weeks (see countdown link) it is even more important to make the jump to OAuth. I have been doing Basic Authentication which is extremely easy. Unfortunately OAuth does not appear to be something that I would whip together in a couple of hours. http://www.countdowntooauth.com/ So I am looking to use a library. I have put together the following list. MPOAuth MGTwitterEngine OAuthConsumer I see that MPOAuth has some great features with a good deal of testing code in place but there is one big problem. It does not work. The sample iPhone project that is supposed to authenticate with Twitter causes an error which others have identified and logged as a bug. http://code.google.com/p/mpoauthconnection/issues/detail?id=29 The last code change was March 11 and this bug was filed on March 30. It has been over a month and this critical bug has not been fixed yet. So I have moved on to MGTwitterEngine. I pulled down the source code and loaded it up in Xcode. Immediately I find that there are a few dependencies and the README file does not have a clear list of steps to fetch those dependencies and integrate them with the project so that it builds successfully. I see this as a sign that the project is not mature enough for prime time. I see also that the project references 2 libraries for JSON when one should be enough. One is TouchJSON which has worked well for me so I am again discouraged from relying on this project for my applications. I did find that MGTwitterEngine makes use of OAuthConsumer which is one of many OAuth projects hosted by an OAuth project on Google Code. http://code.google.com/p/oauth/ http://code.google.com/p/oauthconsumer/wiki/UsingOAuthConsumer It looks like OAuthConsumer is a good choice at first glance. It is hosted with other OAuth libraries and has some nice documentation with it. I pulled down the code and it builds without errors but it does have many warnings. And when I run the new Build and Analyze feature in Xcode 3.2 I see 50 analyzer results. Many are marked as potential memory leaks which would likely lead to instability in any app which uses this library. It seems there is no clear winner and I have to go with something before the big Twitter OAuth deadline. Any suggestions?

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• ASP.Net Web Farm Monitoring

  - by cisellis

  I am looking for suggestions on doing some simple monitoring of an ASP.Net web farm as close to real-time as possible. The objectives of this question are to: Identify the best way to monitor several Windows Server production boxes during short (minutes long) period of ridiculous load Receive near-real-time feedback on a few key metrics about each box. These are simple metrics available via WMI such as CPU, Memory and Disk Paging. I am defining my time constraints as soon as possible with 120 seconds delayed being the absolute upper limit. Monitor whether any given box is up (with "up" being defined as responding web requests in a reasonable amount of time) Here are more details, things I've tried, etc. I am not interested in logging. We have logging solutions in place. I have looked at solutions such as ELMAH which don't provide much in the way of hardware monitoring and are not visible across an entire web farm. ASP.Net Health Monitoring is too broad, focuses too much on logging and is not acceptable for deep analysis. We are on Amazon Web Services and we have looked into CloudWatch. It looks great but messages in the forum indicate that the metrics are often a few minutes behind, with one thread citing 2 minutes as the absolute soonest you could expect to receive the feedback. This would be good to have for later analysis but does not help us real-time Stuff like JetBrains profiler is good for testing but again, not helpful during real-time monitoring. The closest out-of-box solution I've seen is Nagios which is free and appears to measure key indicators on any kind of box, including Windows. However, it appears to require a Linux box to run itself on and a good deal of manual configuration. I'd prefer to not spend my time mining config files and then be up a creek when it fails in production since Linux is not my main (or even secondary) environment. Are there any out-of-box solutions that I am missing? Obviously a windows-based solution that is easy to setup is ideal. I don't require many bells and whistles. In the absence of an out-of-box solution, it seems easy for me to write something simple to handle what I need. I've been thinking a simple client-server setup where the server requests a few WMI metrics from each client over http and sticks them in a database. We could then monitor the metrics via a query or a dashboard or something. If the client doesn't respond, it's effectively down. Any problems with this, best practices, or other ideas? Thanks for any help/feedback.

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• Using FFmpeg in .net?

  - by daniel

  So i know its a fairly big challenge but i want to write a basic movie player/converter in c# using the FFmpeg library. However the first obstacle i need to overcome is wrapping the FFmpeg library in c#. I downloaded ffmpeg but couldn't compile it on windows, so i downloaded a precompiled version for me. Ok awesome. Then i started looking for c# wrappers. I have looked around and have found a few wrappers such as SharpFFmpeg (http://sourceforge.net/projects/sharpffmpeg/) and ffmpeg-sharp (http://code.google.com/p/ffmpeg-sharp/). First of all i wanted to use ffmpeg-sharp as its LGPL and SharpFFmpeg is GPL. However it had quite a few compile errors. Turns out it was written for the mono compiler, i tried compiling it with mon but couldn't figure out how. I then started to manually fix the compiler errors myself, but came across a few scary ones and thought i'd better leave those alone. So i gave up on ffmpeg-sharp. Then i looked at SharpFFmpeg and it looks like what i want, all the functions P/Invoked for me. However its GPL? Both the AVCodec.cs and AVFormat.cs files look like ports of avcodec.c and avformat.c which i reckon i could port myself? Then not have to worry about licencing. But i wan't to get this right before i go ahead and start coding. Should I: Write my own c++ library for interacting with ffmpeg, then have my c# program talk to the c++ library in order to play/convert videos etc. OR Port avcodec.h and avformat.h (is that all i need?) to c# by using a whole lot of DllImports and write it entirely in c#? First of all consider that i'm not great at c++ as i rarely use it but i know enough to get around. The reason i'm thinking #1 might be the better option is that most FFmpeg tutorials are in c++ and i'd also have more control over memory management than if i was to do it in c#. What do you think? Also would you happen to have any usefull links (perhaps a tutorial) for using FFmpeg? EDIT: spelling mistakes

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• C++ How to deep copy a struct with unknown datatype?

  - by Ewald Peters

  hi, i have a "data provider" which stores its output in a struct of a certain type, for instance struct DATA_TYPE1{ std::string data_string; }; then this struct has to be casted into a general datatype, i thought about void * or char *, because the "intermediate" object that copies and stores it in its binary tree should be able to store many different types of such struct data. struct BINARY_TREE_ENTRY{ void * DATA; struct BINARY_TREE_ENTRY * next; }; this void * is then later taken by another object that casts the void * back into the (struct DATA_TYPE1 *) to get the original data. so the sender and the receiver know about the datatype DATA_TYPE1 but not the copying object inbetween. but how can the intermidiate object deep copy the contents of the different structs, when it doesn't know the datatype, only void * and it has no method to copy the real contents; dynamic_cast doesn't work for void *; the "intermediate" object should do something like: void store_data(void * CASTED_DATA_STRUCT){ void * DATA_COPY = create_a_deepcopy_of(CASTED_DATA_STRUCT); push_into_bintree(DATA_COPY); } a simple solution would be that the sending object doesn't delete the sent data struct, til the receiving object got it, but the sending objects are dynamically created and deleted, before the receiver got the data from the intermediate object, for asynchronous communication, therefore i want to copy it. instead of converting it to void * i also tried converting to a superclass pointer of which the intermediate copying object knows about, and which is inherited by all the different datatypes of the structs: struct DATA_BASE_OBJECT{ public: DATA_BASE_OBJECT(){} DATA_BASE_OBJECT(DATA_BASE_OBJECT * old_ptr){ std::cout << "this should be automatically overridden!" << std::endl; } virtual ~DATA_BASE_OBJECT(){} }; struct DATA_TYPE1 : public DATA_BASE_OBJECT { public: string str; DATA_TYPE1(){} ~DATA_TYPE1(){} DATA_TYPE1(DATA_TYPE1 * old_ptr){ str = old_ptr->str; } }; and the corresponding binary tree entry would then be: struct BINARY_TREE_ENTRY{ struct DATA_BASE_OBJECT * DATA; struct BINARY_TREE_ENTRY * next; }; and to then copy the unknown datatype, i tried in the class that just gets the unknown datatype as a struct DATA_BASE_OBJECT * (before it was the void *): void * copy_data(DATA_BASE_OBJECT * data_that_i_get_in_the_sub_struct){ struct DATA_BASE_OBJECT * copy_sub = new DATA_BASE_OBJECT(data_that_i_get_in_the_sub_struct); push_into_bintree(copy_sub); } i then added a copy constructor to the DATA_BASE_OBJECT, but if the struct DATA_TYPE1 is first casted to a DATA_BASE_OBJECT and then copied, the included sub object DATA_TYPE1 is not also copied. i then thought what about finding out the size of the actual object to copy and then just memcopy it, but the bytes are not stored in one row and how do i find out the real size in memory of the struct DATA_TYPE1 which holds a std::string? Which other c++ methods are available to deepcopy an unknown datatype (and to maybe get the datatype information somehow else during runtime) thanks Ewald

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• Some questions about writing on ASP.NET response stream

  - by vtortola

  Hi, I'm making tests with ASP.NET HttpHandler for download a file writting directly on the response stream, and I'm not pretty sure about the way I'm doing it. This is a example method, in the future the file could be stored in a BLOB in the database: public void GetFile(HttpResponse response) { String fileName = "example.iso"; response.ClearHeaders(); response.ClearContent(); response.ContentType = "application/octet-stream"; response.AppendHeader("Content-Disposition", "attachment; filename=" + fileName); using (FileStream fs = new FileStream(Path.Combine(HttpContext.Current.Server.MapPath("~/App_Data"), fileName), FileMode.Open)) { Byte[] buffer = new Byte[4096]; Int32 readed = 0; while ((readed = fs.Read(buffer, 0, buffer.Length)) > 0) { response.OutputStream.Write(buffer, 0, readed); response.Flush(); } } } But, I'm not sure if this is correct or there is a better way to do it. My questions are: When I open the url with the browser, appears the "Save File" dialog... but it seems like the server has started already to push data into the stream before I click "Save", is that normal? If I remove the line"response.Flush()", when I open the url with the browser, ... I see how the web server is pushing data but the "Save File" dialog doesn't come up, (or at least not in a reasonable time fashion) why? When I open the url with a WebRequest object, I see that the HttpResponse.ContentLength is "-1", although I can read the stream and get the file. What is the meaning of -1? When is HttpResponse.ContentLength going to show the length of the response? For example, I have a method that retrieves a big xml compresed with deflate as a binary stream, but in that case... when I access it with a WebRequest, in the HttpResponse I can actually see the ContentLength with the length of the stream, why? What is the optimal length for the Byte[] array that I use as buffer for optimal performance in a web server? I've read that is between 4K and 8K... but which factors should I consider to make the correct decision. Does this method bloat the IIS or client memory usage? or is it actually buffering the transference correctly? Sorry for so many questions, I'm pretty new in web development :P Cheers.

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• Modeling distribution of performance measurements

  - by peterchen

  How would you mathematically model the distribution of repeated real life performance measurements - "Real life" meaning you are not just looping over the code in question, but it is just a short snippet within a large application running in a typical user scenario? My experience shows that you usually have a peak around the average execution time that can be modeled adequately with a Gaussian distribution. In addition, there's a "long tail" containing outliers - often with a multiple of the average time. (The behavior is understandable considering the factors contributing to first execution penalty). My goal is to model aggregate values that reasonably reflect this, and can be calculated from aggregate values (like for the Gaussian, calculate mu and sigma from N, sum of values and sum of squares). In other terms, number of repetitions is unlimited, but memory and calculation requirements should be minimized. A normal Gaussian distribution can't model the long tail appropriately and will have the average biased strongly even by a very small percentage of outliers. I am looking for ideas, especially if this has been attempted/analysed before. I've checked various distributions models, and I think I could work out something, but my statistics is rusty and I might end up with an overblown solution. Oh, a complete shrink-wrapped solution would be fine, too ;) Other aspects / ideas: Sometimes you get "two humps" distributions, which would be acceptable in my scenario with a single mu/sigma covering both, but ideally would be identified separately. Extrapolating this, another approach would be a "floating probability density calculation" that uses only a limited buffer and adjusts automatically to the range (due to the long tail, bins may not be spaced evenly) - haven't found anything, but with some assumptions about the distribution it should be possible in principle. Why (since it was asked) - For a complex process we need to make guarantees such as "only 0.1% of runs exceed a limit of 3 seconds, and the average processing time is 2.8 seconds". The performance of an isolated piece of code can be very different from a normal run-time environment involving varying levels of disk and network access, background services, scheduled events that occur within a day, etc. This can be solved trivially by accumulating all data. However, to accumulate this data in production, the data produced needs to be limited. For analysis of isolated pieces of code, a gaussian deviation plus first run penalty is ok. That doesn't work anymore for the distributions found above. [edit] I've already got very good answers (and finally - maybe - some time to work on this). I'm starting a bounty to look for more input / ideas.

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• Efficiency of Java "Double Brace Initialization"?

  - by Jim Ferrans

  In Hidden Features of Java the top answer mentions Double Brace Initialization, with a very enticing syntax: Set<String> flavors = new HashSet<String>() {{ add("vanilla"); add("strawberry"); add("chocolate"); add("butter pecan"); }}; This idiom creates an anonymous inner class with just an instance initializer in it, which "can use any [...] methods in the containing scope". Main question: Is this as inefficient as it sounds? Should its use be limited to one-off initializations? (And of course showing off!) Second question: The new HashSet must be the "this" used in the instance initializer ... can anyone shed light on the mechanism? Third question: Is this idiom too obscure to use in production code? Summary: Very, very nice answers, thanks everyone. On question (3), people felt the syntax should be clear (though I'd recommend an occasional comment, especially if your code will pass on to developers who may not be familiar with it). On question (1), The generated code should run quickly. The extra .class files do cause jar file clutter, and slow program startup slightly (thanks to coobird for measuring that). Thilo pointed out that garbage collection can be affected, and the memory cost for the extra loaded classes may be a factor in some cases. Question (2) turned out to be most interesting to me. If I understand the answers, what's happening in DBI is that the anonymous inner class extends the class of the object being constructed by the new operator, and hence has a "this" value referencing the instance being constructed. Very neat. Overall, DBI strikes me as something of an intellectual curiousity. Coobird and others point out you can achieve the same effect with Arrays.asList, varargs methods, Google Collections, and the proposed Java 7 Collection literals. Newer JVM languages like Scala, JRuby, and Groovy also offer concise notations for list construction, and interoperate well with Java. Given that DBI clutters up the classpath, slows down class loading a bit, and makes the code a tad more obscure, I'd probably shy away from it. However, I plan to spring this on a friend who's just gotten his SCJP and loves good natured jousts about Java semantics! ;-) Thanks everyone!

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• My block is not retaining some of its objects

  - by Drew Crawford

  From the Blocks documentation: In a reference-counted environment, by default when you reference an Objective-C object within a block, it is retained. This is true even if you simply reference an instance variable of the object. I am trying to implement a completion handler pattern, where a block is given to an object before the work is performed and the block is executed by the receiver after the work is performed. Since I am being a good memory citizen, the block should own the objects it references in the completion handler and then they will be released when the block goes out of scope. I know enough to know that I must copy the block to move it to the heap since the block will survive the stack scope in which it was declared. However, one of my objects is getting deallocated unexpectedly. After some playing around, it appears that certain objects are not retained when the block is copied to the heap, while other objects are. I am not sure what I am doing wrong. Here's the smallest test case I can produce: typedef void (^ActionBlock)(UIView*); In the scope of some method: NSObject *o = [[[NSObject alloc] init] autorelease]; mailViewController = [[[MFMailComposeViewController alloc] init] autorelease]; NSLog(@"o's retain count is %d",[o retainCount]); NSLog(@"mailViewController's retain count is %d",[mailViewController retainCount]); ActionBlock myBlock = ^(UIView *view) { [mailViewController setCcRecipients:[NSArray arrayWithObjects:@"[email protected]",nil]]; [o class]; }; NSLog(@"mailViewController's retain count after the block is %d",[mailViewController retainCount]); NSLog(@"o's retain count after the block is %d",[o retainCount]); Block_copy(myBlock); NSLog(@"o's retain count after the copy is %d",[o retainCount]); NSLog(@"mailViewController's retain count after the copy is %d",[mailViewController retainCount]); I expect both objects to be retained by the block at some point, and I certainly expect their retain counts to be identical. Instead, I get this output: o's retain count is 1 mailViewController's retain count is 1 mailViewController's retain count after the block is 1 o's retain count after the block is 1 o's retain count after the copy is 2 mailViewController's retain count after the copy is 1 o (subclass of NSObject) is getting retained properly and will not go out of scope. However mailViewController is not retained and will be deallocated before the block is run, causing a crash.

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• Unable to cast lists with Reflection in C#

  - by DrLazer

  I am having a lot of trouble with Reflection in C# at the moment. The app I am writing allows the user to modify the attributes of certain objects using a config file. I want to be able to save the object model (users project) to XML. The function below is called in the middle of a foreach loop, looping through a list of objects that contain all the other objects in the project within them. The idea is, that it works recursively to translate the object model into XML. Dont worry about the call to "Unreal" that just modifes the name of the objects slightly if they contain certain words. private void ReflectToXML(object anObject, XmlElement parentElement) { Type aType = anObject.GetType(); XmlElement anXmlElement = m_xml.CreateElement(Unreal(aType.Name)); parentElement.AppendChild(anXmlElement); PropertyInfo[] pinfos = aType.GetProperties(); //loop through this objects public attributes foreach (PropertyInfo aInfo in pinfos) { //if the attribute is a list Type propertyType = aInfo.PropertyType; if ((propertyType.IsGenericType)&&(propertyType.GetGenericTypeDefinition() == typeof(List<>))) { List<object> listObjects = (aInfo.GetValue(anObject,null) as List<object>); foreach (object aListObject in listObjects) { ReflectToXML(aListObject, anXmlElement); } } //attribute is not a list else anXmlElement.SetAttribute(aInfo.Name, ""); } } If an object attributes are just strings then it should be writing them out as string attributes in the XML. If an objects attributes are lists, then it should recursively call "ReflectToXML" passing itself in as a parameter, thereby creating the nested structure I require that nicely reflect the object model in memory. The problem I have is with the line List<object> listObjects = (aInfo.GetValue(anObject,null) as List<object>); The cast doesn't work and it just returns null. While debugging I changed the line to object temp = aInfo.GetValue(anObject,null); slapped a breakpoint on it to see what "GetValue" was returning. It returns a "Generic list of objects" Surely I should be able to cast that? The annoying thing is that temp becomes a generic list of objects but because i declared temp as a singular object, I can't loop through it because it has no Enumerator. How can I loop through a list of objects when I only have it as a propertyInfo of a class? I know at this point I will only be saving a list of empty strings out anyway, but thats fine. I would be happy to see the structure save out for now. Thanks in advance

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• Java ExecutorService java heap space ptoblems

  - by Sergey Aganezov jr

  I have a little bit of a problem in a multitasking java department. I have a class, called public class ThreadWorker implements Runnable { //some code in here public void run(){ // invokes some recursion method in the ThreadWorker itself, // which will stop eventually { } all in all, pretty simple "worker" that can work on it's on. To work with threads I'm using public static int THREAD_NUMBER = 4; public static ExecutorServide es = Executors.newFixedThreadPool(THREAD_NUMBER); adding instances of ThreadWroker class happens here: public void recursiveMethod(Arraylist<Integers> elements, MyClass data){ if (elements.size() == 0 && data.qualifies()){ ThreadWorker tw = new ThreadWorker(data); es.execute(tw); return; } for (int i=0; i< elements.size(); i++){ // some code to prevent my problem MyClass data1 = new MyClass(data); MyClass data2 = new MyClass(data); ArrayList<Integer> newElements = (ArrayList<Integer>)elements.clone(); data1.update(elements.get(i)); data2.update(-1 * elements.get(i)); newElements.remove(i); recursiveMethod(newElements, data1); recursiveMethod(newElements, data2); { } and the problem is that the depth of the recursion tree is quite big, so as it's width, so a lot of ThreadWorkers are added to the ExecutorService, so after some time on the big input a get Exception in thread "pool-1-thread-2" java.lang.OutOfMemoryError: Java heap space which is caused, as I think because of a ginormous number of ThreadWorkers i'm adding to ExecutorSirvice to be executed, so it runs out of memory. Every ThreadWorker takes about 40 Mb of RAM for all it needs. Is there a method to get how many threads (instances of classes implementing runnable interface) have been added to ExecutorService? So I can add it in the shown above code (int the " // some code to prevent my problem"), as while ("number of threads in the ExecutorService" > 10){ Thread.sleep(10000); } so I won't go to deep or to broad with my recursion and prevent those exception-throwing situations. Sincerely, Sergey Aganezov jr.

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• Mercurial over ssh client and server on Windows

  - by Ben Von Handorf

  I'm trying to configure Mercurial for use with both a windows server (freeSSHd) and client (both command line and TortoiseHG). I'm using the most recent versions of everything... all downloaded in the past few days. Using public key auth, I have been able to get connected to the server and I'm able to use plink to execute "hg version" and get a response, but when I try to clone a repository from the ssh server the command appears to hang. Running with -v yields: hg -v clone ssh://<username>@<server>//hg/repositoryA testRepositoryA running "plink.exe -i "<path to private key file>" <username>@<server> "hg -R /hg/repositoryA serve --stdio"" with nothing more forthcoming. Running the hg serve command directly on the server yields an apparently responsive Mercurial server, but the clients do not seem to make any further requests. Running "hg serve" in the repository directory and cloning over http works perfectly. What should I be looking for to help debug this? Is there something the clients (hg and TortoiseHG) aren't sending to continue the request stream? Additional Information: If I change to an invalid repository on the target machine, the appropriate error is displayed, so it does appear that the remote hg is running and correctly evaluating the path. Running with --debug and --traceback results in: sending hello command sending between command It hangs here, until I CTRL-C Traceback (most recent call last): File "mercurial\dispatch.pyo", line 46, in _runcatch File "mercurial\dispatch.pyo", line 452, in _dispatch File "mercurial\dispatch.pyo", line 320, in runcommand File "mercurial\dispatch.pyo", line 504, in _runcommand File "mercurial\dispatch.pyo", line 457, in checkargs File "mercurial\dispatch.pyo", line 451, in <lambda> File "mercurial\util.pyo", line 402, in check File "mercurial\commands.pyo", line 636, in clone File "mercurial\hg.pyo", line 187, in clone File "mercurial\hg.pyo", line 63, in repository File "mercurial\sshrepo.pyo", line 51, in __init__ File "mercurial\sshrepo.pyo", line 73, in validate_repo KeyboardInterrupt interrupted! Responding to Ryan: There does not appear to be any CPU usage or increasing memory usage on the server. It appears to be waiting for the client to send a request or something similar. 11/19/2009 : More information: The problem is definitely in the freeSSHd/server side of the equation. Connecting to bitbucket over ssh with the same keyset works fine. Still working on this.

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