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• TVirtualStringTree - resetting non-visual nodes and memory comsumption

  - by Remy Lebeau - TeamB

  I have an app that loads records from a binary log file and displays them in a virtual TListView. There are potentially millions of records in a file, and the display can be filtered by the user, so I do not load all of the records in memory at one time, and the ListView item indexes are not a 1-to-1 relation with the file record offsets (List item 1 may be file record 100, for instance). I use the ListView's OnDataHint event to load records for just the items the ListView is actually interested in. As the user scrolls around, the range specified by OnDataHint changes, allowing me to free records that are not in the new range, and allocate new records as needed. This works fine, speed is tolerable, and the memory footprint is very low. I am currently evaluating TVirtualStringTree as a replacement for the TListView, mainly because I want to add the ability to expand/collapse records that span multiple lines (I can fudge it with the TListView by incrementing/decrementing the item count dynamically, but this is not as straight forward as using a real tree). For the most part, I have been able to port the TListView logic and have everything work as I need. I notice that TVirtualStringTree's virtual paridigm is vastly different, though. It does not have the same kind of OnDataHint functionality that TListView does (I can use the OnScroll event to fake it, which allows my memory buffer logic to continue working), and I can use the OnInitializeNode event to associate nodes with records that are allocated. However, once a tree node is initialized, it sees that it remains initialized for the lifetime of the tree. That is not good for me. As the user scrolls around and I remove records from memory, I need to reset those non-visual nodes without removing them from the tree completely, or losing their expand/collapse states. When the user scrolls them back into view, I can re-allocate the records and re-initialize the nodes. Basically, I want to make TVirtualStringTree act as much like TListView as possible, as far as its virtualization is concerned. I have seen that TVirtualStringTree has a ResetNode() method, but I encounter various errors whenever I try to use it. I must be using it wrong. I also thought of just storing a data pointer inside each node to my record buffers, and I allocate and free memory, update those pointers accordingly. The end effect does not work so well, either. Worse, my largest test log file has ~5 million records in it. If I initialize the TVirtualStringTree with that many nodes at one time (when the log display is unfiltered), the tree's internal overhead for its nodes takes up a whopping 260MB of memory (without any records being allocated yet). Whereas with the TListView, loading the same log file and all the memory logic behind it, I can get away with using just a few MBs. Any ideas?

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• LSP packet modify

  - by kellogs

  Hello, anybody care to share some insights on how to use LSP for packet modifying ? I am using the non IFS subtype and I can see how (pseudo?) packets first enter WSPRecv. But how do I modify them ? My inquiry is about one single HTTP response that causes WSPRecv to be called 3 times :((. I need to modify several parts of this response, but since it comes in 3 slices, it is pretty hard to modify it accordingly. And, maybe on other machines or under different conditions (such as high traffic) there would only be one sole WSPRecv call, or maybe 10 calls. What is the best way to work arround this (please no NDIS :D), and how to properly change the buffer (lpBuffers-buf) by increasing it ? int WSPAPI WSPRecv( SOCKET s, LPWSABUF lpBuffers, DWORD dwBufferCount, LPDWORD lpNumberOfBytesRecvd, LPDWORD lpFlags, LPWSAOVERLAPPED lpOverlapped, LPWSAOVERLAPPED_COMPLETION_ROUTINE lpCompletionRoutine, LPWSATHREADID lpThreadId, LPINT lpErrno ) { LPWSAOVERLAPPEDPLUS ProviderOverlapped = NULL; SOCK_INFO *SocketContext = NULL; int ret = SOCKET_ERROR; *lpErrno = NO_ERROR; // // Find our provider socket corresponding to this one // SocketContext = FindAndRefSocketContext(s, lpErrno); if ( NULL == SocketContext ) { dbgprint( "WSPRecv: FindAndRefSocketContext failed!" ); goto cleanup; } // // Check for overlapped I/O // if ( NULL != lpOverlapped ) { /*bla bla .. not interesting in my case*/ } else { ASSERT( SocketContext->Provider->NextProcTable.lpWSPRecv ); SetBlockingProvider(SocketContext->Provider); ret = SocketContext->Provider->NextProcTable.lpWSPRecv( SocketContext->ProviderSocket, lpBuffers, dwBufferCount, lpNumberOfBytesRecvd, lpFlags, lpOverlapped, lpCompletionRoutine, lpThreadId, lpErrno); SetBlockingProvider(NULL); //is this the place to modify packet length and contents ? if (strstr(lpBuffers->buf, "var mapObj = null;")) { int nLen = strlen(lpBuffers->buf) + 200; /*CHAR *szNewBuf = new CHAR[]; CHAR *pIndex; pIndex = strstr(lpBuffers->buf, "var mapObj = null;"); nLen = strlen(strncpy(szNewBuf, lpBuffers->buf, (pIndex - lpBuffers->buf) * sizeof (CHAR))); nLen = strlen(strncpy(szNewBuf + nLen * sizeof(CHAR), "var com = null;\r\n", 17 * sizeof(CHAR))); pIndex += 18 * sizeof(CHAR); nLen = strlen(strncpy(szNewBuf + nLen * sizeof(CHAR), pIndex, 1330 * sizeof (CHAR))); nLen = strlen(strncpy(szNewBuf + nLen * sizeof(CHAR), "if (com == null)\r\n" \ "com = new ActiveXObject(\"InterCommJS.Gateway\");\r\n" \ "com.lat = latitude;\r\n" \ "com.lon = longitude;\r\n}", 111 * sizeof (CHAR))); pIndex = strstr(szNewBuf, "Content-Length:"); pIndex += 16 * sizeof(CHAR); strncpy(pIndex, "1465", 4 * sizeof(CHAR)); lpBuffers->buf = szNewBuf; lpBuffers->len += 128;*/ } if ( SOCKET_ERROR != ret ) { SocketContext->BytesRecv += *lpNumberOfBytesRecvd; } } cleanup: if ( NULL != SocketContext ) DerefSocketContext( SocketContext, lpErrno ); return ret; } Thank you

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• Non-linear regression models in PostgreSQL using R

  - by Dave Jarvis

  Background I have climate data (temperature, precipitation, snow depth) for all of Canada between 1900 and 2009. I have written a basic website and the simplest page allows users to choose category and city. They then get back a very simple report (without the parameters and calculations section): The primary purpose of the web application is to provide a simple user interface so that the general public can explore the data in meaningful ways. (A list of numbers is not meaningful to the general public, nor is a website that provides too many inputs.) The secondary purpose of the application is to provide climatologists and other scientists with deeper ways to view the data. (Using too many inputs, of course.) Tool Set The database is PostgreSQL with R (mostly) installed. The reports are written using iReport and generated using JasperReports. Poor Model Choice Currently, a linear regression model is applied against annual averages of daily data. The linear regression model is calculated within a PostgreSQL function as follows: SELECT regr_slope( amount, year_taken ), regr_intercept( amount, year_taken ), corr( amount, year_taken ) FROM temp_regression INTO STRICT slope, intercept, correlation; The results are returned to JasperReports using: SELECT year_taken, amount, year_taken * slope + intercept, slope, intercept, correlation, total_measurements INTO result; JasperReports calls into PostgreSQL using the following parameterized analysis function: SELECT year_taken, amount, measurements, regression_line, slope, intercept, correlation, total_measurements, execute_time FROM climate.analysis( $P{CityId}, $P{Elevation1}, $P{Elevation2}, $P{Radius}, $P{CategoryId}, $P{Year1}, $P{Year2} ) ORDER BY year_taken This is not an optimal solution because it gives the false impression that the climate is changing at a slow, but steady rate. Questions Using functions that take two parameters (e.g., year [X] and amount [Y]), such as PostgreSQL's regr_slope: What is a better regression model to apply? What CPAN-R packages provide such models? (Installable, ideally, using apt-get.) How can the R functions be called within a PostgreSQL function? If no such functions exist: What parameters should I try to obtain for functions that will produce the desired fit? How would you recommend showing the best fit curve? Keep in mind that this is a web app for use by the general public. If the only way to analyse the data is from an R shell, then the purpose has been defeated. (I know this is not the case for most R functions I have looked at so far.) Thank you!

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• Beautifulsoup recursive attribute

  - by Marcos Placona

  Hi, trying to parse an XML with Beautifulsoup, but hit a brick wall when trying to use the "recursive" attribute with findall() I have a pretty odd xml format shown below: <?xml version="1.0"?> <catalog> <book id="bk101"> <author>Gambardella, Matthew</author> <title>XML Developer's Guide</title> <genre>Computer</genre> <price>44.95</price> <publish_date>2000-10-01</publish_date> <description>An in-depth look at creating applications with XML.</description> <catalog>true</catalog> </book> <book id="bk102"> <author>Ralls, Kim</author> <title>Midnight Rain</title> <genre>Fantasy</genre> <price>5.95</price> <publish_date>2000-12-16</publish_date> <description>A former architect battles corporate zombies, an evil sorceress, and her own childhood to become queen of the world.</description> <catalog>false</catalog> </book> </catalog> As you can see, the catalog tag repeats inside the book tag, which causes an error when I try to to something like: from BeautifulSoup import BeautifulStoneSoup as BSS catalog = "catalog.xml" def open_rss(): f = open(catalog, 'r') return f.read() def rss_parser(): rss_contents = open_rss() soup = BSS(rss_contents) items = soup.findAll('catalog', recursive=False) for item in items: print item.title.string rss_parser() As you will see, on my soup.findAll I've added recursive=false, which in theory would make it no recurse through the item found, but skip to the next one. This doesn't seem to work, as I always get the following error: File "catalog.py", line 17, in rss_parser print item.title.string AttributeError: 'NoneType' object has no attribute 'string' I'm sure I'm doing something stupid here, and would appreciate if someone could give me some help on how to solve this problem. Changing the HTML structure is not an option, this this code needs to perform well as it will potentially parse a large XML file. Thanks in advance, Marcos

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• Facing Memory Leaks in AES Encryption Method.

  - by Mubashar Ahmad

  Can anyone please identify is there any possible memory leaks in following code. I have tried with .Net Memory Profiler and it says "CreateEncryptor" and some other functions are leaving unmanaged memory leaks as I have confirmed this using Performance Monitors. but there are already dispose, clear, close calls are placed wherever possible please advise me accordingly. its a been urgent. public static string Encrypt(string plainText, string key) { //Set up the encryption objects byte[] encryptedBytes = null; using (AesCryptoServiceProvider acsp = GetProvider(Encoding.UTF8.GetBytes(key))) { byte[] sourceBytes = Encoding.UTF8.GetBytes(plainText); using (ICryptoTransform ictE = acsp.CreateEncryptor()) { //Set up stream to contain the encryption using (MemoryStream msS = new MemoryStream()) { //Perform the encrpytion, storing output into the stream using (CryptoStream csS = new CryptoStream(msS, ictE, CryptoStreamMode.Write)) { csS.Write(sourceBytes, 0, sourceBytes.Length); csS.FlushFinalBlock(); //sourceBytes are now encrypted as an array of secure bytes encryptedBytes = msS.ToArray(); //.ToArray() is important, don't mess with the buffer csS.Close(); } msS.Close(); } } acsp.Clear(); } //return the encrypted bytes as a BASE64 encoded string return Convert.ToBase64String(encryptedBytes); } private static AesCryptoServiceProvider GetProvider(byte[] key) { AesCryptoServiceProvider result = new AesCryptoServiceProvider(); result.BlockSize = 128; result.KeySize = 256; result.Mode = CipherMode.CBC; result.Padding = PaddingMode.PKCS7; result.GenerateIV(); result.IV = new byte[] { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }; byte[] RealKey = GetKey(key, result); result.Key = RealKey; // result.IV = RealKey; return result; } private static byte[] GetKey(byte[] suggestedKey, SymmetricAlgorithm p) { byte[] kRaw = suggestedKey; List<byte> kList = new List<byte>(); for (int i = 0; i < p.LegalKeySizes[0].MaxSize; i += 8) { kList.Add(kRaw[(i / 8) % kRaw.Length]); } byte[] k = kList.ToArray(); return k; }

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• Creating a System::String object from a BSTR in Managed C++ - is this way a good idea???

  - by Eli

  My co-worker is filling a System::String object with double-byte characters from an unmanaged library by the following method: RFC_PARAMETER aux; Object* target; RFC_UNICODE_TYPE_ELEMENT* elm; elm = &(m_coreObject->m_pStructMeta->m_typeElements[index]); aux.name = NULL; aux.nlen = 0; aux.type = elm->type; aux.leng = elm->c2_length; aux.addr = m_coreObject->m_rfcWa + elm->c2_offset; GlobalFunctions::CreateObjectForRFCField(target,aux,elm->decimals); GlobalFunctions::ReadRFCField(target,aux,elm->decimals); Where GlobalFunctions::CreateObjectForRFCField creates a System::String object filled with spaces (for padding) to what the unmanaged library states the max length should be: static void CreateObjectForRFCField(Object*& object, RFC_PARAMETER& par, unsigned dec) { switch (par.type) { case TYPC: object = new String(' ',par.leng / sizeof(_TCHAR)); break; // unimportant afterwards. } } And GlobalFunctions::ReadRFCField() copies the data from the library into the created String object and preserves the space padding: static void ReadRFCField(String* target, RFC_PARAMETER& par) { int lngt; _TCHAR* srce; switch (par.type) { case TYPC: case TYPDATE: case TYPTIME: case TYPNUM: lngt = par.leng / sizeof(_TCHAR); srce = (_TCHAR*)par.addr; break; case RFCTYPE_STRING: lngt = (*(_TCHAR**)par.addr != NULL) ? (int)_tcslen(*(_TCHAR**)par.addr) : 0; srce = *(_TCHAR**)par.addr; break; default: throw new DotNet_Incomp_RFCType2; } if (lngt > target->Length) lngt = target->Length; GCHandle gh = GCHandle::Alloc(target,GCHandleType::Pinned); wchar_t* buff = reinterpret_cast<wchar_t*>(gh.AddrOfPinnedObject().ToPointer()); _wcsnset(buff,' ',target->Length); _snwprintf(buff,lngt,_T2WFSP,srce); gh.Free(); } Now, on occasion, we see access violations getting thrown in the _snwprintf call. My question really is: Is it appropriate to create a string padded to a length (ideally to pre-allocate the internal buffer), and then to modify the String using GCHandle::Alloc and the mess above. And yes, I know that System::String objects are supposed to be immutable - I'm looking for a definitive "This is WRONG and here is why". Thanks, Eli.

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• Do you still limit line length in code?

  - by Noldorin

  This is a matter on which I would like to gauge the opinion of the community: Do you still limit the length of lines of code to a fixed maximum? This was certainly a convention of the past for many languages; one would typically cap the number of characters per line to a value such as 80 (and more recnetly 100 or 120 I believe). As far as I understand, the primary reasons for limiting line length are: Readability - You don't have to scroll over horizontally when you want to see the end of some lines. Printing - Admittedly (at least in my experience), most code that you are working on does not get printed out on paper, but by limiting the number of characters you can insure that formatting doesn't get messed up when printed. Past editors (?) - Not sure about this one, but I suspect that at some point in the distant past of programming, (at least some) text editors may have been based on a fixed-width buffer. I'm sure there are points that I am still missing out, so feel free to add to these... Now, when I tend to observe C or C# code nowadays, I often see a number of different styles, the main ones being: Line length capped to 80, 100, or even 120 characters. As far as I understand, 80 is the traditional length, but the longer ones of 100 and 120 have appeared because of the widespread use of high resolutions and widescreen monitors nowadays. No line length capping at all. This tends to be pretty horrible to read, and I don't see it too often, though it's certainly not too rare either. Inconsistent capping of line length. The length of some lines are limited to a fixed maximum (or even a maximum that changes depending on the file/location in code), while others (possibly comments) are not at all. My personal preference here (at least recently) has been to cap the line length to 100 in the Visual Studio editor. This means that in a decently sized window (on a non-widescreen monitor), the ends of lines are still fully visible. I can however see a few disadvantages in this, especially when you end up writing code that's indented 3 or 4 levels and then having to include a long string literal - though I often take this as a sign to refactor my code! In particular, I am curious what the C and C# coders (or anyone who uses Visual Studio for that matter) think about this point, though I would be interested in hearing anyone's thoughts on the subject. Edit Thanks for the all answers - I appreciate the variety of opinions here, all presenting sound reasons. Consensus does seem to be tipping in the direction of always (or almost always) limit the line length. Interestingly, it seems to be in various coding standards to limit the line length. Judging by some of the answers, both the Python and Google CPP guidelines set the limit at 80 chars. I haven't seen anything similar regarding C# or VB.NET, but I would be curious to see if there are ones anywhere.

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• wrapping boost::ublas with swig

  - by leon

  I am trying to pass data around the numpy and boost::ublas layers. I have written an ultra thin wrapper because swig cannot parse ublas' header correctly. The code is shown below #include <boost/numeric/ublas/vector.hpp> #include <boost/numeric/ublas/matrix.hpp> #include <boost/lexical_cast.hpp> #include <algorithm> #include <sstream> #include <string> using std::copy; using namespace boost; typedef boost::numeric::ublas::matrix<double> dm; typedef boost::numeric::ublas::vector<double> dv; class dvector : public dv{ public: dvector(const int rhs):dv(rhs){;}; dvector(); dvector(const int size, double* ptr):dv(size){ copy(ptr, ptr+sizeof(double)*size, &(dv::data()[0])); } ~dvector(){} }; with the SWIG interface that looks something like %apply(int DIM1, double* INPLACE_ARRAY1) {(const int size, double* ptr)} class dvector{ public: dvector(const int rhs); dvector(); dvector(const int size, double* ptr); %newobject toString; char* toString(); ~dvector(); }; I have compiled them successfully via gcc 4.3 and vc++9.0. However when I simply run a = dvector(array([1.,2.,3.])) it gives me a segfault. This is the first time I use swigh with numpy and not have fully understanding between the data conversion and memory buffer passing. Does anyone see something obvious I have missed? I have tried to trace through with a debugger but it crashed within the assmeblys of python.exe. I have no clue if this is a swig problem or of my simple wrapper. Anything is appreciated.

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• Experienced developer trying to get outsourcing contract with current client.

  - by Mike

  I work for a major bank as a contract software developer. I've been there a few months, and without exception this place has the worst software practices I've ever seen. The software my team makes has no formal testing, terrible code (not reusable, hard to read, etc), minimal documentation, no defined development process and an absolutely sickening amount of waste due to bureaucratic overhead. Part of my contract is to maintain a group of thousands of very poorly written batch jobs. When one of the jobs fails (read: crashes), it's a developers job to look at the source, figure out what's wrong, fix it, and check it in. There is no quality assurance process or auditing of the results whatsoever. Once the developer says "it works" a manager signs off and it goes into production. What's disturbing is that these jobs essentially grab market data and put it into a third-party risk management system, which provides the bank with critical intelligence. I've discovered the disturbing truth that this has been happening since the 90s and nobody really has evidence the system is getting the correct data! Without going into details, an issue arose on Friday that was so horrible I actually stormed out of the place. I was ready to quit, but I decided to just get out to calm my nerves and possibly go back Monday. I've been reflecting today on how to handle this. I have realized that, in probably less than 6 months, I could (with 2 other developers) remake a large component of this system. The new system would provide them with, as primary benefits, a maintainable codebase less prone to error and a solid QA framework. To do it properly I would have to be outside the bank, the internal bureaucracy is just too much. And moreover, I think a bank is fundamentally not a place that can make good software. This is my plan. Write a report explaining in depth all the problems with their current system Explain why their software practices fail and generate a tremendous amount of error and waste. Use this as the basis for claiming the project must be developed externally. Write a high level development plan, including what resources I will require Hand 1,2,3 to my manager, hopefully he passes it up the chain. Worst case he fires me, but this isn't so bad. Convinced Executive decides to award my company a contract for the new system I have 8 years experience as a software contractor and have delivered my share of successful software products, but all working in-house for small/medium sized companies. When I read this over, I think I have a dynamite plan. But since this is the first time doing something this bold so I have my doubts. My question is, is this a good idea? If you think not, please spare no detail.

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• help with making a password checker in java

  - by Cheesegraterr

  Hello, I am trying to make a program in Java that checks for three specific inputs. It has to be 1. At least 7 characters. 2. Contain both upper and lower case alphabetic characters. 3. Contain at least 1 digit. So far I have been able to make it check if there is 7 characters, but I am having trouble with the last two. What should I put in my loop as an if statement to check for digits and make it upper and lower case. Any help would be greatly appreciated. Here is what I have so far. import java.awt.*; import java.io.*; import java.util.StringTokenizer; public class passCheck { private static String getStrSys () { String myInput = null; //Store the String that is read in from the command line BufferedReader mySystem; //Buffer to store the input mySystem = new BufferedReader (new InputStreamReader (System.in)); //creates a connection to system input try { myInput = mySystem.readLine (); //reads in data from the console myInput = myInput.trim (); } catch (IOException e) //check { System.out.println ("IOException: " + e); return ""; } return myInput; //return the integer to the main program } //**************************************** //main instructions go here //**************************************** static public void main (String[] args) { String pass; //the words the user inputs String temp = ""; //holds temp info int stringLength; //length of string boolean goodPass = false; System.out.print ("Please enter a password: "); //ask for words pass = getStrSys (); //get words from system temp = pass.toLowerCase (); stringLength = pass.length (); //find length of eveyrthing while (goodPass == false) { if (stringLength < 7) { System.out.println ("Your password must consist of at least 7 characters"); System.out.print ("Please enter a password: "); //ask for words pass = getStrSys (); stringLength = pass.length (); goodPass = false; } else if (something to check for digits) { } }

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• Delay keyboard input help

  - by Stradigos

  I'm so close! I'm using the XNA Game State Management example found here and trying to modify how it handles input so I can delay the key/create an input buffer. In GameplayScreen.cs I've declared a double called elapsedTime and set it equal to 0. In the HandleInput method I've changed the Key.Right button press to: if (keyboardState.IsKeyDown(Keys.Left)) movement.X -= 50; if (keyboardState.IsKeyDown(Keys.Right)) { elapsedTime -= gameTime.ElapsedGameTime.TotalMilliseconds; if (elapsedTime <= 0) { movement.X += 50; elapsedTime = 10; } } else { elapsedTime = 0; } The pseudo code: If the right arrow key is not pressed set elapsedTime to 0. If it is pressed, the elapsedTime equals itself minus the milliseconds since the last frame. If the difference then equals 0 or less, move the object 50, and then set the elapsedTime to 10 (the delay). If the key is being held down elapsedTime should never be set to 0 via the else. Instead, after elapsedTime is set to 10 after a successful check, the elapsedTime should get lower and lower because it's being subtracted by the TotalMilliseconds. When that reaches 0, it successfully passes the check again and moves the object once more. The problem is, it moves the object once per press but doesn't work if you hold it down. Can anyone offer any sort of tip/example/bit of knowledge towards this? Thanks in advance, it's been driving me nuts. In theory I thought this would for sure work. CLARIFICATION Think of a grid when your thinking about how I want the block to move. Instead of just fluidly moving across the screen, it's moving by it's width (sorta jumping) to the next position. If I hold down the key, it races across the screen. I want to slow this whole process down so that holding the key creates an X millisecond delay between it 'jumping'/moving by it's width. EDIT: Turns out gameTime.ElapsedGameTime.TotalMilliseconds is returning 0... all of the time. I have no idea why.

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• handling NSStream events when using EASession in MonoTouch

  - by scotru

  Does anyone have an example of how to handle read and write NSStream events in Monotouch when working with accessories via EASession? It looks like there isn't a strongly typed delegate for this and I'm having trouble figuring out what selectors I need to handle on the delegates of my InputStream and OutputStream and what I actually need to do with each selector in order to properly fill and empty the buffers belonging to the EASession object. Basically, I'm trying to port Apple's EADemo app to Monotouch right now. Here's the Objective-C source that I think is relevant to this problem: / / asynchronous NSStream handleEvent method - (void)stream:(NSStream *)aStream handleEvent:(NSStreamEvent)eventCode { switch (eventCode) { case NSStreamEventNone: break; case NSStreamEventOpenCompleted: break; case NSStreamEventHasBytesAvailable: [self _readData]; break; case NSStreamEventHasSpaceAvailable: [self _writeData]; break; case NSStreamEventErrorOccurred: break; case NSStreamEventEndEncountered: break; default: break; } } / low level write method - write data to the accessory while there is space available and data to write - (void)_writeData { while (([[_session outputStream] hasSpaceAvailable]) && ([_writeData length] > 0)) { NSInteger bytesWritten = [[_session outputStream] write:[_writeData bytes] maxLength:[_writeData length]]; if (bytesWritten == -1) { NSLog(@"write error"); break; } else if (bytesWritten > 0) { [_writeData replaceBytesInRange:NSMakeRange(0, bytesWritten) withBytes:NULL length:0]; } } } // low level read method - read data while there is data and space available in the input buffer - (void)_readData { #define EAD_INPUT_BUFFER_SIZE 128 uint8_t buf[EAD_INPUT_BUFFER_SIZE]; while ([[_session inputStream] hasBytesAvailable]) { NSInteger bytesRead = [[_session inputStream] read:buf maxLength:EAD_INPUT_BUFFER_SIZE]; if (_readData == nil) { _readData = [[NSMutableData alloc] init]; } [_readData appendBytes:(void *)buf length:bytesRead]; //NSLog(@"read %d bytes from input stream", bytesRead); } [[NSNotificationCenter defaultCenter] postNotificationName:EADSessionDataReceivedNotification object:self userInfo:nil]; } I'd also appreciate any architectural recommendations on how to best implement this in monotouch. For example, in the Objective C implementation these functions are not contained in any class--but in Monotouch would it make sense to make them members of my

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• What's the best way to do base36 arithmetic in perl?

  - by DVK

  What's the best way to do base36 arithmetic in Perl? To be more specific, I need to be able to do the following: Operate on positive N-digit numbers in base 36 (e.g. digits are 0-9 A-Z) N is finite, say 9 Provide basic arithmetic, at the very least the following 3: Addition (A+B) Subtraction (A-B) Whole division, e.g. floor(A/B). Strictly speaking, I don't really need a base10 conversion ability - the numbers will 100% of time be in base36. So I'm quite OK if the solution does NOT implement conversion from base36 back to base10 and vice versa. I don't much care whether the solution is brute-force "convert to base 10 and back" or converting to binary, or some more elegant approach "natively" performing baseN operations (as stated above, to/from base10 conversion is not a requirement). My only 3 considerations are: It fits the minimum specifications above It's "standard". Currently we're using and old homegrown module based on base10 conversion done by hand that is buggy and sucks. I'd much rather replace that with some commonly used CPAN solution instead of re-writing my own bicycle from scratch, but I'm perfectly capable of building it if no better standard possibility exists. It must be fast-ish (though not lightning fast). Something that takes 1 second to sum up 2 9-digit base36 numbers is worse than anything I can roll on my own :) P.S. Just to provide some context in case people decide to solve my XY problem for me in addition to answering the technical question above :) We have a fairly large tree (stored in DB as a bunch of edges), and we need to superimpose order on a subset of that tree. The tree dimentions are big both depth- and breadth- wise. The tree is VERY actively updated (inserts and deletes and branch moves). This is currently done by having a second table with 3 columns: parent_vertex, child_vertex, local_order, where local_order is an 9-character string built of A-Z0-9 (e.g. base 36 number). Additional considerations: It is required that the local order is unique per child (and obviously unique per parent), Any complete re-ordering of a parent is somewhat expensive, and thus the implementation is to try and assign - for a parent with X children - the orders which are somewhat evenly distributed between 0 and 36**10-1, so that almost no tree inserts result in a full re-ordering.

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• Executing Stored Procedure for each InputRow + SSIS Script Component.

  - by Nev_Rahd

  Hello, In my Script Component, am trying to execute Stored Procedure = which return multiple rows = of which need to generate output rows. Code as below: /* Microsoft SQL Server Integration Services Script Component * Write scripts using Microsoft Visual C# 2008. * ScriptMain is the entry point class of the script.*/ using System; using System.Data; using System.Data.SqlClient; using Microsoft.SqlServer.Dts.Pipeline.Wrapper; using Microsoft.SqlServer.Dts.Runtime.Wrapper; [Microsoft.SqlServer.Dts.Pipeline.SSISScriptComponentEntryPointAttribute] public class ScriptMain : UserComponent { SqlConnection cnn = new SqlConnection(); IDTSConnectionManager100 cnManager; //string cmd; SqlCommand cmd = new SqlCommand(); public override void AcquireConnections(object Transaction) { cnManager = base.Connections.myConnection; cnn = (SqlConnection)cnManager.AcquireConnection(null); } public override void PreExecute() { base.PreExecute(); } public override void PostExecute() { base.PostExecute(); } public override void InputRows_ProcessInputRow(InputRowsBuffer Row) { while(Row.NextRow()) { DataTable dt = new DataTable(); cmd.Connection = cnn; cmd.CommandText = "OSPATTRIBUTE_GetOPNforOP"; cmd.CommandType = CommandType.StoredProcedure; cmd.Parameters.Add("@NK", SqlDbType.VarChar).Value = Row.OPNK.ToString(); cmd.Parameters.Add("@EDWSTARTDATE", SqlDbType.DateTime).Value = Row.EDWEFFECTIVESTARTDATETIME; SqlDataAdapter adapter = new SqlDataAdapter(cmd); adapter.Fill(dt); foreach (DataRow dtrow in dt.Rows) { OutputValidBuffer.AddRow(); OutputValidBuffer.OPNK = Row.OPNK; OutputValidBuffer.OSPTYPECODE = Row.OSPTYPECODE; OutputValidBuffer.ORGPROVTYPEDESC = Row.ORGPROVTYPEDESC; OutputValidBuffer.HEALTHSECTORCODE = Row.HEALTHSECTORCODE; OutputValidBuffer.HEALTHSECTORDESCRIPTION = Row.HEALTHSECTORDESCRIPTION; OutputValidBuffer.EDWEFFECTIVESTARTDATETIME = Row.EDWEFFECTIVESTARTDATETIME; OutputValidBuffer.EDWEFFECTIVEENDDATETIME = Row.EDWEFFECTIVEENDDATETIME; OutputValidBuffer.OPQI = Row.OPQI; OutputValidBuffer.OPNNK = dtrow[0].ToString(); OutputValidBuffer.OSPNAMETYPECODE = dtrow[1].ToString(); OutputValidBuffer.NAMETYPEDESC = dtrow[2].ToString(); OutputValidBuffer.OSPNAME = dtrow[3].ToString(); OutputValidBuffer.EDWEFFECTIVESTARTDATETIME1 = Row.EDWEFFECTIVESTARTDATETIME; OutputValidBuffer.EDWEFFECTIVEENDDATETIME1 = Row.EDWEFFECTIVEENDDATETIME; OutputValidBuffer.OPNQI = dtrow[6].ToString(); } } } public override void ReleaseConnections() { cnManager.ReleaseConnection(cnn); } } This is always skipping the first row. while(Row.NextRow()) is always bringing the second row of the input buffer. What am I doing wrong. Thanks

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• Calling an Excel Add-In method from C# application or vice versa

  - by Jude

  I have an Excel VBA add-in with a public method in a bas file. This method currently creates a VB6 COM object, which exists in a running VB6 exe/vbp. The VB6 app loads in data and then the Excel add-in method can call methods on the VB6 COM object to load the data into an existing Excel xls. This is all currently working. We have since converted our VB6 app to C#. My question is: What is the best/easiest way to mimic this behavior with the C#/.NET app? I'm thinking I may not be able to pull the data from the .NET app into Excel from the add-in method since the .Net app needs to be running with data loaded (so no using a stand-alone C# class library). Maybe we can, instead, push the data from .NET to Excel by accessing the VBA add-in method from the C# code? The following is the existing VBA method accessing the VB6 app: Public Sub UpdateInDataFromApp() Dim wkbInData As Workbook Dim oFPW As Object Dim nMaxCols As Integer Dim nMaxRows As Integer Dim j As Integer Dim sName As String Dim nCol As Integer Dim nRow As Integer Dim sheetCnt As Integer Dim nDepth As Integer Dim sPath As String Dim vData As Variant Dim SheetRange As Range Set wkbInData = wkbOpen("InData.xls") sPath = g_sPathXLSfiles & "\" 'Note: the following will bring up fpw app if not already running Set oFPW = CreateObject("FPW.CProfilesData") If oFPW Is Nothing Then MsgBox "Unable to reference " & sApp Else . . . sheetCnt = wkbInData.Sheets.Count 'get number of sheets in indata workbook For j = 2 To sheetCnt 'set counter to loop over all sheets except the first one which is not input data fields With wkbInData.Worksheets(j) Set SheetRange = .UsedRange End With With SheetRange nMaxRows = .Rows.Count 'get range of sheet(j) nMaxCols = .Columns.Count 'get range of sheet(j) Range(.Cells(2, 2), .Cells(nMaxRows, nMaxCols)).ClearContents 'Clears data from data range (51 Columns) Range(.Cells(2, 2), .Cells(nMaxRows, nMaxCols)).ClearComments End With With oFPW 'vb6 object For nRow = 2 To nMaxRows ' loop through rows sName = SheetRange.Cells(nRow, 1) 'Field name vData = .vntGetSymbol(sName, 0) 'Check if vb6 app identifies the name nDepth = .GetInputTableDepth(sName) 'Get number of data items for this field name from vb6 app nMaxCols = nDepth + 2 'nDepth=0, is single data item For nCol = 2 To nMaxCols 'loop over deep screen fields nDepth = nCol - 2 'current depth vData = .vntGetSymbol(sName, nDepth) 'Get Data from vb6 app If LenB(vData) > 0 And IsNumeric(vData) Then 'Check if data returned SheetRange.Cells(nRow, nCol) = vData 'Poke the data in Else SheetRange.Cells(nRow, nCol) = vData 'Poke a zero in End If Next 'nCol Next 'nRow End With Set SheetRange = Nothing Next 'j End If Set wkbInData = Nothing Set oFPW = Nothing Exit Sub . . . End Sub Any help would be appreciated.

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• Problem with return 2 libc method

  - by jth

  Hi, I'am trying to understand the return2libc method. I'am using an ubuntu linux 9.10, 32 bit with ASLR disabled. In theory, it sounds quite easy, overwrite the saved eip with the address of system() (or whatever function you want), then put the address to which system() should return and after that, the parameter for system, the "/bin/bash"-string. But what happens is that my exploit keeps segfaulting the vulnerable program. I assume something with the system()-address went wrong. This is what I did so far: Determined the address of system(): (gdb) print system $1 = {<text variable, no debug info>} 0x167020 <system> (gdb) x/x system 0x167020 <system>: 0x890cec83 I used the subsequent x/x system because those 3 bytes returned by print system looks like an index in some sort of jumptable (PLT?), so I assume 0x890cec83 is the right address which is used to overwrite the saved eip. After that I determined the address of the /bin/bash string in memory, using a small C program which basically consists of this line: printf("Address of string /bin/bash: %p\n", getenv("SHELL")); Then I looked a little bit around in the memory and fount /bin/bash: (gdb) x/s 0xbffff6ca 0xbffff6ca: "/bin/bash" After I gathered this information, I filled the buffer: (gdb) b 9 Breakpoint 1 at 0x8048407: file victim.c, line 9. (gdb) r `perl -e 'print "A"x9 . "\x83\xec\x0c\x89FAKE\xca\f6\ff\bf";'` Breakpoint 1, main (argc=1111638594, argv=0xc360cca) at victim.c:10 10 return 0; (gdb) x/s 0xbffff6ca 0xbffff6ca: "/bin/bash" Stack frame looks like this: (gdb) i f Stack level 0, frame at 0xbffff440: eip = 0x8048407 in main (victim.c:10); saved eip 0x890cec83 source language c. Arglist at 0xbffff438, args: argc=1111638594, argv=0xc360cca Locals at 0xbffff438, Previous frame's sp is 0xbffff440 Saved registers: ebp at 0xbffff438, eip at 0xbffff43c This seems all right to me, saved eip was overwritten with the (hopefully) correct system()-address, return address for system was set to "FAKE" (shouldn't matter) and the address of /bin/bash also seems to be correct. When I'am continuing the execution, victim segfaults on some strange address and certainly not in 0x890cec83: (gdb) cont Continuing. Program received signal SIGSEGV, Segmentation fault. 0x0804840d in main (argc=Cannot access memory at address 0x41414149 ) at victim.c:11 11 } Has anyone an explanation or a hint what happens here and why the execution isn't redirected to 0x890cec83? Thanks in advance, any hint, and be it only vague, would be appreciated. I have no idea why this doesn't work.

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• Function-Local Static Const variable Initialization semantics.

  - by Hassan Syed

  The questions are in bold, for those that cannot be bothered reading a question in depth. This is a followup to this question. It is to do with the initialization semantics of static variables in functions. Static variables should be initialized once, and their internal state might be altered later - as I (currently) do in the linked question. However, the code in question does not require the feature to change the state of the variable later. Let me clarrify my position, since I don't require the string object's internal state to change. The code is for a trait class for meta programming, and as such would would benifit from a const char * const ptr -- thus Ideally a local cost static const variable is needed. My educated guess is that in this case the string in question will be optimally placed in memory by the link-loader, and that the code is more secure and maps to the intended semantics. This leads to the semantics of such a variable "The C++ Programming language Third Edition -- Stroustrup" does not have anything (that I could find) to say about this matter. All that is said is that the variable is initialized once when the flow of control of the thread first reaches the code. This leads me to ponder if the following code would be sensible, and if not what are the intended semantics ?. #include <iostream> const char * const GetString(const char * x_in) { static const char * const x = x_in; return x; } int main() { const char * const temp = GetString("yahoo"); std::cout << temp << std::endl; const char * const temp2 = GetString("yahoo2"); std::cout << temp2 << std::endl; } The following compiles on GCC and prints "yahoo" twice. Which is what I want -- However it might not be standards compliant (which is why I post this question). It might be more elegant to have two functions, "SetString" and "String" where the latter forwards to the first. If it is standards compliant does someone know of a templates implementation in boost (or elsewhere) ?

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• How to I serialize a large graph of .NET object into a SQL Server BLOB without creating a large bu

  - by Ian Ringrose

  We have code like: ms = New IO.MemoryStream bin = New System.Runtime.Serialization.Formatters.Binary.BinaryFormatter bin.Serialize(ms, largeGraphOfObjects) dataToSaveToDatabase = ms.ToArray() // put dataToSaveToDatabase in a Sql server BLOB But the memory steam allocates a large buffer from the large memory heap that is giving us problems. So how can we stream the data without needing enough free memory to hold the serialized objects. I am looking for a way to get a Stream from SQL server that can then be passed to bin.Serialize() so avoiding keeping all the data in my processes memory. Likewise for reading the data back... Some more background. This is part of a complex numerical processing system that processes data in near real time looking for equipment problems etc, the serialization is done to allow a restart when there is a problem with data quality from a data feed etc. (We store the data feeds and can rerun them after the operator has edited out bad values.) Therefore we serialize the object a lot more often then we de-serialize them. The objects we are serializing include very large arrays mostly of doubles as well as a lot of small “more normal” objects. We are pushing the memory limit on a 32 bit system and make the garage collector work very hard. (Effects are being made elsewhere in the system to improve this, e.g. reusing large arrays rather then create new arrays.) Often the serialization of the state is the last straw that courses an out of memory exception; our peak memory usage is while this serialization is being done. I think we get large memory pool fragmentation when we de-serialize the object, I expect there are also other problem with large memory pool fragmentation given the size of the arrays. (This has not yet been investigated, as the person that first looked at this is a numerical processing expert, not a memory management expert.) Are customers use a mix of Sql Server 2000, 2005 and 2008 and we would rather not have different code paths for each version of Sql Server if possible. We can have many active models at a time (in different process, across many machines), each model can have many saved states. Hence the saved state is stored in a database blob rather then a file. As the spread of saving the state is important, I would rather not serialize the object to a file, and then put the file in a BLOB one block at a time. Other related questions I have asked How to Stream data from/to SQL Server BLOB fields? Is there a SqlFileStream like class that works with Sql Server 2005?

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• Performance Optimization for Matrix Rotation

  - by Summer_More_More_Tea

  Hello everyone: I'm now trapped by a performance optimization lab in the book "Computer System from a Programmer's Perspective" described as following: In a N*N matrix M, where N is multiple of 32, the rotate operation can be represented as: Transpose: interchange elements M(i,j) and M(j,i) Exchange rows: Row i is exchanged with row N-1-i A example for matrix rotation(N is 3 instead of 32 for simplicity): ------- ------- |1|2|3| |3|6|9| ------- ------- |4|5|6| after rotate is |2|5|8| ------- ------- |7|8|9| |1|4|7| ------- ------- A naive implementation is: #define RIDX(i,j,n) ((i)*(n)+(j)) void naive_rotate(int dim, pixel *src, pixel *dst) { int i, j; for (i = 0; i < dim; i++) for (j = 0; j < dim; j++) dst[RIDX(dim-1-j, i, dim)] = src[RIDX(i, j, dim)]; } I come up with an idea by inner-loop-unroll. The result is: Code Version Speed Up original 1x unrolled by 2 1.33x unrolled by 4 1.33x unrolled by 8 1.55x unrolled by 16 1.67x unrolled by 32 1.61x I also get a code snippet from pastebin.com that seems can solve this problem: void rotate(int dim, pixel *src, pixel *dst) { int stride = 32; int count = dim >> 5; src += dim - 1; int a1 = count; do { int a2 = dim; do { int a3 = stride; do { *dst++ = *src; src += dim; } while(--a3); src -= dim * stride + 1; dst += dim - stride; } while(--a2); src += dim * (stride + 1); dst -= dim * dim - stride; } while(--a1); } After carefully read the code, I think main idea of this solution is treat 32 rows as a data zone, and perform the rotating operation respectively. Speed up of this version is 1.85x, overwhelming all the loop-unroll version. Here are the questions: In the inner-loop-unroll version, why does increment slow down if the unrolling factor increase, especially change the unrolling factor from 8 to 16, which does not effect the same when switch from 4 to 8? Does the result have some relationship with depth of the CPU pipeline? If the answer is yes, could the degrade of increment reflect pipeline length? What is the probable reason for the optimization of data-zone version? It seems that there is no too much essential difference from the original naive version. EDIT: My test environment is Intel Centrino Duo processor and the verion of gcc is 4.4 Any advice will be highly appreciated! Kind regards!

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• Java map / nio / NFS issue causing a VM fault: "a fault occurred in a recent unsafe memory access op

  - by Matthew Bloch

  I have written a parser class for a particular binary format (nfdump if anyone is interested) which uses java.nio's MappedByteBuffer to read through files of a few GB each. The binary format is just a series of headers and mostly fixed-size binary records, which are fed out to the called by calling nextRecord(), which pushes on the state machine, returning null when it's done. It performs well. It works on a development machine. On my production host, it can run for a few minutes or hours, but always seems to throw "java.lang.InternalError: a fault occurred in a recent unsafe memory access operation in compiled Java code", fingering one of the Map.getInt, getShort methods, i.e. a read operation in the map. The uncontroversial (?) code that sets up the map is this: /** Set up the map from the given filename and position */ protected void open() throws IOException { // Set up buffer, is this all the flexibility we'll need? channel = new FileInputStream(file).getChannel(); MappedByteBuffer map1 = channel.map(FileChannel.MapMode.READ_ONLY, 0, channel.size()); map1.load(); // we want the whole thing, plus seems to reduce frequency of crashes? map = map1; // assumes the host writing the files is little-endian (x86), ought to be configurable map.order(java.nio.ByteOrder.LITTLE_ENDIAN); map.position(position); } and then I use the various map.get* methods to read shorts, ints, longs and other sequences of bytes, before hitting the end of the file and closing the map. I've never seen the exception thrown on my development host. But the significant point of difference between my production host and development is that on the former, I am reading sequences of these files over NFS (probably 6-8TB eventually, still growing). On my dev machine, I have a smaller selection of these files locally (60GB), but when it blows up on the production host it's usually well before it gets to 60GB of data. Both machines are running java 1.6.0_20-b02, though the production host is running Debian/lenny, the dev host is Ubuntu/karmic. I'm not convinced that will make any difference. Both machines have 16GB RAM, and are running with the same java heap settings. I take the view that if there is a bug in my code, there is enough of a bug in the JVM not to throw me a proper exception! But I think it is just a particular JVM implementation bug due to interactions between NFS and mmap, possibly a recurrence of 6244515 which is officially fixed. I already tried adding in a "load" call to force the MappedByteBuffer to load its contents into RAM - this seemed to delay the error in the one test run I've done, but not prevent it. Or it could be coincidence that was the longest it had gone before crashing! If you've read this far and have done this kind of thing with java.nio before, what would your instinct be? Right now mine is to rewrite it without nio :)

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• cannot retrieve effect.fx file

  - by numerical25

  I am having issues loading my effect.fx from directx. When I step into my application, my ID3D10Effect *m_pDefaultEffect; pointer remains empty. the address remains at 0x000000 below is my code #pragma once #include "stdafx.h" #include "resource.h" #include "d3d10.h" #include "d3dx10.h" #include "dinput.h" #define MAX_LOADSTRING 100 class RenderEngine { protected: RECT m_screenRect; //direct3d Members ID3D10Device *m_pDevice; // The IDirect3DDevice10 // interface ID3D10Texture2D *m_pBackBuffer; // Pointer to the back buffer ID3D10RenderTargetView *m_pRenderTargetView; // Pointer to render target view IDXGISwapChain *m_pSwapChain; // Pointer to the swap chain RECT m_rcScreenRect; // The dimensions of the screen ID3D10Texture2D *m_pDepthStencilBuffer; ID3D10DepthStencilState *m_pDepthStencilState; ID3D10DepthStencilView *m_pDepthStencilView; //transformation matrixs D3DXMATRIX g_mtxWorld; D3DXMATRIX g_mtxView; D3DXMATRIX g_mtxProj; //Effect members ID3D10Effect *m_pDefaultEffect; ID3D10EffectTechnique *m_pDefaultTechnique; ID3DX10Font *m_pFont; // The font used for rendering text // Sprites used to hold font characters ID3DX10Sprite *m_pFontSprite; ATOM RegisterEngineClass(); void DoFrame(float); bool LoadEffects(); public: static HINSTANCE m_hInst; HWND m_hWnd; int m_nCmdShow; TCHAR m_szTitle[MAX_LOADSTRING]; // The title bar text TCHAR m_szWindowClass[MAX_LOADSTRING]; // the main window class name void DrawTextString(int x, int y, D3DXCOLOR color, const TCHAR *strOutput); //static functions static LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam); static INT_PTR CALLBACK About(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam); bool InitWindow(); bool InitDirectX(); bool InitInstance(); int Run(); void ShutDown(); RenderEngine() { m_screenRect.right = 800; m_screenRect.bottom = 600; } }; below is the implementation bool RenderEngine::LoadEffects() { HRESULT hr; ID3D10Blob *pErrors = 0; // Create the default rendering effect hr = D3DX10CreateEffectFromFile(L"effect.fx", NULL, NULL, "fx_4_0", D3D10_SHADER_DEBUG, 0, m_pDevice, NULL, NULL, &m_pDefaultEffect, &pErrors, NULL); if(pErrors)// at this point, m_pDefaultEffect is still empty but pErrors returns data which means there is {//errors return false; //ends here } //m_pDefaultTechnique = m_pDefaultEffect->GetTechniqueByName("DefaultTechnique"); return true; } My directx Device does work. My effect.fx file is in the same folder as my solution files (.cpp and header files)

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• Creating a spam list with a web crawler in python

  - by user313623

  Hey guys, I'm not trying to do anything malicious here, I just need to do some homework. I'm a fairly new programmer, I'm using python 3.0, and I having difficulty using recursion for problem-solving. I've been stuck on this question for quite a while. Here's the assignment: Write a recursive method spam(url, n) that takes a url of a web page as input and a non-negative integer n, collects all the email address contained in the web page and adds them to a global dictionary variable spam_dict, and then recursively calls itself on every http hyperlink contained in the web page. You will use a dictionary so only one copy of every email address is save; your dictionary will store (key,value) pairs (email, email). The recursive call should use the parameter n-1 instead of n. If n = 0, you should collect the email addresses but no recursive calls should be made. The parameter n is used to limit the recursion to at most depth n. You will need to use the solutions of the two above problems; you method spam() will call the methods links2() and emails() and possibly other functions as well. Notes: 1. running spam() directly will produce no output on the screen; to find your spam_dict, you will need to read the value of spam_dict, and you will also need to reset it to the empty dictionary before every run of spam. 2. Recall how global variables are used. Usage: spam_dict = {} spam('http://reed.cs.depaul.edu/lperkovic/csc242/test1.html',0) spam_dict.keys() dict_keys([]) spam_dict = {} spam('http://reed.cs.depaul.edu/lperkovic/csc242/test1.html',1) spam_dict.keys() dict_keys(['[email protected]', '[email protected]']) So far, I've written a function that traverses web pages and puts all the links in a nice little list, and what I wanted to do was call that functions. And why would I use recursion on a dictionary? And how? I don't understand how n ties into all of this. def links2(url): content = str(urlopen(url).read()) myparser = MyHTMLParser() myparser.feed(content) lst = myparser.get() mergelst = [] for link in lst: mergelst.append(urljoin(lst[0],link)) print(mergelst) Any input (except why spam is bad) would be greatly appreciated. Also, I realize that the above function could probably look better, if you have a way to do it, I'm all ears. However, all I need is the point is for the program to produce the proper output.

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• cuda/thrust: Trying to sort_by_key 2.8GB of data in 6GB of gpu RAM throws bad_alloc

  - by Sven K

  I have just started using thrust and one of the biggest issues I have so far is that there seems to be no documentation as to how much memory operations require. So I am not sure why the code below is throwing bad_alloc when trying to sort (before the sorting I still have 50% of GPU memory available, and I have 70GB of RAM available on the CPU)--can anyone shed some light on this? #include <thrust/device_vector.h> #include <thrust/sort.h> #include <thrust/random.h> void initialize_data(thrust::device_vector<uint64_t>& data) { thrust::fill(data.begin(), data.end(), 10); } #define BUFFERS 3 int main(void) { size_t N = 120 * 1024 * 1024; char line[256]; try { std::cout << "device_vector" << std::endl; typedef thrust::device_vector<uint64_t> vec64_t; // Each buffer is 900MB vec64_t c[3] = {vec64_t(N), vec64_t(N), vec64_t(N)}; initialize_data(c[0]); initialize_data(c[1]); initialize_data(c[2]); std::cout << "initialize_data finished... Press enter"; std::cin.getline(line, 0); // nvidia-smi reports 48% memory usage at this point (2959MB of // 6143MB) std::cout << "sort_by_key col 0" << std::endl; // throws bad_alloc thrust::sort_by_key(c[0].begin(), c[0].end(), thrust::make_zip_iterator(thrust::make_tuple(c[1].begin(), c[2].begin()))); std::cout << "sort_by_key col 1" << std::endl; thrust::sort_by_key(c[1].begin(), c[1].end(), thrust::make_zip_iterator(thrust::make_tuple(c[0].begin(), c[2].begin()))); } catch(thrust::system_error &e) { std::cerr << "Error: " << e.what() << std::endl; exit(-1); } return 0; }

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• Accidental Complexity in OpenSSL HMAC functions

  - by Hassan Syed

  SSL Documentation Analaysis This question is pertaining the usage of the HMAC routines in OpenSSL. Since Openssl documentation is a tad on the weak side in certain areas, profiling has revealed that using the: unsigned char *HMAC(const EVP_MD *evp_md, const void *key, int key_len, const unsigned char *d, int n, unsigned char *md, unsigned int *md_len); From here, shows 40% of my library runtime is devoted to creating and taking down **HMAC_CTX's behind the scenes. There are also two additional function to create and destroy a HMAC_CTX explicetly: HMAC_CTX_init() initialises a HMAC_CTX before first use. It must be called. HMAC_CTX_cleanup() erases the key and other data from the HMAC_CTX and releases any associated resources. It must be called when an HMAC_CTX is no longer required. These two function calls are prefixed with: The following functions may be used if the message is not completely stored in memory My data fits entirely in memory, so I choose the HMAC function -- the one whose signature is shown above. The context, as described by the man page, is made use of by using the following two functions: HMAC_Update() can be called repeatedly with chunks of the message to be authenticated (len bytes at data). HMAC_Final() places the message authentication code in md, which must have space for the hash function output. The Scope of the Application My application generates a authentic (HMAC, which is also used a nonce), CBC-BF encrypted protocol buffer string. The code will be interfaced with various web-servers and frameworks Windows / Linux as OS, nginx, Apache and IIS as webservers and Python / .NET and C++ web-server filters. The description above should clarify that the library needs to be thread safe, and potentially have resumeable processing state -- i.e., lightweight threads sharing a OS thread (which might leave thread local memory out of the picture). The Question How do I get rid of the 40% overhead on each invocation in a (1) thread-safe / (2) resume-able state way ? (2) is optional since I have all of the source-data present in one go, and can make sure a digest is created in place without relinquishing control of the thread mid-digest-creation. So, (1) can probably be done using thread local memory -- but how do I resuse the CTX's ? does the HMAC_final() call make the CTX reusable ?. (2) optional: in this case I would have to create a pool of CTX's. (3) how does the HMAC function do this ? does it create a CTX in the scope of the function call and destroy it ? Psuedocode and commentary will be useful.

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• LsaAddAccountRights not working for me

  - by SteveL

  Using: Delphi 2010 and the JEDI Windows API and JWSCL I am trying to assign the Logon As A Service privilege to a user using LsaAddAccountRights function but it does not work ie. after the function returns, checking in Group Policy Editor shows that the user still does not have the above mentioned privilege. I'm running the application on Windows XP. Would be glad if someone could point out what is wrong in my code: unit Unit1; interface uses Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, Dialogs, StdCtrls, JwaWindows, JwsclSid; type TForm1 = class(TForm) Button1: TButton; procedure Button1Click(Sender: TObject); private { Private declarations } public { Public declarations } end; var Form1: TForm1; implementation {$R *.dfm} function AddPrivilegeToAccount(AAccountName, APrivilege: String): DWORD; var lStatus: TNTStatus; lObjectAttributes: TLsaObjectAttributes; lPolicyHandle: TLsaHandle; lPrivilege: TLsaUnicodeString; lSid: PSID; lSidLen: DWORD; lTmpDomain: String; lTmpDomainLen: DWORD; lTmpSidNameUse: TSidNameUse; lPrivilegeWStr: String; begin ZeroMemory(@lObjectAttributes, SizeOf(lObjectAttributes)); lStatus := LsaOpenPolicy(nil, lObjectAttributes, POLICY_LOOKUP_NAMES, lPolicyHandle); if lStatus <> STATUS_SUCCESS then begin Result := LsaNtStatusToWinError(lStatus); Exit; end; try lTmpDomainLen := DNLEN; // In 'clear code' this should be get by LookupAccountName SetLength(lTmpDomain, lTmpDomainLen); lSidLen := SECURITY_MAX_SID_SIZE; GetMem(lSid, lSidLen); try if LookupAccountName(nil, PChar(AAccountName), lSid, lSidLen, PChar(lTmpDomain), lTmpDomainLen, lTmpSidNameUse) then begin lPrivilegeWStr := APrivilege; lPrivilege.Buffer := PChar(lPrivilegeWStr); lPrivilege.Length := Length(lPrivilegeWStr) * SizeOf(Char); lPrivilege.MaximumLength := lPrivilege.Length; lStatus := LsaAddAccountRights(lPolicyHandle, lSid, @lPrivilege, 1); Result := LsaNtStatusToWinError(lStatus); end else Result := GetLastError; finally FreeMem(lSid); end; finally LsaClose(lPolicyHandle); end; end; procedure TForm1.Button1Click(Sender: TObject); begin AddPrivilegeToAccount('Sam', 'SeServiceLogonRight'); end; end. Thanks in advance.

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