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  • In .NET when Aborting Thread, can this piece of code get corrupted?

    - by bosko
    Little intro: In complex multithreaded aplication (enterprise service bus EBS), I need to use Thread.Abort, because this EBS accepts user written modules which communicates with hardware security modules. So if this module gets deadlocked or hardware stops responding - i need to just unload this module and rest of this server aplication must keep runnnig. So there is abort sync mechanism which ensures that code can be aborted only in user section and this section must be marked as AbortAble. If this happen there is possibility that ThreadAbortException will be thrown in this pieace of code: public void StopAbortSection() { var id = Thread.CurrentThread.ManagedThreadId; lock (threadIdMap[id]) { .... } } If module is on AbortSection and Aplication decides to abort module, but after this decision but before actual Thread.Abort, module enters NonAbortableSection by calling this method, but lock is actualy taken on that locking object. So lock will block until Abort or abort can be executed before reaching this block by this code. But Object with this method is essential and i need to be sure that this pieace of code is safe to abort in any moment. Probably i have to mention that threadIdMap is Dictionary(int,ManualResetEvent), so locking object is instance of ManualResetEvent. I hope you now understad my question. Sorry for its largeness.

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  • How to program critical section for reader-writer systems?

    - by Srinivas Nayak
    Hi, Lets say, I have a reader-writer system where reader and writer are concurrently running. 'a' and 'b' are two shared variables, which are related to each other, so modification to them needs to be an atomic operation. A reader-writer system can be of the following types: rr ww r-w r-ww rr-w rr-ww where [ r : single reader rr: multiple reader w : single writer ww: multiple writer ] Now, We can have a read method for a reader and a write method for a writer as follows. I have written them system type wise. rr read_method { read a; read b; } ww write_method { lock(m); write a; write b; unlock(m); } r-w r-ww rr-w rr-ww read_method { lock(m); read a; read b; unlock(m); } write_method { lock(m); write a; write b; unlock(m); } For multiple reader system, shared variable access doesn't need to be atomic. For multiple writer system, shared variable access need to be atomic, so locked with 'm'. But, for system types 3 to 6, is my read_method and write_method correct? How can I improve? Sincerely, Srinivas Nayak

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  • File Locked by Services (after service code reading the text file)

    - by rvpals
    I have a windows services written in C# .NET. The service is running on a internal timer, every time the interval hits, it will go and try to read this log file into a String. My issue is every time the log file is read, the service seem to lock the log file. The lock on that log file will continue until I stop the windows service. At the same time the service is checking the log file, the same log file needs to be continuously updated by another program. If the file lock is on, the other program could not update the log file. Here is the code I use to read the text log file. private string ReadtextFile(string filename) { string res = ""; try { System.IO.FileStream fs = new System.IO.FileStream(filename, System.IO.FileMode.Open, System.IO.FileAccess.Read); System.IO.StreamReader sr = new System.IO.StreamReader(fs); res = sr.ReadToEnd(); sr.Close(); fs.Close(); } catch (System.Exception ex) { HandleEx(ex); } return res; } Thank you.

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  • After rich:extendedDataTable sortby,otheractions are not getting executed

    - by user118802
    I have a RichFaces UI which are having sidebar menu and sidebar had 8 links. I am using Seam @DataModel and @Factory and hibernate criteria to populate all the 8 pages. In all the pages i have sortby functionality which is working fine. I am able to get all data in all the 8 pages and I can freely navigate around all the links/xhtmls. But if in one of the xhtmlpages if I do sorting or groupby after that I am unable to navigate to other pages.If I select any other link the same last query which is executed for sorting is getting executed. Is this an issue? or do I need add any configuration. Please help me in solving this issue. Below is the codesnippet one of the 8 xhtml <rich:column sortable="true" sortBy="#{p.regionid}" width="100px" label="Region Id"> <f:facet name="header"> <h:outputText value="Region Id" /> </f:facet> <h:outputText value="#{p.regionid}" /> </rich:column> <rich:column sortable="true" sortBy="#{p.region}" width="100px" label="Region Name"> <f:facet name="header"> <h:outputText value="Region Name" /> </f:facet> <h:outputText value="#{p.region}" /> </rich:column> Sidebar Action @DataModel("regions") private List<CoreRegion> listRegions; @Factory("regions") public void getRegions() { System.out.println("Inside get Regions"); Session userDatabase = HibernateUtil.getSession(); Criteria crit = userDatabase.createCriteria(CoreRegion.class); listRegions = crit.list();

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  • Atomic int writes on file

    - by Waneck
    Hello! I'm writing an application that will have to be able to handle many concurrent accesses to it, either by threads as by processes. So no mutex'es or locks should be applied to this. To make the use of locks go down to a minimum, I'm designing for the file to be "append-only", so all data is first appended to disk, and then the address pointing to the info it has updated, is changed to refer to the new one. So I will need to implement a small lock system only to change this one int so it refers to the new address. How is the best way to do it? I was thinking about maybe putting a flag before the address, that when it's set, the readers will use a spin lock until it's released. But I'm afraid that it isn't at all atomic, is it? e.g. a reader reads the flag, and it is unset on the same time, a writer writes the flag and changes the value of the int the reader may read an inconsistent value! I'm looking for locking techniques but all I find is either for thread locking techniques, or to lock an entire file, not fields. Is it not possible to do this? How do append-only databases handle this? Thanks! Cauê

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  • Delete throws "deleted object would be re-saved by cascade"

    - by Greg
    I have following model: <class name="Person" table="Person" optimistic-lock="version"> <id name="Id" type="Int32" unsaved-value="0"> <generator class="native" /> </id> <!-- plus some properties here --> </class> <class name="Event" table="Event" optimistic-lock="version"> <id name="Id" type="Int32" unsaved-value="0"> <generator class="native" /> </id> <!-- plus some properties here --> </class> <class name="PersonEventRegistration" table="PersonEventRegistration" optimistic-lock="version"> <id name="Id" type="Int32" unsaved-value="0"> <generator class="native" /> </id> <property name="IsComplete" type="Boolean" not-null="true" /> <property name="RegistrationDate" type="DateTime" not-null="true" /> <many-to-one name="Person" class="Person" column="PersonId" foreign-key="FK_PersonEvent_PersonId" cascade="all-delete-orphan" /> <many-to-one name="Event" class="Event" column="EventId" foreign-key="FK_PersonEvent_EventId" cascade="all-delete-orphan" /> </class> There are no properties pointing to PersonEventRegistration either in Person nor in Event. When I try to delete an entry from PersonEventRegistration, I get the following error: "deleted object would be re-saved by cascade" The problem is, I don't store this object in any other collection - the delete code looks like this: public bool UnregisterFromEvent(Person person, Event entry) { var registrationEntry = this.session .CreateCriteria<PersonEventRegistration>() .Add(Restrictions.Eq("Person", person)) .Add(Restrictions.Eq("Event", entry)) .Add(Restrictions.Eq("IsComplete", false)) .UniqueResult<PersonEventRegistration>(); bool result = false; if (null != registrationEntry) { using (ITransaction tx = this.session.BeginTransaction()) { this.session.Delete(registrationEntry); tx.Commit(); result = true; } } return result; } What am I doing wrong here?

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  • What techniques can be used to detect so called "black holes" (a spider trap) when creating a web crawler?

    - by Tom
    When creating a web crawler, you have to design somekind of system that gathers links and add them to a queue. Some, if not most, of these links will be dynamic, which appear to be different, but do not add any value as they are specifically created to fool crawlers. An example: We tell our crawler to crawl the domain evil.com by entering an initial lookup URL. Lets assume we let it crawl the front page initially, evil.com/index The returned HTML will contain several "unique" links: evil.com/somePageOne evil.com/somePageTwo evil.com/somePageThree The crawler will add these to the buffer of uncrawled URLs. When somePageOne is being crawled, the crawler receives more URLs: evil.com/someSubPageOne evil.com/someSubPageTwo These appear to be unique, and so they are. They are unique in the sense that the returned content is different from previous pages and that the URL is new to the crawler, however it appears that this is only because the developer has made a "loop trap" or "black hole". The crawler will add this new sub page, and the sub page will have another sub page, which will also be added. This process can go on infinitely. The content of each page is unique, but totally useless (it is randomly generated text, or text pulled from a random source). Our crawler will keep finding new pages, which we actually are not interested in. These loop traps are very difficult to find, and if your crawler does not have anything to prevent them in place, it will get stuck on a certain domain for infinity. My question is, what techniques can be used to detect so called black holes? One of the most common answers I have heard is the introduction of a limit on the amount of pages to be crawled. However, I cannot see how this can be a reliable technique when you do not know what kind of site is to be crawled. A legit site, like Wikipedia, can have hundreds of thousands of pages. Such limit could return a false positive for these kind of sites. Any feedback is appreciated. Thanks.

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  • How did this happen?? Git error? Some other fluke?

    - by marfarma
    Every file in this Rails project is duplicated with a -e and again with a -e-e tacked onto the end of it, like the following. It's that way in my GitHub repository too. But I can't figure out how it happened. Any clue? Google searching comes up empty. -rw-r--r--@ 1 usrname staff 959 Jan 7 02:13 Gemfile -rw-r--r-- 1 usrname staff 958 Jan 5 01:10 Gemfile-e -rw-r--r-- 1 usrname staff 958 Jan 5 01:09 Gemfile-e-e -rw-r--r-- 1 usrname staff 6650 Jan 7 02:13 Gemfile.lock -rw-r--r-- 1 usrname staff 6650 Jan 5 01:10 Gemfile.lock-e -rw-r--r-- 1 usrname staff 6650 Jan 5 01:09 Gemfile.lock-e-e lrwxr-xr-x 1 usrname staff 18 Jan 5 00:37 README.rdoc - doc/README_FOR_APP -rw-r--r-- 1 usrname staff 283 Jan 5 01:10 Rakefile -rw-r--r-- 1 usrname staff 283 Jan 5 01:10 Rakefile-e -rw-r--r-- 1 usrname staff 283 Jan 5 01:09 Rakefile-e-e drwxr-xr-x 6 usrname staff 204 Jan 5 00:37 app drwxr-xr-x 5 usrname staff 170 Jan 5 01:10 autotest drwxr-xr-x 28 usrname staff 952 Jan 5 01:15 config -rw-r--r-- 1 usrname staff 173 Jan 5 01:10 config.ru -rw-r--r-- 1 usrname staff 173 Jan 5 01:10 config.ru-e -rw-r--r-- 1 usrname staff 173 Jan 5 01:09 config.ru-e-e

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  • what are all the Optimize tricks that you know for asp.net code ?

    - by Aristos
    After some time of many code programming on asp.net, I discover the very big speed different between string and StringBuilder. I know that is very common and known but I just mention it for start. The second think that I have found to speed up the code, is to use the const, and not the static, for declare my configuration constants value (especial the strings). With the const, the compiler not create new object, but just place the value, on the point that you have ask it, but with the static declaration, is create a new memory object and keep its on the memory. My third trick, is when I search for string, I use hash values, and not the string itself. For example, if I need a List<string SomeValues, and place inside strings that I need to search them, I prefer to use List<int SomeHashValue, and I use the hash value to locate the strings. My forth thought that I was wandering, is if is better to place big strings in one line, or separate them in different lines with the + symbol to be more easy to read out. I make some tests and see that the compiler make a good job is some split the string, in many lines, using the + symbol. What other tricks/tips do you know and use on your programming to make it run faster, and maybe use less memory. Well I know, that some times, to make something run faster, you need more memory, more cache. My priority is on speed. Because Speed Counts.

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  • c# string interning

    - by CodingThunder
    I am trying to understand string interning and why is doesn't seem to work in my example. The point of the example is to show Example 1 uses less (a lot less memory) as it should only have 10 strings in memory. However, in the code below both example use roughly the same amount of memory (virtual size and working set). Please advice why example 1 isn't using a lot less memory? Thanks Example 1: IList<string> list = new List<string>(10000); for (int i = 0; i < 10000; i++) { for (int k = 0; k < 10; k++) { list.Add(string.Intern(k.ToString())); } } Console.WriteLine("intern Done"); Console.ReadLine(); Example 2: IList<string> list = new List<string>(10000); for (int i = 0; i < 10000; i++) { for (int k = 0; k < 10; k++) { list.Add(k.ToString()); } } Console.WriteLine("intern Done"); Console.ReadLine();

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  • SQLite transaction doesn't work as expected

    - by troll
    I prepared 2 files, "1.php" and "2.php". "1.php" is like this. <?php $dbh = new PDO('sqlite:test1'); $dbh->beginTransaction(); print "aaa<br>"; sleep(55); $dbh->commit(); print "bbb"; ?> and "2.php" is like this. <?php $dbh = new PDO('sqlite:test1'); $dbh->beginTransaction(); print "ccc<br>"; $dbh->commit(); print "ddd"; ?> and I excute "1.php". It starts a transaction and waits 55 seconds. So when I immediately excute "2.php", my expectation is this: "1.php" is getting transaction and "1" holds a database lock "2" can not begin a transaction "2" can not get database lock so "2" have to wait 55 seconds BUT, but the test went another way. When I excute "2",then "2" immediately returned it's result "2" did not wait so I have to think that "1" could not get transaction, or could not get database lock. Can anyone help?

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  • Is a call to the following method considered late binding?

    - by AspOnMyNet
    1) Assume: • B1 defines methods virtualM() and nonvirtualM(), where former method is virtual while the latter is non-virtual • B2 derives from B1 • B2 overrides virtualM() • B2 is defined inside assembly A • Application app doesn’t have a reference to assembly A In the following code application app dynamically loads an assembly A, creates an instance of a type B2 and calls methods virtualM() and nonvirtualM(): Assembly a=Assembly.Load(“A”); Type t= a.GetType(“B2”); B1 a = ( B1 ) Activator.CreateInstance ( “t” ); a.virtualM(); a.nonvirtualM(); a) Is call to a.virtualM() considered early binding or late binding? b) I assume a call to a.nonvirtualM() is resolved during compilation time? 2) Does the term late binding refer only to looking up the target method at run time or does it also refer to creating an instance of given type at runtime? thanx EDIT: 1) A a=new A(); a.M(); As far as I know, it is not known at compile time where on the heap (thus at which memory address ) will instance a be created during runtime. Now, with early binding the function calls are replaced with memory addresses during compilation process. But how can compiler replace function call with memory address, if it doesn’t know where on the heap will object a be created during runtime ( here I’m assuming the address of method a.M will also be at same memory location as a )? 2) The method slot is determined at compile time I assume that by method slot you’re referring to the entry point in V-table?

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  • How to deserialize implementation classes in OSGi

    - by Daniel Schneller
    In an eRCP OSGi based application the user can push a button and go to a lock screen similar to that of Windows or Mac OS X. When this happens, the current state of the application is serialized to a file and control is handed over to the lock screen. In this mobile application memory is very tight, so we need to get rid of the original view/controller when the lock screen comes up. This works fine and we end up with a binary serialized file. Once the user logs back in, the file is read in again and the original state of the application restored. This works fine as well, except when the controller that was serialized contained a reference to an object which comes from a different bundle. In my concrete case the original controller (from bundle A) can call a web service and gets a result back. Nothing fancy, just some Strings and Numbers in a simple value holder class. However the controller only sees this as a Result interface; the actual runtime object (ResultImpl) is defined and created in a different bundle (bundle B, the webservice client implementation) and returned via a service call. When the deserialization now tries to thaw the controller from the file, it throws a ClassNotFound exception, complaining about not being able to deserialize the result object, because deserialization is called from bundle A, which cannot see the ResultImpl class from bundle B. Any ideas on how to work around that? The only thing I could come up with is to clone all the individual values into another object, defined in the controller's bundle, but this seems like quite a hassle.

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  • Any way to turn off quips in OOWeb?

    - by Misha Koshelev
    http://ooweb.sourceforge.net/tutorial.html Not really a question, but I can't seem to stop writing stuff like this. Maybe someone will find it useful. I know rewriting an HTTP server is not the way to turn off the quips ;) /* Copyright 2010 Misha Koshelev. All Rights Reserved. */ package com.mksoft.common; import java.io.BufferedReader; import java.io.InputStreamReader; import java.io.IOException; import java.io.PrintWriter; import java.io.UnsupportedEncodingException; import java.net.URLDecoder; import java.text.SimpleDateFormat; import java.util.Date; import java.util.LinkedHashMap; import java.net.ServerSocket; import java.net.Socket; /** * Simple HTTP Server. * * @author Misha Koshelev */ public class HttpServer extends Thread { /* * Constants */ /** * 404 Not Found Result */ protected final static String result404NotFound="<html><head><title>404 Not Found</title></head><body bgcolor='#ffffff'><h1>404 Not Found</h1></body></html>"; /* * Variables */ /** * Port on which HTTP server handles requests. */ protected int port; public int getPort() { return port; } public void setPort(int _port) { port=_port; } /* * Constructors */ public HttpServer(int _port) { setPort(_port); } /* * Helpers */ /** * Errors */ protected void error(String message) { System.err.println(message); System.err.flush(); } /** * Debugging */ protected boolean debugOutput=true; protected void debug(String message) { if (debugOutput) { error(message); } } /** * Lock object */ private Object lock=new Object(); /** * Should we quit? */ protected boolean doQuit=false; /** * Are we done? */ protected boolean areWeDone=false; /** * Process POST request headers */ protected String processPostRequest(String url,LinkedHashMap<String,String> headers,String inputLine) { debug("HttpServer.processPostRequest: url=\""+url); if (debugOutput) { for (String key: headers.keySet()) { debug("HttpServer.processPostRequest: headers."+key+"=\""+headers.get(key)+"\""); } } debug("HttpServer.processPostRequest: inputLine=\""+inputLine+"\""); try { inputLine=new URLDecoder().decode(inputLine,"UTF-8"); } catch (UnsupportedEncodingException uee) { uee.printStackTrace(); } String[] keyValues=inputLine.split("&"); LinkedHashMap<String,String> post=new LinkedHashMap<String,String>(); for (int i=0;i<keyValues.length;i++) { String keyValue=keyValues[i]; int equals=keyValue.indexOf('='); String key=keyValue.substring(0,equals); String value=keyValue.substring(equals+1); post.put(key,value); } return post(url,headers,post); } /** * Server loop (here for exception handling purposes) */ protected void serverLoop() throws IOException { /* Start server socket */ ServerSocket serverSocket=null; try { serverSocket=new ServerSocket(getPort()); } catch (IOException ioe) { ioe.printStackTrace(); System.exit(1); } Socket clientSocket=null; while (true) { /* Quit if necessary */ if (doQuit) { break; } /* Accept incoming connections */ try { clientSocket=serverSocket.accept(); } catch (IOException ioe) { ioe.printStackTrace(); System.exit(1); } /* Read request */ BufferedReader in=null; String inputLine=null; String firstLine=null; String blankLine=null; LinkedHashMap<String,String> headers=new LinkedHashMap<String,String>(); try { in=new BufferedReader(new InputStreamReader(clientSocket.getInputStream())); while (true) { if (blankLine==null) { inputLine=in.readLine(); } else { /* POST request, read Content-length bytes */ int contentLength=new Integer(headers.get("Content-Length")).intValue(); StringBuilder sb=new StringBuilder(contentLength); for (int i=0;i<contentLength;i++) { sb.append((char)in.read()); } inputLine=sb.toString(); break; } if (firstLine==null) { firstLine=inputLine; } else if (blankLine==null) { if (inputLine.equals("")) { if (firstLine.startsWith("GET ")) { break; } blankLine=inputLine; } else { int colon=inputLine.indexOf(": "); String key=inputLine.substring(0,colon); String value=inputLine.substring(colon+2); headers.put(key,value); } } } } catch (IOException ioe) { ioe.printStackTrace(); } /* Process request */ String result=null; firstLine=firstLine.replaceAll(" HTTP/.*",""); if (firstLine.startsWith("GET ")) { result=get(firstLine.replaceFirst("GET ",""),headers); } else if (firstLine.startsWith("POST ")) { result=processPostRequest(firstLine.replaceFirst("POST ",""),headers,inputLine); } else { error("HttpServer.ServerLoop: Unhandled request \""+firstLine+"\""); } debug("HttpServer.ServerLoop: result=\""+result+"\""); /* Send response */ PrintWriter out=null; try { out=new PrintWriter(clientSocket.getOutputStream(),true); } catch (IOException ioe) { ioe.printStackTrace(); } if (result!=null) { out.println("HTTP/1.1 200 OK"); } else { out.println("HTTP/1.0 404 Not Found"); result=result404NotFound; } Date now=new Date(); out.println("Date: "+new SimpleDateFormat("EEE, d MMM yyyy HH:mm:ss z").format(now)); out.println("Content-Type: text/html; charset=UTF-8"); out.println("Content-Length: "+result.length()); out.println(""); out.print(result); /* Clean up */ out.close(); if (in!=null) { in.close(); } clientSocket.close(); } serverSocket.close(); areWeDone=true; synchronized(lock) { lock.notifyAll(); } } /* * Methods */ /** * Run server on port specified in constructor. */ public void run() { try { serverLoop(); } catch (IOException ioe) { ioe.printStackTrace(); System.exit(1); } } /** * Process GET request (should be overwritten). */ public String get(String url,LinkedHashMap<String,String> headers) { debug("HttpServer.get: url=\""+url+"\""); if (debugOutput) { for (String key: headers.keySet()) { debug("HttpServer.get: headers."+key+"=\""+headers.get(key)+"\""); } } if (url.equals("/")) { return "<html><head><title>HttpServer GET Test Page</title></head>\r\n"+ "<body bgcolor='#ffffff'>\r\n"+ "<center><h1>HttpServer GET Test Page</h1></center>\r\n"+ "<hr />\r\n"+ "<center><table>\r\n"+ "<form method='post' action='/'>\r\n"+ "<tr><td align=right>Test 1:</td>\r\n"+ " <td><input type='text' name='text 1' value='test me !!! !@#$'></td></tr>\r\n"+ "<tr><td align=right>Test 2:</td>\r\n"+ " <td><input type='text' name='text 2' value='type smthng'></td></tr>\r\n"+ "<tr><td>&nbsp;</td>\r\n"+ " <td align=right><input type='submit' value='Submit'></td></tr>\r\n"+ "</form>\r\n"+ "</table></center>\r\n"+ "<hr />\r\n"+ "<center><a href='/quit'>Shutdown Server</a></center>\r\n"+ "</html>"; } else if (url.equals("/quit")) { quit(); return ""; } else { return null; } } /** * Process POST request (should be overwritten). */ public String post(String url,LinkedHashMap<String,String> headers,LinkedHashMap<String,String> post) { debug("HttpServer.post: url=\""+url+"\""); if (debugOutput) { for (String key: headers.keySet()) { debug("HttpServer.post: headers."+key+"=\""+headers.get(key)+"\""); } } if (url.equals("/")) { String result="<html><head><title>HttpServer Post Test Page</title></head>\r\n"+ "<body bgcolor='#ffffff'>\r\n"+ "<center><h1>HttpServer Post Test Page</h1></center>\r\n"+ "<hr />\r\n"+ "<center><table>\r\n"+ "<tr><th>Key</th><th>Value</th></tr>\r\n"; for (String key: post.keySet()) { result+="<tr><td align=right>"+key+"</td><td align=left>"+post.get(key)+"</td></tr>\r\n"; } result+="</table></center>\r\n"+ "</html>"; return result; } else { return null; } } /** * Wait for server to quit. */ public void waitForCompletion() { while (areWeDone==false) { synchronized(lock) { try { lock.wait(); } catch (InterruptedException ie) { } } } } /** * Shutdown server. */ public void quit() { doQuit=true; } }

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  • How Can I Compress Texture in OpenGL on iPhone/iPad?

    - by nonamelive
    Hi, I'm making an iPad app which needs OpenGL to do a flip animation. I have a front image texture and a back image texture. Both the two textures are screenshots. // Capture an image of the screen UIGraphicsBeginImageContext(view.bounds.size); [view.layer renderInContext:UIGraphicsGetCurrentContext()]; image = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); // Allocate some memory for the texture GLubyte *textureData = (GLubyte*)calloc(maxTextureSize*4, maxTextureSize); // Create a drawing context to draw image into texture memory CGContextRef textureContext = CGBitmapContextCreate(textureData, maxTextureSize, maxTextureSize, 8, maxTextureSize*4, CGImageGetColorSpace(image.CGImage), kCGImageAlphaPremultipliedLast); CGContextDrawImage(textureContext, CGRectMake(0, maxTextureSize-size.height, size.width, size.height), image.CGImage); CGContextRelease(textureContext); // ...done creating the texture data [EAGLContext setCurrentContext:context]; glGenTextures(1, &textureToView); glBindTexture(GL_TEXTURE_2D, textureToView); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, maxTextureSize, maxTextureSize, 0, GL_RGBA, GL_UNSIGNED_BYTE, textureData); // free texture data which is by now copied into the GL context free(textureData); Each of the texture takes up about 8MB memory, which is unacceptable for an iPhone/iPad app. Could anyone tell me how can I compress the texture to reduce the memory. I'm a complete newbie to OpenGL. Any help would be appreciated!

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  • How do I patch a Windows API at runtime so that it to returns 0 in x64?

    - by Jorge Vasquez
    In x86, I get the function address using GetProcAddress() and write a simple XOR EAX,EAX; RET; in it. Simple and effective. How do I do the same in x64? bool DisableSetUnhandledExceptionFilter() { const BYTE PatchBytes[5] = { 0x33, 0xC0, 0xC2, 0x04, 0x00 }; // XOR EAX,EAX; RET; // Obtain the address of SetUnhandledExceptionFilter HMODULE hLib = GetModuleHandle( _T("kernel32.dll") ); if( hLib == NULL ) return false; BYTE* pTarget = (BYTE*)GetProcAddress( hLib, "SetUnhandledExceptionFilter" ); if( pTarget == 0 ) return false; // Patch SetUnhandledExceptionFilter if( !WriteMemory( pTarget, PatchBytes, sizeof(PatchBytes) ) ) return false; // Ensures out of cache FlushInstructionCache(GetCurrentProcess(), pTarget, sizeof(PatchBytes)); // Success return true; } static bool WriteMemory( BYTE* pTarget, const BYTE* pSource, DWORD Size ) { // Check parameters if( pTarget == 0 ) return false; if( pSource == 0 ) return false; if( Size == 0 ) return false; if( IsBadReadPtr( pSource, Size ) ) return false; // Modify protection attributes of the target memory page DWORD OldProtect = 0; if( !VirtualProtect( pTarget, Size, PAGE_EXECUTE_READWRITE, &OldProtect ) ) return false; // Write memory memcpy( pTarget, pSource, Size ); // Restore memory protection attributes of the target memory page DWORD Temp = 0; if( !VirtualProtect( pTarget, Size, OldProtect, &Temp ) ) return false; // Success return true; } This example is adapted from code found here: http://www.debuginfo.com/articles/debugfilters.html#overwrite .

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  • Powershell finding services using a cmdlet dll

    - by bartonm
    I need to upgrade a dll assemblies, written in C#, in our installation. Before I replace the DLL file, I want to check if the file has a lock and if so display a message. How do I implement this in powershell? I was thinking iterate through Get-Process checking dependencies. Solved. I iterated through list looking a file path match. function IsCaradigmPowershellDLLFree() { # The list of DLLs to check for locks by running processes. $DllsToCheckForLocks = "$env:ProgramFiles\Caradigm Platform\System 3.0\Platform\PowerShell\Caradigm.Platform.Powershell.dll", "$env:ProgramFiles\Caradigm Platform\System 3.0\Platform\PowerShell\Caradigm.Platform.Powershell.InternalPlatformSetup.dll"; # Assume true, then check all process dependencies $result = $true; # Iterate through each process and check module dependencies foreach ($p in Get-Process) { # Iterate through each dll used in a given process foreach ($m in Get-Process -Name $p.ProcessName -Module -ErrorAction SilentlyContinue) { # Check if dll dependency match any DLLs in list foreach ($dll in $DllsToCheckForLocks) { # Compare the fully-qualified file paths, # if there's a match then a lock exists. if ( ($m.FileName.CompareTo($dll) -eq 0) ) { $pName = $p.ProcessName.ToString() Write-Error "$dll is locked by $pName. This dll must be have zero locked prior to upgrade. Stop this service to release this lock on $m1." $result = $false; } } } } return $result; }

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  • Sequential access to asynchronous sockets

    - by Lars A. Brekken
    I have a server that has several clients C1...Cn to each of which there is a TCP connection established. There are less than 10,000 clients. The message protocol is request/response based, where the server sends a request to a client and then the client sends a response. The server has several threads, T1...Tm, and each of these may send requests to any of the clients. I want to make sure that only one of these threads can send a request to a specific client at any one time, while the other threads wanting to send a request to the same client will have to wait. I do not want to block threads from sending requests to different clients at the same time. E.g. If T1 is sending a request to C3, another thread T2 should not be able to send anything to C3 until T1 has received its response. I was thinking of using a simple lock statement on the socket: lock (c3Socket) { // Send request to C3 // Get response from C3 } I am using asynchronous sockets, so I may have to use Monitor instead: Monitor.Enter(c3Socket); // Before calling .BeginReceive() And Monitor.Exit(c3Socket); // In .EndReceive I am worried about stuff going wrong and not letting go of the monitor and therefore blocking all access to a client. I'm thinking that my heartbeat thread could use Monitor.TryEnter() with a timeout and throw out sockets that it cannot get the monitor for. Would it make sense for me to make the Begin and End calls synchronous in order to be able to use the lock() statement? I know that I would be sacrificing concurrency for simplicity in this case, but it may be worth it. Am I overlooking anything here? Any input appreciated.

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  • Really Need a Facebook App to post to Facebook Page Wall?

    - by Lee Englestone
    Hi, I'm using the Facebook API Graph (C# & ASP.NET) to try to dynamically post to a Facebook page I created. Looking at the code samples floating around.. they suggest creating a Facebook App first (which I have done).. However.. I have 3 different pages I want to post to.. Do I need to create an app for each? (I want to post different things to the 3 pages, not the same posts to each) I just want messages & links to appear as Wall posts. I'm not bothered about having an 'app' that has 'canvas' that is placed in an IFrame. Question : So do I still need to write one or more Facebook Apps to post to my 3 different Facebook pages?? Where I am so far.. I can pass in my apps credentials and get back the access_token. But my posts don't appear to be going anywhere. I'd rather drop the 'facebook application /canvas' approach if possible If I can post directly to a wall (For the above reasons). Oh, and before you ask. I don't want to post to my Apps Wall page, I want to post to my other pages (Unless I have to post to my Apps Wall page first?). I'm sure loads of people have the same questions.. Thanks in advance. -- Lee

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  • Sharing a COM port over TCP

    - by guinness
    What would be a simple design pattern for sharing a COM port over TCP to multiple clients? For example, a local GPS device that could transmit co-ordinates to remote hosts in realtime. So I need a program that would open the serial port and accept multiple TCP connections like: class Program { public static void Main(string[] args) { SerialPort sp = new SerialPort("COM4", 19200, Parity.None, 8, StopBits.One); Socket srv = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp); srv.Bind(new IPEndPoint(IPAddress.Any, 8000)); srv.Listen(20); while (true) { Socket soc = srv.Accept(); new Connection(soc); } } } I would then need a class to handle the communication between connected clients, allowing them all to see the data and keeping it synchronized so client commands are received in sequence: class Connection { static object lck = new object(); static List<Connection> cons = new List<Connection>(); public Socket socket; public StreamReader reader; public StreamWriter writer; public Connection(Socket soc) { this.socket = soc; this.reader = new StreamReader(new NetworkStream(soc, false)); this.writer = new StreamWriter(new NetworkStream(soc, true)); new Thread(ClientLoop).Start(); } void ClientLoop() { lock (lck) { connections.Add(this); } while (true) { lock (lck) { string line = reader.ReadLine(); if (String.IsNullOrEmpty(line)) break; foreach (Connection con in cons) con.writer.WriteLine(line); } } lock (lck) { cons.Remove(this); socket.Close(); } } } The problem I'm struggling to resolve is how to facilitate communication between the SerialPort instance and the threads. I'm not certain that the above code is the best way forward, so does anybody have another solution (the simpler the better)?

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  • Unusual heap size limitations in VS2003 C++

    - by Shane MacLaughlin
    I have a C++ app that uses large arrays of data, and have noticed while testing that it is running out of memory, while there is still plenty of memory available. I have reduced the code to a sample test case as follows; void MemTest() { size_t Size = 500*1024*1024; // 512mb if (Size > _HEAP_MAXREQ) TRACE("Invalid Size"); void * mem = malloc(Size); if (mem == NULL) TRACE("allocation failed"); } If I create a new MFC project, include this function, and run it from InitInstance, it works fine in debug mode (memory allocated as expected), yet fails in release mode (malloc returns NULL). Single stepping through release into the C run times, my function gets inlined I get the following // malloc.c void * __cdecl _malloc_base (size_t size) { void *res = _nh_malloc_base(size, _newmode); RTCCALLBACK(_RTC_Allocate_hook, (res, size, 0)); return res; } Calling _nh_malloc_base void * __cdecl _nh_malloc_base (size_t size, int nhFlag) { void * pvReturn; // validate size if (size > _HEAP_MAXREQ) return NULL; ' ' And (size _HEAP_MAXREQ) returns true and hence my memory doesn't get allocated. Putting a watch on size comes back with the exptected 512MB, which suggests the program is linking into a different run-time library with a much smaller _HEAP_MAXREQ. Grepping the VC++ folders for _HEAP_MAXREQ shows the expected 0xFFFFFFE0, so I can't figure out what is happening here. Anyone know of any CRT changes or versions that would cause this problem, or am I missing something way more obvious?

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  • Do entity collections and object sets implement IQueryable<T>?

    - by Chevex
    I am using Entity Framework for the first time and noticed that the entities object returns entity collections. DBEntities db = new DBEntities(); db.Users; //Users is an ObjectSet<User> User user = db.Users.Where(x => x.Username == "test").First(); //Is this getting executed in the SQL or in memory? user.Posts; //Posts is an EntityCollection<Post> Post post = user.Posts.Where(x => x.PostID == "123").First(); //Is this getting executed in the SQL or in memory? Do both ObjectSet and EntityCollection implement IQueryable? I am hoping they do so that I know the queries are getting executed at the data source and not in memory. EDIT: So apparently EntityCollection does not while ObjectSet does. Does that mean I would be better off using this code? DBEntities db = new DBEntities(); User user = db.Users.Where(x => x.Username == "test").First(); //Is this getting executed in the SQL or in memory? Post post = db.Posts.Where(x => (x.PostID == "123")&&(x.Username == user.Username)).First(); // Querying the object set instead of the entity collection. Also, what is the difference between ObjectSet and EntityCollection? Shouldn't they be the same? Thanks in advance!

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  • How to improve multi-threaded access to Cache (custom implementation)

    - by Andy
    I have a custom Cache implementation, which allows to cache TCacheable<TKey> descendants using LRU (Least Recently Used) cache replacement algorithm. Every time an element is accessed, it is bubbled up to the top of the LRU queue using the following synchronized function: // a single instance is created to handle all TCacheable<T> elements public class Cache() { private object syncQueue = new object(); private void topQueue(TCacheable<T> el) { lock (syncQueue) if (newest != el) { if (el.elder != null) el.elder.newer = el.newer; if (el.newer != null) el.newer.elder = el.elder; if (oldest == el) oldest = el.newer; if (oldest == null) oldest = el; if (newest != null) newest.newer = el; el.newer = null; el.elder = newest; newest = el; } } } The bottleneck in this function is the lock() operator, which limits cache access to just one thread at a time. Question: Is it possible to get rid of lock(syncQueue) in this function while still preserving the queue integrity?

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  • Clever Next and Previous Buttons in jQuery

    - by matt
    I have created a webpage which when you press 'down' automatically scrolls down to the next ID (a section which isn't visible due to overflow: hidden) When you press 'up' it scrolls back up. At the moment each arrow simply tells the webpage to go to a specific div e.g. the 'down arrow' says <a class="tab" href="#page2">Down</a> This is ok for just two pages however as I will be having more pages what I would like is to be able to specify the amount of pages and for the arrows to automatically change which link it needs to go to next. For example, on page 1 the 'up arrow' is not visible and when you press the 'down arrow' it scrolls to #page2 whereupon the 'up arrow' is then visible. If you now press the down arrow again it will take you to #page3 whereupon it then becomes hidden as page 3 is the last page. I'm guessing I need to create a 'var' which specifies the amount of pages and that to make the arrows invisible it will change the css property 'display' to none yet I don't know how to do this nor to make the links work out which number to go to next! edit: Just botched together some code which hides the arrows based on the page number however still need to work out how to update the variables and change the links the arrows go to. (please exclude the coding, it's my first time trying to write script as opposed to just editing plugins!) var PageNumber = 1; var PageAmount = 2; function getPageNumber() { } function hideUpArrow() { if(PageNumber==1) { $("#up_arrow").css({ "display": "none" }); } } function hideDownArrow() { if(PageNumber==PageAmount) { $("#down_arrow").css({ "display": "none" }); } } $(document).ready(function(){ hideUpArrow(); });

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  • C# performance methods of receiving data from a socket?

    - by Daniel
    Lets assume we have a simple internet socket, and its going to send 10 megabytes (because i want to ignore memory issues) of random data through. Is there any performance difference or a best practice method that one should use for receiving data? The final output data should be represented by a byte[]. Yes i know writing an arbitrary amount of data to memory is bad, and if I was downloading a large file i wouldn't be doing it like this. But for argument sake lets ignore that and assume its a smallish amount of data. I also realise that the bottleneck here is probably not the memory management but rather the socket receiving. I just want to know what would be the most efficient method of receiving data. A few dodgy ways can think of is: Have a List and a buffer, after the buffer is full, add it to the list and at the end list.ToArray() to get the byte[] Write the buffer to a memory stream, after its complete construct a byte[] of the stream.Length and read it all into it in order to get the byte[] output. Is there a more efficient/better way of doing this?

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