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• Unable to connect SQL Server instance from Visual Studio 2008 Version 9.0

  - by salvationishere

  I am getting the below error from VS on an 32-bit XP Professional server even though I set Tools-Options-Database Tools-Data Connections to "SIDEKICK", which is the name of my computer. In other words SIDEKICK should default to the full SQLSERVER. In other words, I want VS to use SQLSERVER instead of SQLSERVER EXPRESS. And I can clearly see my database both from VS in the Server Explorer and also in SSMS 2008. Furthermore, I can view the tables of this database in Server Explorer from VS. I do not get any build errors. And it looks like all of the naming is consistent in my web.config file. I am developing my website according to a Microsoft tutorial, so I should not be getting an error. Yet I get the following exception when I run this code below: CreateAccounts.aspx.cs file protected void CreateAccountButton_Click(object sender, EventArgs e) { MembershipCreateStatus createStatus; //This line below is where the exception occurs MembershipUser newUser = Membership.CreateUser(Username.Text, Password.Text, Email.Text, passwordQuestion, SecurityAnswer.Text, true, out createStatus); And here is what the exception looks like: System.Web.HttpException was unhandled by user code Message="Unable to connect to SQL Server database." Source="System.Web" ErrorCode=-2147467259 StackTrace: at System.Web.DataAccess.SqlConnectionHelper.CreateMdfFile(String fullFileName, String dataDir, String connectionString) at System.Web.DataAccess.SqlConnectionHelper.EnsureSqlExpressDBFile(String connectionString) at System.Web.DataAccess.SqlConnectionHelper.GetConnection(String connectionString, Boolean revertImpersonation) at System.Web.Security.SqlMembershipProvider.CreateUser(String username, String password, String email, String passwordQuestion, String passwordAnswer, Boolean isApproved, Object providerUserKey, MembershipCreateStatus& status) at System.Web.Security.Membership.CreateUser(String username, String password, String email, String passwordQuestion, String passwordAnswer, Boolean isApproved, Object providerUserKey, MembershipCreateStatus& status) at System.Web.Security.Membership.CreateUser(String username, String password, String email, String passwordQuestion, String passwordAnswer, Boolean isApproved, MembershipCreateStatus& status) at Membership_CreatingUserAccounts.CreateAccountButton_Click(Object sender, EventArgs e) in c:\Documents and Settings\Admin\My Documents\Visual Studio 2008\WebSites\WebSite2\Membership\CreatingUserAccounts.aspx.cs:line 24 at System.Web.UI.WebControls.Button.OnClick(EventArgs e) at System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) at System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) at System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) at System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) InnerException: System.Web.HttpException Message="Unable to connect to SQL Server database." Source="System.Web" ErrorCode=-2147467259 StackTrace: at System.Web.Management.SqlServices.GetSqlConnection(String server, String user, String password, Boolean trusted, String connectionString) at System.Web.Management.SqlServices.SetupApplicationServices(String server, String user, String password, Boolean trusted, String connectionString, String database, String dbFileName, SqlFeatures features, Boolean install) at System.Web.Management.SqlServices.Install(String database, String dbFileName, String connectionString) at System.Web.DataAccess.SqlConnectionHelper.CreateMdfFile(String fullFileName, String dataDir, String connectionString) InnerException: System.Data.SqlClient.SqlException Message="The user instance login flag is not supported on this version of SQL Server. The connection will be closed." Source=".Net SqlClient Data Provider" ErrorCode=-2146232060 Class=14 LineNumber=65536 Number=18493 Procedure="" Server="." State=1 StackTrace: at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection) at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj) at System.Data.SqlClient.TdsParser.Run(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj) at System.Data.SqlClient.SqlInternalConnectionTds.CompleteLogin(Boolean enlistOK) at System.Data.SqlClient.SqlInternalConnectionTds.AttemptOneLogin(ServerInfo serverInfo, String newPassword, Boolean ignoreSniOpenTimeout, Int64 timerExpire, SqlConnection owningObject) at System.Data.SqlClient.SqlInternalConnectionTds.LoginNoFailover(String host, String newPassword, Boolean redirectedUserInstance, SqlConnection owningObject, SqlConnectionString connectionOptions, Int64 timerStart) at System.Data.SqlClient.SqlInternalConnectionTds.OpenLoginEnlist(SqlConnection owningObject, SqlConnectionString connectionOptions, String newPassword, Boolean redirectedUserInstance) at System.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString connectionOptions, Object providerInfo, String newPassword, SqlConnection owningObject, Boolean redirectedUserInstance) at System.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions options, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningConnection) at System.Data.ProviderBase.DbConnectionFactory.CreateNonPooledConnection(DbConnection owningConnection, DbConnectionPoolGroup poolGroup) at System.Data.ProviderBase.DbConnectionFactory.GetConnection(DbConnection owningConnection) at System.Data.ProviderBase.DbConnectionClosed.OpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory) at System.Data.SqlClient.SqlConnection.Open() at System.Web.Management.SqlServices.GetSqlConnection(String server, String user, String password, Boolean trusted, String connectionString) InnerException: The web.config connection string looks like: <connectionStrings> <add name="SecurityTutorialsConnectionString" connectionString="data source=.;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|SecurityTutorialsDatabase3.mdf;User Instance=true" providerName="System.Data.SqlClient"/> </connectionStrings> <system.web> <membership defaultProvider="SecurityTutorialsSqlMembershipProvider"> <providers> <add name="SecurityTutorialsSqlMembershipProvider" type="System.Web.Security.SqlMembershipProvider" connectionStringName="SecurityTutorialsConnectionString" enablePasswordRetrieval="false" enablePasswordReset="true" requiresQuestionAndAnswer="true" applicationName="SecurityTutorials" requiresUniqueEmail="true" passwordFormat="Hashed" maxInvalidPasswordAttempts="5" minRequiredPasswordLength="7" minRequiredNonalphanumericCharacters="1" passwordAttemptWindow="10" passwordStrengthRegularExpression=""/> </providers> </membership>

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• C# Asynchronous Network IO and OutOfMemoryException

  - by The.Anti.9

  I'm working on a client/server application in C#, and I need to get Asynchronous sockets working so I can handle multiple connections at once. Technically it works the way it is now, but I get an OutOfMemoryException after about 3 minutes of running. MSDN says to use a WaitHandler to do WaitOne() after the socket.BeginAccept(), but it doesn't actually let me do that. When I try to do that in the code it says WaitHandler is an abstract class or interface, and I can't instantiate it. I thought maybe Id try a static reference, but it doesnt have teh WaitOne() method, just WaitAll() and WaitAny(). The main problem is that in the docs it doesn't give a full code snippet, so you can't actually see what their "wait handler" is coming from. its just a variable called allDone, which also has a Reset() method in the snippet, which a waithandler doesn't have. After digging around in their docs, I found some related thing about an AutoResetEvent in the Threading namespace. It has a WaitOne() and a Reset() method. So I tried that around the while(true) { ... socket.BeginAccept( ... ); ... }. Unfortunately this makes it only take one connection at a time. So I'm not really sure where to go. Here's my code: class ServerRunner { private Byte[] data = new Byte[2048]; private int size = 2048; private Socket server; static AutoResetEvent allDone = new AutoResetEvent(false); public ServerRunner() { server = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp); IPEndPoint iep = new IPEndPoint(IPAddress.Any, 33333); server.Bind(iep); Console.WriteLine("Server initialized.."); } public void Run() { server.Listen(100); Console.WriteLine("Listening..."); while (true) { //allDone.Reset(); server.BeginAccept(new AsyncCallback(AcceptCon), server); //allDone.WaitOne(); } } void AcceptCon(IAsyncResult iar) { Socket oldserver = (Socket)iar.AsyncState; Socket client = oldserver.EndAccept(iar); Console.WriteLine(client.RemoteEndPoint.ToString() + " connected"); byte[] message = Encoding.ASCII.GetBytes("Welcome"); client.BeginSend(message, 0, message.Length, SocketFlags.None, new AsyncCallback(SendData), client); } void SendData(IAsyncResult iar) { Socket client = (Socket)iar.AsyncState; int sent = client.EndSend(iar); client.BeginReceive(data, 0, size, SocketFlags.None, new AsyncCallback(ReceiveData), client); } void ReceiveData(IAsyncResult iar) { Socket client = (Socket)iar.AsyncState; int recv = client.EndReceive(iar); if (recv == 0) { client.Close(); server.BeginAccept(new AsyncCallback(AcceptCon), server); return; } string receivedData = Encoding.ASCII.GetString(data, 0, recv); //process received data here byte[] message2 = Encoding.ASCII.GetBytes("reply"); client.BeginSend(message2, 0, message2.Length, SocketFlags.None, new AsyncCallback(SendData), client); } }

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• Java Applet Deployment, ClassNotFoundException (primary class)

  - by Matt

  This is driving me up the wall. I have checked and rechecked spelling and paths. I have tried just about every combination of paths, including relative, absolute, and full http paths. I continue to get the following error when trying to load a Java applet: java.lang.ClassNotFoundException: AppletClient.class at sun.plugin2.applet.Applet2ClassLoader.findClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at sun.plugin2.applet.Plugin2ClassLoader.loadCode(Unknown Source) at sun.plugin2.applet.Plugin2Manager.createApplet(Unknown Source) at sun.plugin2.applet.Plugin2Manager$AppletExecutionRunnable.run(Unknown Source) at java.lang.Thread.run(Unknown Source) Exception: java.lang.ClassNotFoundException: AppletClient.class The HTML used to load the applet: <applet width="100" height="100" archive="applet/myapplet.jar, applet/applet_dependency.jar" code="AppletClient.class"> <param value="blahblah" name="username"> <param value="false" name="codebase_lookup"> </applet> The applet is in a relative directory, "applet", from the path of the current page. I have unzipped the jar file and can see AppletClient.class. Also, in the source of the project, it is spelled that way (casing and all). I have tried with/without the parameters. I have changed the names of the archive jars in the applet include tag just to see if I get a different error for bad file names (same error). I have manually done GETs on the jars to make sure the server is responding to the requests (it is). I have tried with and without the codebase tag, with all different varieties of paths (start getting bad "magic number" errors on those). I know that this error sometimes pops up when a dependency fails to load, so it can be misleading, but all dependencies are present, accounted for, and are fetchable via manual GETs. Between each and every attempt I always clear my cache in FireFox. These problems are reproduced in IE8 and Chrome as well. Per my Java Console from the browser, I am running Java Plug-in 1.6.0_20. This is from the same machine that I develop the applet on, which runs fine via Eclipse. Finally, I kicked on Fiddler2, and I don't see a single request for the jar files anywhere The host site is running from my Visual Studio debugger, so it's running on localhost. But I see the requests for all the other resources on Fiddler. Just... no Jars. ANYWHERE. I clear the log, cleared my browser cache, and did a ctrl-R refresh. And still, not a single Jar request on the Fiddler log. I even did a delayed write (with JS) of the applet tag after the page loaded, once all the Fiddler activity slowed down. The element gets written to the document (and I can see the 100x100 Java error window), but not a single request shows up on Fiddler. Any suggestions, before I go crawl into the corner and cry myself to sleep? EDIT: From the Java console, if I hit "l" (el) to "dump classloader list", I see something that looks like this: Live entry: key=http://localhost:55446/BaseWebSite/,http://localhost:55446/BaseWebSite/applet/myappliet.jar, http://localhost:55446/BaseWebSite/applet/applet_dependency.jar, refCount=1, threadGroup=sun.plugin2.applet.Applet2ThreadGroup[name=http://localhost:55446/BaseWebSite/-threadGroup,maxpri=4]

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• My server app works strangely. What could be the reason(s)?

  - by Poni

  Hi! I've written a server app (two parts actually; proxy server and a game server) using C++ (board game). It uses IOCP as the sockets interface. For that app I've also written a "client simulator" (hereafter "client") app that spawns many client connections, where each of them plays, in very high speed, getting the CPU to be 100% utilized. So, that's how it goes in terms of topology: Game server - holds the game state. Real players do not connect it directly but through the proxy server. When a player joins a game, the proxy actually asks for it on behalf of that player, and the game server spawns a "player instance" for that player, and from now on, every notification between the game server and the player is being passed through the proxy. Proxy server - holds TCP connections with the real players. Players communicate with the game server through it only. Client simulator - connects to the proxy only. When running the server (again, it's actually two server apps) & client locally it all works just fine. I'm talking about 40k+ player instances in which all of them are active in a game. On the other hand, when running the server remotely with, say, 1000 clients who play things getting strange. For example, I run it as said above. Then with Task Manager I kill the client simulator app ("End Process Tree"). Then it seems like the buffer of the remote server got modified by another thread, or in other words, a memory corruption has been occurred. The server crashes because it got an unknown message id (it's a custom protocol where each message has it's own unique number). To make things clear, here is how I run the apps: PC1 - game server and clients simulator (because the clients will connect the proxy). PC2 - proxy server. The strangest thing is this: Only the remote side gets "corrupted". Remote in terms that it's not the PC I use to code the app (VC++ 2008). Let's call the PC I use to code the apps "PC1". Now for example, if this time I ran the game server on PC1 (it means that proxy server on PC2 and clients simulator on PC1), then the proxy server crashes with an "unknown message id" error. Another variation is when I run the proxy server on PC1 (again, the dev machine), the game server and the clients simulator on PC2, then the game server on PC2 gets crashed. As for the IOCP config: The servers' internal connections use the default receive/send buffer sizes. Tried even with setting them to 1MB, but no luck. I have three PCs in total; 2 x Vista 64bit <<-- one of those is the dev machine. The other is connected through WiFi. 1 x WinXP 32bit They're all connected in a "full duplex" manner. What could be the reason? Tried about everything; Stack tracing, recording some actions (like read/write logging).. I want to stress that only the PC I'm not using to code the apps crashes (actually the server app "role" which is running on it - sometimes the game server and sometimes the proxy server). At first I thought that maybe the wireless PC has problems (it's wireless..) but: TCP has it's own mechanisms to make sure the packet is delivered properly. Also, a crash also happens when trying it with the two PCs that are physically connected (Vista vs. XP). Another option is that the Windows DLLs versions might have problems, but then again, one of the tests is Vista vs. Vista, and the other is Vista vs. XP. Any idea?

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• STL vector reserve() and copy()

  - by natersoz

  Greetings, I am trying to perform a copy from one vector (vec1) to another vector (vec2) using the following 2 abbreviated lines of code (full test app follows): vec2.reserve( vec1.size() ); copy(vec1.begin(), vec1.end(), vec2.begin()); While the call to vec2 sets the capacity of vector vec2, the copying of data to vec2 seems to not fill in the values from vec1 to vec2. Replacing the copy() function with calls to push_back() works as expected. What am I missing here? Thanks for your help. vectest.cpp test program followed by resulting output follows. Compiler: gcc 3.4.4 on cygwin. Nat /** * vectest.cpp */ #include <iostream> #include <vector> using namespace std; int main() { vector<int> vec1; vector<int> vec2; vec1.push_back(1); vec1.push_back(2); vec1.push_back(3); vec1.push_back(4); vec1.push_back(5); vec1.push_back(6); vec1.push_back(7); vec2.reserve( vec1.size() ); copy(vec1.begin(), vec1.end(), vec2.begin()); cout << "vec1.size() = " << vec1.size() << endl; cout << "vec1.capacity() = " << vec1.capacity() << endl; cout << "vec1: "; for( vector<int>::const_iterator iter = vec1.begin(); iter < vec1.end(); ++iter ) { cout << *iter << " "; } cout << endl; cout << "vec2.size() = " << vec2.size() << endl; cout << "vec2.capacity() = " << vec2.capacity() << endl; cout << "vec2: "; for( vector<int>::const_iterator iter = vec2.begin(); iter < vec2.end(); ++iter ) { cout << *iter << endl; } cout << endl; } output: vec1.size() = 7 vec1.capacity() = 8 vec1: 1 2 3 4 5 6 7 vec2.size() = 0 vec2.capacity() = 7 vec2:

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• Pass MSBuild condition to library project

  - by Billy Talented

  I have tried several solutions for this problem. Enough to know I do not know enough about MSBuild to do this elegantly but I feel like there should be a method. I have a set of libraries for working with .net projects. A few of the projects utilize System.Web.Mvc - which recently released Version 2 - and we are looking forward to the upgrade. Currently sites which reference this library reference it directly by the project(csproj) on the developer's computer - not a built version of the library so that changes and source code case easily be viewed when dealing code from this library. This works quite well and would prefer to not have to switch to binary references (but will if this is the only solution). The problem I have is that because of some of the functionality that was added onto the MVC1 based library (view engines, model binders etc) several of the sites reliant on these libraries need to stay on MVC1 until we have full evaluated and tested them on MVC2. I would prefer to not have to fork or have two copies on each dev machine. So what I would like to be able to do is set a property group value in the referencing web application and have this read by the above mentions library with the caviat that when working directly on the library via its containing solution I would like to be able to control this via Configuration Manager by selecting a build type and that property overriding the build behavior of the solution (i.e. 'Debug - MVC1' vs 'Debug -MVC2') - I have this working via: <Choose> <When Condition=" '$(Configuration)|$(Platform)' == 'Release - MVC2|AnyCPU' Or '$(Configuration)|$(Platform)' == 'Debug - MVC2|AnyCPU'"> <ItemGroup> <Reference Include="System.Web.Mvc, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL"> </Reference> <Reference Include="Microsoft.Web.Mvc, Version=1.0.0.0, Culture=neutral, processorArchitecture=MSIL"> <SpecificVersion>False</SpecificVersion> <HintPath>..\Dependancies\Web\MVC2\Microsoft.Web.Mvc.dll</HintPath> </Reference> </ItemGroup> </When> <Otherwise> <ItemGroup> <Reference Include="System.Web.Mvc, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL"> <SpecificVersion>False</SpecificVersion> <HintPath>..\Dependancies\Web\MVC\System.Web.Mvc.dll</HintPath> </Reference> </ItemGroup> </Otherwise> The item that I am struggling with is the cross solution issue(solution TheWebsite references this project and needs to control which build property to use) that I have not found a way to work with that I think is a solid solution that enabled the build within visual studio to work as it has to date. Other bits: we are using VS2008, Resharper, TeamCity for CI, SVN for source control.

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• C++/msvc6 application crashes due to heap corruption, any hints?

  - by David Alfonso

  Hello all, let me say first that I'm writing this question after months of trying to find out the root of a crash happening in our application. I'll try to detail as much as possible what I've already found out about it. About the application It runs on Windows XP Professional SP2. It's built with Microsoft Visual C++ 6.0 with Service Pack 6. It's MFC based. It uses several external dlls (e.g. Xerces, ZLib or ACE). It has high performance requirements. It does a lot of network and hard disk I/O, but it's also cpu intensive. It has an exception handling mechanism which generates a minidump when an unhandled exception occurs. Facts about the crash It only happens on multiprocessor/multicore machines and under heavy loads of work. It happens at random (neither we nor our client have found a pattern yet). We cannot reproduce the crash on our testing lab. It only happens on some production systems (but always in multicore machines) It always ends up crashing at the same point, although the complete stack is not always the same. Let me add the stack of the crashing thread (obtained using WinDbg, sorry we don't have symbols) ChildEBP RetAddr Args to Child WARNING: Stack unwind information not available. Following frames may be wrong. 030af6c8 7c9206eb 77bfc3c9 01a80000 00224bc3 MyApplication+0x2a85b9 030af960 7c91e9c0 7c92901b 00000ab4 00000000 ntdll!RtlAllocateHeap+0xeac (FPO: [Non-Fpo]) 030af98c 7c9205c8 00000001 00000000 00000000 ntdll!ZwWaitForSingleObject+0xc (FPO: [3,0,0]) 030af9c0 7c920551 01a80898 7c92056d 313adfb0 ntdll!RtlpFreeToHeapLookaside+0x22 (FPO: [2,0,4]) 030afa8c 4ba3ae96 000307da 00130005 00040012 ntdll!RtlFreeHeap+0x1e9 (FPO: [Non-Fpo]) 030afacc 77bfc2e3 0214e384 3087c8d8 02151030 0x4ba3ae96 030afb00 7c91e306 7c80bfc1 00000948 00000001 msvcrt!free+0xc8 (FPO: [Non-Fpo]) 030afb20 0042965b 030afcc0 0214d780 02151218 ntdll!ZwReleaseSemaphore+0xc (FPO: [3,0,0]) 030afb7c 7c9206eb 02e6c471 02ea0000 00000008 MyApplication+0x2965b 030afe60 7c9205c8 02151248 030aff38 7c920551 ntdll!RtlAllocateHeap+0xeac (FPO: [Non-Fpo]) 030afe74 7c92056d 0210bfb8 02151250 02151250 ntdll!RtlpFreeToHeapLookaside+0x22 (FPO: [2,0,4]) 030aff38 77bfc2de 01a80000 00000000 77bfc2e3 ntdll!RtlFreeHeap+0x647 (FPO: [Non-Fpo]) 7c92056d c5ffffff ce7c94be ff7c94be 00ffffff msvcrt!free+0xc3 (FPO: [Non-Fpo]) 7c920575 ff7c94be 00ffffff 12000000 907c94be 0xc5ffffff 7c920579 00ffffff 12000000 907c94be 90909090 0xff7c94be *** WARNING: Unable to verify checksum for xerces-c_2_7.dll *** ERROR: Symbol file could not be found. Defaulted to export symbols for xerces-c_2_7.dll - 7c92057d 12000000 907c94be 90909090 8b55ff8b MyApplication+0xbfffff 7c920581 907c94be 90909090 8b55ff8b 08458bec xerces_c_2_7 7c920585 90909090 8b55ff8b 08458bec 04408b66 0x907c94be 7c920589 8b55ff8b 08458bec 04408b66 0004c25d 0x90909090 7c92058d 08458bec 04408b66 0004c25d 90909090 0x8b55ff8b The address MyApplication+0x2a85b9 corresponds to a call to erase() of a std::list. What I have tried so far Reviewing all the code related to the point where the crash ends happening. Trying to enable pageheap on our testing lab though nothing useful has been found by now. We have substituted the std::list for a C array and then it crashes in other part of the code (although it is related code, it's not in the code where the old list resided). Coincidentally, now it crashes in another erase, though this time of a std::multiset. Let me copy the stack contained in the dump: ntdll.dll!_RtlpCoalesceFreeBlocks@16() + 0x124e bytes ntdll.dll!_RtlFreeHeap@12() + 0x91f bytes msvcrt.dll!_free() + 0xc3 bytes MyApplication.exe!006a4fda() [Frames below may be incorrect and/or missing, no symbols loaded for MyApplication.exe] MyApplication.exe!0069f305() ntdll.dll!_NtFreeVirtualMemory@16() + 0xc bytes ntdll.dll!_RtlpSecMemFreeVirtualMemory@16() + 0x1b bytes ntdll.dll!_ZwWaitForSingleObject@12() + 0xc bytes ntdll.dll!_RtlpFreeToHeapLookaside@8() + 0x26 bytes ntdll.dll!_RtlFreeHeap@12() + 0x114 bytes msvcrt.dll!_free() + 0xc3 bytes c5ffffff() Possible solutions (that I'm aware of) which cannot be applied "Migrate the application to a newer compiler": We are working on this but It's not a solution at the moment. "Enable pageheap (normal or full)": We can't enable pageheap on production machines as this affects performance heavily. I think that's all I remember now, if I have forgotten something I'll add it asap. If you can give me some hint or propose some possible solution, don't hesitate to answer! Thank you in advance for your time and advice.

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• Problem on getting the vendor id and product id of a usb device

  - by new

  Hi... my application comes and prints this "\?\usb#vid_04f2&pid_0111#5&1ba5a77f&0&2#{a5dcbf1 0-6530-11d2-901f-00c04fb951ed}" again it goes to while loop .... here it gets breaked in the else statement... Qt Code: if (GetLastError() == ERROR_INSUFFICIENT_BUFFER) { // Change the buffer size. if (buffer) LocalFree(buffer); buffer = (LPTSTR)LocalAlloc(LPTR,buffersize); } else { qDebug ()<<"Here it quits the application"; // Insert error handling here. break; } Any ideas in this.... full source code comes here static GUID GUID_DEVINTERFACE_USB_DEVICE = { 0xA5DCBF10L, 0x6530, 0x11D2, { 0x90, 0x1F, 0x00, 0xC0, 0x4F, 0xB9, 0x51, 0xED } }; HANDLE hInfo = SetupDiGetClassDevs(&GUID_DEVINTERFACE_USB_DEVICE,NULL,NULL, DIGCF_PRESENT | DIGCF_INTERFACEDEVICE); if ( hInfo == INVALID_HANDLE_VALUE ) { qDebug ()<<"invalid"; } else { qDebug ()<<"valid handle"; SP_DEVINFO_DATA DeviceInfoData; DeviceInfoData.cbSize = sizeof(SP_DEVINFO_DATA); SP_INTERFACE_DEVICE_DATA Interface_Info; Interface_Info.cbSize = sizeof(Interface_Info); BYTE Buf[1024]; DWORD i; DWORD InterfaceNumber= 0; PSP_DEVICE_INTERFACE_DETAIL_DATA pspdidd = (PSP_DEVICE_INTERFACE_DETAIL_DATA) Buf; for (i=0;SetupDiEnumDeviceInfo(hInfo,i,&DeviceInfoData);i++) { DWORD DataT; LPTSTR buffer = NULL; DWORD buffersize = 0; while (!SetupDiGetDeviceRegistryProperty( hInfo, &DeviceInfoData,SPDRP_DEVICEDESC, &DataT,(PBYTE)buffer,buffersize, &buffersize)) { if (GetLastError() == ERROR_INSUFFICIENT_BUFFER) { // Change the buffer size. if (buffer) LocalFree(buffer); buffer = (LPTSTR)LocalAlloc(LPTR,buffersize); } else { // Insert error handling here. break; } qDebug ()<<(TEXT("Device Number %i is: %s\n"),i, buffer); if (buffer) LocalFree(buffer); if ( GetLastError() != NO_ERROR && GetLastError() != ERROR_NO_MORE_ITEMS ) { // Insert error handling here. qDebug ()<<"return false"; } InterfaceNumber = 0; // this just returns the first one, you can iterate on this if (SetupDiEnumDeviceInterfaces(hInfo, NULL, &GUID_DEVINTERFACE_USB_DEVICE, InterfaceNumber, &Interface_Info)) { printf("Got interface"); DWORD needed; pspdidd->cbSize = sizeof(*pspdidd); SP_DEVICE_INTERFACE_DETAIL_DATA *pDetData = NULL; DWORD dwDetDataSize = sizeof (SP_DEVICE_INTERFACE_DETAIL_DATA) + 256; pDetData = (SP_DEVICE_INTERFACE_DETAIL_DATA*) malloc (dwDetDataSize); pDetData->cbSize = sizeof (SP_DEVICE_INTERFACE_DETAIL_DATA); SetupDiGetDeviceInterfaceDetail(hInfo,&Interface_Info, pDetData,dwDetDataSize, NULL,&DeviceInfoData); qDebug ()<<pDetData->DevicePath; qDebug ()<<QString::fromWCharArray(pDetData->DevicePath); free(pDetData); } else { printf("\nNo interface"); //ErrorExit((LPTSTR) "SetupDiEnumDeviceInterfaces"); if ( GetLastError() == ERROR_NO_MORE_ITEMS) printf(", since there are no more items found."); else printf(", unknown reason."); } // Cleanup SetupDiDestroyDeviceInfoList(hInfo); } } }

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• Rendering a Long Document on iPad

  - by benjismith

  I'm implementing a document viewer with highlighting/annotation capabilities for a custom document format on iPad. The documents are kind of long (100 to 200 pages, if printed on paper) and I've had a hard time finding the right approach. Here are the requirments: 1) Basic rich-text styling: control of left/right margins. Control of font name, size, foreground/background color, and line spacing. Bold, italics, underline, etc. 2) Selection and highlighting of arbitrary text regions (not limited to paragraph boundaries, like in Safari/UIWebView). 3) Customization of the Cut/Copy/Paste popup (what is that thing called anyhow? UIActionBar?) This is one of the essential requirements of the app. My first implementation was based on UIWebView. I just rendered the document as HTML with CSS for text styling. But I couldn't get the kind of text selection behavior I wanted (across paragraph boundaries) and the UIActionBar can't be customized from within UIWebView. So I started working on a javascript approach, faking the device text-selection behavior using JQuery to trap touch events and dynamically modifying the DOM to change the background color of selected regions of text. I built a fake UIActionBar control as a hidden DIV, positioning it and unhiding it whenever there was an active selection region. Not too shabby. The main problem is that it's SLOOOOOOOW. Scrolling through the document is nice and quick, but dynamically changing the DOM is not very snappy. Plus, I couldn't figure out how to recreate the magnifier loupe, so my fake text-selection GUI doesn't look quite the same as the native implementation. Also, I haven't yet implemented the communication bridge between the javascript layer and the objective-c layer (where the rest of the app lives), but it was shaping up to be a huge hassle. So I've been looking at CoreText, but there are precious few examples on the web. I spent a little time with this simple little demo: http://github.com/jonasschnelli/I7CoreTextExample/ It shows how to use CoreText to draw an NSAttributedText string into a UIView. But it has its own problems: It doesn't implement text-selection behavior, and it doesn't present a UIActionBar, so I don't have any idea how to make that happen. And, more importantly, it tries to draw the entire document all at once, with significant performance degradations for long documents. My documents can have thousands of paragraphs, and less than 1% of the document is ever on screen at a time. On the plus side, these documents already contain precise formatting information. I know the exact page-position of every line of text, so I don't need a layout engine. Does anyone know how to implement this sort of view using CoreText? I understand that a full-fledged implementation is overkill for a question like this, but I'm looking for a good CoreText example with a few basic requirements: 1) Precise layout & formatting control (using the formatting metrics and text styles I've already calculated). 2) Arbitrary selection of text. 3) Customization of the UIActionBar. 4) Efficient recycling of resources for off-screen objects. I'd be happy to implement my own recycling when text elements scroll off-screen, but wouldn't that require re-implementing UIScrollView? I'm brand-new to iPhone development, and still getting used to Objective-C, but I've been working in other languages (Java, C#, flex/actionscript, etc) for more than ten years, so I feel confident in my ability to get the work done, if only I had a better feel for the iPhone SDK and the common coding patterns for stuff like this. Is it just me, or does the SDK documentation really suck? Anyhow, thanks for your help!

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• jquery scope issue

  - by matthewb

  I am having issue with the following: I can't seem to keep the link I am selecting in each repeated item. The word "this" is getting lost. the Var event_id works for each element, but the var $something is undefined? Why is that, Ideally I wanted to do a switch statement but same issue, can't seem to get it to know what link I click and the elements around it to do the action. Updated Full Function: function rsvp (selector,function_url) { $(selector).livequery('click',function(){ var $select = $(selector).attr('rel'); var $event_id= $(this).parents('ul.event-options').attr('rel'); if ($select == "attending") { $(this).closest('span.rsvp-status').html("I'm Attending &ndash; <a href='javascript:;' class='remove' rel='remove'>Remove</a>"); var $something = $(this).parents('ul.event-options').attr('rel'); alert($something); } if ($select == "remove") { $(this).closest('span.rsvp-status').html("Not Attending &ndash; <a href='javascript:;' class='rsvp' rel='attending'>RSVP?</a>"); } if ($select == "interested") { $(this).closest('li').addClass('interested'); $(this).closest('li').removeClass('not-interested'); $(this).closest('li').html("You're Interested"); } $.ajax({ type: "POST", url: "/events/set_member/"+function_url, data: "event_id="+$event_id, beforeSend: function() { $("<span class='notice'>Updating...</span>").prependTo('body'); }, complete: function() { $('span.notice').fadeOut(500); } }); }); } rsvp ('a.rsvp','rsvp'); rsvp ('a.interests','interested'); rsvp ('a.remove','remove'); HTML <ul class="event-options" rel="<?=$event['event_id']?>"> <?php if($event['rsvp_total'] > 0) { ?> <!-- Show Only When Count is Greater than 0 --> <li class="group"><span class="total"><?= $event['rsvp_total']?></span>Interested </li> <?php } ?> <li class="rsvp"><span class="rsvp-status"> Not Attending &ndash; <a href="javascript:;" class="rsvp" rel="attending">RSVP?</a></span></li> <li class="not-interested"> <a href="javascript:;" class="interests" rel="interested"> Interested? </a> </li> <li class="place"><span><a href="<?=$place_path.$event['place_id']?>"><?=$event['place_name']?></a></span></li> <li class="share" rel="<?=$event['event_name']?>"> <a class="sharethis"></a> </li> </ul>

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• Add options to select box without Internet Explorer closing the box?

  - by Paul Colby

  Hi, I'm trying to build a web page with a number of drop-down select boxes that load their options asynchronously when the box is first opened. This works very well under Firefox, but not under Internet Explorer. Below is a small example of what I'm trying to achieve. Basically, there is a select box (with the id "selectBox"), which contains just one option ("Any"). Then there is an onmousedown handler that loads the other options when the box is clicked. <html> <head> <script type="text/javascript"> function appendOption(select,option) { try { selectBox.add(option,null); // Standards compliant. } catch (e) { selectBox.add(option); // IE only version. } } function loadOptions() { // Simulate an AJAX request that will call the // loadOptionsCallback function after 500ms. setTimeout(loadOptionsCallback,500); } function loadOptionsCallback() { var selectBox = document.getElementById('selectBox'); var option = document.createElement('option'); option.text = 'new option'; appendOption(selectBox,option); } </script> </head> <body> <select id="selectBox" onmousedown="loadOptions();"> <option>Any</option> </select> </body> </html> The desired behavior (which Firefox does) is: the user see's a closed select box containing "Any". the user clicks on the select box. the select box opens to reveal the one and only option ("Any"). 500ms later (or when the AJAX call has returned) the dropped-down list expands to include the new options (hard coded to 'new option' in this example). So that's exactly what Firefox does, which is great. However, in Internet Explorer, as soon as the new option is added in "4" the browser closes the select box. The select box does contain the correct options, but the box is closed, requiring the user to click to re-open it. So, does anyone have any suggestions for how I can load the select control's options asynchronously without IE closing the drop-down box? I know that I can load the list before the box is even clicked, but the real form I'm developing contains many such select boxes, which are all interrelated, so it will be much better for both the client and server if I can load each set of options only when needed. Also, if the results are loaded synchronously, before the select box's onmousedown handler completes, then IE will show the full list as expected - however, synchronous loading is a bad idea here, since it will completely "lock" the browser while the network requests are taking place. Finally, I've also tried using IE's click() method to open the select box once the new options have been added, but that does not re-open the select box. Any ideas or suggestions would be really appreciated!! :) Thanks! Paul.

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• Two-way databinding of a custom templated control. Eval works, but not Bind.

  - by Jason

  I hate long code snippets and I'm sorry about this one, but it turns out that this asp.net stuff can't get much shorter and it's so specific that I haven't been able to generalize it without a full code listing. I just want simple two-way, declarative databinding to a single instance of an object. Not a list of objects of a type with a bunch of NotImplementedExceptions for Add, Delete, and Select, but just a single view-state persisted object. This is certainly something that can be done but I've struggled with an implementation for years. This newest, closest implementation was inspired by this article from 4-Guys-From-Rolla, http://msdn.microsoft.com/en-us/library/aa478964.aspx. Unfortunately, after implementing, I'm getting the following error and I don't know what I'm missing: System.InvalidOperationException: Databinding methods such as Eval(), XPath(), and Bind() can only be used in the context of a databound control. If I don't use Bind(), and only use Eval() functionality, it works. In that way, the error is especially confusing. Here's the simplified codeset that still produces the error: using System.ComponentModel; namespace System.Web.UI.WebControls.Special { public class SampleFormData { public string SampleString = "Sample String Data"; public int SampleInt = -1; } [ToolboxItem(false)] public class SampleSpecificFormDataContainer : WebControl, INamingContainer { SampleSpecificEntryForm entryForm; internal SampleSpecificEntryForm EntryForm { get { return entryForm; } } [Bindable(true), Category("Data")] public string SampleString { get { return entryForm.FormData.SampleString; } set { entryForm.FormData.SampleString = value; } } [Bindable(true), Category("Data")] public int SampleInt { get { return entryForm.FormData.SampleInt; } set { entryForm.FormData.SampleInt = value; } } internal SampleSpecificFormDataContainer(SampleSpecificEntryForm entryForm) { this.entryForm = entryForm; } } public class SampleSpecificEntryForm : WebControl, INamingContainer { #region Template private IBindableTemplate formTemplate = null; [Browsable(false), DefaultValue(null), TemplateContainer(typeof(SampleSpecificFormDataContainer), ComponentModel.BindingDirection.TwoWay), PersistenceMode(PersistenceMode.InnerProperty)] public virtual IBindableTemplate FormTemplate { get { return formTemplate; } set { formTemplate = value; } } #endregion #region Viewstate SampleFormData FormDataVS { get { return (ViewState["FormData"] as SampleFormData) ?? new SampleFormData(); } set { ViewState["FormData"] = value; SaveViewState(); } } #endregion public override ControlCollection Controls { get { EnsureChildControls(); return base.Controls; } } private SampleSpecificFormDataContainer formDataContainer = null; [Browsable(false), DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)] public SampleSpecificFormDataContainer FormDataContainer { get { EnsureChildControls(); return formDataContainer; } } [Bindable(true), Browsable(false)] public SampleFormData FormData { get { return FormDataVS; } set { FormDataVS = value; } } protected override void CreateChildControls() { if (!this.ChildControlsCreated) { Controls.Clear(); formDataContainer = new SampleSpecificFormDataContainer(this); Controls.Add(formDataContainer); FormTemplate.InstantiateIn(formDataContainer); this.ChildControlsCreated = true; } } public override void DataBind() { CreateChildControls(); base.DataBind(); } } } With an ASP.NET page the following: <%@ Page Title="Home Page" Language="C#" MasterPageFile="~/Site.master" AutoEventWireup="true" CodeBehind="Default2.aspx.cs" Inherits="EntryFormTest._Default2" EnableEventValidation="false" %> <%@ Register Assembly="EntryForm" Namespace="System.Web.UI.WebControls.Special" TagPrefix="cc1" %> <asp:Content ID="HeaderContent" runat="server" ContentPlaceHolderID="HeadContent"> </asp:Content> <asp:Content ID="BodyContent" runat="server" ContentPlaceHolderID="MainContent"> <h2> Welcome to ASP.NET! </h2> <cc1:SampleSpecificEntryForm ID="EntryForm1" runat="server"> <FormTemplate> <asp:TextBox ID="TextBox1" runat="server" Text='<%# Bind("SampleString") %>'></asp:TextBox><br /> <h3>(<%# Container.SampleString %>)</h3><br /> <asp:Button ID="Button1" runat="server" Text="Button" /> </FormTemplate> </cc1:SampleSpecificEntryForm> </asp:Content> Default2.aspx.cs using System; namespace EntryFormTest { public partial class _Default2 : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { EntryForm1.DataBind(); } } } Thanks for any help!

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• Entity Framework Generic Repository Error

  - by Jeff Ancel

  I am trying to create a very generic generics repository for my Entity Framework repository that has the basic CRUD statements and uses an Interface. I have hit a brick wall head first and been knocked over. Here is my code, written in a console application, using a Entity Framework Model, with a table named Hurl. Simply trying to pull back the object by its ID. Here is the full application code. using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Data.Objects; using System.Linq.Expressions; using System.Reflection; using System.Data.Objects.DataClasses; namespace GenericsPlay { class Program { static void Main(string[] args) { var hs = new HurlRepository(new hurladminEntity()); var hurl = hs.Load<Hurl>(h => h.Id == 1); Console.Write(hurl.ShortUrl); Console.ReadLine(); } } public interface IHurlRepository { T Load<T>(Expression<Func<T, bool>> expression); } public class HurlRepository : IHurlRepository, IDisposable { private ObjectContext _objectContext; public HurlRepository(ObjectContext objectContext) { _objectContext = objectContext; } public ObjectContext ObjectContext { get { return _objectContext; } } private Type GetBaseType(Type type) { Type baseType = type.BaseType; if (baseType != null && baseType != typeof(EntityObject)) { return GetBaseType(type.BaseType); } return type; } private bool HasBaseType(Type type, out Type baseType) { Type originalType = type.GetType(); baseType = GetBaseType(type); return baseType != originalType; } public IQueryable<T> GetQuery<T>() { Type baseType; if (HasBaseType(typeof(T), out baseType)) { return this.ObjectContext.CreateQuery<T>("[" + baseType.Name.ToString() + "]").OfType<T>(); } else { return this.ObjectContext.CreateQuery<T>("[" + typeof(T).Name.ToString() + "]"); } } public T Load<T>(Expression<Func<T, bool>> whereCondition) { return this.GetQuery<T>().Where(whereCondition).First(); } public void Dispose() { if (_objectContext != null) { _objectContext.Dispose(); } } } } Here is the error that I am getting: System.Data.EntitySqlException was unhandled Message="'Hurl' could not be resolved in the current scope or context. Make sure that all referenced variables are in scope, that required schemas are loaded, and that namespaces are referenced correctly., near escaped identifier, line 3, column 1." Source="System.Data.Entity" Column=1 ErrorContext="escaped identifier" ErrorDescription="'Hurl' could not be resolved in the current scope or context. Make sure that all referenced variables are in scope, that required schemas are loaded, and that namespaces are referenced correctly." This is where I am attempting to extract this information from. http://blog.keithpatton.com/2008/05/29/Polymorphic+Repository+For+ADONet+Entity+Framework.aspx

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• Optimizing Python code with many attribute and dictionary lookups

  - by gotgenes

  I have written a program in Python which spends a large amount of time looking up attributes of objects and values from dictionary keys. I would like to know if there's any way I can optimize these lookup times, potentially with a C extension, to reduce the time of execution, or if I need to simply re-implement the program in a compiled language. The program implements some algorithms using a graph. It runs prohibitively slowly on our data sets, so I profiled the code with cProfile using a reduced data set that could actually complete. The vast majority of the time is being burned in one function, and specifically in two statements, generator expressions, within the function: The generator expression at line 202 is neighbors_in_selected_nodes = (neighbor for neighbor in node_neighbors if neighbor in selected_nodes) and the generator expression at line 204 is neighbor_z_scores = (interaction_graph.node[neighbor]['weight'] for neighbor in neighbors_in_selected_nodes) The source code for this function of context provided below. selected_nodes is a set of nodes in the interaction_graph, which is a NetworkX Graph instance. node_neighbors is an iterator from Graph.neighbors_iter(). Graph itself uses dictionaries for storing nodes and edges. Its Graph.node attribute is a dictionary which stores nodes and their attributes (e.g., 'weight') in dictionaries belonging to each node. Each of these lookups should be amortized constant time (i.e., O(1)), however, I am still paying a large penalty for the lookups. Is there some way which I can speed up these lookups (e.g., by writing parts of this as a C extension), or do I need to move the program to a compiled language? Below is the full source code for the function that provides the context; the vast majority of execution time is spent within this function. def calculate_node_z_prime( node, interaction_graph, selected_nodes ): """Calculates a z'-score for a given node. The z'-score is based on the z-scores (weights) of the neighbors of the given node, and proportional to the z-score (weight) of the given node. Specifically, we find the maximum z-score of all neighbors of the given node that are also members of the given set of selected nodes, multiply this z-score by the z-score of the given node, and return this value as the z'-score for the given node. If the given node has no neighbors in the interaction graph, the z'-score is defined as zero. Returns the z'-score as zero or a positive floating point value. :Parameters: - `node`: the node for which to compute the z-prime score - `interaction_graph`: graph containing the gene-gene or gene product-gene product interactions - `selected_nodes`: a `set` of nodes fitting some criterion of interest (e.g., annotated with a term of interest) """ node_neighbors = interaction_graph.neighbors_iter(node) neighbors_in_selected_nodes = (neighbor for neighbor in node_neighbors if neighbor in selected_nodes) neighbor_z_scores = (interaction_graph.node[neighbor]['weight'] for neighbor in neighbors_in_selected_nodes) try: max_z_score = max(neighbor_z_scores) # max() throws a ValueError if its argument has no elements; in this # case, we need to set the max_z_score to zero except ValueError, e: # Check to make certain max() raised this error if 'max()' in e.args[0]: max_z_score = 0 else: raise e z_prime = interaction_graph.node[node]['weight'] * max_z_score return z_prime Here are the top couple of calls according to cProfiler, sorted by time. ncalls tottime percall cumtime percall filename:lineno(function) 156067701 352.313 0.000 642.072 0.000 bpln_contextual.py:204(<genexpr>) 156067701 289.759 0.000 289.759 0.000 bpln_contextual.py:202(<genexpr>) 13963893 174.047 0.000 816.119 0.000 {max} 13963885 69.804 0.000 936.754 0.000 bpln_contextual.py:171(calculate_node_z_prime) 7116883 61.982 0.000 61.982 0.000 {method 'update' of 'set' objects}

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• How to design a C / C++ library to be usable in many client languages?

  - by Brian Schimmel

  I'm planning to code a library that should be usable by a large number of people in on a wide spectrum of platforms. What do I have to consider to design it right? To make this questions more specific, there are four "subquestions" at the end. Choice of language Considering all the known requirements and details, I concluded that a library written in C or C++ was the way to go. I think the primary usage of my library will be in programs written in C, C++ and Java SE, but I can also think of reasons to use it from Java ME, PHP, .NET, Objective C, Python, Ruby, bash scrips, etc... Maybe I cannot target all of them, but if it's possible, I'll do it. Requirements It would be to much to describe the full purpose of my library here, but there are some aspects that might be important to this question: The library itself will start out small, but definitely will grow to enormous complexity, so it is not an option to maintain several versions in parallel. Most of the complexity will be hidden inside the library, though The library will construct an object graph that is used heavily inside. Some clients of the library will only be interested in specific attributes of specific objects, while other clients must traverse the object graph in some way Clients may change the objects, and the library must be notified thereof The library may change the objects, and the client must be notified thereof, if it already has a handle to that object The library must be multi-threaded, because it will maintain network connections to several other hosts While some requests to the library may be handled synchronously, many of them will take too long and must be processed in the background, and notify the client on success (or failure) Of course, answers are welcome no matter if they address my specific requirements, or if they answer the question in a general way that matters to a wider audience! My assumptions, so far So here are some of my assumptions and conclusions, which I gathered in the past months: Internally I can use whatever I want, e.g. C++ with operator overloading, multiple inheritance, template meta programming... as long as there is a portable compiler which handles it (think of gcc / g++) But my interface has to be a clean C interface that does not involve name mangling Also, I think my interface should only consist of functions, with basic/primitive data types (and maybe pointers) passed as parameters and return values If I use pointers, I think I should only use them to pass them back to the library, not to operate directly on the referenced memory For usage in a C++ application, I might also offer an object oriented interface (Which is also prone to name mangling, so the App must either use the same compiler, or include the library in source form) Is this also true for usage in C# ? For usage in Java SE / Java EE, the Java native interface (JNI) applies. I have some basic knowledge about it, but I should definitely double check it. Not all client languages handle multithreading well, so there should be a single thread talking to the client For usage on Java ME, there is no such thing as JNI, but I might go with Nested VM For usage in Bash scripts, there must be an executable with a command line interface For the other client languages, I have no idea For most client languages, it would be nice to have kind of an adapter interface written in that language. I think there are tools to automatically generate this for Java and some others For object oriented languages, it might be possible to create an object oriented adapter which hides the fact that the interface to the library is function based - but I don't know if its worth the effort Possible subquestions is this possible with manageable effort, or is it just too much portability? are there any good books / websites about this kind of design criteria? are any of my assumptions wrong? which open source libraries are worth studying to learn from their design / interface / souce? meta: This question is rather long, do you see any way to split it into several smaller ones? (If you reply to this, do it as a comment, not as an answer)

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• File Upload drops with no reason

  - by sufoid

  Hallo I want to make an file upload. The script should take the image, resize it and upload it. But it seems that there is any unknown to me error in the upload. Here the code define ("MAX_SIZE","2000"); // maximum size for uploaded images define ("WIDTH","107"); // width of thumbnail define ("HEIGHT","107"); // alternative height of thumbnail (portrait 107x80) define ("WIDTH2","600"); // width of (compressed) photo define ("HEIGHT2","600"); // alternative height of (compressed) photo (portrait 600x450) if (isset($_POST['Submit'])) { // iterate thorugh all upload fields foreach ($_FILES as $key => $value) { //read name of user-file $image = $_FILES[$key]['name']; // if it is not empty if ($image) { $filename = stripslashes($_FILES[$key]['name']); // get original name of file from clients machine $extension = getExtension($filename); // get extension of file in lower case format $extension = strtolower($extension); // if extension not known, output error // otherwise continue if (($extension != "jpg") && ($extension != "jpeg") && ($extension != "png") && ($extension != "gif")) { echo '<div class="failure">Fehler bei Datei '. $_FILES[$key]['name'] .': Unbekannter Dateityp: Es können nur Dateien vom Typ .gif, .jpg oder .png hochgeladen werden.</div>'; } else { // get size of image in bytes // $_FILES[\'image\'][\'tmp_name\'] >> temporary filename of file in which the uploaded file was stored on server $size = getimagesize($_FILES[$key]['tmp_name']); $sizekb = filesize($_FILES[$key]['tmp_name']); // if image size exceeds defined maximum size, output error // otherwise continue if ($sizekb > MAX_SIZE*1024) { echo '<div class="failure">Fehler bei Datei '. $_FILES[$key]['name'] .': Die Datei konnte nicht hochgeladen werden: die Dateigröße überschreitet das Limit von 2MB.</div>'; } else { $rand = md5(rand() * time()); // create random file name $image_name = $rand.'.'.$extension; // unique name (random number) // new name contains full path of storage location (images folder) $consname = "photos/".$image_name; // path to big image $consname2 = "photos/thumbs/".$image_name; // path to thumbnail $copied = copy($_FILES[$key]['tmp_name'], $consname); $copied = copy($_FILES[$key]['tmp_name'], $consname2); $sql="INSERT INTO photos (galery_id, photo, thumb) VALUES (". $id .", '$consname', '$consname2')" or die(mysql_error()); $query = mysql_query($sql) or die(mysql_error()); // if image hasnt been uploaded successfully, output error // otherwise continue if (!$copied) { echo '<div class="failure">Fehler bei Datei '. $_FILES[$key]['name'] .': Die Datei konnte nicht hochgeladen werden.</div>'; } else { $thumb_name = $consname2; // path for thumbnail for creation & storage // call to function: create thumbnail // parameters: image name, thumbnail name, specified width and height $thumb = make_thumb($consname,$thumb_name,WIDTH,HEIGHT); $thumb = make_thumb($consname,$consname,WIDTH2,HEIGHT2); } } } } } // current image could be uploaded successfully echo '<div class="success">'. $success .' Foto(s) erfolgreich hochgeladen!</div>'; showForm(); // call to function: create upload form }

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• evaluating cost/benefits of using extension methods in C# => 3.0

  - by BillW

  Hi, In what circumstances (usage scenarios) would you choose to write an extension rather than sub-classing an object ? < full disclosure : I am not an MS employee; I do not know Mitsu Furota personally; I do know the author of the open-source Componax library mentioned here, but I have no business dealings with him whatsoever; I am not creating, or planning to create any commercial product using extensions : in sum : this post is from pure intellectal curiousity related to my trying to (continually) become aware of "best practices" I find the idea of extension methods "cool," and obviously you can do "far-out" things with them as in the many examples you can in Mitsu Furota's (MS) blog postslink text. A personal friend wrote the open-source Componax librarylink text, and there's some remarkable facilities in there; but he is in complete command of his small company with total control over code guidelines, and every line of code "passes through his hands." While this is speculation on my part : I think/guess other issues might come into play in a medium-to-large software team situation re use of Extensions. Looking at MS's guidelines at link text, you find : In general, you will probably be calling extension methods far more often than implementing your own. ... In general, we recommend that you implement extension methods sparingly and only when you have to. Whenever possible, client code that must extend an existing type should do so by creating a new type derived from the existing type. For more information, see Inheritance (C# Programming Guide). ... When the compiler encounters a method invocation, it first looks for a match in the type's instance methods. If no match is found, it will search for any extension methods that are defined for the type, and bind to the first extension method that it finds. And at Ms's link text : Extension methods present no specific security vulnerabilities. They can never be used to impersonate existing methods on a type, because all name collisions are resolved in favor of the instance or static method defined by the type itself. Extension methods cannot access any private data in the extended class. Factors that seem obvious to me would include : I assume you would not write an extension unless you expected it be used very generally and very frequently. On the other hand : couldn't you say the same thing about sub-classing ? Knowing we can compile them into a seperate dll, and add the compiled dll, and reference it, and then use the extensions : is "cool," but does that "balance out" the cost inherent in the compiler first having to check to see if instance methods are defined as described above. Or the cost, in case of a "name clash," of using the Static invocation methods to make sure your extension is invoked rather than the instance definition ? How frequent use of Extensions would affect run-time performance or memory use : I have no idea. So, I'd appreciate your thoughts, or knowing about how/when you do, or don't do, use Extensions, compared to sub-classing. thanks, Bill

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• Help with Silverlight Sockets and Message delivery

  - by pixel3cs

  There are 4 months since I stopped developing my Silverlight Multiplayer Chess game. The problem was a bug wich I couldn't reproduce. Sice I got some free time this week I managed to discover the problem and I am now able to reproduce the bug. It seems that if I send 10 messages from client, one after another, with no delay between them, just like in the below example // when I press Enter, the client will 10 messages with no delay between them private void textBox_KeyDown(object sender, KeyEventArgs e) { if (e.Key == Key.Enter && textBox.Text.Length > 0) { for (int i = 0; i < 10; i++) { MessageBuilder mb = new MessageBuilder(); mb.Writer.Write((byte)GameCommands.NewChatMessageInTable); mb.Writer.Write(string.Format("{0}{2}: {1}", ClientVars.PlayerNickname, textBox.Text, i)); SendChatMessageEvent(mb.GetMessage()); //System.Threading.Thread.Sleep(100); } textBox.Text = string.Empty; } } // the method used by client to send a message to server public void SendData(Message message) { if (socket.Connected) { SocketAsyncEventArgs myMsg = new SocketAsyncEventArgs(); myMsg.RemoteEndPoint = socket.RemoteEndPoint; byte[] buffer = message.Buffer; myMsg.SetBuffer(buffer, 0, buffer.Length); socket.SendAsync(myMsg); } else { string err = "Server does not respond. You are disconnected."; socket.Close(); uiContext.Post(this.uiClient.ProcessOnErrorData, err); } } // the method used by server to receive data from client private void OnDataReceived(IAsyncResult async) { ClientSocketPacket client = async.AsyncState as ClientSocketPacket; int count = 0; try { if (client.Socket.Connected) count = client.Socket.EndReceive(async); // THE PROBLEM IS HERE // IF SERVER WAS RECEIVE ALL MESSAGES SEPARATELY, ONE BY ONE, THE COUNT // WAS ALWAYS 15, BUT BECAUSE THE SERVER RECEIVE 3 MESSAGES IN 1, THE COUNT // IS SOMETIME 45 } catch { HandleException(client); } client.MessageStream.Write(client.Buffer, 0, count); Message message; while (client.MessageStream.Read(out message)) { message.Tag = client; ThreadPool.QueueUserWorkItem(new WaitCallback(this.processingThreadEvent.ServerGotData), message); totalReceivedBytes += message.Buffer.Length; } try { if (client.Socket.Connected) client.Socket.BeginReceive(client.Buffer, 0, client.Buffer.Length, 0, new AsyncCallback(OnDataReceived), client); } catch { HandleException(client); } } there are sent only 3 big messages, and every big message contain 3 or 4 small messages. This is not the behavior I want. If I put a 100 milliseconds delay between message delivery, everything is work fine, but in a real world scenario users can send messages to server even at 1 millisecond between them. Are there any settings to be done in order to make the client send only one message at a time, or Even if I receive 3 messages in 1, are they full messages all the time (I dont't want to receive 2.5 messages in one big message) ? because if they are, I can read them and treat this new situation

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• WebClient.DownloadDataAsync is freezing my UI

  - by Matías

  Hi, I have in my Form constructor, after the InitializeComponent the following code: using (WebClient client = new WebClient()) { client.DownloadDataCompleted += new DownloadDataCompletedEventHandler(client_DownloadDataCompleted); client.DownloadDataAsync("http://example.com/version.txt"); } When I start my form, the UI doesn't appears till client_DownloadDataCompleted is raised. The client_DownloadDataCompleted method is empty, so there's no problem there. What I'm doing wrong? How is supposed to do this without freezing the UI? Thanks for your time. Best regards. FULL CODE: Program.cs using System; using System.Windows.Forms; namespace Lala { static class Program { /// <summary> /// The main entry point for the application. /// </summary> [STAThread] static void Main() { Application.EnableVisualStyles(); Application.SetCompatibleTextRenderingDefault(false); Application.Run(new Form1()); } } } Form1.cs using System; using System.Net; using System.Windows.Forms; namespace Lala { public partial class Form1 : Form { WebClient client = new WebClient(); public Form1() { client.DownloadDataCompleted += new DownloadDataCompletedEventHandler(client_DownloadDataCompleted); client.DownloadDataAsync(new Uri("http://www.google.com")); InitializeComponent(); } void client_DownloadDataCompleted(object sender, DownloadDataCompletedEventArgs e) { textBox1.Text += "A"; } } partial class Form1 { /// <summary> /// Required designer variable. /// </summary> private System.ComponentModel.IContainer components = null; /// <summary> /// Clean up any resources being used. /// </summary> /// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param> protected override void Dispose(bool disposing) { if (disposing && (components != null)) { components.Dispose(); } base.Dispose(disposing); } #region Windows Form Designer generated code /// <summary> /// Required method for Designer support - do not modify /// the contents of this method with the code editor. /// </summary> private void InitializeComponent() { this.button1 = new System.Windows.Forms.Button(); this.textBox1 = new System.Windows.Forms.TextBox(); this.SuspendLayout(); // // button1 // this.button1.Location = new System.Drawing.Point(12, 12); this.button1.Name = "button1"; this.button1.Size = new System.Drawing.Size(75, 23); this.button1.TabIndex = 0; this.button1.Text = "button1"; this.button1.UseVisualStyleBackColor = true; // // textBox1 // this.textBox1.Location = new System.Drawing.Point(12, 41); this.textBox1.Multiline = true; this.textBox1.Name = "textBox1"; this.textBox1.Size = new System.Drawing.Size(468, 213); this.textBox1.TabIndex = 1; // // Form1 // this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F); this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font; this.ClientSize = new System.Drawing.Size(492, 266); this.Controls.Add(this.textBox1); this.Controls.Add(this.button1); this.Name = "Form1"; this.Text = "Form1"; this.ResumeLayout(false); this.PerformLayout(); } #endregion private System.Windows.Forms.Button button1; private System.Windows.Forms.TextBox textBox1; } }

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• The type '' was not mapped

  - by Mike

  I've been trying to fix this error for awhile now. I get this error any time my application tries to create an instance of my data context. Below is the code: using System; using System.Collections.Generic; using System.Linq; using System.Web; using RandomRentals.Models; using System.Data.Entity; namespace RandomRentals.Models { public class RentalContext : DbContext { public DbSet<Rental> Rentals { get; set; } public DbSet<Category> Categories { get; set; } public DbSet<Item> Items { get; set; } public DbSet<Billing> Billings { get; set; } public DbSet<User> Users { get; set; } public DbSet<Video> Videos { get; set; } public DbSet<Picture> Pictures { get; set; } public DbSet<ServiceType> ServiceTypes { get; set; } public DbSet<Rating> Ratings { get; set; } public DbSet<Business> Businesses { get; set; } public DbSet<BusinessHour> BusinessHours { get; set; } } } Here is the stack Trace: [InvalidOperationException: The type 'RandomRentals.Rental' was not mapped. Check that the type has not been explicitly excluded by using the Ignore method or NotMappedAttribute data annotation. Verify that the type was defined as a class, is not primitive, nested or generic, and does not inherit from EntityObject.] System.Data.Entity.Internal.DbSetDiscoveryService.GetSets() +706 System.Data.Entity.Internal.DbSetDiscoveryService.InitializeSets() +31 System.Data.Entity.DbContext.DiscoverAndInitializeSets() +56 System.Data.Entity.DbContext.InitializeLazyInternalContext(IInternalConnection internalConnection, DbCompiledModel model) +79 System.Data.Entity.DbContext..ctor() +99 RandomRentals.Models.RentalContext..ctor() +44 RandomRentals.Models.UserModel..ctor() in C:\Users\nikka\Desktop\RandomRentals\RandomRentals\Models\UserModel.cs:11 [TargetInvocationException: Exception has been thrown by the target of an invocation.] System.RuntimeTypeHandle.CreateInstance(RuntimeType type, Boolean publicOnly, Boolean noCheck, Boolean& canBeCached, RuntimeMethodHandleInternal& ctor, Boolean& bNeedSecurityCheck) +0 System.RuntimeType.CreateInstanceSlow(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache) +98 System.RuntimeType.CreateInstanceDefaultCtor(Boolean publicOnly, Boolean skipVisibilityChecks, Boolean skipCheckThis, Boolean fillCache) +241 System.Activator.CreateInstance(Type type, Boolean nonPublic) +69 System.Web.Mvc.DefaultModelBinder.CreateModel(ControllerContext controllerContext, ModelBindingContext bindingContext, Type modelType) +199 System.Web.Mvc.DefaultModelBinder.BindComplexModel(ControllerContext controllerContext, ModelBindingContext bindingContext) +572 System.Web.Mvc.DefaultModelBinder.BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext) +449 System.Web.Mvc.ControllerActionInvoker.GetParameterValue(ControllerContext controllerContext, ParameterDescriptor parameterDescriptor) +317 System.Web.Mvc.ControllerActionInvoker.GetParameterValues(ControllerContext controllerContext, ActionDescriptor actionDescriptor) +117 System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName) +343 System.Web.Mvc.Controller.ExecuteCore() +116 System.Web.Mvc.ControllerBase.Execute(RequestContext requestContext) +97 System.Web.Mvc.ControllerBase.System.Web.Mvc.IController.Execute(RequestContext requestContext) +10 System.Web.Mvc.<>c__DisplayClassb.<BeginProcessRequest>b__5() +37 System.Web.Mvc.Async.<>c__DisplayClass1.<MakeVoidDelegate>b__0() +21 System.Web.Mvc.Async.<>c__DisplayClass8`1.<BeginSynchronous>b__7(IAsyncResult _) +12 System.Web.Mvc.Async.WrappedAsyncResult`1.End() +62 System.Web.Mvc.<>c__DisplayClasse.<EndProcessRequest>b__d() +50 System.Web.Mvc.SecurityUtil.<GetCallInAppTrustThunk>b__0(Action f) +7 System.Web.Mvc.SecurityUtil.ProcessInApplicationTrust(Action action) +22 System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +60 System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) +9 System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +8970061 System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +184 Here is the full error text: The type 'RandomRentals.Rental' was not mapped. Check that the type has not been explicitly excluded by using the Ignore method or NotMappedAttribute data annotation. Verify that the type was defined as a class, is not primitive, nested or generic, and does not inherit from EntityObject. Any help would be greatly appreciated

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• How do I get jqGrid to work using ASP.NET + JSON on the backend?

  - by briandus

  Hi friends, ok, I'm back. I totally simplified my problem to just three simple fields and I'm still stuck on the same line using the addJSONData method. I've been stuck on this for days and no matter how I rework the ajax call, the json string, blah blah blah...I can NOT get this to work! I can't even get it to work as a function when adding one row of data manually. Can anyone PLEASE post a working sample of jqGrid that works with ASP.NET and JSON? Would you please include 2-3 fields (string, integer and date preferably?) I would be happy to see a working sample of jqGrid and just the manual addition of a JSON object using the addJSONData method. Thanks SO MUCH!! If I ever get this working, I will post a full code sample for all the other posting for help from ASP.NET, JSON users stuck on this as well. Again. THANKS!! tbl.addJSONData(objGridData); //err: tbl.addJSONData is not a function!! Here is what Firebug is showing when I receive this message: • objGridData Object total=1 page=1 records=5 rows=[5] ? Page "1" Records "5" Total "1" Rows [Object ID=1 PartnerID=BCN, Object ID=2 PartnerID=BCN, Object ID=3 PartnerID=BCN, 2 more... 0=Object 1=Object 2=Object 3=Object 4=Object] (index) 0 (prop) ID (value) 1 (prop) PartnerID (value) "BCN" (prop) DateTimeInserted (value) Thu May 29 2008 12:08:45 GMT-0700 (Pacific Daylight Time) * There are three more rows Here is the value of the variable tbl (value) 'Table.scroll' <TABLE cellspacing="0" cellpadding="0" border="0" style="width: 245px;" class="scroll grid_htable"><THEAD><TR><TH class="grid_sort grid_resize" style="width: 55px;"><SPAN> </SPAN><DIV id="jqgh_ID" style="cursor: pointer;">ID <IMG src="http://localhost/DNN5/js/jQuery/jqGrid-3.4.3/themes/sand/images/sort_desc.gif"/></DIV></TH><TH class="grid_resize" style="width: 90px;"><SPAN> </SPAN><DIV id="jqgh_PartnerID" style="cursor: pointer;">PartnerID </DIV></TH><TH class="grid_resize" style="width: 100px;"><SPAN> </SPAN><DIV id="jqgh_DateTimeInserted" style="cursor: pointer;">DateTimeInserted </DIV></TH></TR></THEAD></TABLE> Here is the complete function: $('table.scroll').jqGrid({ datatype: function(postdata) { mtype: "POST", $.ajax({ url: 'EDI.asmx/GetTestJSONString', type: "POST", contentType: "application/json; charset=utf-8", data: "{}", dataType: "text", //not json . let me try to parse success: function(msg, st) { if (st == "success") { var gridData; //strip of "d:" notation var result = JSON.parse(msg); for (var property in result) { gridData = result[property]; break; } var objGridData = eval("(" + gridData + ")"); //creates an object with visible data and structure var tbl = jQuery('table.scroll')[0]; alert(objGridData.rows[0].PartnerID); //displays the correct data //tbl.addJSONData(objGridData); //error received: addJSONData not a function //error received: addJSONData not a function (This uses eval as shown in the documentation) //tbl.addJSONData(eval("(" + objGridData + ")")); //the line below evaluates fine, creating an object and visible data and structure //var objGridData = eval("(" + gridData + ")"); //BUT, the same thing will not work here //tbl.addJSONData(eval("(" + gridData + ")")); //FIREBUG SHOWS THIS AS THE VALUE OF gridData: // "{"total":"1","page":"1","records":"5","rows":[{"ID":1,"PartnerID":"BCN","DateTimeInserted":new Date(1214412777787)},{"ID":2,"PartnerID":"BCN","DateTimeInserted":new Date(1212088125000)},{"ID":3,"PartnerID":"BCN","DateTimeInserted":new Date(1212088125547)},{"ID":4,"PartnerID":"EHG","DateTimeInserted":new Date(1235603192033)},{"ID":5,"PartnerID":"EMDEON","DateTimeInserted":new Date(1235603192000)}]}" } } }); }, jsonReader: { root: "rows", //arry containing actual data page: "page", //current page total: "total", //total pages for the query records: "records", //total number of records repeatitems: false, id: "ID" //index of the column with the PK in it }, colNames: [ 'ID', 'PartnerID', 'DateTimeInserted' ], colModel: [ { name: 'ID', index: 'ID', width: 55 }, { name: 'PartnerID', index: 'PartnerID', width: 90 }, { name: 'DateTimeInserted', index: 'DateTimeInserted', width: 100}], rowNum: 10, rowList: [10, 20, 30], imgpath: 'http://localhost/DNN5/js/jQuery/jqGrid-3.4.3/themes/sand/images', pager: jQuery('#pager'), sortname: 'ID', viewrecords: true, sortorder: "desc", caption: "TEST Example")};

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• Constructor ambiguous quesiton

  - by Crystal

  I'm trying to create a simple date class, but I get an error on my main file that says, "call of overloaded Date() is ambiguous." I'm not sure why since I thought as long as I had different parameters for my constructor, I was ok. Here is my code: header file: #ifndef DATE_H #define DATE_H using std::string; class Date { public: static const int monthsPerYear = 12; // num of months in a yr Date(int = 1, int = 1, int = 1900); // default constructor Date(); // uses system time to create object void print() const; // print date in month/day/year format ~Date(); // provided to confirm destruction order string getMonth(int month) const; // gets month in text format private: int month; // 1 - 12 int day; // 1 - 31 int year; // any year int checkDay(int) const; }; #endif .cpp file #include <iostream> #include <iomanip> #include <string> #include <ctime> #include "Date.h" using namespace std; Date::Date() { time_t seconds = time(NULL); struct tm* t = localtime(&seconds); month = t->tm_mon; day = t->tm_mday; year = t->tm_year; } Date::Date(int mn, int dy, int yr) { if (mn > 0 && mn <= monthsPerYear) month = mn; else { month = 1; // invalid month set to 1 cout << "Invalid month (" << mn << ") set to 1.\n"; } year = yr; // could validate yr day = checkDay(dy); // validate the day // output Date object to show when its constructor is called cout << "Date object constructor for date "; print(); cout << endl; } void Date::print() const { string str; cout << month << '/' << day << '/' << year << '\n'; // new code for HW2 cout << setfill('0') << setw(3) << day; // prints in ddd cout << " " << year << '\n'; // yyyy format str = getMonth(month); // prints in month (full word), day, year cout << str << " " << day << ", " << year << '\n'; } and my main.cpp #include <iostream> #include "Date.h" using std::cout; int main() { Date date1(4, 30, 1980); date1.print(); cout << '\n'; Date date2; date2.print(); }

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• Php template caching design

  - by Thomas

  Hello to all, I want to include caching in my app design. Caching templates for starters. The design I have used so far is very modular. I have created an ORM implementation for all my tables and each table is represented by the corresponding class. All the requests are handled by one controller which routes them to the appropriate webmethod functions. I am using a template class for handling UI parts. What I have in mind for caching includes the implementation of a separate Cache class for handling caching with the flexibility to either store in files, apc or memcache. Right now I am testing with file caching. Some thoughts Should I include the logic of checking for cached versions in the Template class or in the webmethods which handle the incoming requests and which eventually call the Template class. In the first case, things are pretty simple as I will not have to change anything more than pass the template class an extra argument (whether to load from cache or not). In the second case however, I am thinking of checking for a cached version immediately in the webmethod and if found return it. This will save all the processing done until the logic reaches the template (first case senario). Both senarios however, rely on an accurate mechanism of invalidating caches, which brings as to Invalidating caches As I see it (and you can add your input freely) a template cached file, becomes invalidate if: a. the expiration set, is reached. b. the template file itself is updated (ie by the developer when adding a new line) c. the webmethod that handles the request changes (ie the developer adds/deletes something in the code) d. content coming from the db and ending in the template file is modified I am thinking of storing a json encoded array inside the cached file. The first value will be the expiration timestamp of the cache. The second value will be the modification time of the php file with the code handling the request (to cope with option c above) The third will be the content itself The validation process I am considering, according to the above senarios, is: a. If the expiration of the cached file (stored in the array) is reached, delete the cache file b. if the cached file's mod time is smaller than the template's skeleton file mod time, delete the cached file c. if the mod time of the php file is greated than the one stored in the cache, delete the cached file. d. This is tricky. In the ORM implementation I ahve added event handlers (which fire when adding, updating, deleting objects). I could delete the cache file every time an object thatprovides content to the template, is modified. The problem is how to keep track which cached files correpond to each schema object. Take this example, a user has his shortprofile page and a full profile page (2 templates) These templates can be cached. Now, every time the user modifies his profile, the event handler would need to know which templates or cached files correspond to the User, so that these files can be deleted. I could store them in the db but I am looking for a beter approach

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• Lock free multiple readers single writer

  - by dummzeuch

  I have got an in memory data structure that is read by multiple threads and written by only one thread. Currently I am using a critical section to make this access threadsafe. Unfortunately this has the effect of blocking readers even though only another reader is accessing it. There are two options to remedy this: use TMultiReadExclusiveWriteSynchronizer do away with any blocking by using a lock free approach For 2. I have got the following so far (any code that doesn't matter has been left out): type TDataManager = class private FAccessCount: integer; FData: TDataClass; public procedure Read(out _Some: integer; out _Data: double); procedure Write(_Some: integer; _Data: double); end; procedure TDataManager.Read(out _Some: integer; out _Data: double); var Data: TDAtaClass; begin InterlockedIncrement(FAccessCount); try // make sure we get both values from the same TDataClass instance Data := FData; // read the actual data _Some := Data.Some; _Data := Data.Data; finally InterlockedDecrement(FAccessCount); end; end; procedure TDataManager.Write(_Some: integer; _Data: double); var NewData: TDataClass; OldData: TDataClass; ReaderCount: integer; begin NewData := TDataClass.Create(_Some, _Data); InterlockedIncrement(FAccessCount); OldData := TDataClass(InterlockedExchange(integer(FData), integer(NewData)); // now FData points to the new instance but there might still be // readers that got the old one before we exchanged it. ReaderCount := InterlockedDecrement(FAccessCount); if ReaderCount = 0 then // no active readers, so we can safely free the old instance FreeAndNil(OldData) else begin /// here is the problem end; end; Unfortunately there is the small problem of getting rid of the OldData instance after it has been replaced. If no other thread is currently within the Read method (ReaderCount=0), it can safely be disposed and that's it. But what can I do if that's not the case? I could just store it until the next call and dispose it there, but Windows scheduling could in theory let a reader thread sleep while it is within the Read method and still has got a reference to OldData. If you see any other problem with the above code, please tell me about it. This is to be run on computers with multiple cores and the above methods are to be called very frequently. In case this matters: I am using Delphi 2007 with the builtin memory manager. I am aware that the memory manager probably enforces some lock anyway when creating a new class but I want to ignore that for the moment. Edit: It may not have been clear from the above: For the full lifetime of the TDataManager object there is only one thread that writes to the data, not several that might compete for write access. So this is a special case of MREW.

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• Limiting TCP sends with a "to-be-sent" queue and other design issues.

  - by Poni

  Hello all! This question is the result of two other questions I've asked in the last few days. I'm creating a new question because I think it's related to the "next step" in my understanding of how to control the flow of my send/receive, something I didn't get a full answer to yet. The other related questions are: http://stackoverflow.com/questions/3028376/an-iocp-documentation-interpretation-question-buffer-ownership-ambiguity http://stackoverflow.com/questions/3028998/non-blocking-tcp-buffer-issues In summary, I'm using Windows I/O Completion Ports. I have several threads that process notifications from the completion port. I believe the question is platform-independent and would have the same answer as if to do the same thing on a *nix, *BSD, Solaris system. So, I need to have my own flow control system. Fine. So I send send and send, a lot. How do I know when to start queueing the sends, as the receiver side is limited to X amount? Let's take an example (closest thing to my question): FTP protocol. I have two servers; One is on a 100Mb link and the other is on a 10Mb link. I order the 100Mb one to send to the other one (the 10Mb linked one) a 1GB file. It finishes with an average transfer rate of 1.25MB/s. How did the sender (the 100Mb linked one) knew when to hold the sending, so the slower one wouldn't be flooded? Another way to ask this: Can I get a "hold-your-sendings" notification from the remote side? Is it built-in in TCP or the so called "reliable network protocol" needs me to do so? Again, I have a loop with many sends to a remote server, and at some point, within that loop I'll have to determine if I should queue that send or I can pass it on to the transport layer (TCP). How do I do that? What would you do? Of course that when I get a completion notification from IOCP that the send was done I'll issue other pending sends, that's clear. Another design question related to this: Since I am to use a custom buffers with a send queue, and these buffers are being freed to be reused (thus not using the "delete" keyword) when a "send-done" notification has been arrived, I'll have to use a mutual exlusion on that buffer pool. Using a mutex slows things down, so I've been thinking; Why not have each thread have its own buffers pool, thus accessing it , at least when getting the required buffers for a send operation, will require no mutex, because it belongs to that thread only. The buffers pool is located at the thread local storage (TLS) level. No mutual pool implies no lock needed, implies faster operations BUT also implies more memory used by the app, because even if one thread already allocated 1000 buffers, the other one that is sending right now and need 1000 buffers to send something will need to allocated these to its own. This is a long question and I hope none got hurt (: Thank you all!

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