How to add global lock to an ASP.NET web application?

Question

I am writing an ASP.NET web application using C # that can read and write a text file from an IIS server (using System.IO.FileStream ), and I am wondering how to implement a global lock on this operation?

Answer 1

From what @Aristos and this post suggested, I came up with this class:

 using System.Threading; using System.Security.AccessControl; using System.Security.Principal; using System.Runtime.InteropServices; //GuidAttribute using System.Reflection; //Assembly namespace ITXClimateSaverWebApp { public class GlobalNamedLock { private Mutex mtx; public GlobalNamedLock(string strLockName) { //Name must be provided! if(string.IsNullOrWhiteSpace(strLockName)) { //Use default name strLockName = ((GuidAttribute)Assembly.GetExecutingAssembly().GetCustomAttributes(typeof(GuidAttribute), false).GetValue(0)).Value.ToString(); } //Create security permissions for everyone //It is needed in case the mutex is used by a process with //different set of privileges than the one that created it //Setting it will avoid access_denied errors. MutexSecurity mSec = new MutexSecurity(); mSec.AddAccessRule(new MutexAccessRule(new SecurityIdentifier(WellKnownSidType.WorldSid, null), MutexRights.FullControl, AccessControlType.Allow)); //Create the global mutex bool bCreatedNew; mtx = new Mutex(false, @"Global\" + strLockName, out bCreatedNew, mSec); } public bool enterCRITICAL_SECTION() { //Enter critical section //INFO: May throw an exception! //RETURN: // = 'true' if successfully entered // = 'false' if failed (DO NOT continue!) //Wait return mtx.WaitOne(); } public void leaveCRITICAL_SECTION() { //Leave critical section //INFO: May throw an exception! //Release it mtx.ReleaseMutex(); } } } 

and then the way to call it for global locking:

 try { GlobalNamedLock gl = new GlobalNamedLock("MyLockName"); try { if (gl.enterCRITICAL_SECTION()) { //Use the global resource now } } finally { gl.leaveCRITICAL_SECTION(); } } catch (Exception ex) { //Failed -- log it } 

So this seems to be doing this job. What do you think?

Answer 2

For global blocking you need mutex

  // The key can be part of the file name - // be careful not all characters are valid var mut = new Mutex(true, key); try { // Wait until it is safe to enter. mut.WaitOne(); // here you manipulate your file } finally { // Release the Mutex. mut.ReleaseMutex(); } 

Answer 3

The simplest solution is to create a new object in a Cache or Application object, preferably in Application_Startup in the global.asax file. For instance:

 Cache["myLocker"] = new object(); 

Then you can use the standard "lock" syntax.

 lock(Cache["myLocker"]) { // do file access here... } 

Answer 4

Why not just use the global root sync object?

 internal static class Lock { public static object SyncRoot = new object{}; } 

Using:

 lock (Lock.SyncRoot) { }