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POWhat is wrong with this solution to locking and managing locked exceptions?
 

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  1. POWhat is wrong with this solution to locking and managing locked exceptions?
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    <p>My objective is a convention for thread-safe functionality and exception handling within my application. I'm relatively new to the concept of thread management/multithreading. I am using <code>.NET 3.5</code></p> <p>I wrote the following helper method to wrap all my locked actions after reading this article <a href="http://blogs.msdn.com/b/ericlippert/archive/2009/03/06/locks-and-exceptions-do-not-mix.aspx" rel="nofollow noreferrer">http://blogs.msdn.com/b/ericlippert/archive/2009/03/06/locks-and-exceptions-do-not-mix.aspx</a>, which was linked in response to this question, <a href="https://stackoverflow.com/questions/4978850/monitor-vs-lock/4979002#4979002">Monitor vs lock</a>.</p> <p>My thought is that if I use this convention consistently in my application, it will be easier to write thread-safe code and to handle errors within thread safe code without corrupting the state.</p> <pre><code>public static class Locking { private static readonly Dictionary&lt;object,bool&gt; CorruptionStateDictionary = new Dictionary&lt;object, bool&gt;(); private static readonly object CorruptionLock = new object(); public static bool TryLockedAction(object lockObject, Action action, out Exception exception) { if (IsCorrupt(lockObject)) { exception = new LockingException("Cannot execute locked action on a corrupt object."); return false; } exception = null; Monitor.Enter(lockObject); try { action.Invoke(); } catch (Exception ex) { exception = ex; } finally { lock (CorruptionLock) // I don't want to release the lockObject until its corruption-state is updated. // As long as the calling class locks the lockObject via TryLockedAction(), this should work { Monitor.Exit(lockObject); if (exception != null) { if (CorruptionStateDictionary.ContainsKey(lockObject)) { CorruptionStateDictionary[lockObject] = true; } else { CorruptionStateDictionary.Add(lockObject, true); } } } } return exception == null; } public static void Uncorrupt(object corruptLockObject) { if (IsCorrupt(corruptLockObject)) { lock (CorruptionLock) { CorruptionStateDictionary[corruptLockObject] = false; } } else { if(!CorruptionStateDictionary.ContainsKey(corruptLockObject)) { throw new LockingException("Uncorrupt() is not valid on object that have not been corrupted."); } else { // The object has previously been uncorrupted. // My thought is to ignore the call. } } } public static bool IsCorrupt(object lockObject) { lock(CorruptionLock) { return CorruptionStateDictionary.ContainsKey(lockObject) &amp;&amp; CorruptionStateDictionary[lockObject]; } } } </code></pre> <p>I use a LockingException class for ease of debugging.</p> <pre><code> public class LockingException : Exception { public LockingException(string message) : base(message) { } } </code></pre> <p>Here is an example usage class to show how I intend to use this.</p> <pre><code>public class ExampleUsage { private readonly object ExampleLock = new object(); public void ExecuteLockedMethod() { Exception exception; bool valid = Locking.TryLockedAction(ExampleLock, ExecuteMethod, out exception); if (!valid) { bool revalidated = EnsureValidState(); if (revalidated) { Locking.Uncorrupt(ExampleLock); } } } private void ExecuteMethod() { //does something, maybe throws an exception } public bool EnsureValidState() { // code to make sure the state is valid // if there is an exception returns false, return true; } } </code></pre>
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