// Funnel all delegates through here to ensure proper procedure for getting and releasing locks.
private bool Execute(TKey key, LockType type, Action <ReaderWriterLockSlim> closure, int?millisecondsTimeout = null, bool throwsOnTimeout = false)
{
if (key == null)
{
throw new ArgumentNullException(nameof(key));
}
if (closure == null)
{
throw new ArgumentNullException(nameof(closure));
}
ReaderWriterLockSlimExensions.ValidateMillisecondsTimeout(millisecondsTimeout);
Contract.EndContractBlock();
var context = ContextPool.Take();
var rwlock = GetLock(key, type, context, millisecondsTimeout, throwsOnTimeout);
if (rwlock == null)
{
return(false);
}
try
{
closure(rwlock.Lock);
}
finally
{
try
{
ReleaseLock(rwlock.Lock, type);
rwlock.Clear(context);
ContextPool.Give(context);
}
catch (Exception ex)
{
ex.WriteToDebug();
// The above cannot fail or dire concequences...
Debugger.Break();
throw;
}
}
return(true);
}
private bool AcquireLock(ReaderWriterLockSlim target, LockType type, int?millisecondsTimeout = null, bool throwsOnTimeout = false)
{
if (target == null)
{
throw new ArgumentNullException(nameof(target));
}
ReaderWriterLockSlimExensions.ValidateMillisecondsTimeout(millisecondsTimeout);
Contract.EndContractBlock();
switch (type)
{
case LockType.Read:
return(target.EnterReadLock(millisecondsTimeout, throwsOnTimeout));
case LockType.ReadUpgradeable:
return(target.EnterUpgradeableReadLock(millisecondsTimeout, throwsOnTimeout));
case LockType.Write:
return(target.EnterWriteLock(millisecondsTimeout, throwsOnTimeout));
}
return(false);
}
private ReaderWriterLockTracker GetLock(TKey key, LockType type, object context, int?millisecondsTimeout = null, bool throwsOnTimeout = false)
{
if (key == null)
{
throw new ArgumentNullException(nameof(key));
}
if (context == null)
{
throw new ArgumentNullException(nameof(context));
}
ReaderWriterLockSlimExensions.ValidateMillisecondsTimeout(millisecondsTimeout);
Contract.EndContractBlock();
if (IsDisposed)
{
return(null);
}
// Need to be able to enter a lock before releasing access in order to prevent removal...
var r = CleanupManager.ReadValue(
() =>
{
// It is possible that a read could be acquired while disposing just before the dispose.
if (IsDisposed)
{
return(null);
}
// Get a tracker...
ReaderWriterLockTracker result;
{
// Compare the tracker retrieved with the one created...
ReaderWriterLockTracker created = null;
do
{
result = Locks.GetOrAdd(key, k => created = LockPool.Take());
}
// Safeguard against rare case of when a disposed tracker is retained via an exception (possibly?). :(
while (!IsDisposed && result.IsDisposed);
// If the one created is not the one retrieved, go ahead and add it to the pool so it doesn't go to waste.
if (created != null && created != result)
{
if (IsDisposed)
{
created.Dispose();
}
else
{
LockPool.Give(created);
}
}
// This should never get out of sync, but just in case...
var rlock = result.Lock;
if (rlock == null || result.IsDisposed)
{
Debug.Fail("A lock tracker was retained after it was disposed.");
return(null);
}
else if (Debugger.IsAttached && rlock.RecursionPolicy == LockRecursionPolicy.NoRecursion)
{
if (rlock.IsWriteLockHeld && type == LockType.Read)
{
Debugger.Break(); //
}
}
}
// Quick check to avoid further processes...
if (IsDisposed)
{
return(null);
}
var lockHeld = false;
if (!result.Reserve(context))
{
return(null);
}
try
{
// result.Lock will only be null if the tracker has been disposed.
lockHeld = AcquireLock(result.Lock, type, millisecondsTimeout, throwsOnTimeout);
}
catch (LockRecursionException lrex)
{
lrex.WriteToDebug();
Debugger.Break(); // Need to be able to track down source.
throw;
}
finally
{
if (!lockHeld)
{
result.Clear(context);
}
}
return(lockHeld ? result : null);
});
// In the rare case that a dispose could be initiated during this ReadValue:
// We need to not propagate locking...
if (r == null || !IsDisposed)
{
return(r);
}
ReleaseLock(r.Lock, type);
r.Clear(context);
return(null);
}
