/// <inheritdoc />
public override int Next()
{
int intReturn;
_objLock.SafeWait();
try
{
intReturn = _objRandom.Next();
}
finally
{
_objLock.Release();
}
return(intReturn);
}
private async ValueTask DisposeCoreAsync()
{
try
{
if (_objCurrentSemaphore.CurrentCount == 0)
{
await _objNextSemaphore.WaitAsync();
try
{
_objCurrentSemaphore.Release();
}
finally
{
_objNextSemaphore.Release();
}
}
}
finally
{
Utils.SemaphorePool.Return(ref _objNextSemaphore);
}
}
/// <summary>
/// Try to synchronously obtain a lock for reading.
/// </summary>
public void EnterReadLock(CancellationToken token = default)
{
if (_intDisposedStatus != 0)
{
throw new ObjectDisposedException(nameof(AsyncFriendlyReaderWriterLock));
}
token.ThrowIfCancellationRequested();
// Only do the complicated steps if any write lock is currently being held, otherwise skip it and just process the read lock
if (_objTopLevelWriterSemaphore.CurrentCount == 0)
{
// Temporarily acquiring a write lock just to mess with the read locks is a bottleneck, so don't do any such setting unless we need it
DebuggableSemaphoreSlim objCurrentSemaphore = _objCurrentWriterSemaphore.Value?.Item2 ?? _objTopLevelWriterSemaphore;
objCurrentSemaphore.SafeWait(token);
try
{
if (Interlocked.Increment(ref _intCountActiveReaders) == 1)
{
try
{
_objReaderSemaphore.SafeWait(token);
}
catch
{
Interlocked.Decrement(ref _intCountActiveReaders);
throw;
}
}
}
finally
{
objCurrentSemaphore.Release();
}
}
else if (Interlocked.Increment(ref _intCountActiveReaders) == 1)
{
try
{
_objReaderSemaphore.SafeWait(token);
}
catch
{
Interlocked.Decrement(ref _intCountActiveReaders);
throw;
}
}
}
/// <summary>
/// Heavier read lock entrant, used if a write lock is already being held somewhere
/// </summary>
private async Task TakeReadLockCoreAsync(DebuggableSemaphoreSlim objCurrentSemaphore, CancellationToken token = default)
{
await objCurrentSemaphore.WaitAsync(token);
try
{
if (Interlocked.Increment(ref _intCountActiveReaders) == 1)
{
try
{
await _objReaderSemaphore.WaitAsync(token);
}
catch
{
Interlocked.Decrement(ref _intCountActiveReaders);
throw;
}
}
}
finally
{
objCurrentSemaphore.Release();
}
}
/// <summary>
/// Try to synchronously obtain a lock for writing.
/// The returned SafeSemaphoreWriterRelease must be stored for when the write lock is to be released.
/// </summary>
public IDisposable EnterWriteLock(CancellationToken token = default)
{
if (_intDisposedStatus != 0)
{
throw new ObjectDisposedException(nameof(AsyncFriendlyReaderWriterLock));
}
token.ThrowIfCancellationRequested();
(DebuggableSemaphoreSlim objLastSemaphore, DebuggableSemaphoreSlim objCurrentSemaphore)
= _objCurrentWriterSemaphore.Value
?? new Tuple <DebuggableSemaphoreSlim, DebuggableSemaphoreSlim>(null, _objTopLevelWriterSemaphore);
DebuggableSemaphoreSlim objNextSemaphore = Utils.SemaphorePool.Get();
// Extremely hacky solution to buggy semaphore (re)cycling in AsyncLocal
// TODO: Fix this properly. The problem is that after an AsyncLocal shallow-copy in a different context, the semaphores can get returned in the copy without altering the original AsyncLocal
while (objNextSemaphore == objCurrentSemaphore || objNextSemaphore == objLastSemaphore)
{
objNextSemaphore = Utils.SemaphorePool.Get();
}
_objCurrentWriterSemaphore.Value = new Tuple <DebuggableSemaphoreSlim, DebuggableSemaphoreSlim>(objCurrentSemaphore, objNextSemaphore);
SafeWriterSemaphoreRelease objRelease = new SafeWriterSemaphoreRelease(objLastSemaphore, objCurrentSemaphore, objNextSemaphore, this);
try
{
objCurrentSemaphore.SafeWait(token);
}
catch
{
_objCurrentWriterSemaphore.Value = new Tuple <DebuggableSemaphoreSlim, DebuggableSemaphoreSlim>(objLastSemaphore, objCurrentSemaphore);
Utils.SemaphorePool.Return(ref objNextSemaphore);
throw;
}
try
{
if (Interlocked.Increment(ref _intCountActiveReaders) == 1)
{
try
{
// Wait for the reader lock only if there have been no other write locks before us
if (_objTopLevelWriterSemaphore.CurrentCount != 0 || objCurrentSemaphore == _objTopLevelWriterSemaphore)
{
_objReaderSemaphore.SafeWait(token);
}
}
catch
{
Interlocked.Decrement(ref _intCountActiveReaders);
throw;
}
}
}
catch
{
_objCurrentWriterSemaphore.Value = new Tuple <DebuggableSemaphoreSlim, DebuggableSemaphoreSlim>(objLastSemaphore, objCurrentSemaphore);
try
{
// ReSharper disable once MethodSupportsCancellation
objNextSemaphore.SafeWait();
try
{
objCurrentSemaphore.Release();
}
finally
{
objNextSemaphore.Release();
}
}
finally
{
Utils.SemaphorePool.Return(ref objNextSemaphore);
}
throw;
}
return(objRelease);
}
