internal SpinLockContext(SpinLock spinLock)
{
_spinLock = spinLock;
_spinLock.Acquire();
_disposed = false;
}
/// <summary>
/// Acquires the lock in exclusive mode, blocking
/// if necessary.
/// </summary>
/// <remarks>
/// Exclusive acquires are given precedence over shared
/// acquires.
/// </remarks>
public void AcquireExclusive()
{
int value;
int i = 0;
#if ENABLE_STATISTICS
Interlocked.Increment(ref _acqExclCount);
#endif
while (true)
{
value = _value;
// Try to obtain the lock.
if ((value & LockOwned) == 0)
{
#if RIGOROUS_CHECKS
System.Diagnostics.Trace.Assert(((value >> LockSharedOwnersShift) & LockSharedOwnersMask) == 0);
#endif
if (Interlocked.CompareExchange(
ref _value,
value + LockOwned,
value
) == value)
{
break;
}
}
else if (i >= _spinCount)
{
// We need to wait.
WaitBlock waitBlock;
waitBlock.Flags = WaiterExclusive | WaiterSpinning;
// Obtain the waiters list lock.
_lock.Acquire();
try
{
// Try to set the waiters bit.
if (Interlocked.CompareExchange(
ref _value,
value | LockWaiters,
value
) != value)
{
#if ENABLE_STATISTICS
Interlocked.Increment(ref _insWaitBlkRetryCount);
#endif
// Unfortunately we have to go back. This is
// very wasteful since the waiters list lock
// must be released again, but must happen since
// the lock may have been released.
continue;
}
// Put our wait block behind other exclusive waiters but
// in front of all shared waiters.
this.InsertWaitBlock(&waitBlock, ListPosition.LastExclusive);
#if ENABLE_STATISTICS
_exclusiveWaitersCount++;
if (_peakExclWtrsCount < _exclusiveWaitersCount)
{
_peakExclWtrsCount = _exclusiveWaitersCount;
}
#endif
}
finally
{
_lock.Release();
}
#if ENABLE_STATISTICS
Interlocked.Increment(ref _acqExclBlkCount);
#endif
this.Block(&waitBlock);
// Go back and try again.
continue;
}
#if ENABLE_STATISTICS
Interlocked.Increment(ref _acqExclContCount);
#endif
i++;
}
}
internal SpinLockContext(SpinLock spinLock)
{
_spinLock = spinLock;
_spinLock.Acquire();
_disposed = false;
}