AtomicBoolean upgradableTaken;
[ThreadStatic]
- ThreadLockState currentThreadState;
+ IDictionary<ReaderWriterLockSlim, ThreadLockState> currentThreadState;
public ReaderWriterLockSlim (LockRecursionPolicy.None)
{
}
if ((Interlocked.Add (ref rwlock, RwRead) & (RwWrite | RwWait)) == 0) {
- currentThreadState = ThreadLockState.Read;
+ CurrentThreadState = ThreadLockState.Read;
return true;
}
public void ExitReadLock ()
{
- if (currentThreadState != Read)
+ if (CurrentThreadState != Read)
throw new SynchronizationLockException ("The current thread has not entered the lock in read mode");
- currentThreadState = None;
+ CurrentThreadState = None;
Interlocked.Add (ref rwlock, -RwRead);
}
if (state < RwWrite) {
if (Interlocked.CompareExchange (ref rwlock, state, RwWrite) == state) {
- currentThreadState = Write;
+ CurrentThreadState = Write;
return true;
}
state = rwlock;
public void ExitWriteLock ()
{
- if (currentThreadState != Read)
+ if (CurrentThreadState != Read)
throw new SynchronizationLockException ("The current thread has not entered the lock in read mode");
- currentThreadState = None;
+ CurrentThreadState = None;
Interlocked.Add (ref rwlock, -RwWrite);
}
if (CheckState (millisecondsTimeout, ThreadLockState.Upgradable))
return true;
- if (currentThreadState == ThreadLockState.Read)
+ if (CurrentThreadState == ThreadLockState.Read)
throw new LockRecursionException ("The current thread has already entered read mode");
}
public void ExitUpgradeableReadLock ()
{
- EnterMyLock ();
- Debug.Assert (owners > 0, "Releasing an upgradable lock, but there was no reader!");
- --owners;
- upgradable_thread = null;
- ExitAndWakeUpAppropriateWaiters ();
+
}
bool CheckState (int millisecondsTimeout, ThreadLockState validState)
throw new ArgumentOutOfRangeException ("millisecondsTimeout");
// Detect and prevent recursion
- if (recursionPolicy == LockRecursionPolicy.None && currentThreadState != None)
+ if (recursionPolicy == LockRecursionPolicy.None && CurrentThreadState != None)
throw new LockRecursionException ("The current thread has already a lock and recursion isn't supported");
// If we already had write lock, just return
- if (currentThreadState == validState)
+ if (CurrentThreadState == validState)
return true;
}
}
#region Private methods
- void EnterMyLock ()
- {
- if (Interlocked.CompareExchange(ref myLock, 1, 0) != 0)
- EnterMyLockSpin ();
- }
-
- void EnterMyLockSpin ()
- {
-
- for (int i = 0; ;i++) {
- if (i < 3 && smp)
- Thread.SpinWait (20); // Wait a few dozen instructions to let another processor release lock.
- else
- Thread.Sleep (0); // Give up my quantum.
-
- if (Interlocked.CompareExchange(ref myLock, 1, 0) == 0)
- return;
- }
- }
-
- void ExitMyLock()
- {
- Debug.Assert (myLock != 0, "Exiting spin lock that is not held");
- myLock = 0;
- }
-
- bool MyLockHeld { get { return myLock != 0; } }
-
- /// <summary>
- /// Determines the appropriate events to set, leaves the locks, and sets the events.
- /// </summary>
- private void ExitAndWakeUpAppropriateWaiters()
- {
- Debug.Assert (MyLockHeld);
-
- // First a writing thread waiting on being upgraded
- if (owners == 1 && numUpgradeWaiters != 0){
- // Exit before signaling to improve efficiency (wakee will need the lock)
- ExitMyLock ();
- // release all upgraders (however there can be at most one).
- upgradeEvent.Set ();
- //
- // TODO: What does the following comment mean?
- // two threads upgrading is a guarenteed deadlock, so we throw in that case.
- } else if (owners == 0 && numWriteWaiters > 0) {
- // Exit before signaling to improve efficiency (wakee will need the lock)
- ExitMyLock ();
- // release one writer.
- writeEvent.Set ();
- }
- else if (owners >= 0 && numReadWaiters != 0) {
- // Exit before signaling to improve efficiency (wakee will need the lock)
- ExitMyLock ();
- // release all readers.
- readEvent.Set();
- } else
- ExitMyLock();
- }
-
- /// <summary>
- /// A routine for lazily creating a event outside the lock (so if errors
- /// happen they are outside the lock and that we don't do much work
- /// while holding a spin lock). If all goes well, reenter the lock and
- /// set 'waitEvent'
- /// </summary>
- void LazyCreateEvent(ref EventWaitHandle waitEvent, bool makeAutoResetEvent)
- {
- Debug.Assert (MyLockHeld);
- Debug.Assert (waitEvent == null);
-
- ExitMyLock ();
- EventWaitHandle newEvent;
- if (makeAutoResetEvent)
- newEvent = new AutoResetEvent (false);
- else
- newEvent = new ManualResetEvent (false);
-
- EnterMyLock ();
-
- // maybe someone snuck in.
- if (waitEvent == null)
- waitEvent = newEvent;
- }
-
- /// <summary>
- /// Waits on 'waitEvent' with a timeout of 'millisceondsTimeout.
- /// Before the wait 'numWaiters' is incremented and is restored before leaving this routine.
- /// </summary>
- bool WaitOnEvent (EventWaitHandle waitEvent, ref uint numWaiters, int millisecondsTimeout)
- {
- Debug.Assert (MyLockHeld);
-
- waitEvent.Reset ();
- numWaiters++;
+ ThreadLockState CurrentThreadState {
+ get {
+ // TODO: provide a IEqualityComparer thingie to have better hashes
+ if (currentThreadState == null)
+ currentThreadState = new Dictionary<ReaderWriterLockSlim, ThreadLockState> ();
- bool waitSuccessful = false;
+ ThreadLockState state;
+ if (!currentThreadState.TryGetValue (this, out state))
+ currentThreadState[this] = state = ThreadLockState.None;
- // Do the wait outside of any lock
- ExitMyLock();
- try {
- waitSuccessful = waitEvent.WaitOne (millisecondsTimeout, false);
- } finally {
- EnterMyLock ();
- --numWaiters;
- if (!waitSuccessful)
- ExitMyLock ();
+ return state;
}
- return waitSuccessful;
- }
-
- static int CheckTimeout (TimeSpan timeout)
- {
- try {
- return checked((int) timeout.TotalMilliseconds);
- } catch (System.OverflowException) {
- throw new ArgumentOutOfRangeException ("timeout");
- }
- }
+ set {
+ if (currentThreadState == null)
+ currentThreadState = new Dictionary<ReaderWriterLockSlim, ThreadLockState> ();
- LockDetails GetReadLockDetails (int threadId, bool create)
- {
- int i;
- LockDetails ld;
- for (i = 0; i < read_locks.Length; ++i) {
- ld = read_locks [i];
- if (ld == null)
- break;
-
- if (ld.ThreadId == threadId)
- return ld;
+ currentThreadState[this] = value;
}
-
- if (!create)
- return null;
-
- if (i == read_locks.Length)
- Array.Resize (ref read_locks, read_locks.Length * 2);
-
- ld = read_locks [i] = new LockDetails ();
- ld.ThreadId = threadId;
- return ld;
}
#endregion
}
projects / mono.git / commitdiff