internal bool FinishBind(ref InstanceHandleReference reference, ref long instanceVersion, ref List <InstanceHandleReference> handlesPendingResolution)
{
Fx.Assert(reference != null, "Bind not in progress in FinishBind.");
Fx.Assert(reference.InstanceHandle != null, "Reference already canceled in FinishBind.");
Fx.Assert(object.ReferenceEquals(this, reference.InstanceHandle.Owner), "FinishBind called on the wrong owner for a handle.");
Fx.Assert(reference is LockResolutionMarker, "Must have started reclaim in order to finish it.");
lock (HandlesLock)
{
LockResolutionMarker marker = (LockResolutionMarker)reference;
Fx.AssertAndThrow(marker.IsComplete, "Called FinishBind prematurely.");
if (marker.NonConflicting)
{
instanceVersion = marker.InstanceVersion;
return(true);
}
try
{
if (marker.Reason != null)
{
throw Fx.Exception.AsError(marker.Reason);
}
Fx.Assert(marker.ConflictingHandle != null, "Should either have a conflicting handle or a reason in the conflicting case.");
marker.InstanceHandle.ConflictingHandle = marker.ConflictingHandle;
return(false);
}
finally
{
CancelReference(ref reference, ref handlesPendingResolution);
}
}
}
// Must be called with HandlesLock held.
// This process the top-level InProgressHandles queue, demuxing entries into the per-instance queues and completing markers.
private void ProcessInProgressHandles(ref List <InstanceHandleReference> handlesPendingResolution)
{
while (InProgressHandles.Count > 0)
{
InstanceHandleReference handleRef = InProgressHandles.Peek();
if (handleRef.InstanceHandle != null)
{
if (handleRef.InstanceHandle.Id == Guid.Empty)
{
break;
}
if (!InProgressHandlesPerInstance.TryGetValue(handleRef.InstanceHandle.Id, out Queue <InstanceHandleReference> acceptingQueue))
{
if (CheckOldestReference(handleRef, ref handlesPendingResolution))
{
acceptingQueue = new Queue <InstanceHandleReference>(2);
acceptingQueue.Enqueue(handleRef);
InProgressHandlesPerInstance.Add(handleRef.InstanceHandle.Id, acceptingQueue);
}
}
else
{
// It's ok to enqueue first, then dequeue, to err on the side of duplicates. Duplicates do not cause a problem.
acceptingQueue.Enqueue(handleRef);
}
}
InProgressHandles.Dequeue();
}
}
internal void FaultBind(ref InstanceHandleReference reference, ref List <InstanceHandleReference> handlesPendingResolution, Exception reason)
{
Fx.Assert(reference != null, "Bind not in progress in FaultBind.");
Fx.Assert(reference.InstanceHandle != null, "Reference already canceled in FaultBind.");
Fx.Assert(object.ReferenceEquals(this, reference.InstanceHandle.Owner), "FaultBind called on the wrong owner for a handle.");
lock (HandlesLock)
{
if (reference is LockResolutionMarker marker && !marker.IsComplete)
{
try
{
// Nothing to do here - following the patterns of dealing with handlesPendingResolution and setting NotifyMarkerComplete in a finally.
}
finally
{
marker.Reason = reason ?? new OperationCanceledException(SR.HandleFreed);
marker.NotifyMarkerComplete(false);
if (handlesPendingResolution == null)
{
handlesPendingResolution = new List <InstanceHandleReference>(1);
}
handlesPendingResolution.Add(marker);
}
}
}
}
internal void CancelBind(ref InstanceHandleReference reference, ref List <InstanceHandleReference> handlesPendingResolution)
{
Fx.Assert(reference != null, "Bind not in progress.");
Fx.Assert(reference.InstanceHandle != null, "Reference already canceled in CancelBind.");
Fx.Assert(object.ReferenceEquals(this, reference.InstanceHandle.Owner), "CancelBind called on the wrong owner for a handle.");
lock (HandlesLock)
{
CancelReference(ref reference, ref handlesPendingResolution);
}
}
// This doesn't check the bound handles, since one of the scenarios is to re-bind to an instance and kick out the stale handle.
internal void StartBind(InstanceHandle handle, ref InstanceHandleReference reference)
{
Fx.Assert(object.ReferenceEquals(this, handle.Owner), "StartBind called on the wrong owner for a handle.");
lock (HandlesLock)
{
Fx.Assert(reference == null, "Already have a bind in progress.");
reference = new InstanceHandleReference(handle);
EnqueueReference(reference);
}
}
// Called when a handle is bound to an instance while the handle is in-progress for a lock. This can progress the queue-states since
// this once can move from the general queue to the per-instance queue.
internal void InstanceBound(ref InstanceHandleReference reference, ref List <InstanceHandleReference> handlesPendingResolution)
{
Fx.Assert(reference != null, "InstanceBound called when no operation is in progress.");
Fx.Assert(reference.InstanceHandle != null, "InstanceBound called after cancelling.");
Fx.Assert(reference.InstanceHandle.Id != Guid.Empty, "InstanceBound called, but the handle isn't bound.");
Fx.AssertAndThrow(!(reference is LockResolutionMarker), "InstanceBound called after trying to bind the lock version, which alredy required an instance.");
lock (HandlesLock)
{
ProcessInProgressHandles(ref handlesPendingResolution);
}
}
// Must be called with HandlesLock held.
// This is called when a reference becomes the oldest in-progress reference for an instance. This triggers the end of resolution for markers.
// Returns false if the resolution failed, meaning that the marker can be removed.
private bool CheckOldestReference(InstanceHandleReference handleRef, ref List <InstanceHandleReference> handlesPendingResolution)
{
LockResolutionMarker marker = handleRef as LockResolutionMarker;
if (marker == null || marker.IsComplete)
{
return(true);
}
bool returnValue = true;
try
{
InstanceHandle existingHandle;
if (BoundHandles.TryGetValue(marker.InstanceHandle.Id, out existingHandle))
{
Fx.AssertAndFailFast(!object.ReferenceEquals(existingHandle, marker.InstanceHandle), "InstanceStore lock state is not correct in CheckOldestReference.");
if (existingHandle.Version <= 0 || marker.InstanceVersion <= 0)
{
if (existingHandle.Version != 0 || marker.InstanceVersion != 0)
{
marker.Reason = new InvalidOperationException(SR.InvalidLockToken);
returnValue = false;
}
else
{
marker.ConflictingHandle = existingHandle;
returnValue = false;
}
}
else if (existingHandle.Version >= marker.InstanceVersion)
{
marker.ConflictingHandle = existingHandle;
returnValue = false;
}
}
// No other handles have committed a bind to this or a higher version! We are ok to do so, but it is still not committed, so we stay in queue.
return(returnValue);
}
finally
{
marker.NotifyMarkerComplete(returnValue);
if (handlesPendingResolution == null)
{
handlesPendingResolution = new List <InstanceHandleReference>(1);
}
handlesPendingResolution.Add(marker);
}
}
// Must be called with HandlesLock held.
private void CancelReference(ref InstanceHandleReference reference, ref List <InstanceHandleReference> handlesPendingResolution)
{
Guid wasBoundToInstanceId = reference.InstanceHandle.Id;
try
{
LockResolutionMarker marker = reference as LockResolutionMarker;
if (marker != null && !marker.IsComplete)
{
if (handlesPendingResolution == null)
{
handlesPendingResolution = new List <InstanceHandleReference>(1);
}
handlesPendingResolution.Add(marker);
}
}
finally
{
reference.Cancel();
reference = null;
}
ProcessInProgressHandles(ref handlesPendingResolution);
if (wasBoundToInstanceId != Guid.Empty)
{
Queue <InstanceHandleReference> instanceQueue;
if (InProgressHandlesPerInstance.TryGetValue(wasBoundToInstanceId, out instanceQueue))
{
while (instanceQueue.Count > 0)
{
InstanceHandleReference handleRef = instanceQueue.Peek();
if (handleRef.InstanceHandle != null)
{
if (CheckOldestReference(handleRef, ref handlesPendingResolution))
{
break;
}
}
instanceQueue.Dequeue();
}
if (instanceQueue.Count == 0)
{
InProgressHandlesPerInstance.Remove(wasBoundToInstanceId);
}
}
}
}
// Must be called with HandlesLock held.
private void EnqueueReference(InstanceHandleReference handleRef)
{
if (InProgressHandles.Count > 0)
{
InProgressHandles.Enqueue(handleRef);
}
else if (handleRef.InstanceHandle.Id != Guid.Empty)
{
if (!InProgressHandlesPerInstance.TryGetValue(handleRef.InstanceHandle.Id, out Queue <InstanceHandleReference> queue))
{
queue = new Queue <InstanceHandleReference>(2);
InProgressHandlesPerInstance.Add(handleRef.InstanceHandle.Id, queue);
}
queue.Enqueue(handleRef);
}
else
{
InProgressHandles.Enqueue(handleRef);
}
}
// This is called if we found an existing lock. This handle doesn't own the lock, but it could claim it, if it can prove
// that no other live handle owns it. If this returns non-null, the outcome will be available later on the
// InstanceHandleReference once the AsyncWaitHandle completes. (Null indicates a conflict with another handle.)
//
// The instanceVersion reported here was read under the transaction, but not changed. Either it was already committed, or it was written under
// this transaction in a prior command on a different handle. Due to the latter case, we treat it as dirty - we do not publish it or take
// any visible action (such as dooming handles) based on its value.
internal AsyncWaitHandle InitiateLockResolution(long instanceVersion, ref InstanceHandleReference reference, ref List <InstanceHandleReference> handlesPendingResolution)
{
Fx.Assert(reference != null, "Bind wasn't registered - RegisterStartBind must be called.");
Fx.Assert(reference.InstanceHandle != null, "Cannot cancel and complete a bind.");
Fx.Assert(reference.InstanceHandle.Id != Guid.Empty, "Must be bound to an instance already.");
Fx.AssertAndThrow(!(reference is LockResolutionMarker), "InitiateLockResolution already called.");
lock (HandlesLock)
{
InstanceHandleReference cancelReference = reference;
LockResolutionMarker markerReference = null;
try
{
if (BoundHandles.TryGetValue(reference.InstanceHandle.Id, out InstanceHandle existingHandle))
{
Fx.AssertAndFailFast(!object.ReferenceEquals(existingHandle, reference.InstanceHandle), "InstanceStore lock state is not correct in InitiateLockResolution.");
if (existingHandle.Version <= 0 || instanceVersion <= 0)
{
if (existingHandle.Version != 0 || instanceVersion != 0)
{
throw Fx.Exception.AsError(new InvalidOperationException(SR.InvalidLockToken));
}
reference.InstanceHandle.ConflictingHandle = existingHandle;
return(null);
}
if (existingHandle.Version >= instanceVersion)
{
reference.InstanceHandle.ConflictingHandle = existingHandle;
return(null);
}
}
// Put a marker in the InProgressHandles. If it makes it through, and there's still no conflicting handle,
// then the lock can be claimed at this version. Only currently in-progress bindings have a chance of
// staking a stronger claim to the lock version (if the store actually acquired the lock for the handle).
markerReference = new LockResolutionMarker(reference.InstanceHandle, instanceVersion);
EnqueueReference(markerReference);
reference = markerReference;
Fx.Assert(markerReference.MarkerWaitHandle != null, "Null MarkerWaitHandle?");
return(markerReference.MarkerWaitHandle);
}
finally
{
if (!object.ReferenceEquals(markerReference, reference))
{
CancelReference(ref reference, ref handlesPendingResolution);
if (markerReference != null)
{
cancelReference = markerReference;
CancelReference(ref cancelReference, ref handlesPendingResolution);
}
}
else
{
CancelReference(ref cancelReference, ref handlesPendingResolution);
}
}
}
}
// This happens only when the transaction under which the handle was bound is committed.
internal bool TryCompleteBind(ref InstanceHandleReference reference, ref List <InstanceHandleReference> handlesPendingResolution, out InstanceHandle handleToFree)
{
Fx.Assert(reference != null, "Bind wasn't registered - RegisterStartBind must be called.");
Fx.Assert(reference.InstanceHandle != null, "Cannot cancel and complete a bind.");
Fx.Assert(reference.InstanceHandle.Version != -1, "Handle state must be set first.");
Fx.Assert(object.ReferenceEquals(this, reference.InstanceHandle.Owner), "TryCompleteBind called on the wrong owner for a handle.");
Fx.Assert(!(reference is LockResolutionMarker) || ((LockResolutionMarker)reference).NonConflicting, "How did a Version get set if we're still resolving.");
handleToFree = null;
lock (HandlesLock)
{
try
{
if (BoundHandles.TryGetValue(reference.InstanceHandle.Id, out InstanceHandle existingHandle))
{
Fx.AssertAndFailFast(!object.ReferenceEquals(existingHandle, reference.InstanceHandle), "InstanceStore lock state is not correct.");
if (existingHandle.Version <= 0 || reference.InstanceHandle.Version <= 0)
{
if (existingHandle.Version != 0 || reference.InstanceHandle.Version != 0)
{
throw Fx.Exception.AsError(new InvalidOperationException(SR.InvalidLockToken));
}
reference.InstanceHandle.ConflictingHandle = existingHandle;
return(false);
}
if (existingHandle.Version > reference.InstanceHandle.Version)
{
reference.InstanceHandle.ConflictingHandle = existingHandle;
return(false);
}
if (existingHandle.Version < reference.InstanceHandle.Version)
{
existingHandle.ConflictingHandle = reference.InstanceHandle;
handleToFree = existingHandle;
BoundHandles[reference.InstanceHandle.Id] = reference.InstanceHandle;
return(true);
}
if (existingHandle.Version == reference.InstanceHandle.Version)
{
// This could be a case of amnesia (backup / restore).
throw Fx.Exception.AsError(new InvalidOperationException(SR.InstanceStoreBoundSameVersionTwice));
}
throw Fx.AssertAndThrow("All cases covered above.");
}
else
{
BoundHandles.Add(reference.InstanceHandle.Id, reference.InstanceHandle);
return(true);
}
}
finally
{
CancelReference(ref reference, ref handlesPendingResolution);
}
}
}