// 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.
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(SRCore.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);
}
}
// This can be called to remove a handle from the BoundHandles table. It should be called only after no more commands are in progress or could be made on the handle.
internal void Unbind(InstanceHandle handle)
{
Fx.Assert(object.ReferenceEquals(this, handle.Owner), "Unbind called on the wrong owner for a handle.");
Fx.Assert(handle.Id != Guid.Empty, "Unbind called on a handle not even bound to an instance.");
lock (HandlesLock)
{
// The handle may have already been bumped - only remove it if it's still it.
if (BoundHandles.TryGetValue(handle.Id, out InstanceHandle existingHandle) && object.ReferenceEquals(handle, existingHandle))
{
BoundHandles.Remove(handle.Id);
}
}
}
// 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
{
InstanceHandle existingHandle;
if (BoundHandles.TryGetValue(reference.InstanceHandle.Id, out 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(SRCore.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
{
InstanceHandle existingHandle;
if (BoundHandles.TryGetValue(reference.InstanceHandle.Id, out 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(SRCore.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(SRCore.InstanceStoreBoundSameVersionTwice));
}
throw Fx.AssertAndThrow("All cases covered above.");
}
else
{
BoundHandles.Add(reference.InstanceHandle.Id, reference.InstanceHandle);
return(true);
}
}
finally
{
CancelReference(ref reference, ref handlesPendingResolution);
}
}
}
