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//----------------------------------------------------------------
// Copyright (c) Microsoft Corporation. All rights reserved.
//----------------------------------------------------------------
namespace System.Runtime.DurableInstancing
{
using System.Collections.Generic;
using System.Threading;
using System.Xml.Linq;
[Fx.Tag.XamlVisible(false)]
public sealed class InstanceOwner
{
// These collections are synchronized by the HandlesLock.
readonly Dictionary<Guid, InstanceHandle> boundHandles = new Dictionary<Guid, InstanceHandle>();
readonly Queue<InstanceHandleReference> inProgressHandles = new Queue<InstanceHandleReference>();
readonly Dictionary<Guid, Queue<InstanceHandleReference>> inProgressHandlesPerInstance = new Dictionary<Guid, Queue<InstanceHandleReference>>();
// This is synchronized by the InstanceStore.
readonly Dictionary<XName, InstanceNormalEvent> events = new Dictionary<XName, InstanceNormalEvent>(1);
internal InstanceOwner(Guid ownerId, Guid lockToken)
{
InstanceOwnerId = ownerId;
OwnerToken = lockToken;
}
public Guid InstanceOwnerId { get; private set; }
internal Guid OwnerToken { get; private set; }
internal Dictionary<XName, InstanceNormalEvent> Events
{
get
{
return this.events;
}
}
object HandlesLock
{
get
{
return this.boundHandles;
}
}
Dictionary<Guid, InstanceHandle> BoundHandles
{
get
{
return this.boundHandles;
}
}
Queue<InstanceHandleReference> InProgressHandles
{
get
{
return this.inProgressHandles;
}
}
Dictionary<Guid, Queue<InstanceHandleReference>> InProgressHandlesPerInstance
{
get
{
return this.inProgressHandlesPerInstance;
}
}
// 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.
InstanceHandle existingHandle;
if (BoundHandles.TryGetValue(handle.Id, out existingHandle) && object.ReferenceEquals(handle, existingHandle))
{
BoundHandles.Remove(handle.Id);
}
}
}
// 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);
}
}
// 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);
}
}
}
// 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);
}
}
}
}
// 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);
}
}
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);
}
}
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)
{
LockResolutionMarker marker = reference as LockResolutionMarker;
if (marker != null && !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(SRCore.HandleFreed);
marker.NotifyMarkerComplete(false);
if (handlesPendingResolution == null)
{
handlesPendingResolution = new List<InstanceHandleReference>(1);
}
handlesPendingResolution.Add(marker);
}
}
}
}
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.
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.
// This process the top-level InProgressHandles queue, demuxing entries into the per-instance queues and completing markers.
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;
}
Queue<InstanceHandleReference> acceptingQueue;
if (!InProgressHandlesPerInstance.TryGetValue(handleRef.InstanceHandle.Id, out 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();
}
}
// Must be called with HandlesLock held.
void EnqueueReference(InstanceHandleReference handleRef)
{
if (InProgressHandles.Count > 0)
{
InProgressHandles.Enqueue(handleRef);
}
else if (handleRef.InstanceHandle.Id != Guid.Empty)
{
Queue<InstanceHandleReference> queue;
if (!InProgressHandlesPerInstance.TryGetValue(handleRef.InstanceHandle.Id, out queue))
{
queue = new Queue<InstanceHandleReference>(2);
InProgressHandlesPerInstance.Add(handleRef.InstanceHandle.Id, queue);
}
queue.Enqueue(handleRef);
}
else
{
InProgressHandles.Enqueue(handleRef);
}
}
// 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);
}
}
// Must be called ouside InstanceHandle.ThisLock and HandlesLock.
internal static void ResolveHandles(List<InstanceHandleReference> handlesPendingResolution)
{
if (handlesPendingResolution != null)
{
foreach (InstanceHandleReference handleRef in handlesPendingResolution)
{
LockResolutionMarker marker = handleRef as LockResolutionMarker;
Fx.Assert(marker != null, "How did a non-marker get in here.");
marker.MarkerWaitHandle.Set();
}
}
}
class LockResolutionMarker : InstanceHandleReference
{
AsyncWaitHandle waitHandle = new AsyncWaitHandle(EventResetMode.ManualReset);
internal LockResolutionMarker(InstanceHandle instanceHandle, long instanceVersion)
: base(instanceHandle)
{
InstanceVersion = instanceVersion;
}
// This is signalled when the marker reaches the end of the queue.
internal AsyncWaitHandle MarkerWaitHandle
{
get
{
return this.waitHandle;
}
}
// The initial state of the attempt.
internal long InstanceVersion { get; private set; }
// State regarding a failed attempt which can be used to construct an exception.
internal InstanceHandle ConflictingHandle { get; set; }
internal Exception Reason { get; set; }
// State about the success / failure of the attempt.
internal bool IsComplete { get; private set; }
internal bool NonConflicting { get; private set; }
internal void NotifyMarkerComplete(bool success)
{
Fx.Assert(InstanceHandle != null, "NotifyNonConflicting called on a cancelled LockResolutionMarker.");
NonConflicting = success;
IsComplete = true;
}
}
}
}
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