InstanceOwner.cs source code in C# .NET

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Code:

/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / cdf / src / System.Runtime.DurableInstancing / System / Runtime / DurableInstancing / InstanceOwner.cs / 1305376 / InstanceOwner.cs

                            //---------------------------------------------------------------- 
// 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 boundHandles = new Dictionary();
        readonly Queue inProgressHandles = new Queue(); 
        readonly Dictionary> inProgressHandlesPerInstance = new Dictionary>(); 

        // This is synchronized by the InstanceStore. 
        readonly Dictionary events = new Dictionary(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 Events 
        {
            get 
            { 
                return this.events;
            } 
        }

        object HandlesLock
        { 
            get
            { 
                return this.boundHandles; 
            }
        } 

        Dictionary BoundHandles
        {
            get 
            {
                return this.boundHandles; 
            } 
        }
 
        Queue InProgressHandles
        {
            get
            { 
                return this.inProgressHandles;
            } 
        } 

        Dictionary> 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 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 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 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 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 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(1); 
                        }
                        handlesPendingResolution.Add(marker); 
                    }
                }
            }
        } 

        internal bool FinishBind(ref InstanceHandleReference reference, ref long instanceVersion, ref List 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 handlesPendingResolution)
        { 
            Guid wasBoundToInstanceId = reference.InstanceHandle.Id; 

            try 
            {
                LockResolutionMarker marker = reference as LockResolutionMarker;
                if (marker != null && !marker.IsComplete)
                { 
                    if (handlesPendingResolution == null)
                    { 
                        handlesPendingResolution = new List(1); 
                    }
                    handlesPendingResolution.Add(marker); 
                }
            }
            finally
            { 
                reference.Cancel();
                reference = null; 
            } 

            ProcessInProgressHandles(ref handlesPendingResolution); 

            if (wasBoundToInstanceId != Guid.Empty)
            {
                Queue 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 handlesPendingResolution)
        { 
            while (InProgressHandles.Count > 0)
            { 
                InstanceHandleReference handleRef = InProgressHandles.Peek(); 
                if (handleRef.InstanceHandle != null)
                { 
                    if (handleRef.InstanceHandle.Id == Guid.Empty)
                    {
                        break;
                    } 

                    Queue acceptingQueue; 
                    if (!InProgressHandlesPerInstance.TryGetValue(handleRef.InstanceHandle.Id, out acceptingQueue)) 
                    {
                        if (CheckOldestReference(handleRef, ref handlesPendingResolution)) 
                        {
                            acceptingQueue = new Queue(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 queue;
                if (!InProgressHandlesPerInstance.TryGetValue(handleRef.InstanceHandle.Id, out queue)) 
                {
                    queue = new Queue(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 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(1); 
                } 
                handlesPendingResolution.Add(marker);
            } 
        }

        // Must be called ouside InstanceHandle.ThisLock and HandlesLock.
        internal static void ResolveHandles(List 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; 
            } 
        }
    } 
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
                        

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