Lock.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / cdf / src / WF / RunTime / Lock.cs / 1305376 / Lock.cs
                        
                        
                            // **************************************************************************** 
// Copyright (C)  Microsoft Corporation.  All rights reserved.
//
// CONTENTS
//     Value-add wrapper on top of standard CLR monitor 
//
 
using System; 
using System.Collections;
using System.Collections.Generic; 
using System.Collections.ObjectModel;
using System.Globalization;
using System.Xml;
using System.Reflection; 
using System.Threading;
using System.Diagnostics; 
using System.Transactions; 

using System.Workflow.Runtime.Hosting; 

namespace System.Workflow.Runtime
{
    internal static class LockFactory 
    {
        internal static InstanceLock CreateWorkflowExecutorLock(Guid id) 
        { 
            return new InstanceLock(id, "Workflow Executor Lock: " + id.ToString(), 50, LockPriorityOperator.GreaterThanOrReentrant);
        } 

        internal static InstanceLock CreateWorkflowSchedulerLock(Guid id)
        {
            return new InstanceLock(id, "Workflow Scheduler Lock: " + id.ToString(), 40, LockPriorityOperator.GreaterThan); 
        }
 
        internal static InstanceLock CreateWorkflowMessageDeliveryLock(Guid id) 
        {
            return new InstanceLock(id, "Workflow Message Delivery Lock: " + id.ToString(), 35, LockPriorityOperator.GreaterThanOrReentrant); 
        }
    }

    internal enum LockPriorityOperator 
    {
        GreaterThan, 
        GreaterThanOrReentrant, 
    }
 
    internal sealed class InstanceLock
    {
        #region Static Data/Methods
 
        [ThreadStaticAttribute()]
        private static List t_heldLocks = null; 
 
        [Conditional("DEBUG")]
        internal static void AssertNoLocksHeld() 
        {
#if DEBUG
            System.Diagnostics.Debug.Assert(HeldLocks.Count == 0, "No locks should be held.");
#endif 
        }
 
        [Conditional("DEBUG")] 
        internal static void AssertIsLocked(InstanceLock theLock)
        { 
#if DEBUG
            System.Diagnostics.Debug.Assert(HeldLocks.Contains(theLock), "Lock should be held.");
#endif
        } 

        private static List HeldLocks 
        { 
            get
            { 
                List tLocks = InstanceLock.t_heldLocks;
                if (tLocks == null)
                {
                    InstanceLock.t_heldLocks = new List(); 
                    tLocks = InstanceLock.t_heldLocks;
                } 
                return tLocks; 
            }
        } 

        #endregion Static Data/Methods

        private Guid m_instanceId; 
        private String m_name;
        private int m_priority; 
        private LockPriorityOperator m_operator; 

        internal int Priority 
        {
            get
            {
                return this.m_priority; 
            }
        } 
 
        internal LockPriorityOperator Operator
        { 
            get
            {
                return this.m_operator;
            } 
        }
 
        internal InstanceLock(Guid id, String name, int priority, LockPriorityOperator lockOperator) 
        {
            this.m_instanceId = id; 
            this.m_name = name;
            this.m_priority = priority;
            this.m_operator = lockOperator;
        } 

        internal Guid InstanceId 
        { 
            get
            { 
                return this.m_instanceId;
            }
        }
 
        internal InstanceLockGuard Enter()
        { 
            return new InstanceLockGuard(this); 
        }
 
        internal bool TryEnter()
        {
            InstanceLockGuard.EnforceGuard(this);
 
            bool lockHeld = false;
            bool success = false; 
            try 
            {
                Monitor.TryEnter(this, ref lockHeld); 

                if (lockHeld)
                {
                    HeldLocks.Add(this); 
                    success = true;
                } 
            } 
            finally
            { 
                if (lockHeld && !success)
                {
                    Monitor.Exit(this);
                } 
            }
            return success; 
        } 

        internal void Exit() 
        {
            try
            {
                HeldLocks.Remove(this); 
            }
            finally 
            { 
                Monitor.Exit(this);
            } 
        }

        internal struct InstanceLockGuard : IDisposable
        { 
            readonly InstanceLock m_lock;
 
            internal static void EnforceGuard(InstanceLock theLock) 
            {
                foreach (InstanceLock heldLock in HeldLocks) 
                {
                    switch (theLock.Operator)
                    {
                        case LockPriorityOperator.GreaterThan: 
                            if (heldLock.InstanceId == theLock.InstanceId && heldLock.Priority <= theLock.Priority)
                                throw new InvalidOperationException(ExecutionStringManager.InstanceOperationNotValidinWorkflowThread); 
                            break; 

                        case LockPriorityOperator.GreaterThanOrReentrant: 
                            // the checks here assume that locks have unique priorities
                            if (heldLock.InstanceId == theLock.InstanceId && heldLock.Priority < theLock.Priority)
                                throw new InvalidOperationException(ExecutionStringManager.InstanceOperationNotValidinWorkflowThread);
                            break; 

                        default: 
                            System.Diagnostics.Debug.Assert(false, "Unrecognized lock operator"); 
                            break;
                    } 
                }
            }

            internal InstanceLockGuard(InstanceLock theLock) 
            {
                this.m_lock = theLock; 
 
                // Note: the following operations are logically atomic, but since the
                // list we are using is thread local there is no need to take a lock. 

                EnforceGuard(theLock);

                try 
                {
                } 
                finally 
                {
                    bool success = false; 
#pragma warning disable 0618
//@
                    Monitor.Enter(this.m_lock);
#pragma warning restore 0618 
                    try
                    { 
                        HeldLocks.Add(this.m_lock); 
                        success = true;
                    } 
                    finally
                    {
                        if (!success)
                        { 
                            Monitor.Exit(this.m_lock);
                        } 
                    } 
                }
            } 

            internal void Pulse()
            {
                Monitor.Pulse(this.m_lock); 
            }
 
            internal void Wait() 
            {
                Monitor.Wait(this.m_lock); 
            }

            public void Dispose()
            { 
                // Note: the following operations are logically atomic, but since the
                // list we are using is thread local there is no need to take a lock. 
                try 
                {
                    HeldLocks.Remove(this.m_lock); 
                }
                finally
                {
                    Monitor.Exit(this.m_lock); 
                }
            } 
        } 
    }
 
    internal sealed class SchedulerLockGuard : IDisposable
    {
        private InstanceLock.InstanceLockGuard lg;
        private WorkflowExecutor workflowExec; 

        internal SchedulerLockGuard(InstanceLock il, WorkflowExecutor w) 
        { 
            lg = il.Enter();
            workflowExec = w; 
        }

        private static void FireEvents(List eventList, WorkflowExecutor workflowExec)
        { 
            if (!workflowExec.IsInstanceValid && (workflowExec.WorkflowStatus == WorkflowStatus.Completed || workflowExec.WorkflowStatus == WorkflowStatus.Terminated))
            { 
                // The workflow is dead, let the instance have a hard ref to the corpse for support of the query apis. 
                workflowExec.WorkflowInstance.DeadWorkflow = workflowExec;
            } 
            for (int i = 0; i < eventList.Count; i++)
            {
                SchedulerLockGuardInfo eseg = eventList[i];
                // eseg.EventInfo is non-null only if the event type is Suspended or Terminated 
                // If the event type is Suspended, then call FireWorkflowSuspended after casting
                //   the event argument to a String. 
                // If the event type is Terminated, then call FireWorkflowTerminated after casting 
                //   the event argument to either a String or an Exception.
                switch (eseg.EventType) 
                {
                    case WorkflowEventInternal.Suspended:
                        workflowExec.FireWorkflowSuspended((String)eseg.EventInfo);
                        break; 
                    case WorkflowEventInternal.Terminated:
                        if ((eseg.EventInfo as System.Exception) != null) 
                        { 
                            workflowExec.FireWorkflowTerminated((Exception)eseg.EventInfo);
                        } 
                        else
                        {
                            workflowExec.FireWorkflowTerminated((String)eseg.EventInfo);
                        } 
                        break;
                    default: 
                        workflowExec.FireWorkflowExecutionEvent(eseg.Sender, eseg.EventType); 
                        break;
                } 
            }
        }

        internal static void Exit(InstanceLock il, WorkflowExecutor w) 
        {
            List eventList = new List(w.EventsToFireList); 
            w.EventsToFireList.Clear(); 
            il.Exit();
            FireEvents(eventList, w); 
        }

        public void Dispose()
        { 
            List eventList = new List(workflowExec.EventsToFireList);
            workflowExec.EventsToFireList.Clear(); 
            lg.Dispose(); 
            FireEvents(eventList, workflowExec);
        } 
    }

    internal sealed class SchedulerLockGuardInfo
    { 
        private Object sender;
        private WorkflowEventInternal eventType; 
        private object eventInfo; 

        internal SchedulerLockGuardInfo(Object _sender, WorkflowEventInternal _eventType) 
        {
            sender = _sender;
            eventType = _eventType;
            eventInfo = null; 
        }
 
        internal SchedulerLockGuardInfo(Object _sender, WorkflowEventInternal _eventType, object _eventInfo) 
            : this(_sender, _eventType)
        { 
            eventInfo = _eventInfo;
        }

        internal Object Sender 
        {
            get 
            { 
                return sender;
            } 
        }

        internal WorkflowEventInternal EventType
        { 
            get
            { 
                return eventType; 
            }
        } 

        internal Object EventInfo
        {
            get 
            {
                return eventInfo; 
            } 
        }
    } 
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
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