IdlingCommunicationPool.cs source code in C# .NET

                        Code:
                         / WCF / WCF / 3.5.30729.1 / untmp / Orcas / SP / ndp / cdf / src / WCF / ServiceModel / System / ServiceModel / Channels / IdlingCommunicationPool.cs / 1 / IdlingCommunicationPool.cs
                        
                        
                            //------------------------------------------------------------ 
// Copyright (c) Microsoft Corporation.  All rights reserved.
//-----------------------------------------------------------
namespace System.ServiceModel.Channels
{ 
    using System.Diagnostics;
    using System.Threading; 
    using System.ServiceModel.Diagnostics; 
    using System.Collections.Generic;
 
    abstract class IdlingCommunicationPool
        : CommunicationPool
        where TKey : class
        where TItem : class 
    {
        TimeSpan idleTimeout; 
        TimeSpan leaseTimeout; 

        protected IdlingCommunicationPool(int maxCount, TimeSpan idleTimeout, TimeSpan leaseTimeout) 
            : base(maxCount)
        {
            this.idleTimeout = idleTimeout;
            this.leaseTimeout = leaseTimeout; 
        }
 
        public TimeSpan IdleTimeout 
        {
            get { return this.idleTimeout; } 
        }

        protected TimeSpan LeaseTimeout
        { 
            get { return this.leaseTimeout; }
        } 
 
        protected override EndpointConnectionPool CreateEndpointConnectionPool(TKey key)
        { 
            if (idleTimeout != TimeSpan.MaxValue || leaseTimeout != TimeSpan.MaxValue)
            {
                return new IdleTimeoutEndpointConnectionPool(this, key);
            } 
            else
            { 
                return base.CreateEndpointConnectionPool(key); 
            }
        } 

        protected class IdleTimeoutEndpointConnectionPool : EndpointConnectionPool
        {
            IdleTimeoutIdleConnectionPool connections; 

            public IdleTimeoutEndpointConnectionPool(IdlingCommunicationPool parent, TKey key) 
                : base(parent, key) 
            {
                this.connections = new IdleTimeoutIdleConnectionPool(this, this.ThisLock); 
            }

            protected override IdleConnectionPool GetIdleConnectionPool()
            { 
                return this.connections;
            } 
 
            protected override void AbortItem(TItem item)
            { 
                this.connections.OnItemClosing(item);
                base.AbortItem(item);
            }
 
            protected override void CloseItem(TItem item, TimeSpan timeout)
            { 
                this.connections.OnItemClosing(item); 
                base.CloseItem(item, timeout);
            } 

            public override void Prune(List itemsToClose)
            {
                if (this.connections != null) 
                {
                    this.connections.Prune(itemsToClose, false); 
                } 
            }
 
            protected class IdleTimeoutIdleConnectionPool : PoolIdleConnectionPool
            {
                // for performance reasons we don't just blindly start a timer up to clean up
                // idle connections. However, if we're above a certain threshold of connections 
                const int timerThreshold = 1;
 
                IdleTimeoutEndpointConnectionPool parent; 
                TimeSpan idleTimeout;
                TimeSpan leaseTimeout; 
                IOThreadTimer idleTimer;
                static WaitCallback onIdle;
                object thisLock;
                Exception pendingException; 

                // Note that Take/Add/Return are already synchronized by ThisLock, so we don't need an extra 
                // lock around our Dictionary access 
                Dictionary connectionMapping;
 
                public IdleTimeoutIdleConnectionPool(IdleTimeoutEndpointConnectionPool parent, object thisLock)
                    : base(parent.Parent.MaxIdleConnectionPoolCount)
                {
                    this.parent = parent; 
                    IdlingCommunicationPool idlingCommunicationPool = ((IdlingCommunicationPool)parent.Parent);
                    this.idleTimeout = idlingCommunicationPool.idleTimeout; 
                    this.leaseTimeout = idlingCommunicationPool.leaseTimeout; 
                    this.thisLock = thisLock;
                    this.connectionMapping = new Dictionary(); 
                }

                public override bool Add(TItem connection)
                { 
                    this.ThrowPendingException();
 
                    bool result = base.Add(connection); 
                    if (result)
                    { 
                        this.connectionMapping.Add(connection, new IdlingConnectionSettings());
                        StartTimerIfNecessary();
                    }
                    return result; 
                }
 
                public override bool Return(TItem connection) 
                {
                    this.ThrowPendingException(); 

                    if (!this.connectionMapping.ContainsKey(connection))
                    {
                        return false; 
                    }
 
                    bool result = base.Return(connection); 
                    if (result)
                    { 
                        this.connectionMapping[connection].LastUsage = DateTime.UtcNow;
                        StartTimerIfNecessary();
                    }
                    return result; 
                }
 
                public override TItem Take(out bool closeItem) 
                {
                    this.ThrowPendingException(); 

                    DateTime now = DateTime.UtcNow;
                    TItem item = base.Take(out closeItem);
 
                    if (!closeItem)
                    { 
                        closeItem = IdleOutConnection(item, now); 
                    }
                    return item; 
                }

                public void OnItemClosing(TItem connection)
                { 
                    this.ThrowPendingException();
 
                    lock (thisLock) 
                    {
                        this.connectionMapping.Remove(connection); 
                    }
                }

                void CancelTimer() 
                {
                    if (this.idleTimer != null) 
                    { 
                        this.idleTimer.Cancel();
                    } 
                }

                void StartTimerIfNecessary()
                { 
                    if (this.Count > timerThreshold)
                    { 
                        if (idleTimer == null) 
                        {
                            if (onIdle == null) 
                            {
                                onIdle = new WaitCallback(OnIdle);
                            }
 
                            idleTimer = new IOThreadTimer(onIdle, this, false);
                        } 
 
                        idleTimer.Set(idleTimeout);
                    } 
                }

                static void OnIdle(object state)
                { 
                    IdleTimeoutIdleConnectionPool pool = (IdleTimeoutIdleConnectionPool)state;
                    pool.OnIdle(); 
                } 

                void OnIdle() 
                {
                    List itemsToClose = new List();
                    lock (thisLock)
                    { 
                        try
                        { 
                            this.Prune(itemsToClose, true); 
                        }
                        catch (Exception e) 
                        {
                            if (DiagnosticUtility.IsFatal(e))
                            {
                                throw; 
                            }
                            this.pendingException = e; 
                            this.CancelTimer(); 
                        }
                    } 

                    // allocate half the idle timeout for our graceful shutdowns
                    TimeoutHelper timeoutHelper = new TimeoutHelper(TimeoutHelper.Divide(this.idleTimeout, 2));
                    for (int i = 0; i < itemsToClose.Count; i++) 
                    {
                        parent.CloseIdleConnection(itemsToClose[i], timeoutHelper.RemainingTime()); 
                    } 
                }
 
                public void Prune(List itemsToClose, bool calledFromTimer)
                {
                    if (!calledFromTimer)
                    { 
                        this.ThrowPendingException();
                    } 
 
                    if (this.Count == 0)
                        return; 

                    DateTime now = DateTime.UtcNow;
                    bool setTimer = false;
 
                    lock (thisLock)
                    { 
                        TItem[] connectionsCopy = new TItem[this.Count]; 
                        for (int i = 0; i < connectionsCopy.Length; i++)
                        { 
                            bool closeItem;
                            connectionsCopy[i] = base.Take(out closeItem);
                            DiagnosticUtility.DebugAssert(connectionsCopy[i] != null, "IdleConnections should only be modified under thisLock");
                            if (closeItem || IdleOutConnection(connectionsCopy[i], now)) 
                            {
                                itemsToClose.Add(connectionsCopy[i]); 
                                connectionsCopy[i] = null; 
                            }
                        } 

                        for (int i = 0; i < connectionsCopy.Length; i++)
                        {
                            if (connectionsCopy[i] != null) 
                            {
                                bool successfulReturn = base.Return(connectionsCopy[i]); 
                                DiagnosticUtility.DebugAssert(successfulReturn, "IdleConnections should only be modified under thisLock"); 
                            }
                        } 

                        setTimer = (this.Count > 0);
                    }
 
                    if (calledFromTimer && setTimer)
                    { 
                        idleTimer.Set(idleTimeout); 
                    }
                } 

                bool IdleOutConnection(TItem connection, DateTime now)
                {
                    if (connection == null) 
                    {
                        return false; 
                    } 

                    bool result = false; 
                    IdlingConnectionSettings idlingSettings = this.connectionMapping[connection];
                    if (now > (idlingSettings.LastUsage + this.idleTimeout))
                    {
                        TraceConnectionIdleTimeoutExpired(); 
                        result = true;
                    } 
                    else if (now - idlingSettings.CreationTime >= this.leaseTimeout) 
                    {
                        TraceConnectionLeaseTimeoutExpired(); 
                        result = true;
                    }

                    return result; 
                }
 
                void ThrowPendingException() 
                {
                    if (this.pendingException != null) 
                    {
                        lock (thisLock)
                        {
                            if (this.pendingException != null) 
                            {
                                Exception exceptionToThrow = this.pendingException; 
                                this.pendingException = null; 
                                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(exceptionToThrow);
                            } 
                        }
                    }
                }
 
                void TraceConnectionLeaseTimeoutExpired()
                { 
                    if (DiagnosticUtility.ShouldTraceInformation) 
                    {
                        DiagnosticUtility.DiagnosticTrace.TraceEvent(TraceEventType.Information, 
                            TraceCode.ConnectionPoolLeaseTimeoutReached,
                            SR.GetString(SR.TraceCodeConnectionPoolLeaseTimeoutReached, this.leaseTimeout),
                            null, null, this);
                    } 
                }
 
                void TraceConnectionIdleTimeoutExpired() 
                {
                    if (DiagnosticUtility.ShouldTraceInformation) 
                    {
                        DiagnosticUtility.DiagnosticTrace.TraceEvent(TraceEventType.Information,
                            TraceCode.ConnectionPoolIdleTimeoutReached,
                            SR.GetString(SR.TraceCodeConnectionPoolIdleTimeoutReached, this.idleTimeout), 
                            null, null, this);
                    } 
                } 

                class IdlingConnectionSettings 
                {
                    DateTime creationTime;
                    DateTime lastUsage;
 
                    public IdlingConnectionSettings()
                    { 
                        this.creationTime = DateTime.UtcNow; 
                        this.lastUsage = this.creationTime;
                    } 

                    public DateTime CreationTime
                    {
                        get { return this.creationTime; } 
                    }
 
                    public DateTime LastUsage 
                    {
                        get { return this.lastUsage; } 
                        set { this.lastUsage = value; }
                    }
                }
            } 
        }
    } 
} 

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