LifetimeMonitor.cs source code in C# .NET

                        Code:
                         / WCF / WCF / 3.5.30729.1 / untmp / Orcas / SP / ndp / cdf / src / WCF / infocard / Service / managed / Microsoft / InfoCards / LifetimeMonitor.cs / 1 / LifetimeMonitor.cs
                        
                        
                            //------------------------------------------------------------------------------ 
// Copyright (c) Microsoft Corporation.  All rights reserved.
//-----------------------------------------------------------------------------
//
// Presharp uses the c# pragma mechanism to supress its warnings. 
// These are not recognised by the base compiler so we need to explictly
// disable the following warnings. See http://winweb/cse/Tools/PREsharp/userguide/default.asp 
// for details. 
//
#pragma warning disable 1634, 1691      // unknown message, unknown pragma 



namespace Microsoft.InfoCards 
{
    using System; 
    using Microsoft.Win32; 
    using System.ServiceProcess;
    using System.Timers; 
    using Microsoft.InfoCards.Diagnostics;
    using IDT = Microsoft.InfoCards.Diagnostics.InfoCardTrace;

 
    //
    // Summary: 
    // Manages the lifetime of the service, 
    // Watches for incoming and outgoing
    // requests and shuts down the service after a certain period of inactivity. 
    //
    class LifeTimeMonitor
    {
        // 
        // How long we wait with no activity before shutting down.
        // 
        const int DefaultShutdownInterval       = 60 * 60 * 1000 ;    // in milliseconds. 

        // 
        // The minimum wait we can define.
        //
        const int MinimumShutdownInterval       = 60 * 1000;          // in milliseconds
 
        //
        // Registry value to override the shutdown time. 
        // 
        const string ServiceIdleTimeValue = "ServiceIdleTime";
 
        //
        // The number of active clients.
        //
        int m_activeCount                       = 0; 
        //
        // Are we in the process of shutting down 
        // 
        bool m_isShuttingDown                   = false;
 
        //
        // The shutdown timer.
        //
        System.Timers.Timer m_shutdownTimer; 

        object m_syncRoot                       = new Object(); 
 
        public LifeTimeMonitor()
        { 

            //
            // Read the idle time from the registry.
            // 
            int shutdownInterval = DefaultShutdownInterval;
 
            using( SystemIdentity system = new SystemIdentity( false ) ) 
            {
                using( RegistryKey rk = Registry.LocalMachine.OpenSubKey( InfoCardConstants.RegistryKey, false ) ) 
                {
                    if( null != rk )
                    {
                        object idleTime = rk.GetValue( ServiceIdleTimeValue , DefaultShutdownInterval ); 
                        if( idleTime is int && (int)idleTime >= MinimumShutdownInterval )
                        { 
                            shutdownInterval = (int)idleTime; 
                        }
                    } 
                }
            }
            IDT.TraceDebug( "LIFETIME: Setting service idle time to {0} seconds\n", shutdownInterval / 1000.0 );
 
            m_activeCount               = 0;
            m_shutdownTimer             = new System.Timers.Timer( shutdownInterval ); 
            m_shutdownTimer.Elapsed     += this.OnShutdown; 
            m_shutdownTimer.AutoReset   = false;
 
            m_isShuttingDown            = false;

            StartShutdownTimer();
        } 

        // 
        // Summary: 
        // Register that a client request has entered the system.
        // Stops the idle timer if this is the first request in. 
        //
        public void AddClient()
        {
            lock( m_syncRoot ) 
            {
                IDT.Assert( m_activeCount >= 0, "incorrect active count" ); 
 

                // 
                // We could have been blocked on a shutdown. If so, then throw the service busy
                // exception
                //
                if( m_isShuttingDown ) 
                {
                    IDT.TraceDebug( "LIFETIME: Shutdown in progress, aborting incoming client request" ); 
                    throw IDT.ThrowHelperError( new ServiceBusyException() ); 
                }
                m_activeCount++; 
                IDT.TraceDebug( "LIFETIME: Adding client - active count is now {0}", m_activeCount );
                if( 1 == m_activeCount )
                {
                    IDT.TraceDebug( "LIFETIME: Shutdown timer detecting first incoming client" ); 
                    StopShutdownTimer();
                } 
            } 
        }
 
        //
        // Summary:
        // Called when a client request is disposed.
        // Starts the idle timer if there are no outstanding requests. 
        //
        public void RemoveClient() 
        { 
            lock( m_syncRoot )
            { 
                IDT.Assert( m_activeCount > 0, "invalid active count" );
                IDT.TraceDebug( "LIFETIME: Removing client {0}", m_activeCount );
                m_activeCount--;
                if( m_activeCount == 0 ) 
                {
                    IDT.TraceDebug( "LIFETIME: Shutdown timer becoming active" ); 
                    StartShutdownTimer(); 
                }
            } 
        }

        //
        // Summary: 
        // Callback function fired when the inactivity period has elapsed.
        // Parameters 
        //  Unused. 
        //
        private void OnShutdown( object sender, ElapsedEventArgs args ) 
        {
            lock( m_syncRoot )
            {
                // 
                // Conceivably we could have been waiting on someone adding a client. Exit if so.
                // 
                // There is an additional race here that we don't handle: 
                // A caller could have called AddClient() and ReleaseClient() in between our
                // being sent the shutdown event and acquiring the lock, but this would only cause an immediate 
                // shutdown following that client request and will not break things functionally.
                // We could extend the remove code to record the timestamp of when the last remove
                // occurred, but this is overkill as the extended lifetime of our
                // requests make this very unlikely to happen. 
                //
                if( m_activeCount > 0 ) 
                { 
                    IDT.TraceDebug( "LIFETIME: Detected race with incoming request. Aborting service shutdown" );
                    return; 
                }
                IDT.TraceDebug( "LIFETIME: Shutting down the service due to idle timeout" );
                m_shutdownTimer.Enabled = false;
 
                //
                // Prevent any more incoming callers. 
                // 
                m_isShuttingDown = true;
 
                //
                // Audit that we are shutting down due to idle timeout.
                //
                IDT.Audit( EventCode.AUDIT_SERVICE_IDLE_STOP ); 
            }
            using( SystemIdentity system = new SystemIdentity( false ) ) 
            { 
                new ServiceController( InfoCardService.FullServiceName ).Stop();
            } 

        }

        private void StartShutdownTimer() 
        {
            m_shutdownTimer.Start(); 
        } 
        private void StopShutdownTimer()
        { 
            m_shutdownTimer.Stop();
        }
    }
} 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
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LifetimeMonitor.cs source code in C# .NET

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