ManualWorkflowSchedulerService.cs source code in C# .NET

Source code for the .NET framework in C#

                        

Code:

/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / cdf / src / WF / RunTime / Hosting / ManualWorkflowSchedulerService.cs / 1305376 / ManualWorkflowSchedulerService.cs

                            using System; 
using System.Threading;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Collections.ObjectModel; 
using System.Workflow.Runtime;
using System.Diagnostics; 
using System.Globalization; 

namespace System.Workflow.Runtime.Hosting 
{
    public class ManualWorkflowSchedulerService : WorkflowSchedulerService
    {
        private class CallbackInfo 
        {
            WaitCallback callback; 
            Guid instanceId; 
            Guid timerId;
            DateTime when; 

            public CallbackInfo(WaitCallback callback, Guid instanceId, Guid timerId, DateTime when)
            {
                this.callback = callback; 
                this.when = when;
                this.instanceId = instanceId; 
                this.timerId = timerId; 
            }
 
            public DateTime When
            {
                get { return when; }
            } 

            public bool IsExpired 
            { 
                get { return DateTime.UtcNow >= when; }
            } 

            public Guid InstanceId { get { return instanceId; } }

            public Guid TimerId { get { return timerId; } } 

            public WaitCallback Callback 
            { 
                get { return callback; }
            } 
        }

        private KeyedPriorityQueue pendingScheduleRequests = new KeyedPriorityQueue();
        private Dictionary scheduleRequests = new Dictionary(); 
        private object locker = new Object();
        private Timer callbackTimer; 
        private readonly TimerCallback timerCallback;   // non-null indicates that active timers are enabled 
        private volatile bool threadRunning;    // indicates that the timer thread is running
        private static TimeSpan infinite = new TimeSpan(Timeout.Infinite); 
        private IList queueCounters;
        private static TimeSpan fiveMinutes = new TimeSpan(0, 5, 0);

        private const string USE_ACTIVE_TIMERS_KEY = "UseActiveTimers"; 

            // Note that pendingScheduleRequests are keyed by instance ID under the assertion that there is at most one outstanding 
            // timer for any given instance ID. To support cancellation, and additional map is kept of timerID-to-instanceID so that 
            // we can find the appropriate pending  given a timer ID
 
        public ManualWorkflowSchedulerService()
        {
        }
 
        public ManualWorkflowSchedulerService(bool useActiveTimers)
        { 
            if (useActiveTimers) 
            {
                timerCallback = new TimerCallback(OnTimerCallback); 
                pendingScheduleRequests.FirstElementChanged += OnFirstElementChanged;
                WorkflowTrace.Host.TraceEvent(TraceEventType.Information, 0, "ManualWorkflowSchedulerService: started with active timers");
            }
        } 
        public ManualWorkflowSchedulerService(NameValueCollection parameters)
        { 
            if (parameters == null) 
                throw new ArgumentNullException("parameters");
 
            foreach (string key in parameters.Keys)
            {
                if (key == null)
                    throw new ArgumentException(String.Format(Thread.CurrentThread.CurrentCulture, ExecutionStringManager.UnknownConfigurationParameter, "null")); 
                string p = parameters[key];
                if (!key.Equals(USE_ACTIVE_TIMERS_KEY, StringComparison.OrdinalIgnoreCase)) 
                    throw new ArgumentException(String.Format(Thread.CurrentThread.CurrentCulture, ExecutionStringManager.UnknownConfigurationParameter, key)); 
                bool useActiveTimers;
                if (!bool.TryParse(p, out useActiveTimers)) 
                    throw new FormatException(USE_ACTIVE_TIMERS_KEY);
                if (useActiveTimers)
                {
                    timerCallback = new TimerCallback(OnTimerCallback); 
                    pendingScheduleRequests.FirstElementChanged += OnFirstElementChanged;
                    WorkflowTrace.Host.TraceEvent(TraceEventType.Information, 0, "ManualWorkflowSchedulerService: Started with active timers"); 
                } 
            }
        } 

        internal protected override void Schedule(WaitCallback callback, Guid workflowInstanceId)
        {
            if (callback == null) 
                throw new ArgumentNullException("callback");
            if (workflowInstanceId.Equals(Guid.Empty)) 
                throw new ArgumentException(String.Format(CultureInfo.CurrentCulture, ExecutionStringManager.CantBeEmptyGuid, "workflowInstanceId")); 

            lock (locker) 
            {
                WorkflowTrace.Host.TraceEvent(TraceEventType.Information, 0, "ManualWorkflowSchedulerService: Schedule workflow {0}", workflowInstanceId);
                if (!scheduleRequests.ContainsKey(workflowInstanceId))
                    scheduleRequests.Add(workflowInstanceId, new DefaultWorkflowSchedulerService.WorkItem(callback, workflowInstanceId)); 
            }
            if (queueCounters != null) 
            { 
                foreach (PerformanceCounter p in queueCounters)
                { 
                    p.RawValue = scheduleRequests.Count;
                }
            }
        } 

        internal protected override void Schedule(WaitCallback callback, Guid workflowInstanceId, DateTime whenUtc, Guid timerId) 
        { 
            if (callback == null)
                throw new ArgumentNullException("callback"); 
            if (workflowInstanceId.Equals(Guid.Empty))
                throw new ArgumentException(String.Format(CultureInfo.CurrentCulture, ExecutionStringManager.CantBeEmptyGuid, "workflowInstanceId"));
            if (timerId.Equals(Guid.Empty))
                throw new ArgumentException(String.Format(CultureInfo.CurrentCulture, ExecutionStringManager.CantBeEmptyGuid, "timerId")); 

            lock (locker) 
            { 
                WorkflowTrace.Host.TraceEvent(TraceEventType.Information, 0, "ManualWorkflowSchedulerService: Schedule timer {0} for workflow {1} at {2}", timerId, workflowInstanceId, whenUtc);
                pendingScheduleRequests.Enqueue(timerId, new CallbackInfo(callback, workflowInstanceId, timerId, whenUtc), whenUtc); 
            }
        }

        internal protected override void Cancel(Guid timerId) 
        {
            if (timerId.Equals(Guid.Empty)) 
                throw new ArgumentException(String.Format(CultureInfo.CurrentCulture, ExecutionStringManager.CantBeEmptyGuid, "timerId")); 

            lock (locker) 
            {
                WorkflowTrace.Host.TraceEvent(TraceEventType.Information, 0, "ManualWorkflowSchedulerService: Cancel timer {0}", timerId);
                pendingScheduleRequests.Remove(timerId);
            } 
        }
 
        private bool RunOne(Guid workflowInstanceId) 
        {
            bool retval = false; 
            DefaultWorkflowSchedulerService.WorkItem cs = null;
            lock (locker)
            {
                if (scheduleRequests.ContainsKey(workflowInstanceId)) 
                {
                    cs = scheduleRequests[workflowInstanceId]; 
                    scheduleRequests.Remove(workflowInstanceId); 
                }
            } 
            try
            {
                if (cs != null)
                { 
                    WorkflowTrace.Host.TraceEvent(TraceEventType.Information, 0, "ManualWorkflowSchedulerService: Executing {0}", workflowInstanceId);
                    if (queueCounters != null) 
                    { 
                        foreach (PerformanceCounter p in queueCounters)
                        { 
                            p.RawValue = scheduleRequests.Count;
                        }
                    }
                    cs.Invoke(this); 
                    retval = true;
                } 
            } 
            catch (Exception e)
            { 
                RaiseServicesExceptionNotHandledEvent(e, workflowInstanceId);
            }
            return retval;
        } 

        private bool HasExpiredTimer(Guid workflowInstanceId, out Guid timerId) 
        { 
            lock (locker)
            { 
                CallbackInfo ci = pendingScheduleRequests.FindByPriority(DateTime.UtcNow,
                    delegate(CallbackInfo c) { return c.InstanceId == workflowInstanceId; });
                if (ci != null)
                { 
                    timerId = ci.TimerId;
                    return true; 
                } 
            }
            timerId = Guid.Empty; 
            return false;
        }
        private bool ProcessTimer(Guid workflowInstanceId)
        { 
            bool retval = false;
            CallbackInfo cs = null; 
            Guid timerId = Guid.Empty; 
            lock (locker)
            { 
                Guid expTimerId;
                if (HasExpiredTimer(workflowInstanceId, out expTimerId))
                {
                    cs = pendingScheduleRequests.Remove(expTimerId); 
                }
            } 
            try 
            {
                if (cs != null) 
                {
                    WorkflowTrace.Host.TraceEvent(TraceEventType.Information, 0, "ManualWorkflowSchedulerService: Processing timer {0}", timerId);
                    cs.Callback(cs.InstanceId);
                    retval = true; 
                }
            } 
            catch (Exception e) 
            {
                RaiseServicesExceptionNotHandledEvent(e, workflowInstanceId); 
            }
            return retval;
        }
 
        private bool CanRun(Guid workflowInstanceId)
        { 
            bool retval = false; 
            lock(locker)
            { 
                Guid timerId;
                retval = scheduleRequests.ContainsKey(workflowInstanceId) || HasExpiredTimer(workflowInstanceId, out timerId);
                WorkflowTrace.Host.TraceEvent(TraceEventType.Information, 0, "ManualWorkflowSchedulerService: CanRun is {0}", retval);
            } 
            return retval;
        } 
 
        public bool RunWorkflow(Guid workflowInstanceId)
        { 
            if (workflowInstanceId.Equals(Guid.Empty))
                throw new ArgumentException(String.Format(CultureInfo.CurrentCulture, ExecutionStringManager.CantBeEmptyGuid, "workflowInstanceId"));

            WorkflowTrace.Host.TraceEvent(TraceEventType.Information, 0, "ManualWorkflowSchedulerService: Running workflow {0}", workflowInstanceId); 

            bool retval = false; // return true if we do any work at all 
            while (CanRun(workflowInstanceId)) 
            {
                if (RunOne(workflowInstanceId) || ProcessTimer(workflowInstanceId)) 
                    retval = true;  // did some work, try again
                else
                    break;  // no work done this iteration
            } 
            return retval;
        } 
        private Timer CreateTimerCallback(CallbackInfo info) 
        {
            DateTime now = DateTime.UtcNow; 
            TimeSpan span = (info.When > now) ? info.When - now : TimeSpan.Zero;
            // never let more than five minutes go by without checking
            if (span > fiveMinutes)
            { 
                span = fiveMinutes;
            } 
            return new Timer(timerCallback, info.InstanceId, span, infinite); 
        }
        override protected void OnStarted() 
        {
            base.OnStarted();
            if (this.timerCallback != null)
            { 
                lock (locker)
                { 
                    CallbackInfo ci = pendingScheduleRequests.Peek(); 
                    if (ci != null)
                        callbackTimer = CreateTimerCallback(ci); 
                }
            }
            lock (locker)
            { 
                if (queueCounters == null && this.Runtime.PerformanceCounterManager != null)
                { 
                    queueCounters = this.Runtime.PerformanceCounterManager.CreateCounters(ExecutionStringManager.PerformanceCounterWorkflowsWaitingName); 
                }
            } 
        }
        protected internal override void Stop()
        {
            base.Stop(); 
            if (this.timerCallback != null)
            { 
                lock (locker) 
                {
                    if (callbackTimer != null) 
                    {
                        callbackTimer.Dispose();
                        callbackTimer = null;
                    } 
                }
            } 
        } 
        private void OnTimerCallback(object ignored)
        { 
            CallbackInfo ci = null;
            try
            {
                lock (locker) 
                {
                    if (State.Equals(WorkflowRuntimeServiceState.Started)) 
                    { 
                        ci = pendingScheduleRequests.Peek();
                        if (ci != null) 
                        {
                            if (ci.IsExpired)
                            {
                                WorkflowTrace.Host.TraceEvent(TraceEventType.Information, 0, "Timeout occured for timer for instance {0}", ci.InstanceId); 
                                threadRunning = true;
                                pendingScheduleRequests.Dequeue(); 
                            } 
                            else
                            { 
                                callbackTimer = CreateTimerCallback(ci);
                            }
                        }
                    } 
                }
                if (threadRunning) 
                { 
                    ci.Callback(ci.InstanceId);  // delivers the timer message
                    RunWorkflow(ci.InstanceId); 
                }
            }
            catch (ThreadAbortException e)
            { 
                WorkflowTrace.Host.TraceEvent(TraceEventType.Error, 0, "Timeout for instance, {0} threw exception {1}", ci == null ? Guid.Empty : ci.InstanceId, e.Message);
                RaiseServicesExceptionNotHandledEvent(e, ci.InstanceId); 
                throw; 
            }
            catch (Exception e) 
            {
                WorkflowTrace.Host.TraceEvent(TraceEventType.Error, 0, "Timeout for instance, {0} threw exception {1}", ci == null ? Guid.Empty : ci.InstanceId, e.Message);
                RaiseServicesExceptionNotHandledEvent(e, ci.InstanceId);
            } 
            finally
            { 
                lock (locker) 
                {
                    if (threadRunning) 
                    {
                        threadRunning = false;
                        ci = pendingScheduleRequests.Peek();
                        if (ci != null) 
                            callbackTimer = CreateTimerCallback(ci);
                    } 
                } 
            }
        } 
        private void OnFirstElementChanged(object source, KeyedPriorityQueueHeadChangedEventArgs e)
        {
            lock (locker)
            { 
                if (threadRunning)
                    return;     // ignore when a timer thread is already processing a timer request 
                if (callbackTimer != null) 
                {
                    callbackTimer.Dispose(); 
                    callbackTimer = null;
                }
                if (e.NewFirstElement != null && this.State == WorkflowRuntimeServiceState.Started)
                { 
                    callbackTimer = CreateTimerCallback(e.NewFirstElement);
                } 
            } 
        }
    } 
}

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

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