117 lines
3.7 KiB
Plaintext
117 lines
3.7 KiB
Plaintext
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///////////////////////////////////////////////////////////////////////////////
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//
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// Microsoft Research Singularity
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//
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// Copyright (c) Microsoft Corporation. All rights reserved.
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//
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// File: CassiniThreadPool.sg
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//
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// Note: adapted from FatThreadPool.sg
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//
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#if THREAD_POOL
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using System.Collections;
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using System.Threading;
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namespace Microsoft.VisualStudio.WebHost
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{
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/// <remarks>This class implements a non-Singleton
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/// threadpool and has a configurable work queue
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/// size. </remarks>
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internal sealed class CassiniThreadPool
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{
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object monitor;
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Queue commands; // Queue of ThreadStart
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int queuedItems;
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readonly int maxQueuedItems;
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volatile int threadCount;
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volatile bool shutdown;
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ManualResetEvent shutdownEvent;
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[Microsoft.Contracts.NotDelayed]
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internal CassiniThreadPool(int maxThreads, int maxQueuedItems)
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requires maxThreads > 0;
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requires maxQueuedItems > 0;
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requires maxThreads <= maxQueuedItems;
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{
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this.monitor = new object();
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this.commands = new Queue();
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this.queuedItems = 0;
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this.maxQueuedItems = maxQueuedItems;
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this.threadCount = maxThreads;
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this.shutdown = false;
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this.shutdownEvent = new ManualResetEvent(false);
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for (int i = 0; i < maxThreads; i++) {
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Thread t = new Thread(new ThreadStart(WorkerMain));
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t.Start();
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}
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}
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/// <summary> Queues call to constructor supplied
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/// delegate with user supplied object. This method
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/// blocks if maximum queue size is reached. </summary>
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internal void QueueUserWorkItem(ThreadStart! command)
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{
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Monitor.Enter(this.monitor);
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while (this.queuedItems == this.maxQueuedItems) {
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Monitor.Wait(this.monitor);
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}
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commands.Enqueue(command);
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this.queuedItems++;
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Monitor.Pulse(this.monitor);
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Monitor.Exit(this.monitor);
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}
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private void WorkerMain()
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{
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while (true) {
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ThreadStart command;
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lock (this.monitor) {
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while (queuedItems == 0 && !shutdown) {
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Monitor.Wait(this.monitor);
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}
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if (queuedItems == 0 && shutdown) {
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break;
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}
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command = (ThreadStart) (commands.Dequeue());
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assert(command != null);
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if (this.queuedItems-- == this.maxQueuedItems) {
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Monitor.Pulse(this.monitor);
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}
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}
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command();
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}
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lock (this.monitor) {
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if (--this.threadCount == 0) {
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shutdownEvent.Set();
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}
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}
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}
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/// <summary>
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/// Shutdown thread pool instance. Caller blocks until
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/// the threads in the pool have finished outstanding
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/// work items.
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/// </summary>
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internal void Shutdown()
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{
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lock (this.monitor) {
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shutdown = true;
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Monitor.PulseAll(this.monitor);
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}
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shutdownEvent.WaitOne();
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Microsoft.Singularity.DebugStub.Assert(commands.Count == 0);
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}
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}
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}
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#endif // THREAD_POOL
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