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https://github.com/microsoft/PowerToys.git
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135 lines
5.2 KiB
C#
135 lines
5.2 KiB
C#
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using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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using System.Threading;
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namespace Wox.Helper
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{
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/// <summary>
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/// Provides a caller-friendly wrapper around parallel actions.
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/// http://stackoverflow.com/a/540380
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/// </summary>
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public sealed class Forker
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{
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int running;
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private readonly object joinLock = new object(), eventLock = new object();
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/// <summary>Raised when all operations have completed.</summary>
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public event EventHandler AllComplete
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{
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add { lock (eventLock) { allComplete += value; } }
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remove { lock (eventLock) { allComplete -= value; } }
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}
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private EventHandler allComplete;
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/// <summary>Raised when each operation completes.</summary>
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public event EventHandler<ParallelEventArgs> ItemComplete
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{
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add { lock (eventLock) { itemComplete += value; } }
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remove { lock (eventLock) { itemComplete -= value; } }
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}
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private EventHandler<ParallelEventArgs> itemComplete;
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private void OnItemComplete(object state, Exception exception)
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{
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EventHandler<ParallelEventArgs> itemHandler = itemComplete; // don't need to lock
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if (itemHandler != null) itemHandler(this, new ParallelEventArgs(state, exception));
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if (Interlocked.Decrement(ref running) == 0)
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{
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EventHandler allHandler = allComplete; // don't need to lock
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if (allHandler != null) allHandler(this, EventArgs.Empty);
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lock (joinLock)
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{
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Monitor.PulseAll(joinLock);
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}
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}
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}
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/// <summary>Adds a callback to invoke when each operation completes.</summary>
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/// <returns>Current instance (for fluent API).</returns>
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public Forker OnItemComplete(EventHandler<ParallelEventArgs> handler)
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{
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if (handler == null) throw new ArgumentNullException("handler");
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ItemComplete += handler;
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return this;
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}
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/// <summary>Adds a callback to invoke when all operations are complete.</summary>
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/// <returns>Current instance (for fluent API).</returns>
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public Forker OnAllComplete(EventHandler handler)
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{
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if (handler == null) throw new ArgumentNullException("handler");
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AllComplete += handler;
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return this;
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}
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/// <summary>Waits for all operations to complete.</summary>
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public void Join()
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{
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Join(-1);
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}
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/// <summary>Waits (with timeout) for all operations to complete.</summary>
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/// <returns>Whether all operations had completed before the timeout.</returns>
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public bool Join(int millisecondsTimeout)
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{
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lock (joinLock)
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{
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if (CountRunning() == 0) return true;
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Thread.SpinWait(1); // try our luck...
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return (CountRunning() == 0) ||
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Monitor.Wait(joinLock, millisecondsTimeout);
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}
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}
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/// <summary>Indicates the number of incomplete operations.</summary>
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/// <returns>The number of incomplete operations.</returns>
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public int CountRunning()
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{
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return Interlocked.CompareExchange(ref running, 0, 0);
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}
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/// <summary>Enqueues an operation.</summary>
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/// <param name="action">The operation to perform.</param>
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/// <returns>The current instance (for fluent API).</returns>
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public Forker Fork(ThreadStart action) { return Fork(action, null); }
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/// <summary>Enqueues an operation.</summary>
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/// <param name="action">The operation to perform.</param>
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/// <param name="state">An opaque object, allowing the caller to identify operations.</param>
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/// <returns>The current instance (for fluent API).</returns>
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public Forker Fork(ThreadStart action, object state)
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{
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if (action == null) throw new ArgumentNullException("action");
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Interlocked.Increment(ref running);
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ThreadPool.QueueUserWorkItem(delegate
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{
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Exception exception = null;
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try { action(); }
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catch (Exception ex) { exception = ex; }
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OnItemComplete(state, exception);
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});
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return this;
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}
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/// <summary>Event arguments representing the completion of a parallel action.</summary>
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public class ParallelEventArgs : EventArgs
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{
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private readonly object state;
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private readonly Exception exception;
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internal ParallelEventArgs(object state, Exception exception)
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{
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this.state = state;
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this.exception = exception;
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}
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/// <summary>The opaque state object that identifies the action (null otherwise).</summary>
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public object State { get { return state; } }
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/// <summary>The exception thrown by the parallel action, or null if it completed without exception.</summary>
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public Exception Exception { get { return exception; } }
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}
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}
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}
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