986 lines
45 KiB
C#
986 lines
45 KiB
C#
// ==++==
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//
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// Copyright (c) Microsoft Corporation. All rights reserved.
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//
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// ==--==
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// =+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
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//
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// Barrier.cs
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//
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// <OWNER>[....]</OWNER>
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//
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// A barrier allows multiple tasks to cooperatively work on some algorithm in parallel.
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// A group of tasks cooperate by moving through a series of phases, where each in the group signals it has arrived at
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// the barrier in a given phase and implicitly waits for all others to arrive.
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// The same barrier can be used for multiple phases.
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//
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// =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
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using System;
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using System.Collections.Generic;
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using System.Diagnostics;
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using System.Security.Permissions;
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using System.Runtime.InteropServices;
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using System.Threading;
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using System.Runtime.Serialization;
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using System.Security;
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namespace System.Threading
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{
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/// <summary>
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/// The exception that is thrown when the post-phase action of a <see cref="Barrier"/> fails.
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/// </summary>
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#if !SILVERLIGHT
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[Serializable]
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#endif
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public class BarrierPostPhaseException : Exception
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{
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/// <summary>
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/// Initializes a new instance of the <see cref="BarrierPostPhaseException"/> class.
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/// </summary>
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public BarrierPostPhaseException():this((string)null)
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{
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}
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/// <summary>
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/// Initializes a new instance of the <see cref="BarrierPostPhaseException"/> class with the specified inner exception.
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/// </summary>
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/// <param name="innerException">The exception that is the cause of the current exception.</param>
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public BarrierPostPhaseException(Exception innerException): this(null, innerException)
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{
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}
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/// <summary>
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/// Initializes a new instance of the <see cref="BarrierPostPhaseException"/> class with a specified error message.
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/// </summary>
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/// <param name="message">A string that describes the exception.</param>
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public BarrierPostPhaseException(string message):this(message, null)
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{
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}
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/// <summary>
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/// Initializes a new instance of the <see cref="BarrierPostPhaseException"/> class with a specified error message and inner exception.
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/// </summary>
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/// <param name="message">A string that describes the exception.</param>
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/// <param name="innerException">The exception that is the cause of the current exception.</param>
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public BarrierPostPhaseException(string message, Exception innerException)
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: base(message == null ? SR.GetString(SR.BarrierPostPhaseException) : message, innerException)
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{
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}
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#if !SILVERLIGHT
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/// <summary>
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/// Initializes a new instance of the <see cref="BarrierPostPhaseException"/> class with serialized data.
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/// </summary>
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/// <param name="info">The object that holds the serialized object data.</param>
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/// <param name="context">An object that describes the source or destination of the serialized data.</param>
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[SecurityCritical]
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protected BarrierPostPhaseException(SerializationInfo info, StreamingContext context)
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: base(info, context)
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{
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}
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#endif
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}
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/// <summary>
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/// Enables multiple tasks to cooperatively work on an algorithm in parallel through multiple phases.
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/// </summary>
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/// <remarks>
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/// <para>
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/// A group of tasks cooperate by moving through a series of phases, where each in the group signals it
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/// has arrived at the <see cref="Barrier"/> in a given phase and implicitly waits for all others to
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/// arrive. The same <see cref="Barrier"/> can be used for multiple phases.
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/// </para>
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/// <para>
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/// All public and protected members of <see cref="Barrier"/> are thread-safe and may be used
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/// concurrently from multiple threads, with the exception of Dispose, which
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/// must only be used when all other operations on the <see cref="Barrier"/> have
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/// completed.
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/// </para>
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/// </remarks>
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[ComVisible(false)]
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#if !FEATURE_NETCORE
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#pragma warning disable 0618
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[HostProtection(SecurityAction.LinkDemand, Synchronization = true, ExternalThreading = true)]
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#pragma warning restore 0618
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#endif
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[DebuggerDisplay("Participant Count={ParticipantCount},Participants Remaining={ParticipantsRemaining}")]
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public class Barrier : IDisposable
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{
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//This variable holds the basic barrier variables:
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// 1- The current particiants count
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// 2- The total participants count
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// 3- The sense flag (true if the cuurrent phase is even, false otherwise)
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// The first 15 bits are for the total count which means the maximum participants for the barrier is about 32K
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// The 16th bit is dummy
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// The next 15th bit for the current
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// And the last highest bit is for the sense
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volatile int m_currentTotalCount;
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// Bitmask to extract the current count
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const int CURRENT_MASK = 0x7FFF0000;
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// Bitmask to extract the total count
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const int TOTAL_MASK = 0x00007FFF;
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// Bitmask to extratc the sense flag
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const int SENSE_MASK = unchecked((int)0x80000000);
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// The maximum participants the barrier can operate = 32767 ( 2 power 15 - 1 )
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const int MAX_PARTICIPANTS = TOTAL_MASK;
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// The current barrier phase
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// We don't need to worry about overflow, the max value is 2^63-1; If it starts from 0 at a
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// rate of 4 billion increments per second, it will takes about 64 years to overflow.
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long m_currentPhase;
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// dispose flag
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bool m_disposed;
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// Odd phases event
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ManualResetEventSlim m_oddEvent;
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// Even phases event
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ManualResetEventSlim m_evenEvent;
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// The execution context of the creator thread
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ExecutionContext m_ownerThreadContext;
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// The EC callback that invokes the psot phase action
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[SecurityCritical]
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private static ContextCallback s_invokePostPhaseAction;
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// Post phase action after each phase
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Action<Barrier> m_postPhaseAction;
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// In case the post phase action throws an exception, wraps it in BarrierPostPhaseException
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Exception m_exception;
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// This is the ManagedThreadID of the postPhaseAction caller thread, this is used to determine if the SignalAndWait, Dispose or Add/RemoveParticipant caller thread is
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// the same thread as the postPhaseAction thread which means this method was called from the postPhaseAction which is illegal.
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// This value is captured before calling the action and reset back to zero after it.
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int m_actionCallerID;
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#region Properties
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/// <summary>
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/// Gets the number of participants in the barrier that haven’t yet signaled
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/// in the current phase.
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/// </summary>
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/// <remarks>
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/// This could be 0 during a post-phase action delegate execution or if the
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/// ParticipantCount is 0.
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/// </remarks>
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public int ParticipantsRemaining
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{
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get
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{
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int currentTotal = m_currentTotalCount;
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int total = (int)(currentTotal & TOTAL_MASK);
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int current = (int)((currentTotal & CURRENT_MASK) >> 16);
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return total - current;
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}
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}
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/// <summary>
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/// Gets the total number of participants in the barrier.
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/// </summary>
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public int ParticipantCount
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{
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get { return (int)(m_currentTotalCount & TOTAL_MASK); }
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}
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/// <summary>
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/// Gets the number of the barrier's current phase.
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/// </summary>
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public long CurrentPhaseNumber
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{
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// use the new Volatile.Read/Write method because it is cheaper than Interlocked.Read on AMD64 architecture
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get { return Volatile.Read(ref m_currentPhase); }
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internal set { Volatile.Write(ref m_currentPhase, value); }
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}
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#endregion
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/// <summary>
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/// Initializes a new instance of the <see cref="Barrier"/> class.
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/// </summary>
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/// <param name="participantCount">The number of participating threads.</param>
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/// <exception cref="ArgumentOutOfRangeException"> <paramref name="participantCount"/> is less than 0
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/// or greater than <see cref="T:System.Int16.MaxValue"/>.</exception>
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public Barrier(int participantCount)
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: this(participantCount, null)
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{
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}
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/// <summary>
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/// Initializes a new instance of the <see cref="Barrier"/> class.
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/// </summary>
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/// <param name="participantCount">The number of participating threads.</param>
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/// <param name="postPhaseAction">The <see cref="T:System.Action`1"/> to be executed after each
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/// phase.</param>
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/// <exception cref="T:System.ArgumentOutOfRangeException"> <paramref name="participantCount"/> is less than 0
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/// or greater than <see cref="T:System.Int32.MaxValue"/>.</exception>
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/// <remarks>
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/// The <paramref name="postPhaseAction"/> delegate will be executed after
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/// all participants have arrived at the barrier in one phase. The participants
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/// will not be released to the next phase until the postPhaseAction delegate
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/// has completed execution.
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/// </remarks>
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public Barrier(int participantCount, Action<Barrier> postPhaseAction)
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{
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// the count must be non negative value
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if (participantCount < 0 || participantCount > MAX_PARTICIPANTS)
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{
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throw new ArgumentOutOfRangeException("participantCount", participantCount, SR.GetString(SR.Barrier_ctor_ArgumentOutOfRange));
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}
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m_currentTotalCount = (int)participantCount;
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m_postPhaseAction = postPhaseAction;
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//Lazily initialize the events
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m_oddEvent = new ManualResetEventSlim(true);
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m_evenEvent = new ManualResetEventSlim(false);
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// Capture the context if the post phase action is not null
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if (postPhaseAction != null && !ExecutionContext.IsFlowSuppressed())
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{
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m_ownerThreadContext = ExecutionContext.Capture();
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}
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m_actionCallerID = 0;
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}
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/// <summary>
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/// Extract the three variables current, total and sense from a given big variable
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/// </summary>
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/// <param name="currentTotal">The integer variable that contains the other three variables</param>
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/// <param name="current">The current cparticipant count</param>
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/// <param name="total">The total participants count</param>
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/// <param name="sense">The sense flag</param>
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private void GetCurrentTotal(int currentTotal, out int current, out int total, out bool sense)
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{
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total = (int)(currentTotal & TOTAL_MASK);
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current = (int)((currentTotal & CURRENT_MASK) >> 16);
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sense = (currentTotal & SENSE_MASK) == 0 ? true : false;
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}
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/// <summary>
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/// Write the three variables current. total and the sense to the m_currentTotal
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/// </summary>
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/// <param name="currentTotal">The old current total to compare</param>
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/// <param name="current">The current cparticipant count</param>
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/// <param name="total">The total participants count</param>
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/// <param name="sense">The sense flag</param>
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/// <returns>True if the CAS succeeded, false otherwise</returns>
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private bool SetCurrentTotal(int currentTotal, int current, int total, bool sense)
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{
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int newCurrentTotal = (current <<16) | total;
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if (!sense)
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{
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newCurrentTotal |= SENSE_MASK;
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}
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#pragma warning disable 0420
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return Interlocked.CompareExchange(ref m_currentTotalCount, newCurrentTotal, currentTotal) == currentTotal;
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#pragma warning restore 0420
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}
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/// <summary>
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/// Notifies the <see cref="Barrier"/> that there will be an additional participant.
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/// </summary>
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/// <returns>The phase number of the barrier in which the new participants will first
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/// participate.</returns>
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/// <exception cref="T:System.InvalidOperationException">
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/// Adding a participant would cause the barrier's participant count to
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/// exceed <see cref="T:System.Int16.MaxValue"/>.
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/// </exception>
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/// <exception cref="T:System.InvalidOperationException">
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/// The method was invoked from within a post-phase action.
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/// </exception>
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/// <exception cref="T:System.ObjectDisposedException">The current instance has already been
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/// disposed.</exception>
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public long AddParticipant()
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{
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try
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{
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return AddParticipants(1);
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}
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catch (ArgumentOutOfRangeException)
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{
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throw new InvalidOperationException(SR.GetString(SR.Barrier_AddParticipants_Overflow_ArgumentOutOfRange));
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}
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}
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/// <summary>
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/// Notifies the <see cref="Barrier"/> that there will be additional participants.
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/// </summary>
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/// <param name="participantCount">The number of additional participants to add to the
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/// barrier.</param>
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/// <returns>The phase number of the barrier in which the new participants will first
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/// participate.</returns>
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/// <exception cref="T:System.ArgumentOutOfRangeException"><paramref name="participantCount"/> is less than
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/// 0.</exception>
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/// <exception cref="T:System.ArgumentOutOfRangeException">Adding <paramref name="participantCount"/> participants would cause the
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/// barrier's participant count to exceed <see cref="T:System.Int16.MaxValue"/>.</exception>
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/// <exception cref="T:System.InvalidOperationException">
|
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/// The method was invoked from within a post-phase action.
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/// </exception>
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/// <exception cref="T:System.ObjectDisposedException">The current instance has already been
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/// disposed.</exception>
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public long AddParticipants(int participantCount)
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{
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// check dispose
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ThrowIfDisposed();
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if (participantCount < 1 )
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{
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throw new ArgumentOutOfRangeException("participantCount", participantCount,
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SR.GetString(SR.Barrier_AddParticipants_NonPositive_ArgumentOutOfRange));
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}
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else if (participantCount > MAX_PARTICIPANTS) //overflow
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{
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throw new ArgumentOutOfRangeException("participantCount",
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SR.GetString(SR.Barrier_AddParticipants_Overflow_ArgumentOutOfRange));
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}
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// in case of this is called from the PHA
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if (m_actionCallerID != 0 && Thread.CurrentThread.ManagedThreadId == m_actionCallerID)
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{
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throw new InvalidOperationException(SR.GetString(SR.Barrier_InvalidOperation_CalledFromPHA));
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}
|
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SpinWait spinner = new SpinWait();
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long newPhase = 0;
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while (true)
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{
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int currentTotal = m_currentTotalCount;
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int total;
|
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int current;
|
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bool sense;
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GetCurrentTotal(currentTotal, out current, out total, out sense);
|
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if (participantCount + total > MAX_PARTICIPANTS) //overflow
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{
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throw new ArgumentOutOfRangeException("participantCount",
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SR.GetString(SR.Barrier_AddParticipants_Overflow_ArgumentOutOfRange));
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}
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if (SetCurrentTotal(currentTotal, current, total + participantCount, sense))
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{
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// Calculating the first phase for that participant, if the current phase already finished return the nextphase else return the current phase
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// To know that the current phase is the sense doesn't match the
|
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// phase odd even, so that means it didn't yet change the phase count, so currentPhase +1 is returned, otherwise currentPhase is returned
|
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long currPhase = CurrentPhaseNumber;
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newPhase = (sense != (currPhase % 2 == 0)) ? currPhase + 1 : currPhase;
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// If this participant is going to join the next phase, which means the postPhaseAction is being running, this participants must wait until this done
|
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// and its event is reset.
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// Without that, if the postPhaseAction takes long time, this means the event ehich the current participant is goint to wait on is still set
|
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// (FinishPPhase didn't reset it yet) so it should wait until it reset
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if (newPhase != currPhase)
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{
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// Wait on the opposite event
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if (sense)
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{
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m_oddEvent.Wait();
|
||
}
|
||
else
|
||
{
|
||
m_evenEvent.Wait();
|
||
}
|
||
}
|
||
|
||
//This else to fix the racing where the current phase has been finished, m_currentPhase has been updated but the events have not been set/reset yet
|
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// otherwise when this participant calls SignalAndWait it will wait on a set event however all other participants have not arrived yet.
|
||
else
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||
{
|
||
if (sense && m_evenEvent.IsSet)
|
||
m_evenEvent.Reset();
|
||
else if (!sense && m_oddEvent.IsSet)
|
||
m_oddEvent.Reset();
|
||
}
|
||
break;
|
||
}
|
||
spinner.SpinOnce();
|
||
}
|
||
return newPhase;
|
||
}
|
||
|
||
/// <summary>
|
||
/// Notifies the <see cref="Barrier"/> that there will be one less participant.
|
||
/// </summary>
|
||
/// <exception cref="T:System.InvalidOperationException">The barrier already has 0
|
||
/// participants.</exception>
|
||
/// <exception cref="T:System.InvalidOperationException">
|
||
/// The method was invoked from within a post-phase action.
|
||
/// </exception>
|
||
/// <exception cref="T:System.ObjectDisposedException">The current instance has already been
|
||
/// disposed.</exception>
|
||
public void RemoveParticipant()
|
||
{
|
||
RemoveParticipants(1);
|
||
}
|
||
|
||
/// <summary>
|
||
/// Notifies the <see cref="Barrier"/> that there will be fewer participants.
|
||
/// </summary>
|
||
/// <param name="participantCount">The number of additional participants to remove from the barrier.</param>
|
||
/// <exception cref="T:System.ArgumentOutOfRangeException"><paramref name="participantCount"/> is less than
|
||
/// 0.</exception>
|
||
/// <exception cref="T:System.InvalidOperationException">The barrier already has 0 participants.</exception>
|
||
/// <exception cref="T:System.InvalidOperationException">
|
||
/// The method was invoked from within a post-phase action.
|
||
/// </exception>
|
||
/// <exception cref="T:System.ObjectDisposedException">The current instance has already been
|
||
/// disposed.</exception>
|
||
public void RemoveParticipants(int participantCount)
|
||
{
|
||
// check dispose
|
||
ThrowIfDisposed();
|
||
|
||
// Validate input
|
||
if (participantCount < 1)
|
||
{
|
||
throw new ArgumentOutOfRangeException("participantCount", participantCount,
|
||
SR.GetString(SR.Barrier_RemoveParticipants_NonPositive_ArgumentOutOfRange));
|
||
}
|
||
|
||
// in case of this is called from the PHA
|
||
if (m_actionCallerID != 0 && Thread.CurrentThread.ManagedThreadId == m_actionCallerID)
|
||
{
|
||
throw new InvalidOperationException(SR.GetString(SR.Barrier_InvalidOperation_CalledFromPHA));
|
||
}
|
||
|
||
SpinWait spinner = new SpinWait();
|
||
while (true)
|
||
{
|
||
int currentTotal = m_currentTotalCount;
|
||
int total;
|
||
int current;
|
||
bool sense;
|
||
GetCurrentTotal(currentTotal, out current, out total, out sense);
|
||
|
||
if (total < participantCount)
|
||
{
|
||
throw new ArgumentOutOfRangeException("participantCount",
|
||
SR.GetString(SR.Barrier_RemoveParticipants_ArgumentOutOfRange));
|
||
}
|
||
if (total - participantCount < current)
|
||
{
|
||
throw new InvalidOperationException(SR.GetString(SR.Barrier_RemoveParticipants_InvalidOperation));
|
||
}
|
||
// If the remaining participats = current participants, then finish the current phase
|
||
int remaingParticipants = total - participantCount;
|
||
if (remaingParticipants > 0 && current == remaingParticipants )
|
||
{
|
||
if (SetCurrentTotal(currentTotal, 0, total - participantCount, !sense))
|
||
{
|
||
FinishPhase(sense);
|
||
break;
|
||
}
|
||
}
|
||
else
|
||
{
|
||
if (SetCurrentTotal(currentTotal, current, total - participantCount, sense))
|
||
{
|
||
break;
|
||
}
|
||
}
|
||
spinner.SpinOnce();
|
||
}
|
||
}
|
||
|
||
/// <summary>
|
||
/// Signals that a participant has reached the <see cref="Barrier"/> and waits for all other
|
||
/// participants to reach the barrier as well.
|
||
/// </summary>
|
||
/// <exception cref="T:System.InvalidOperationException">
|
||
/// The method was invoked from within a post-phase action, the barrier currently has 0 participants,
|
||
/// or the barrier is being used by more threads than are registered as participants.
|
||
/// </exception>
|
||
/// <exception cref="T:System.ObjectDisposedException">The current instance has already been
|
||
/// disposed.</exception>
|
||
public void SignalAndWait()
|
||
{
|
||
SignalAndWait(new CancellationToken());
|
||
}
|
||
|
||
/// <summary>
|
||
/// Signals that a participant has reached the <see cref="Barrier"/> and waits for all other
|
||
/// participants to reach the barrier, while observing a <see
|
||
/// cref="T:System.Threading.CancellationToken"/>.
|
||
/// </summary>
|
||
/// <param name="cancellationToken">The <see cref="T:System.Threading.CancellationToken"/> to
|
||
/// observe.</param>
|
||
/// <exception cref="T:System.InvalidOperationException">
|
||
/// The method was invoked from within a post-phase action, the barrier currently has 0 participants,
|
||
/// or the barrier is being used by more threads than are registered as participants.
|
||
/// </exception>
|
||
/// <exception cref="T:System.OperationCanceledException"><paramref name="cancellationToken"/> has been
|
||
/// canceled.</exception>
|
||
/// <exception cref="T:System.ObjectDisposedException">The current instance has already been
|
||
/// disposed.</exception>
|
||
public void SignalAndWait(CancellationToken cancellationToken)
|
||
{
|
||
#if DEBUG
|
||
bool result =
|
||
#endif
|
||
SignalAndWait(Timeout.Infinite, cancellationToken);
|
||
#if DEBUG
|
||
Debug.Assert(result);
|
||
#endif
|
||
}
|
||
|
||
/// <summary>
|
||
/// Signals that a participant has reached the <see cref="Barrier"/> and waits for all other
|
||
/// participants to reach the barrier as well, using a
|
||
/// <see cref="T:System.TimeSpan"/> to measure the time interval.
|
||
/// </summary>
|
||
/// <param name="timeout">A <see cref="T:System.TimeSpan"/> that represents the number of
|
||
/// milliseconds to wait, or a <see cref="T:System.TimeSpan"/> that represents -1 milliseconds to
|
||
/// wait indefinitely.</param>
|
||
/// <returns>true if all other participants reached the barrier; otherwise, false.</returns>
|
||
/// <exception cref="T:System.ArgumentOutOfRangeException"><paramref name="timeout"/>is a negative number
|
||
/// other than -1 milliseconds, which represents an infinite time-out, or it is greater than
|
||
/// <see cref="T:System.Int32.MaxValue"/>.</exception>
|
||
/// <exception cref="T:System.InvalidOperationException">
|
||
/// The method was invoked from within a post-phase action, the barrier currently has 0 participants,
|
||
/// or the barrier is being used by more threads than are registered as participants.
|
||
/// </exception>
|
||
/// <exception cref="T:System.ObjectDisposedException">The current instance has already been
|
||
/// disposed.</exception>
|
||
public Boolean SignalAndWait(TimeSpan timeout)
|
||
{
|
||
return SignalAndWait(timeout, new CancellationToken());
|
||
}
|
||
|
||
/// <summary>
|
||
/// Signals that a participant has reached the <see cref="Barrier"/> and waits for all other
|
||
/// participants to reach the barrier as well, using a
|
||
/// <see cref="T:System.TimeSpan"/> to measure the time interval, while observing a <see
|
||
/// cref="T:System.Threading.CancellationToken"/>.
|
||
/// </summary>
|
||
/// <param name="timeout">A <see cref="T:System.TimeSpan"/> that represents the number of
|
||
/// milliseconds to wait, or a <see cref="T:System.TimeSpan"/> that represents -1 milliseconds to
|
||
/// wait indefinitely.</param>
|
||
/// <param name="cancellationToken">The <see cref="T:System.Threading.CancellationToken"/> to
|
||
/// observe.</param>
|
||
/// <returns>true if all other participants reached the barrier; otherwise, false.</returns>
|
||
/// <exception cref="T:System.ArgumentOutOfRangeException"><paramref name="timeout"/>is a negative number
|
||
/// other than -1 milliseconds, which represents an infinite time-out.</exception>
|
||
/// <exception cref="T:System.InvalidOperationException">
|
||
/// The method was invoked from within a post-phase action, the barrier currently has 0 participants,
|
||
/// or the barrier is being used by more threads than are registered as participants.
|
||
/// </exception>
|
||
/// <exception cref="T:System.OperationCanceledException"><paramref name="cancellationToken"/> has been
|
||
/// canceled.</exception>
|
||
/// <exception cref="T:System.ObjectDisposedException">The current instance has already been
|
||
/// disposed.</exception>
|
||
public Boolean SignalAndWait(TimeSpan timeout, CancellationToken cancellationToken)
|
||
{
|
||
Int64 totalMilliseconds = (Int64)timeout.TotalMilliseconds;
|
||
if (totalMilliseconds < -1 || totalMilliseconds > int.MaxValue)
|
||
{
|
||
throw new System.ArgumentOutOfRangeException("timeout", timeout,
|
||
SR.GetString(SR.Barrier_SignalAndWait_ArgumentOutOfRange));
|
||
}
|
||
return SignalAndWait((int)timeout.TotalMilliseconds, cancellationToken);
|
||
}
|
||
|
||
/// <summary>
|
||
/// Signals that a participant has reached the <see cref="Barrier"/> and waits for all other
|
||
/// participants to reach the barrier as well, using a
|
||
/// 32-bit signed integer to measure the time interval.
|
||
/// </summary>
|
||
/// <param name="millisecondsTimeout">The number of milliseconds to wait, or <see
|
||
/// cref="Timeout.Infinite"/>(-1) to wait indefinitely.</param>
|
||
/// <returns>true if all other participants reached the barrier; otherwise, false.</returns>
|
||
/// <exception cref="T:System.ArgumentOutOfRangeException"><paramref name="millisecondsTimeout"/> is a
|
||
/// negative number other than -1, which represents an infinite time-out.</exception>
|
||
/// <exception cref="T:System.InvalidOperationException">
|
||
/// The method was invoked from within a post-phase action, the barrier currently has 0 participants,
|
||
/// or the barrier is being used by more threads than are registered as participants.
|
||
/// </exception>
|
||
/// <exception cref="T:System.ObjectDisposedException">The current instance has already been
|
||
/// disposed.</exception>
|
||
public bool SignalAndWait(int millisecondsTimeout)
|
||
{
|
||
return SignalAndWait(millisecondsTimeout, new CancellationToken());
|
||
}
|
||
|
||
/// <summary>
|
||
/// Signals that a participant has reached the barrier and waits for all other participants to reach
|
||
/// the barrier as well, using a
|
||
/// 32-bit signed integer to measure the time interval, while observing a <see
|
||
/// cref="T:System.Threading.CancellationToken"/>.
|
||
/// </summary>
|
||
/// <param name="millisecondsTimeout">The number of milliseconds to wait, or <see
|
||
/// cref="Timeout.Infinite"/>(-1) to wait indefinitely.</param>
|
||
/// <param name="cancellationToken">The <see cref="T:System.Threading.CancellationToken"/> to
|
||
/// observe.</param>
|
||
/// <returns>true if all other participants reached the barrier; otherwise, false.</returns>
|
||
/// <exception cref="T:System.ArgumentOutOfRangeException"><paramref name="millisecondsTimeout"/> is a
|
||
/// negative number other than -1, which represents an infinite time-out.</exception>
|
||
/// <exception cref="T:System.InvalidOperationException">
|
||
/// The method was invoked from within a post-phase action, the barrier currently has 0 participants,
|
||
/// or the barrier is being used by more threads than are registered as participants.
|
||
/// </exception>
|
||
/// <exception cref="T:System.OperationCanceledException"><paramref name="cancellationToken"/> has been
|
||
/// canceled.</exception>
|
||
/// <exception cref="T:System.ObjectDisposedException">The current instance has already been
|
||
/// disposed.</exception>
|
||
public bool SignalAndWait(int millisecondsTimeout, CancellationToken cancellationToken)
|
||
{
|
||
ThrowIfDisposed();
|
||
cancellationToken.ThrowIfCancellationRequested();
|
||
|
||
if (millisecondsTimeout < -1)
|
||
{
|
||
throw new System.ArgumentOutOfRangeException("millisecondsTimeout", millisecondsTimeout,
|
||
SR.GetString(SR.Barrier_SignalAndWait_ArgumentOutOfRange));
|
||
}
|
||
|
||
// in case of this is called from the PHA
|
||
if (m_actionCallerID != 0 && Thread.CurrentThread.ManagedThreadId == m_actionCallerID)
|
||
{
|
||
throw new InvalidOperationException(SR.GetString(SR.Barrier_InvalidOperation_CalledFromPHA));
|
||
}
|
||
|
||
// local variables to extract the basic barrier variable and update them
|
||
// The are declared here instead of inside the loop body because the will be used outside the loop
|
||
bool sense; // The sense of the barrier *before* the phase associated with this SignalAndWait call completes
|
||
int total;
|
||
int current;
|
||
int currentTotal;
|
||
long phase;
|
||
SpinWait spinner = new SpinWait();
|
||
while (true)
|
||
{
|
||
currentTotal = m_currentTotalCount;
|
||
GetCurrentTotal(currentTotal, out current, out total, out sense);
|
||
phase = CurrentPhaseNumber;
|
||
// throw if zero participants
|
||
if (total == 0)
|
||
{
|
||
throw new InvalidOperationException(SR.GetString(SR.Barrier_SignalAndWait_InvalidOperation_ZeroTotal));
|
||
}
|
||
// Try to detect if the number of threads for this phase exceeded the total number of participants or not
|
||
// This can be detected if the current is zero which means all participants for that phase has arrived and the phase number is not changed yet
|
||
if (current == 0 && sense != (CurrentPhaseNumber % 2 == 0))
|
||
{
|
||
throw new InvalidOperationException(SR.GetString(SR.Barrier_SignalAndWait_InvalidOperation_ThreadsExceeded));
|
||
}
|
||
//This is the last thread, finish the phase
|
||
if (current + 1 == total)
|
||
{
|
||
if (SetCurrentTotal(currentTotal, 0, total, !sense))
|
||
{
|
||
#if !FEATURE_PAL && !SILVERLIGHT // PAL doesn't support eventing
|
||
if (CdsSyncEtwBCLProvider.Log.IsEnabled())
|
||
{
|
||
CdsSyncEtwBCLProvider.Log.Barrier_PhaseFinished(sense, CurrentPhaseNumber);
|
||
}
|
||
#endif
|
||
FinishPhase(sense);
|
||
return true;
|
||
}
|
||
}
|
||
else if (SetCurrentTotal(currentTotal, current + 1, total, sense))
|
||
{
|
||
break;
|
||
}
|
||
|
||
spinner.SpinOnce();
|
||
|
||
}
|
||
|
||
// ** Perform the real wait **
|
||
// select the correct event to wait on, based on the current sense.
|
||
ManualResetEventSlim eventToWaitOn = (sense) ? m_evenEvent : m_oddEvent;
|
||
|
||
bool waitWasCanceled = false;
|
||
bool waitResult = false;
|
||
try
|
||
{
|
||
waitResult = DiscontinuousWait(eventToWaitOn, millisecondsTimeout, cancellationToken, phase);
|
||
}
|
||
catch (OperationCanceledException )
|
||
{
|
||
waitWasCanceled = true;
|
||
}
|
||
catch (ObjectDisposedException)// in case a ---- happen where one of the thread returned from SignalAndWait and the current thread calls Wait on a disposed event
|
||
{
|
||
// make sure the current phase for this thread is already finished, otherwise propagate the exception
|
||
if (phase < CurrentPhaseNumber)
|
||
waitResult = true;
|
||
else
|
||
throw;
|
||
}
|
||
|
||
|
||
|
||
if (!waitResult)
|
||
{
|
||
//reset the spinLock to prepare it for the next loop
|
||
spinner.Reset();
|
||
|
||
//If the wait timeout expired and all other thread didn't reach the barrier yet, update the current count back
|
||
while (true)
|
||
{
|
||
bool newSense;
|
||
currentTotal = m_currentTotalCount;
|
||
GetCurrentTotal(currentTotal, out current, out total, out newSense);
|
||
// If the timeout expired and the phase has just finished, return true and this is considered as succeeded SignalAndWait
|
||
//otherwise the timeout expired and the current phase has not been finished yet, return false
|
||
//The phase is finished if the phase member variable is changed (incremented) or the sense has been changed
|
||
// we have to use the statements in the comparison below for two cases:
|
||
// 1- The sense is changed but the last thread didn't update the phase yet
|
||
// 2- The phase is already incremented but the sense flipped twice due to the termination of the next phase
|
||
if (phase < CurrentPhaseNumber || sense != newSense)
|
||
{
|
||
|
||
// The current phase has been finished, but we shouldn't return before the events are set/reset otherwise this thread could start
|
||
// next phase and the appropriate event has not reset yet which could make it return immediately from the next phase SignalAndWait
|
||
// before waiting other threads
|
||
WaitCurrentPhase(eventToWaitOn, phase);
|
||
Debug.Assert(phase < CurrentPhaseNumber);
|
||
break;
|
||
}
|
||
//The phase has not been finished yet, try to update the current count.
|
||
if (SetCurrentTotal(currentTotal, current - 1, total, sense))
|
||
{
|
||
//if here, then the attempt to backout was successful.
|
||
//throw (a fresh) oce if cancellation woke the wait
|
||
//or return false if it was the timeout that woke the wait.
|
||
//
|
||
if (waitWasCanceled)
|
||
throw new OperationCanceledException(SR.GetString(SR.Common_OperationCanceled), cancellationToken);
|
||
else
|
||
return false;
|
||
}
|
||
spinner.SpinOnce();
|
||
}
|
||
}
|
||
|
||
if (m_exception != null)
|
||
throw new BarrierPostPhaseException(m_exception);
|
||
|
||
return true;
|
||
|
||
}
|
||
|
||
/// <summary>
|
||
/// Finish the phase by invoking the post phase action, and setting the event, this must be called by the
|
||
/// last arrival thread
|
||
/// </summary>
|
||
/// <param name="observedSense">The current phase sense</param>
|
||
[SecuritySafeCritical]
|
||
private void FinishPhase(bool observedSense)
|
||
{
|
||
// Execute the PHA in try/finally block to reset the variables back in case of it threw an exception
|
||
if (m_postPhaseAction != null)
|
||
{
|
||
try
|
||
{
|
||
// Capture the caller thread ID to check if the Add/RemoveParticipant(s) is called from the PHA
|
||
m_actionCallerID = Thread.CurrentThread.ManagedThreadId;
|
||
if (m_ownerThreadContext != null)
|
||
{
|
||
var currentContext = m_ownerThreadContext;
|
||
m_ownerThreadContext = m_ownerThreadContext.CreateCopy(); // create a copy for the next run
|
||
|
||
ContextCallback handler = s_invokePostPhaseAction;
|
||
if (handler == null)
|
||
{
|
||
s_invokePostPhaseAction = handler = InvokePostPhaseAction;
|
||
}
|
||
ExecutionContext.Run(currentContext, handler, this);
|
||
#if !PFX_LEGACY_3_5
|
||
// Dispose the context directly after using it,
|
||
// the copy will either be used and siposed in the next phase or in the Dispose
|
||
currentContext.Dispose();
|
||
#endif
|
||
}
|
||
else
|
||
{
|
||
m_postPhaseAction(this);
|
||
}
|
||
m_exception = null; // reset the exception if it was set previously
|
||
}
|
||
catch (Exception ex)
|
||
{
|
||
m_exception = ex;
|
||
}
|
||
finally
|
||
{
|
||
m_actionCallerID = 0;
|
||
SetResetEvents(observedSense);
|
||
if(m_exception != null)
|
||
throw new BarrierPostPhaseException(m_exception);
|
||
}
|
||
|
||
}
|
||
else
|
||
{
|
||
SetResetEvents(observedSense);
|
||
}
|
||
}
|
||
|
||
/// <summary>
|
||
/// Helper method to call the post phase action
|
||
/// </summary>
|
||
/// <param name="obj"></param>
|
||
[SecurityCritical]
|
||
private static void InvokePostPhaseAction(object obj)
|
||
{
|
||
var thisBarrier = (Barrier)obj;
|
||
thisBarrier.m_postPhaseAction(thisBarrier);
|
||
}
|
||
|
||
/// <summary>
|
||
/// Sets the current phase event and reset the next phase event
|
||
/// </summary>
|
||
/// <param name="observedSense">The current phase sense</param>
|
||
private void SetResetEvents(bool observedSense)
|
||
{
|
||
// Increment the phase count using Volatile class because m_currentPhase is 64 bit long type, that could cause torn write on 32 bit machines
|
||
CurrentPhaseNumber = CurrentPhaseNumber + 1;
|
||
if (observedSense)
|
||
{
|
||
m_oddEvent.Reset();
|
||
m_evenEvent.Set();
|
||
}
|
||
else
|
||
{
|
||
m_evenEvent.Reset();
|
||
m_oddEvent.Set();
|
||
}
|
||
}
|
||
|
||
/// <summary>
|
||
/// Wait until the current phase finishes completely by spinning until either the event is set,
|
||
/// or the phase count is incremented more than one time
|
||
/// </summary>
|
||
/// <param name="currentPhaseEvent">The current phase event</param>
|
||
/// <param name="observedPhase">The current phase for that thread</param>
|
||
private void WaitCurrentPhase(ManualResetEventSlim currentPhaseEvent, long observedPhase)
|
||
{
|
||
//spin until either of these two conditions succeeds
|
||
//1- The event is set
|
||
//2- the phase count is incremented more than one time, this means the next phase is finished as well,
|
||
//but the event will be reset again, so we check the phase count instead
|
||
SpinWait spinner = new SpinWait();
|
||
while (!currentPhaseEvent.IsSet && CurrentPhaseNumber - observedPhase <= 1)
|
||
{
|
||
spinner.SpinOnce();
|
||
}
|
||
}
|
||
|
||
/// <summary>
|
||
/// The reason of discontinuous waiting instead of direct waiting on the event is to avoid the ---- where the sense is
|
||
/// changed twice because the next phase is finished (due to either RemoveParticipant is called or another thread joined
|
||
/// the next phase instead of the current thread) so the current thread will be stuck on the event because it is reset back
|
||
/// The maxwait and the shift numbers are arbitrarily choosen, there were no references picking them
|
||
/// </summary>
|
||
/// <param name="currentPhaseEvent">The current phase event</param>
|
||
/// <param name="totalTimeout">wait timeout in milliseconds</param>
|
||
/// <param name="token">cancellation token passed to SignalAndWait</param>
|
||
/// <param name="observedPhase">The current phase number for this thread</param>
|
||
/// <returns>True if the event is set or the phasenumber changed, false if the timeout expired</returns>
|
||
private bool DiscontinuousWait(ManualResetEventSlim currentPhaseEvent, int totalTimeout, CancellationToken token, long observedPhase)
|
||
{
|
||
int maxWait = 100; // 100 ms
|
||
int waitTimeCeiling = 10000; // 10 seconds
|
||
while (observedPhase == CurrentPhaseNumber)
|
||
{
|
||
// the next wait time, the min of the maxWait and the totalTimeout
|
||
int waitTime = totalTimeout == Timeout.Infinite ? maxWait : Math.Min(maxWait, totalTimeout);
|
||
|
||
if (currentPhaseEvent.Wait(waitTime, token)) return true;
|
||
|
||
//update the total wait time
|
||
if (totalTimeout != Timeout.Infinite)
|
||
{
|
||
totalTimeout -= waitTime;
|
||
if (totalTimeout <= 0) return false;
|
||
}
|
||
|
||
//if the maxwait exceeded 10 seconds then we will stop increasing the maxWait time and keep it 10 seconds, otherwise keep doubling it
|
||
maxWait = maxWait >= waitTimeCeiling ? waitTimeCeiling : Math.Min(maxWait << 1, waitTimeCeiling);
|
||
}
|
||
|
||
//if we exited the loop because the observed phase doesn't match the current phase, then we have to spin to mske sure
|
||
//the event is set or the next phase is finished
|
||
WaitCurrentPhase(currentPhaseEvent, observedPhase);
|
||
|
||
return true;
|
||
}
|
||
|
||
/// <summary>
|
||
/// Releases all resources used by the current instance of <see cref="Barrier"/>.
|
||
/// </summary>
|
||
/// <exception cref="T:System.InvalidOperationException">
|
||
/// The method was invoked from within a post-phase action.
|
||
/// </exception>
|
||
/// <remarks>
|
||
/// Unlike most of the members of <see cref="Barrier"/>, Dispose is not thread-safe and may not be
|
||
/// used concurrently with other members of this instance.
|
||
/// </remarks>
|
||
public void Dispose()
|
||
{
|
||
// in case of this is called from the PHA
|
||
if (m_actionCallerID != 0 && Thread.CurrentThread.ManagedThreadId == m_actionCallerID)
|
||
{
|
||
throw new InvalidOperationException(SR.GetString(SR.Barrier_InvalidOperation_CalledFromPHA));
|
||
}
|
||
Dispose(true);
|
||
GC.SuppressFinalize(this);
|
||
}
|
||
|
||
/// <summary>
|
||
/// When overridden in a derived class, releases the unmanaged resources used by the
|
||
/// <see cref="Barrier"/>, and optionally releases the managed resources.
|
||
/// </summary>
|
||
/// <param name="disposing">true to release both managed and unmanaged resources; false to release
|
||
/// only unmanaged resources.</param>
|
||
/// <remarks>
|
||
/// Unlike most of the members of <see cref="Barrier"/>, Dispose is not thread-safe and may not be
|
||
/// used concurrently with other members of this instance.
|
||
/// </remarks>
|
||
protected virtual void Dispose(bool disposing)
|
||
{
|
||
if (!m_disposed)
|
||
{
|
||
if (disposing)
|
||
{
|
||
m_oddEvent.Dispose();
|
||
m_evenEvent.Dispose();
|
||
#if !PFX_LEGACY_3_5
|
||
if (m_ownerThreadContext != null)
|
||
{
|
||
m_ownerThreadContext.Dispose();
|
||
m_ownerThreadContext = null;
|
||
}
|
||
#endif
|
||
}
|
||
m_disposed = true;
|
||
}
|
||
}
|
||
|
||
/// <summary>
|
||
/// Throw ObjectDisposedException if the barrier is disposed
|
||
/// </summary>
|
||
private void ThrowIfDisposed()
|
||
{
|
||
if (m_disposed)
|
||
{
|
||
throw new ObjectDisposedException("Barrier", SR.GetString(SR.Barrier_Dispose));
|
||
}
|
||
}
|
||
}
|
||
}
|