127 lines
3.5 KiB
C#
127 lines
3.5 KiB
C#
//-----------------------------------------------------------------------------
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// Copyright (c) Microsoft Corporation. All rights reserved.
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//-----------------------------------------------------------------------------
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namespace System.Runtime
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{
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using System;
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using System.Threading;
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[Fx.Tag.SynchronizationPrimitive(Fx.Tag.BlocksUsing.NonBlocking)]
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class SignalGate
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{
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[Fx.Tag.SynchronizationObject(Blocking = false, Kind = Fx.Tag.SynchronizationKind.InterlockedNoSpin)]
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int state;
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public SignalGate()
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{
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}
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internal bool IsLocked
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{
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get
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{
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return this.state == GateState.Locked;
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}
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}
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internal bool IsSignalled
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{
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get
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{
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return this.state == GateState.Signalled;
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}
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}
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// Returns true if this brings the gate to the Signalled state.
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// Transitions - Locked -> SignalPending | Completed before it was unlocked
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// Unlocked -> Signaled
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public bool Signal()
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{
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int lastState = this.state;
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if (lastState == GateState.Locked)
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{
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lastState = Interlocked.CompareExchange(ref this.state, GateState.SignalPending, GateState.Locked);
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}
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if (lastState == GateState.Unlocked)
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{
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this.state = GateState.Signalled;
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return true;
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}
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if (lastState != GateState.Locked)
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{
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ThrowInvalidSignalGateState();
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}
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return false;
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}
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// Returns true if this brings the gate to the Signalled state.
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// Transitions - SignalPending -> Signaled | return the AsyncResult since the callback already
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// | completed and provided the result on its thread
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// Locked -> Unlocked
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public bool Unlock()
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{
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int lastState = this.state;
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if (lastState == GateState.Locked)
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{
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lastState = Interlocked.CompareExchange(ref this.state, GateState.Unlocked, GateState.Locked);
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}
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if (lastState == GateState.SignalPending)
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{
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this.state = GateState.Signalled;
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return true;
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}
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if (lastState != GateState.Locked)
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{
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ThrowInvalidSignalGateState();
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}
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return false;
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}
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// This is factored out to allow Signal and Unlock to be inlined.
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void ThrowInvalidSignalGateState()
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{
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throw Fx.Exception.AsError(new InvalidOperationException(InternalSR.InvalidSemaphoreExit));
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}
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static class GateState
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{
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public const int Locked = 0;
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public const int SignalPending = 1;
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public const int Unlocked = 2;
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public const int Signalled = 3;
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}
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}
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[Fx.Tag.SynchronizationPrimitive(Fx.Tag.BlocksUsing.NonBlocking)]
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class SignalGate<T> : SignalGate
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{
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T result;
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public SignalGate()
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: base()
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{
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}
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public bool Signal(T result)
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{
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this.result = result;
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return Signal();
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}
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public bool Unlock(out T result)
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{
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if (Unlock())
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{
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result = this.result;
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return true;
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}
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result = default(T);
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return false;
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}
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}
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}
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