76 lines
2.2 KiB
C#
76 lines
2.2 KiB
C#
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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: ServiceRequestQueue.cs
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//
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// Note:
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//
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using System.Threading;
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namespace Microsoft.Singularity
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{
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public class ServiceRequestQueue
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{
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// Invariant: head == null <==> tail == null
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// tail.next is undefined.
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private ServiceRequest head = null;
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private ServiceRequest tail = null;
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private SpinLock spinLock;
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private AutoResetEvent enqueueEvent = new AutoResetEvent(false);
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// Insert an element at the tail of the queue.
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public void Enqueue(ServiceRequest req)
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{
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bool iflag = Processor.DisableInterrupts();
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spinLock.Acquire();
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try {
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if (head == null) {
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head = req;
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tail = req;
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}
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else {
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tail.next = req;
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tail = req;
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}
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enqueueEvent.Set();
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}
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finally {
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spinLock.Release();
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Processor.RestoreInterrupts(iflag);
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}
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}
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// Block while the queue is empty, then return the head of the queue.
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public ServiceRequest Dequeue()
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{
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while (true) {
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bool iflag = Processor.DisableInterrupts();
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spinLock.Acquire();
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try {
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if (tail != null)
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{
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ServiceRequest req = head;
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if (req != tail) {
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head = req.next;
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}
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else {
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head = null;
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tail = null;
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}
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return req;
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}
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}
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finally {
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spinLock.Release();
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Processor.RestoreInterrupts(iflag);
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}
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enqueueEvent.WaitOne();
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}
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}
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}
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}
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