102 lines
3.1 KiB
Plaintext
102 lines
3.1 KiB
Plaintext
////////////////////////////////////////////////////////////////////////////////
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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: XRef.cs
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//
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// Note: File is part of Sing# runtime files and copied into Singularity tree
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// whenever a new version of Sing# is dropped.
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//
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using System;
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using Microsoft.SingSharp;
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using Microsoft.Singularity.Memory;
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namespace Microsoft.Singularity.Channels
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{
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using System.Threading;
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using Allocation = Microsoft.Singularity.Memory.SharedHeap.Allocation;
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public sealed class ExRef<T> where T : unmanaged struct, ITracked
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{
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unsafe T* opt(ExHeap) obj;
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Mutex mutex;
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public ExRef([Claims] T* opt(ExHeap)! i_obj, bool synchronized)
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{
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if (i_obj == null) {
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throw new ArgumentNullException("ExRef must be initialized with a non-null value!");
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}
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i_obj->Release();
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obj = i_obj;
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if (synchronized) {
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this.mutex = new Mutex();
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}
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}
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// invariant:
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// If mutex is held, thread holding mutex is
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// responsible for calling Release during that time,
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// the obj slot is empty and if the thread tries to
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// acquire it again, an exception is thrown.
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/// <summary>
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/// Will block until the ExRef is free.
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/// </summary>
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/// <returns>Acquired tracked type protected by ExRef</returns>
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public T* opt(ExHeap)! Acquire()
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{
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if (this.mutex != null) {
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this.mutex.WaitOne();
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}
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T* opt(ExHeap) elem = this.obj;
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if (elem == null) {
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throw new ApplicationException("thread already holds ExRef!");
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}
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elem->Acquire();
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this.obj = null;
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return elem;
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}
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/// <summary>
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/// Releases tracked data into the ExRef so other
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/// threads can access it.
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/// </summary>
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/// <param name="newObj">tracked data to be released</param>
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public void Release([Claims] T* opt(ExHeap)! newObj)
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{
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if (newObj == null) {
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throw new ArgumentNullException("ExRef must be released with a non-null value!");
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}
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T* opt(ExHeap) elem = this.obj;
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if (elem != null) {
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throw new ApplicationException("Releasing into occupied slot!");
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}
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newObj->Release();
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obj = newObj;
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if (this.mutex != null) {
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this.mutex.ReleaseMutex();
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}
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}
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/// <summary>
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/// Finalizer to dispose of any left over contents
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/// </summary>
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~ExRef()
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{
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T* opt(ExHeap) toDelete = this.obj;
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if (toDelete != null) {
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this.obj = null;
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unsafe {
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toDelete->Dispose(); // Explicit call needed due to generics
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}
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delete toDelete;
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}
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}
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}
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}
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