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//------------------------------------------------------------------------------
// <copyright file="CustomRuntimeSuspendManager.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
//------------------------------------------------------------------------------
namespace System.Web.Hosting {
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Web.Util;
// Handles calling suspend and resume methods, including issues around
// synchronization and timeout handling.
internal sealed class CustomRuntimeManager : ICustomRuntimeManager {
private readonly ConcurrentDictionary<CustomRuntimeRegistration, object> _activeRegistrations = new ConcurrentDictionary<CustomRuntimeRegistration, object>();
private List<IProcessSuspendListener> GetAllSuspendListeners() {
List<IProcessSuspendListener> suspendListeners = new List<IProcessSuspendListener>();
foreach (var registration in _activeRegistrations.Keys) {
var suspendListener = registration.CustomRuntime as IProcessSuspendListener;
if (suspendListener != null) {
suspendListeners.Add(suspendListener);
}
}
return suspendListeners;
}
public ICustomRuntimeRegistrationToken Register(ICustomRuntime customRuntime) {
CustomRuntimeRegistration registration = new CustomRuntimeRegistration(this, customRuntime);
_activeRegistrations[registration] = null;
return registration;
}
// Custom runtimes are expected to be well-behaved so will be suspended sequentially and aren't
// subject to the 5-second timeout that normal applications are subject to.
public Action SuspendAllCustomRuntimes() {
var suspendListeners = GetAllSuspendListeners();
if (suspendListeners == null || suspendListeners.Count == 0) {
return null;
}
List<IProcessResumeCallback> callbacks = new List<IProcessResumeCallback>(suspendListeners.Count);
foreach (var suspendListener in suspendListeners) {
IProcessResumeCallback callback = null;
try {
callback = suspendListener.Suspend();
}
catch (AppDomainUnloadedException) {
// There exists a race condition where a custom runtime could have been stopped (unloaded)
// while a call to Suspend is in progress, so AD unloads may leak out. Don't treat this
// as a failure; just move on.
}
if (callback != null) {
callbacks.Add(callback);
}
}
return () => {
foreach (var callback in callbacks) {
try {
callback.Resume();
}
catch (AppDomainUnloadedException) {
// There exists a race condition where a custom runtime could have been stopped (unloaded)
// while a call to Suspend is in progress, so AD unloads may leak out. Don't treat this
// as a failure; just move on.
}
}
};
}
private sealed class CustomRuntimeRegistration : ICustomRuntimeRegistrationToken {
private readonly CustomRuntimeManager _customRuntimeManager;
public CustomRuntimeRegistration(CustomRuntimeManager customRuntimeManager, ICustomRuntime customRuntime) {
_customRuntimeManager = customRuntimeManager;
CustomRuntime = customRuntime;
}
public ICustomRuntime CustomRuntime { get; private set; }
public void Unregister() {
object dummy;
bool removed = _customRuntimeManager._activeRegistrations.TryRemove(this, out dummy);
Debug.Assert(removed, "Entry did not exist in the dictionary; was it removed twice?");
}
}
}
}
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