277 lines
12 KiB
C#
277 lines
12 KiB
C#
//------------------------------------------------------------------------------
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// <copyright file="RootedObjects.cs" company="Microsoft">
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// Copyright (c) Microsoft Corporation. All rights reserved.
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// </copyright>
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//------------------------------------------------------------------------------
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namespace System.Web {
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using System;
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using System.Runtime.CompilerServices;
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using System.Runtime.InteropServices;
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using System.Security.Permissions;
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using System.Security.Principal;
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using System.Web.Hosting;
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using System.Web.Management;
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using System.Web.Security;
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using System.Web.Util;
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// Used by the IIS integrated pipeline to reference managed objects so that they're not claimed by the GC while unmanaged code is executing.
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[SecurityPermission(SecurityAction.LinkDemand, UnmanagedCode = true)]
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internal sealed class RootedObjects : IPrincipalContainer {
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// These two fields are for ETW scenarios. In .NET 4.5.1, the API SetCurrentThreadActivityId
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// can be used to correlate operations back to a given activity ID, where [in our case] an
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// activity ID corresponds to a single request. We need to ref count since we have multiple
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// threads operating on (or destroying) the request at once, and we need to know when the
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// managed request has actually finished. For example, we can't just release an activity ID
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// inside of our Destroy method since Destroy might be called on a thread pool thread while
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// some other managed thread is still unwinding inside of PipelineRuntime. When this counter
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// hits zero, we can fully release the activity ID.
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private readonly bool _activityIdTracingIsEnabled;
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private readonly Guid _requestActivityId;
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private int _requestActivityIdRefCount = 1;
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private SubscriptionQueue<IDisposable> _pipelineCompletedQueue;
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private GCHandle _handle;
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private RootedObjects() {
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_handle = GCHandle.Alloc(this);
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Pointer = (IntPtr)_handle;
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// Increment active request count as soon as possible to prevent
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// shutdown of the appdomain while requests are in flight. It
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// is decremented in Destroy().
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HttpRuntime.IncrementActivePipelineCount();
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// this is an instance field instead of a static field since ETW can be enabled at any time
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_activityIdTracingIsEnabled = ActivityIdHelper.Instance != null && AspNetEventSource.Instance.IsEnabled();
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if (_activityIdTracingIsEnabled) {
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_requestActivityId = ActivityIdHelper.UnsafeCreateNewActivityId();
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}
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}
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// The HttpContext associated with this request.
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// May be null if this is a WebSocket request or if the request has completed.
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public HttpContext HttpContext {
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get;
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set;
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}
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// The principal associated with this request.
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// May be null if there is no associated principal or if the request has completed.
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public IPrincipal Principal {
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get;
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set;
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}
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// A pointer that can be used (via FromPointer) to reference this RootedObjects instance.
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public IntPtr Pointer {
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get;
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private set;
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}
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// The WebSocketPipeline that's associated with this request.
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// May be null if this request won't be transitioned to a WebSocket request or if it has completed.
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public WebSocketPipeline WebSocketPipeline {
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get;
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set;
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}
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// The worker request (IIS7+) associated with this request.
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// May be null if the request has completed.
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public IIS7WorkerRequest WorkerRequest {
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get;
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set;
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}
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// Using a static factory instead of a public constructor since there's a side effect.
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// Namely, the new object will never be garbage collected unless Destroy() is called.
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public static RootedObjects Create() {
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return new RootedObjects();
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}
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// Fully releases all managed resources associated with this request, including
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// the HttpContext, WebSocketContext, principal, worker request, etc.
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public void Destroy() {
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Debug.Trace("RootedObjects", "Destroy");
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// 'isDestroying = true' means that we'll release the implicit 'this' ref in _requestActivityIdRefCount
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using (WithinTraceBlock(isDestroying: true)) {
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try {
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ReleaseHttpContext();
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ReleaseWebSocketPipeline();
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ReleaseWorkerRequest();
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ReleasePrincipal();
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// need to raise OnPipelineCompleted outside of the ThreadContext so that HttpContext.Current, User, etc. are unavailable
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RaiseOnPipelineCompleted();
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PerfCounters.DecrementCounter(AppPerfCounter.REQUESTS_EXECUTING);
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}
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finally {
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if (_handle.IsAllocated) {
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_handle.Free();
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}
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Pointer = IntPtr.Zero;
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HttpRuntime.DecrementActivePipelineCount();
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AspNetEventSource.Instance.RequestCompleted();
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}
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}
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}
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// Analog of HttpContext.DisposeOnPipelineCompleted for the integrated pipeline
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internal ISubscriptionToken DisposeOnPipelineCompleted(IDisposable target) {
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return _pipelineCompletedQueue.Enqueue(target);
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}
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public static RootedObjects FromPointer(IntPtr pointer) {
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GCHandle handle = (GCHandle)pointer;
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return (RootedObjects)handle.Target;
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}
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internal void RaiseOnPipelineCompleted() {
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// The callbacks really shouldn't throw exceptions, but we have a catch block just in case.
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// Since there's nobody else that can listen for these errors (the request is unwinding and
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// user code will no longer run), we'll just log the error.
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try {
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_pipelineCompletedQueue.FireAndComplete(disposable => disposable.Dispose());
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}
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catch (Exception e) {
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WebBaseEvent.RaiseRuntimeError(e, null);
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}
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}
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// Fully releases the HttpContext instance associated with this request.
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public void ReleaseHttpContext() {
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Debug.Trace("RootedObjects", "ReleaseHttpContext");
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if (HttpContext != null) {
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HttpContext.FinishPipelineRequest();
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}
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HttpContext = null;
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}
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// Disposes of the principal associated with this request.
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public void ReleasePrincipal() {
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Debug.Trace("RootedObjects", "ReleasePrincipal");
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if (Principal != null && Principal != WindowsAuthenticationModule.AnonymousPrincipal) {
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WindowsIdentity identity = Principal.Identity as WindowsIdentity; // original code only disposed of WindowsIdentity, not arbitrary IDisposable types
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if (identity != null) {
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Principal = null;
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identity.Dispose();
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}
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}
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// Fix Bug 640366: Setting the Principal to null (irrespective of Identity)
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// only if framework version is above .NetFramework 4.5 as this change is new and
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// we want to keep the functionality same for previous versions.
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if (BinaryCompatibility.Current.TargetsAtLeastFramework45) {
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Principal = null;
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}
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}
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// Disposes of the WebSocketPipeline instance associated with this request.
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public void ReleaseWebSocketPipeline() {
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Debug.Trace("RootedObjects", "ReleaseWebSocketContext");
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if (WebSocketPipeline != null) {
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WebSocketPipeline.Dispose();
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}
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WebSocketPipeline = null;
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}
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// Disposes of the worker request associated with this request.
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public void ReleaseWorkerRequest() {
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Debug.Trace("RootedObjects", "ReleaseWorkerRequest");
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if (WorkerRequest != null) {
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WorkerRequest.Dispose();
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}
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WorkerRequest = null;
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}
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// Sets up the ETW Activity ID on the current thread; caller should be:
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// using (rootedObjects.WithinTraceBlock()) {
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// .. something that might require tracing ..
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// }
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//
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// This is designed to be *very* cheap if tracing isn't enabled.
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[MethodImpl(MethodImplOptions.AggressiveInlining)]
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public ActivityIdToken WithinTraceBlock() {
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return WithinTraceBlock(isDestroying: false);
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}
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[MethodImpl(MethodImplOptions.AggressiveInlining)]
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private ActivityIdToken WithinTraceBlock(bool isDestroying) {
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if (_activityIdTracingIsEnabled) {
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return new ActivityIdToken(this, isDestroying);
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}
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else {
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return default(ActivityIdToken);
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}
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}
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// Called once per request; emits an ETW event saying that we transitioned from IIS -> ASP.NET
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public void WriteTransferEventIfNecessary() {
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Debug.Assert(WorkerRequest != null);
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if (_activityIdTracingIsEnabled) {
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Debug.Assert(_requestActivityId != Guid.Empty);
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AspNetEventSource.Instance.RequestEnteredAspNetPipeline(WorkerRequest, _requestActivityId);
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}
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}
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internal struct ActivityIdToken : IDisposable {
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private readonly bool _isDestroying;
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private readonly Guid _originalActivityId;
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private readonly RootedObjects _rootedObjects; // might be null if this is a dummy token
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internal ActivityIdToken(RootedObjects rootedObjects, bool isDestroying) {
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Debug.Assert(ActivityIdHelper.Instance != null);
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ActivityIdHelper.Instance.SetCurrentThreadActivityId(rootedObjects._requestActivityId, out _originalActivityId);
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lock (rootedObjects) {
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rootedObjects._requestActivityIdRefCount++;
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Debug.Assert(rootedObjects._requestActivityIdRefCount >= 2, "The original ref count should have been 1 or higher, else the activity ID could already have been released.");
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}
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_rootedObjects = rootedObjects;
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_isDestroying = isDestroying;
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}
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[MethodImpl(MethodImplOptions.AggressiveInlining)]
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public void Dispose() {
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if (_rootedObjects == null) {
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return; // this was a dummy token; no-op
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}
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DisposeImpl();
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}
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private void DisposeImpl() {
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Debug.Assert(ActivityIdHelper.Instance != null);
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Debug.Assert(ActivityIdHelper.Instance.CurrentThreadActivityId == _rootedObjects._requestActivityId, "Unexpected activity ID on current thread.");
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// We use a lock instead of Interlocked.Decrement so that we can guarantee that no thread
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// ever invokes the 'if' code path below before some other thread invokes the 'else' code
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// path.
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lock (_rootedObjects) {
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_rootedObjects._requestActivityIdRefCount -= (_isDestroying) ? 2 : 1;
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Debug.Assert(_rootedObjects._requestActivityIdRefCount >= 0, "Somebody called Dispose() too many times.");
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if (_rootedObjects._requestActivityIdRefCount == 0) {
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// this overload restores the original activity ID and releases the current activity ID
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ActivityIdHelper.Instance.SetCurrentThreadActivityId(_originalActivityId);
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}
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else {
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// this overload restores the original activity ID but preserves the current activity ID
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Guid unused;
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ActivityIdHelper.Instance.SetCurrentThreadActivityId(_originalActivityId, out unused);
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}
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}
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}
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}
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}
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}
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