515 lines
22 KiB
C#
515 lines
22 KiB
C#
//------------------------------------------------------------------------------
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// <copyright file="InProcStateClientManager.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.SessionState {
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using System.Threading;
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using System.Runtime.Serialization.Formatters.Binary;
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using System.Runtime.Serialization;
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using System.Text;
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using System.Collections;
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using System.IO;
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using System.Web;
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using System.Web.Caching;
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using System.Web.Util;
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using System.Xml;
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using System.Collections.Specialized;
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using System.Configuration.Provider;
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internal sealed class InProcSessionStateStore : SessionStateStoreProviderBase {
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internal static readonly int CACHEKEYPREFIXLENGTH = CacheInternal.PrefixInProcSessionState.Length;
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internal static readonly int NewLockCookie = 1;
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CacheItemRemovedCallback _callback;
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SessionStateItemExpireCallback _expireCallback;
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/*
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* Handle callbacks from the cache for session state expiry
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*/
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public void OnCacheItemRemoved(String key, Object value, CacheItemRemovedReason reason) {
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InProcSessionState state;
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String id;
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Debug.Trace("SessionOnEnd", "OnCacheItemRemoved called, reason = " + reason);
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PerfCounters.DecrementCounter(AppPerfCounter.SESSIONS_ACTIVE);
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state = (InProcSessionState) value;
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if ((state._flags & (int)SessionStateItemFlags.IgnoreCacheItemRemoved) != 0 ||
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(state._flags & (int)SessionStateItemFlags.Uninitialized) != 0) {
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Debug.Trace("SessionOnEnd", "OnCacheItemRemoved ignored");
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return;
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}
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switch (reason) {
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case CacheItemRemovedReason.Expired:
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PerfCounters.IncrementCounter(AppPerfCounter.SESSIONS_TIMED_OUT);
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break;
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case CacheItemRemovedReason.Removed:
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PerfCounters.IncrementCounter(AppPerfCounter.SESSIONS_ABANDONED);
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break;
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default:
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break;
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}
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TraceSessionStats();
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if (_expireCallback != null) {
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id = key.Substring(CACHEKEYPREFIXLENGTH);
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_expireCallback(id, SessionStateUtility.CreateLegitStoreData(null,
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state._sessionItems,
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state._staticObjects,
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state._timeout));
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}
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}
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private string CreateSessionStateCacheKey(String id) {
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return CacheInternal.PrefixInProcSessionState + id;
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}
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public override void Initialize(string name, NameValueCollection config)
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{
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if (String.IsNullOrEmpty(name))
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name = "InProc Session State Provider";
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base.Initialize(name, config);
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_callback = new CacheItemRemovedCallback(this.OnCacheItemRemoved);
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}
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public override bool SetItemExpireCallback(SessionStateItemExpireCallback expireCallback)
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{
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_expireCallback = expireCallback;
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return true;
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}
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public override void Dispose()
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{
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}
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public override void InitializeRequest(HttpContext context)
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{
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}
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SessionStateStoreData DoGet(HttpContext context,
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String id,
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bool exclusive,
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out bool locked,
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out TimeSpan lockAge,
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out object lockId,
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out SessionStateActions actionFlags) {
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string key = CreateSessionStateCacheKey(id);
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// Set default return values
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locked = false;
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lockId = null;
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lockAge = TimeSpan.Zero;
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actionFlags = 0;
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// Not technically necessary for InProc, but we do it to be consistent
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// with SQL provider
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SessionIDManager.CheckIdLength(id, true /* throwOnFail */);
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InProcSessionState state = (InProcSessionState)HttpRuntime.Cache.InternalCache.Get(key);
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if (state != null) {
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bool lockedByOther; // True if the state is locked by another session
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int initialFlags;
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initialFlags = (int)state._flags;
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if ((initialFlags & (int)SessionStateItemFlags.Uninitialized) != 0) {
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// It is an uninitialized item. We have to remove that flag.
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// We only allow one request to do that.
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// For details, see inline doc for SessionStateItemFlags.Uninitialized flag.
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// If initialFlags != return value of CompareExchange, it means another request has
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// removed the flag.
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Debug.Trace("SessionStateClientSet", "Removing the Uninit flag for item; key = " + key);
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if (initialFlags == Interlocked.CompareExchange(
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ref state._flags,
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initialFlags & (~((int)SessionStateItemFlags.Uninitialized)),
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initialFlags)) {
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actionFlags = SessionStateActions.InitializeItem;
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}
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}
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if (exclusive) {
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lockedByOther = true;
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// If unlocked, use a spinlock to test and lock the state.
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if (!state._locked) {
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state._spinLock.AcquireWriterLock();
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try {
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if (!state._locked) {
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lockedByOther = false;
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state._locked = true;
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state._utcLockDate = DateTime.UtcNow;
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state._lockCookie++;
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}
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lockId = state._lockCookie;
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}
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finally {
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state._spinLock.ReleaseWriterLock();
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}
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}
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else {
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// It's already locked by another request. Return the lockCookie to caller.
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lockId = state._lockCookie;
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}
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}
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else {
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state._spinLock.AcquireReaderLock();
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try {
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lockedByOther = state._locked;
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lockId = state._lockCookie;
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}
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finally {
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state._spinLock.ReleaseReaderLock();
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}
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}
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if (lockedByOther) {
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// Item found, but locked
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locked = true;
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lockAge = DateTime.UtcNow - state._utcLockDate;
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return null;
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}
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else {
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return SessionStateUtility.CreateLegitStoreData(context, state._sessionItems,
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state._staticObjects, state._timeout);
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}
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}
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// Not found
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return null;
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}
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public override SessionStateStoreData GetItem(HttpContext context,
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String id,
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out bool locked,
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out TimeSpan lockAge,
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out object lockId,
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out SessionStateActions actionFlags) {
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return DoGet(context, id, false, out locked, out lockAge, out lockId, out actionFlags);
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}
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public override SessionStateStoreData GetItemExclusive(HttpContext context,
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String id,
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out bool locked,
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out TimeSpan lockAge,
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out object lockId,
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out SessionStateActions actionFlags) {
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return DoGet(context, id, true, out locked, out lockAge, out lockId, out actionFlags);
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}
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// Unlock an item locked by GetExclusive
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// 'lockId' is the lock context returned by previous call to GetExclusive
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public override void ReleaseItemExclusive(HttpContext context,
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String id,
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object lockId) {
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Debug.Assert(lockId != null, "lockId != null");
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string key = CreateSessionStateCacheKey(id);
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int lockCookie = (int)lockId;
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SessionIDManager.CheckIdLength(id, true /* throwOnFail */);
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InProcSessionState state = (InProcSessionState)HttpRuntime.Cache.InternalCache.Get(key);
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/* If the state isn't there, we probably took too long to run. */
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if (state == null)
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return;
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if (state._locked) {
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state._spinLock.AcquireWriterLock();
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try {
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if (state._locked && lockCookie == state._lockCookie) {
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state._locked = false;
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}
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}
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finally {
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state._spinLock.ReleaseWriterLock();
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}
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}
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}
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public override void SetAndReleaseItemExclusive(HttpContext context,
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String id,
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SessionStateStoreData item,
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object lockId,
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bool newItem) {
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string key = CreateSessionStateCacheKey(id);
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bool doInsert = true;
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CacheStoreProvider cacheInternal = HttpRuntime.Cache.InternalCache;
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int lockCookieForInsert = NewLockCookie;
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ISessionStateItemCollection items = null;
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HttpStaticObjectsCollection staticObjects = null;
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Debug.Assert(item.Items != null, "item.Items != null");
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Debug.Assert(item.StaticObjects != null, "item.StaticObjects != null");
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Debug.Assert(item.Timeout <= SessionStateModule.MAX_CACHE_BASED_TIMEOUT_MINUTES, "item.Timeout <= SessionStateModule.MAX_CACHE_BASED_TIMEOUT_MINUTES");
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SessionIDManager.CheckIdLength(id, true /* throwOnFail */);
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if (item.Items.Count > 0) {
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items = item.Items;
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}
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if (!item.StaticObjects.NeverAccessed) {
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staticObjects = item.StaticObjects;
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}
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if (!newItem) {
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Debug.Assert(lockId != null, "lockId != null");
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InProcSessionState stateCurrent = (InProcSessionState) cacheInternal.Get(key);
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int lockCookie = (int)lockId;
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/* If the state isn't there, we probably took too long to run. */
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if (stateCurrent == null)
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return;
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Debug.Trace("SessionStateClientSet", "state is inStorage; key = " + key);
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Debug.Assert((stateCurrent._flags & (int)SessionStateItemFlags.Uninitialized) == 0, "Should never set an unitialized item; key = " + key);
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stateCurrent._spinLock.AcquireWriterLock();
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try {
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/* Only set the state if we are the owner */
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if (!stateCurrent._locked || stateCurrent._lockCookie != lockCookie) {
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Debug.Trace("SessionStateClientSet", "Leave because we're not the owner; key = " + key);
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return;
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}
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/* We can change the state in place if the timeout hasn't changed */
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if (stateCurrent._timeout == item.Timeout) {
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stateCurrent.Copy(
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items,
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staticObjects,
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item.Timeout,
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false,
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DateTime.MinValue,
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lockCookie,
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stateCurrent._flags);
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// Don't need to insert into the Cache because an in-place copy is good enough.
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doInsert = false;
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Debug.Trace("SessionStateClientSet", "Changing state inplace; key = " + key);
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}
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else {
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/* We are going to insert a new item to replace the current one in Cache
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because the expiry time has changed.
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Pleas note that an insert will cause the Session_End to be incorrectly raised.
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Please note that the item itself should not expire between now and
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where we do UtcInsert below because cacheInternal.Get above have just
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updated its expiry time.
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*/
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stateCurrent._flags |= (int)SessionStateItemFlags.IgnoreCacheItemRemoved;
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/* By setting _lockCookie to 0, we prevent an overwriting by ReleaseExclusive
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when we drop the lock.
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The scenario can happen if another request is polling and trying to prempt
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the lock we have on the item.
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*/
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lockCookieForInsert = lockCookie;
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stateCurrent._lockCookie = 0;
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}
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}
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finally {
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stateCurrent._spinLock.ReleaseWriterLock();
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}
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}
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if (doInsert) {
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Debug.Trace("SessionStateClientSet", "Inserting state into Cache; key = " + key);
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InProcSessionState state = new InProcSessionState(
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items,
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staticObjects,
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item.Timeout,
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false,
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DateTime.MinValue,
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lockCookieForInsert,
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0);
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try {
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}
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finally {
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// protected from ThreadAbortEx
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cacheInternal.Insert(key, state, new CacheInsertOptions() {
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SlidingExpiration = new TimeSpan(0, state._timeout, 0),
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Priority = CacheItemPriority.NotRemovable,
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OnRemovedCallback = _callback
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});
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PerfCounters.IncrementCounter(AppPerfCounter.SESSIONS_TOTAL);
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PerfCounters.IncrementCounter(AppPerfCounter.SESSIONS_ACTIVE);
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TraceSessionStats();
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}
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}
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}
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public override void CreateUninitializedItem(HttpContext context, String id, int timeout) {
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string key = CreateSessionStateCacheKey(id);
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Debug.Assert(timeout <= SessionStateModule.MAX_CACHE_BASED_TIMEOUT_MINUTES, "item.Timeout <= SessionStateModule.MAX_CACHE_BASED_TIMEOUT_MINUTES");
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SessionIDManager.CheckIdLength(id, true /* throwOnFail */);
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Debug.Trace("SessionStateClientSet", "Inserting an uninitialized item into Cache; key = " + key);
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InProcSessionState state = new InProcSessionState(
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null,
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null,
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timeout,
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false,
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DateTime.MinValue,
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NewLockCookie,
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(int)SessionStateItemFlags.Uninitialized);
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// DevDivBugs 146875
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// We do not want to overwrite an item with an uninitialized item if it is
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// already in the cache
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try {
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}
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finally {
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// protected from ThreadAbortEx
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object existingEntry = HttpRuntime.Cache.InternalCache.Add(key, state, new CacheInsertOptions() {
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SlidingExpiration = new TimeSpan(0, timeout, 0),
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Priority = CacheItemPriority.NotRemovable,
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OnRemovedCallback = _callback
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});
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if (existingEntry == null) {
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PerfCounters.IncrementCounter(AppPerfCounter.SESSIONS_TOTAL);
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PerfCounters.IncrementCounter(AppPerfCounter.SESSIONS_ACTIVE);
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}
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}
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}
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// Remove an item. Note that the item is originally obtained by GetExclusive
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// Same note as Set on lockId
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public override void RemoveItem(HttpContext context,
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String id,
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object lockId,
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SessionStateStoreData item) {
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Debug.Assert(lockId != null, "lockId != null");
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string key = CreateSessionStateCacheKey(id);
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CacheStoreProvider cacheInternal = HttpRuntime.Cache.InternalCache;
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int lockCookie = (int)lockId;
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SessionIDManager.CheckIdLength(id, true /* throwOnFail */);
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InProcSessionState state = (InProcSessionState) cacheInternal.Get(key);
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/* If the item isn't there, we probably took too long to run. */
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if (state == null)
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return;
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state._spinLock.AcquireWriterLock();
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try {
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/* Only remove the item if we are the owner */
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if (!state._locked || state._lockCookie != lockCookie)
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return;
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/* prevent overwriting when we drop the lock */
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state._lockCookie = 0;
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}
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finally {
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state._spinLock.ReleaseWriterLock();
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}
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cacheInternal.Remove(key);
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TraceSessionStats();
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}
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// Reset the expire time of an item based on its timeout value
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public override void ResetItemTimeout(HttpContext context, String id)
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{
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string key = CreateSessionStateCacheKey(id);
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SessionIDManager.CheckIdLength(id, true /* throwOnFail */);
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HttpRuntime.Cache.InternalCache.Get(key);
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}
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// Create a new SessionStateStoreData.
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public override SessionStateStoreData CreateNewStoreData(HttpContext context, int timeout)
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{
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return SessionStateUtility.CreateLegitStoreData(context, null, null, timeout);
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}
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// Called during EndRequest event
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public override void EndRequest(HttpContext context)
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{
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}
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[System.Diagnostics.Conditional("DBG")]
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internal static void TraceSessionStats() {
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#if DBG
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Debug.Trace("SessionState",
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"sessionsTotal=" + PerfCounters.GetCounter(AppPerfCounter.SESSIONS_TOTAL) +
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", sessionsActive=" + PerfCounters.GetCounter(AppPerfCounter.SESSIONS_ACTIVE) +
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", sessionsAbandoned=" + PerfCounters.GetCounter(AppPerfCounter.SESSIONS_ABANDONED) +
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", sessionsTimedout=" + PerfCounters.GetCounter(AppPerfCounter.SESSIONS_TIMED_OUT)
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);
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#endif
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}
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}
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internal sealed class InProcSessionState {
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internal ISessionStateItemCollection _sessionItems;
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internal HttpStaticObjectsCollection _staticObjects;
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internal int _timeout; // USed to set slidingExpiration in CacheEntry
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internal bool _locked; // If it's locked by another thread
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internal DateTime _utcLockDate;
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internal int _lockCookie;
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#pragma warning disable 0649
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internal ReadWriteSpinLock _spinLock;
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#pragma warning restore 0649
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internal int _flags;
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internal InProcSessionState(
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ISessionStateItemCollection sessionItems,
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HttpStaticObjectsCollection staticObjects,
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int timeout,
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bool locked,
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DateTime utcLockDate,
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int lockCookie,
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int flags) {
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Copy(sessionItems, staticObjects, timeout, locked, utcLockDate, lockCookie, flags);
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}
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internal void Copy(
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ISessionStateItemCollection sessionItems,
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HttpStaticObjectsCollection staticObjects,
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int timeout,
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bool locked,
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DateTime utcLockDate,
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int lockCookie,
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int flags) {
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this._sessionItems = sessionItems;
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this._staticObjects = staticObjects;
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this._timeout = timeout;
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this._locked = locked;
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this._utcLockDate = utcLockDate;
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this._lockCookie = lockCookie;
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this._flags = flags;
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}
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}
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}
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