Code:
/ Dotnetfx_Win7_3.5.1 / Dotnetfx_Win7_3.5.1 / 3.5.1 / DEVDIV / depot / DevDiv / releases / whidbey / NetFXspW7 / ndp / fx / src / Data / System / Data / SqlClient / TdsParserSessionPool.cs / 1 / TdsParserSessionPool.cs
//------------------------------------------------------------------------------
//
// Copyright (c) Microsoft Corporation. All rights reserved.
//
// [....]
// [....]
//-----------------------------------------------------------------------------
namespace System.Data.SqlClient {
using System;
using System.Collections.Generic;
using System.Data.Common;
using System.Data.ProviderBase;
using System.Diagnostics;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using System.Threading;
internal class TdsParserSessionPool {
// NOTE: This is a very simplistic, lightweight pooler. It wasn't
// intended to handle huge number of items, just to keep track
// of the session objects to ensure that they're cleaned up in
// a timely manner, to avoid holding on to an unacceptible
// amount of server-side resources in the event that consumers
// let their data readers be GC'd, instead of explicitly
// closing or disposing of them
private const int MaxInactiveCount = 10; // pick something, preferably small...
private static int _objectTypeCount; // Bid counter
private readonly int _objectID = System.Threading.Interlocked.Increment(ref _objectTypeCount);
private readonly TdsParser _parser; // parser that owns us
private readonly List _cache; // collection of all known sessions
private int _cachedCount; // lock-free _cache.Count
private TdsParserStateObjectListStack _freeStack; // collection of all sessions available for reuse
internal TdsParserSessionPool(TdsParser parser) {
_parser = parser;
_cache = new List();
_freeStack = new TdsParserStateObjectListStack();
if (Bid.AdvancedOn) {
Bid.Trace(" %d# created session pool for parser %d\n", ObjectID, parser.ObjectID);
}
}
private bool IsDisposed {
get {
return (null == _freeStack);
}
}
internal int ObjectID {
get {
return _objectID;
}
}
internal TdsParserStateObject CreateSession() {
// NOTE: In the event of a thread abort, we may lose track of
// the session we create here, but since the SNI handle
// contained in it is a SafeHandle, it will eventually
// get reclaimed. I see no reason to go through
// herculean effort to make this section of code a CER,
// since the lock below will force an AppDomain unload.
TdsParserStateObject session = _parser.CreateSession();
//
lock (_cache) {
if (Bid.AdvancedOn) {
Bid.Trace(" %d# adding session %d to pool\n", ObjectID, session.ObjectID);
}
_cache.Add(session);
_cachedCount = _cache.Count;
}
return session;
}
internal void Deactivate() {
// When being deactivated, we check all the sessions in the
// cache to make sure they're cleaned up and then we dispose of
// sessions that are past what we want to keep around.
IntPtr hscp;
Bid.ScopeEnter(out hscp, " %d# deactivating cachedCount=%d\n", ObjectID, _cachedCount);
try {
lock(_cache) {
// NOTE: The PutSession call below may choose to remove the
// session from the cache, which will throw off our
// enumerator. We avoid that by simply indexing backward
// through the array.
for (int i = _cache.Count - 1; i >= 0 ; i--) {
TdsParserStateObject session = _cache[i];
if (null != session) {
if (session.IsOrphaned) {
//
if (Bid.AdvancedOn) {
Bid.Trace(" %d# reclaiming session %d\n", ObjectID, session.ObjectID);
}
PutSession(session);
}
}
}
//
}
}
finally {
Bid.ScopeLeave(ref hscp);
}
}
internal void Dispose() {
if (Bid.AdvancedOn) {
Bid.Trace(" %d# disposing cachedCount=%d\n", ObjectID, _cachedCount);
}
_freeStack = null; // shutting down, dude
lock(_cache) {
for (int i = 0; i < _cache.Count; i++) {
TdsParserStateObject session = _cache[i];
if (null != session) {
session.Dispose();
}
}
_cache.Clear();
}
}
internal TdsParserStateObject GetSession(object owner) {
TdsParserStateObject session = _freeStack.SynchronizedPop();
if (null == session) {
session = CreateSession();
}
session.Activate(owner);
if (Bid.AdvancedOn) {
Bid.Trace(" %d# using session %d\n", ObjectID, session.ObjectID);
}
return session;
}
internal void PutSession(TdsParserStateObject session) {
Debug.Assert (null != session, "null session?");
//Debug.Assert(null != session.Owner, "session without owner?");
bool okToReuse = session.Deactivate();
if (!IsDisposed) {
if (okToReuse && _cachedCount < MaxInactiveCount) {
if (Bid.AdvancedOn) {
Bid.Trace(" %d# keeping session %d cachedCount=%d\n", ObjectID, session.ObjectID, _cachedCount);
}
Debug.Assert(!session._pendingData, "pending data on a pooled session?");
_freeStack.SynchronizedPush(session);
}
else {
if (Bid.AdvancedOn) {
Bid.Trace(" %d# disposing session %d cachedCount=%d\n", ObjectID, session.ObjectID, _cachedCount);
}
lock (_cache) {
bool removed = _cache.Remove(session);
Debug.Assert(removed, "session not in pool?");
_cachedCount = _cache.Count;
}
session.Dispose();
}
}
}
internal string TraceString() {
return String.Format(/*IFormatProvider*/ null,
"(ObjID={0}, free={1}, cached={2}, total={3})",
_objectID,
null == _freeStack ? "(null)" : _freeStack.CountDebugOnly.ToString((IFormatProvider) null),
_cachedCount,
_cache.Count);
}
private class TdsParserStateObjectListStack {
private TdsParserStateObject _stack;
#if DEBUG
private int _version;
private int _count;
#endif
internal int CountDebugOnly {
get {
#if DEBUG
return _count;
#else
return -1;
#endif
}
}
internal TdsParserStateObjectListStack() {
}
internal TdsParserStateObject SynchronizedPop() {
TdsParserStateObject value;
lock(this) {
value = _stack;
if (null != value) {
_stack = value.NextPooledObject;
value.NextPooledObject = null;
#if DEBUG
_version++;
_count--;
#endif
}
#if DEBUG
Debug.Assert((null != value || 0 == _count) && (0 <= _count), "broken SynchronizedPop");
#endif
}
return value;
}
internal void SynchronizedPush(TdsParserStateObject value) {
Debug.Assert(null != value, "pushing null value");
lock(this) {
#if DEBUG
Debug.Assert(null == value.NextPooledObject, "pushing value with non-null NextPooledObject");
int index = 0;
for(TdsParserStateObject x = _stack; null != x; x = x.NextPooledObject, ++index) {
Debug.Assert(x != value, "double push: object already in stack");
}
Debug.Assert(_count == index, "SynchronizedPush count is corrupt");
#endif
value.NextPooledObject = _stack;
_stack = value;
#if DEBUG
_version++;
_count++;
#endif
}
}
}
}
}
// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
//------------------------------------------------------------------------------
//
// Copyright (c) Microsoft Corporation. All rights reserved.
//
// [....]
// [....]
//-----------------------------------------------------------------------------
namespace System.Data.SqlClient {
using System;
using System.Collections.Generic;
using System.Data.Common;
using System.Data.ProviderBase;
using System.Diagnostics;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using System.Threading;
internal class TdsParserSessionPool {
// NOTE: This is a very simplistic, lightweight pooler. It wasn't
// intended to handle huge number of items, just to keep track
// of the session objects to ensure that they're cleaned up in
// a timely manner, to avoid holding on to an unacceptible
// amount of server-side resources in the event that consumers
// let their data readers be GC'd, instead of explicitly
// closing or disposing of them
private const int MaxInactiveCount = 10; // pick something, preferably small...
private static int _objectTypeCount; // Bid counter
private readonly int _objectID = System.Threading.Interlocked.Increment(ref _objectTypeCount);
private readonly TdsParser _parser; // parser that owns us
private readonly List _cache; // collection of all known sessions
private int _cachedCount; // lock-free _cache.Count
private TdsParserStateObjectListStack _freeStack; // collection of all sessions available for reuse
internal TdsParserSessionPool(TdsParser parser) {
_parser = parser;
_cache = new List();
_freeStack = new TdsParserStateObjectListStack();
if (Bid.AdvancedOn) {
Bid.Trace(" %d# created session pool for parser %d\n", ObjectID, parser.ObjectID);
}
}
private bool IsDisposed {
get {
return (null == _freeStack);
}
}
internal int ObjectID {
get {
return _objectID;
}
}
internal TdsParserStateObject CreateSession() {
// NOTE: In the event of a thread abort, we may lose track of
// the session we create here, but since the SNI handle
// contained in it is a SafeHandle, it will eventually
// get reclaimed. I see no reason to go through
// herculean effort to make this section of code a CER,
// since the lock below will force an AppDomain unload.
TdsParserStateObject session = _parser.CreateSession();
//
lock (_cache) {
if (Bid.AdvancedOn) {
Bid.Trace(" %d# adding session %d to pool\n", ObjectID, session.ObjectID);
}
_cache.Add(session);
_cachedCount = _cache.Count;
}
return session;
}
internal void Deactivate() {
// When being deactivated, we check all the sessions in the
// cache to make sure they're cleaned up and then we dispose of
// sessions that are past what we want to keep around.
IntPtr hscp;
Bid.ScopeEnter(out hscp, " %d# deactivating cachedCount=%d\n", ObjectID, _cachedCount);
try {
lock(_cache) {
// NOTE: The PutSession call below may choose to remove the
// session from the cache, which will throw off our
// enumerator. We avoid that by simply indexing backward
// through the array.
for (int i = _cache.Count - 1; i >= 0 ; i--) {
TdsParserStateObject session = _cache[i];
if (null != session) {
if (session.IsOrphaned) {
//
if (Bid.AdvancedOn) {
Bid.Trace(" %d# reclaiming session %d\n", ObjectID, session.ObjectID);
}
PutSession(session);
}
}
}
//
}
}
finally {
Bid.ScopeLeave(ref hscp);
}
}
internal void Dispose() {
if (Bid.AdvancedOn) {
Bid.Trace(" %d# disposing cachedCount=%d\n", ObjectID, _cachedCount);
}
_freeStack = null; // shutting down, dude
lock(_cache) {
for (int i = 0; i < _cache.Count; i++) {
TdsParserStateObject session = _cache[i];
if (null != session) {
session.Dispose();
}
}
_cache.Clear();
}
}
internal TdsParserStateObject GetSession(object owner) {
TdsParserStateObject session = _freeStack.SynchronizedPop();
if (null == session) {
session = CreateSession();
}
session.Activate(owner);
if (Bid.AdvancedOn) {
Bid.Trace(" %d# using session %d\n", ObjectID, session.ObjectID);
}
return session;
}
internal void PutSession(TdsParserStateObject session) {
Debug.Assert (null != session, "null session?");
//Debug.Assert(null != session.Owner, "session without owner?");
bool okToReuse = session.Deactivate();
if (!IsDisposed) {
if (okToReuse && _cachedCount < MaxInactiveCount) {
if (Bid.AdvancedOn) {
Bid.Trace(" %d# keeping session %d cachedCount=%d\n", ObjectID, session.ObjectID, _cachedCount);
}
Debug.Assert(!session._pendingData, "pending data on a pooled session?");
_freeStack.SynchronizedPush(session);
}
else {
if (Bid.AdvancedOn) {
Bid.Trace(" %d# disposing session %d cachedCount=%d\n", ObjectID, session.ObjectID, _cachedCount);
}
lock (_cache) {
bool removed = _cache.Remove(session);
Debug.Assert(removed, "session not in pool?");
_cachedCount = _cache.Count;
}
session.Dispose();
}
}
}
internal string TraceString() {
return String.Format(/*IFormatProvider*/ null,
"(ObjID={0}, free={1}, cached={2}, total={3})",
_objectID,
null == _freeStack ? "(null)" : _freeStack.CountDebugOnly.ToString((IFormatProvider) null),
_cachedCount,
_cache.Count);
}
private class TdsParserStateObjectListStack {
private TdsParserStateObject _stack;
#if DEBUG
private int _version;
private int _count;
#endif
internal int CountDebugOnly {
get {
#if DEBUG
return _count;
#else
return -1;
#endif
}
}
internal TdsParserStateObjectListStack() {
}
internal TdsParserStateObject SynchronizedPop() {
TdsParserStateObject value;
lock(this) {
value = _stack;
if (null != value) {
_stack = value.NextPooledObject;
value.NextPooledObject = null;
#if DEBUG
_version++;
_count--;
#endif
}
#if DEBUG
Debug.Assert((null != value || 0 == _count) && (0 <= _count), "broken SynchronizedPop");
#endif
}
return value;
}
internal void SynchronizedPush(TdsParserStateObject value) {
Debug.Assert(null != value, "pushing null value");
lock(this) {
#if DEBUG
Debug.Assert(null == value.NextPooledObject, "pushing value with non-null NextPooledObject");
int index = 0;
for(TdsParserStateObject x = _stack; null != x; x = x.NextPooledObject, ++index) {
Debug.Assert(x != value, "double push: object already in stack");
}
Debug.Assert(_count == index, "SynchronizedPush count is corrupt");
#endif
value.NextPooledObject = _stack;
_stack = value;
#if DEBUG
_version++;
_count++;
#endif
}
}
}
}
}
// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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