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linux-packaging-mono/mcs/class/referencesource/System.Data/System/Data/ProviderBase/DbConnectionPool.cs

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Imported Upstream version 4.6.0.125 Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4
2016-08-03 10:59:49 +00:00
//------------------------------------------------------------------------------
// <copyright file="DbConnectionPool.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
// <owner current="true" primary="true">[....]</owner>
// <owner current="true" primary="false">[....]</owner>
//------------------------------------------------------------------------------
namespace System.Data.ProviderBase {
using System;
using System.Collections;
using System.Collections.Generic;
using System.Data.Common;
using System.Diagnostics;
using System.Globalization;
using System.Runtime.CompilerServices;
using System.Runtime.ConstrainedExecution;
using System.Runtime.InteropServices;
using System.Security;
using System.Security.Permissions;
using System.Security.Principal;
using System.Threading;
using System.Threading.Tasks;
using SysTx = System.Transactions;
using System.Runtime.Versioning;
using System.Diagnostics.CodeAnalysis;
using System.Collections.Concurrent;
sealed internal class DbConnectionPool {
private enum State {
Initializing,
Running,
ShuttingDown,
}
internal const Bid.ApiGroup PoolerTracePoints = Bid.ApiGroup.Pooling;
// This class is a way to stash our cloned Tx key for later disposal when it's no longer needed.
// We can't get at the key in the dictionary without enumerating entries, so we stash an extra
// copy as part of the value.
sealed private class TransactedConnectionList : List<DbConnectionInternal> {
private SysTx.Transaction _transaction;
internal TransactedConnectionList(int initialAllocation, SysTx.Transaction tx) : base(initialAllocation) {
_transaction = tx;
}
internal void Dispose() {
if (null != _transaction) {
_transaction.Dispose();
}
}
}
sealed class PendingGetConnection {
public PendingGetConnection(long dueTime, DbConnection owner, TaskCompletionSource<DbConnectionInternal> completion, DbConnectionOptions userOptions) {
DueTime = dueTime;
Owner = owner;
Completion = completion;
}
public long DueTime { get; private set; }
public DbConnection Owner { get; private set; }
public TaskCompletionSource<DbConnectionInternal> Completion { get; private set; }
public DbConnectionOptions UserOptions { get; private set; }
}
sealed private class TransactedConnectionPool
{
Dictionary<SysTx.Transaction, TransactedConnectionList> _transactedCxns;
DbConnectionPool _pool;
private static int _objectTypeCount; // Bid counter
internal readonly int _objectID = System.Threading.Interlocked.Increment(ref _objectTypeCount);
internal TransactedConnectionPool(DbConnectionPool pool)
{
Debug.Assert(null != pool, "null pool?");
_pool = pool;
_transactedCxns = new Dictionary<SysTx.Transaction, TransactedConnectionList> ();
Bid.PoolerTrace("<prov.DbConnectionPool.TransactedConnectionPool.TransactedConnectionPool|RES|CPOOL> %d#, Constructed for connection pool %d#\n", ObjectID, _pool.ObjectID);
}
internal int ObjectID {
get {
return _objectID;
}
}
internal DbConnectionPool Pool {
get {
return _pool;
}
}
internal DbConnectionInternal GetTransactedObject(SysTx.Transaction transaction)
{
Debug.Assert(null != transaction, "null transaction?");
DbConnectionInternal transactedObject = null;
TransactedConnectionList connections;
bool txnFound = false;
lock (_transactedCxns)
{
txnFound = _transactedCxns.TryGetValue ( transaction, out connections );
}
// NOTE: GetTransactedObject is only used when AutoEnlist = True and the ambient transaction
// (Sys.Txns.Txn.Current) is still valid/non-null. This, in turn, means that we don't need
// to worry about a pending asynchronous TransactionCompletedEvent to trigger processing in
// TransactionEnded below and potentially wipe out the connections list underneath us. It
// is similarly alright if a pending addition to the connections list in PutTransactedObject
// below is not completed prior to the lock on the connections object here...getting a new
// connection is probably better than unnecessarily locking
if (txnFound)
{
Debug.Assert ( connections != null );
// synchronize multi-threaded access with PutTransactedObject (TransactionEnded should
// not be a concern, see comments above)
lock ( connections )
{
int i = connections.Count - 1;
if (0 <= i)
{
transactedObject = connections[i];
connections.RemoveAt(i);
}
}
}
if (null != transactedObject) {
Bid.PoolerTrace("<prov.DbConnectionPool.TransactedConnectionPool.GetTransactedObject|RES|CPOOL> %d#, Transaction %d#, Connection %d#, Popped.\n", ObjectID, transaction.GetHashCode(), transactedObject.ObjectID);
}
return transactedObject;
}
internal void PutTransactedObject(SysTx.Transaction transaction, DbConnectionInternal transactedObject) {
Debug.Assert(null != transaction, "null transaction?");
Debug.Assert(null != transactedObject, "null transactedObject?");
TransactedConnectionList connections;
bool txnFound = false;
// NOTE: because TransactionEnded is an asynchronous notification, there's no guarantee
// around the order in which PutTransactionObject and TransactionEnded are called.
lock ( _transactedCxns )
{
// Check if a transacted pool has been created for this transaction
if ( txnFound = _transactedCxns.TryGetValue ( transaction, out connections ) )
{
Debug.Assert ( connections != null );
// synchronize multi-threaded access with GetTransactedObject
lock ( connections )
{
Debug.Assert(0 > connections.IndexOf(transactedObject), "adding to pool a second time?");
Bid.PoolerTrace("<prov.DbConnectionPool.TransactedConnectionPool.PutTransactedObject|RES|CPOOL> %d#, Transaction %d#, Connection %d#, Pushing.\n", ObjectID, transaction.GetHashCode(), transactedObject.ObjectID);
connections.Add(transactedObject);
}
}
}
//
if ( !txnFound )
{
// create the transacted pool, making sure to clone the associated transaction
// for use as a key in our internal dictionary of transactions and connections
SysTx.Transaction transactionClone = null;
TransactedConnectionList newConnections = null;
try
{
transactionClone = transaction.Clone();
newConnections = new TransactedConnectionList(2, transactionClone); // start with only two connections in the list; most times we won't need that many.
lock ( _transactedCxns )
{
// NOTE: in the interim between the locks on the transacted pool (this) during
// execution of this method, another thread (threadB) may have attempted to
// add a different connection to the transacted pool under the same
// transaction. As a result, threadB may have completed creating the
// transacted pool while threadA was processing the above instructions.
if (txnFound = _transactedCxns.TryGetValue(transaction, out connections))
{
Debug.Assert ( connections != null );
// synchronize multi-threaded access with GetTransactedObject
lock ( connections )
{
Debug.Assert(0 > connections.IndexOf(transactedObject), "adding to pool a second time?");
Bid.PoolerTrace("<prov.DbConnectionPool.TransactedConnectionPool.PutTransactedObject|RES|CPOOL> %d#, Transaction %d#, Connection %d#, Pushing.\n", ObjectID, transaction.GetHashCode(), transactedObject.ObjectID);
connections.Add(transactedObject);
}
}
else
{
Bid.PoolerTrace("<prov.DbConnectionPool.TransactedConnectionPool.PutTransactedObject|RES|CPOOL> %d#, Transaction %d#, Connection %d#, Adding List to transacted pool.\n", ObjectID, transaction.GetHashCode(), transactedObject.ObjectID);
// add the connection/transacted object to the list
newConnections.Add ( transactedObject );
_transactedCxns.Add(transactionClone, newConnections);
transactionClone = null; // we've used it -- don't throw it or the TransactedConnectionList that references it away.
}
}
}
finally
{
if (null != transactionClone)
{
if ( newConnections != null )
{
// another thread created the transaction pool and thus the new
// TransactedConnectionList was not used, so dispose of it and
// the transaction clone that it incorporates.
newConnections.Dispose();
}
else
{
// memory allocation for newConnections failed...clean up unused transactionClone
transactionClone.Dispose();
}
}
}
Bid.PoolerTrace("<prov.DbConnectionPool.TransactedConnectionPool.PutTransactedObject|RES|CPOOL> %d#, Transaction %d#, Connection %d#, Added.\n", ObjectID, transaction.GetHashCode(), transactedObject.ObjectID );
}
#if !MOBILE
Pool.PerformanceCounters.NumberOfFreeConnections.Increment();
#endif
}
internal void TransactionEnded(SysTx.Transaction transaction, DbConnectionInternal transactedObject)
{
Bid.PoolerTrace("<prov.DbConnectionPool.TransactedConnectionPool.TransactionEnded|RES|CPOOL> %d#, Transaction %d#, Connection %d#, Transaction Completed\n", ObjectID, transaction.GetHashCode(), transactedObject.ObjectID);
TransactedConnectionList connections;
int entry = -1;
// NOTE: because TransactionEnded is an asynchronous notification, there's no guarantee
// around the order in which PutTransactionObject and TransactionEnded are called. As
// such, it is possible that the transaction does not yet have a pool created.
//
lock ( _transactedCxns )
{
if (_transactedCxns.TryGetValue(transaction, out connections))
{
Debug.Assert ( connections != null );
bool shouldDisposeConnections = false;
// Lock connections to avoid conflict with GetTransactionObject
lock (connections)
{
entry = connections.IndexOf(transactedObject);
if ( entry >= 0 )
{
connections.RemoveAt(entry);
}
// Once we've completed all the ended notifications, we can
// safely remove the list from the transacted pool.
if (0 >= connections.Count)
{
Bid.PoolerTrace("<prov.DbConnectionPool.TransactedConnectionPool.TransactionEnded|RES|CPOOL> %d#, Transaction %d#, Removing List from transacted pool.\n", ObjectID, transaction.GetHashCode());
_transactedCxns.Remove(transaction);
// we really need to dispose our connection list; it may have
// native resources via the tx and GC may not happen soon enough.
shouldDisposeConnections = true;
}
}
if (shouldDisposeConnections) {
connections.Dispose();
}
}
else
{
//Debug.Assert ( false, "TransactionCompletedEvent fired before PutTransactedObject put the connection in the transacted pool." );
Bid.PoolerTrace("<prov.DbConnectionPool.TransactedConnectionPool.TransactionEnded|RES|CPOOL> %d#, Transaction %d#, Connection %d#, Transacted pool not yet created prior to transaction completing. Connection may be leaked.\n", ObjectID, transaction.GetHashCode(), transactedObject.ObjectID );
}
}
// If (and only if) we found the connection in the list of
// connections, we'll put it back...
if (0 <= entry)
{
#if !MOBILE
Pool.PerformanceCounters.NumberOfFreeConnections.Decrement();
#endif
Pool.PutObjectFromTransactedPool(transactedObject);
}
}
}
private sealed class PoolWaitHandles : DbBuffer {
private readonly Semaphore _poolSemaphore;
private readonly ManualResetEvent _errorEvent;
// Using a Mutex requires ThreadAffinity because SQL CLR can swap
// the underlying Win32 thread associated with a managed thread in preemptive mode.
// Using an AutoResetEvent does not have that complication.
private readonly Semaphore _creationSemaphore;
private readonly SafeHandle _poolHandle;
private readonly SafeHandle _errorHandle;
private readonly SafeHandle _creationHandle;
private readonly int _releaseFlags;
[ResourceExposure(ResourceScope.None)] // SxS: this method does not create named objects
[ResourceConsumption(ResourceScope.Machine, ResourceScope.Machine)]
internal PoolWaitHandles() : base(3*IntPtr.Size) {
bool mustRelease1 = false, mustRelease2 = false, mustRelease3 = false;
_poolSemaphore = new Semaphore(0, MAX_Q_SIZE);
_errorEvent = new ManualResetEvent(false);
_creationSemaphore = new Semaphore(1, 1);
RuntimeHelpers.PrepareConstrainedRegions();
try {
// because SafeWaitHandle doesn't have reliability contract
_poolHandle = _poolSemaphore.SafeWaitHandle;
_errorHandle = _errorEvent.SafeWaitHandle;
_creationHandle = _creationSemaphore.SafeWaitHandle;
_poolHandle.DangerousAddRef(ref mustRelease1);
_errorHandle.DangerousAddRef(ref mustRelease2);
_creationHandle.DangerousAddRef(ref mustRelease3);
Debug.Assert(0 == SEMAPHORE_HANDLE, "SEMAPHORE_HANDLE");
Debug.Assert(1 == ERROR_HANDLE, "ERROR_HANDLE");
Debug.Assert(2 == CREATION_HANDLE, "CREATION_HANDLE");
WriteIntPtr(SEMAPHORE_HANDLE*IntPtr.Size, _poolHandle.DangerousGetHandle());
WriteIntPtr(ERROR_HANDLE*IntPtr.Size, _errorHandle.DangerousGetHandle());
WriteIntPtr(CREATION_HANDLE*IntPtr.Size, _creationHandle.DangerousGetHandle());
}
finally {
if (mustRelease1) {
_releaseFlags |= 1;
}
if (mustRelease2) {
_releaseFlags |= 2;
}
if (mustRelease3) {
_releaseFlags |= 4;
}
}
}
internal SafeHandle CreationHandle {
[ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
get { return _creationHandle; }
}
internal Semaphore CreationSemaphore {
get { return _creationSemaphore; }
}
internal ManualResetEvent ErrorEvent {
get { return _errorEvent; }
}
internal Semaphore PoolSemaphore {
get { return _poolSemaphore; }
}
protected override bool ReleaseHandle() {
// NOTE: The SafeHandle class guarantees this will be called exactly once.
// we know we can touch these other managed objects because of our original DangerousAddRef
if (0 != (1 & _releaseFlags)) {
_poolHandle.DangerousRelease();
}
if (0 != (2 & _releaseFlags)) {
_errorHandle.DangerousRelease();
}
if (0 != (4 & _releaseFlags)) {
_creationHandle.DangerousRelease();
}
return base.ReleaseHandle();
}
}
private const int MAX_Q_SIZE = (int)0x00100000;
// The order of these is important; we want the WaitAny call to be signaled
// for a free object before a creation signal. Only the index first signaled
// object is returned from the WaitAny call.
private const int SEMAPHORE_HANDLE = (int)0x0;
private const int ERROR_HANDLE = (int)0x1;
private const int CREATION_HANDLE = (int)0x2;
private const int BOGUS_HANDLE = (int)0x3;
private const int WAIT_OBJECT_0 = 0;
private const int WAIT_TIMEOUT = (int)0x102;
private const int WAIT_ABANDONED = (int)0x80;
private const int WAIT_FAILED = -1;
private const int ERROR_WAIT_DEFAULT = 5 * 1000; // 5 seconds
// we do want a testable, repeatable set of generated random numbers
private static readonly Random _random = new Random(5101977); // Value obtained from Dave Driver
private readonly int _cleanupWait;
private readonly DbConnectionPoolIdentity _identity;
private readonly DbConnectionFactory _connectionFactory;
private readonly DbConnectionPoolGroup _connectionPoolGroup;
private readonly DbConnectionPoolGroupOptions _connectionPoolGroupOptions;
private DbConnectionPoolProviderInfo _connectionPoolProviderInfo;
/// <summary>
/// The private member which carries the set of authenticationcontexts for this pool (based on the user's identity).
/// </summary>
private readonly ConcurrentDictionary<DbConnectionPoolAuthenticationContextKey, DbConnectionPoolAuthenticationContext> _pooledDbAuthenticationContexts;
private State _state;
private readonly ConcurrentStack<DbConnectionInternal> _stackOld = new ConcurrentStack<DbConnectionInternal>();
private readonly ConcurrentStack<DbConnectionInternal> _stackNew = new ConcurrentStack<DbConnectionInternal>();
private readonly ConcurrentQueue<PendingGetConnection> _pendingOpens = new ConcurrentQueue<PendingGetConnection>();
private int _pendingOpensWaiting = 0;
private readonly WaitCallback _poolCreateRequest;
private int _waitCount;
private readonly PoolWaitHandles _waitHandles;
private Exception _resError;
private volatile bool _errorOccurred;
private int _errorWait;
private Timer _errorTimer;
private Timer _cleanupTimer;
private readonly TransactedConnectionPool _transactedConnectionPool;
private readonly List<DbConnectionInternal> _objectList;
private int _totalObjects;
private static int _objectTypeCount; // Bid counter
internal readonly int _objectID = System.Threading.Interlocked.Increment(ref _objectTypeCount);
// only created by DbConnectionPoolGroup.GetConnectionPool
internal DbConnectionPool(
DbConnectionFactory connectionFactory,
DbConnectionPoolGroup connectionPoolGroup,
DbConnectionPoolIdentity identity,
DbConnectionPoolProviderInfo connectionPoolProviderInfo ) {
Debug.Assert(ADP.IsWindowsNT, "Attempting to construct a connection pool on Win9x?");
Debug.Assert(null != connectionPoolGroup, "null connectionPoolGroup");
if ((null != identity) && identity.IsRestricted) {
throw ADP.InternalError(ADP.InternalErrorCode.AttemptingToPoolOnRestrictedToken);
}
_state= State.Initializing;
lock(_random) { // Random.Next is not thread-safe
_cleanupWait = _random.Next(12, 24)*10*1000; // 2-4 minutes in 10 sec intervals, WebData 103603
}
_connectionFactory = connectionFactory;
_connectionPoolGroup = connectionPoolGroup;
_connectionPoolGroupOptions = connectionPoolGroup.PoolGroupOptions;
_connectionPoolProviderInfo = connectionPoolProviderInfo;
_identity = identity;
_waitHandles = new PoolWaitHandles();
_errorWait = ERROR_WAIT_DEFAULT;
_errorTimer = null; // No error yet.
_objectList = new List<DbConnectionInternal>(MaxPoolSize);
_pooledDbAuthenticationContexts = new ConcurrentDictionary<DbConnectionPoolAuthenticationContextKey, DbConnectionPoolAuthenticationContext>(concurrencyLevel: 4 * Environment.ProcessorCount /* default value in ConcurrentDictionary*/,
capacity: 2);
if(ADP.IsPlatformNT5) {
_transactedConnectionPool = new TransactedConnectionPool(this);
}
_poolCreateRequest = new WaitCallback(PoolCreateRequest); // used by CleanupCallback
_state = State.Running;
Bid.PoolerTrace("<prov.DbConnectionPool.DbConnectionPool|RES|CPOOL> %d#, Constructed.\n", ObjectID);
//_cleanupTimer & QueuePoolCreateRequest is delayed until DbConnectionPoolGroup calls
// StartBackgroundCallbacks after pool is actually in the collection
}
private int CreationTimeout {
get { return PoolGroupOptions.CreationTimeout; }
}
internal int Count {
get { return _totalObjects; }
}
internal DbConnectionFactory ConnectionFactory {
get { return _connectionFactory; }
}
internal bool ErrorOccurred {
get { return _errorOccurred; }
}
private bool HasTransactionAffinity {
get { return PoolGroupOptions.HasTransactionAffinity; }
}
internal TimeSpan LoadBalanceTimeout {
get { return PoolGroupOptions.LoadBalanceTimeout; }
}
private bool NeedToReplenish {
get {
if (State.Running != _state) // SQL BU DT 364595 - don't allow connection create when not running.
return false;
int totalObjects = Count;
if (totalObjects >= MaxPoolSize)
return false;
if (totalObjects < MinPoolSize)
return true;
int freeObjects = (_stackNew.Count + _stackOld.Count);
int waitingRequests = _waitCount;
bool needToReplenish = (freeObjects < waitingRequests) || ((freeObjects == waitingRequests) && (totalObjects > 1));
return needToReplenish;
}
}
internal DbConnectionPoolIdentity Identity {
get { return _identity; }
}
internal bool IsRunning {
get { return State.Running == _state; }
}
private int MaxPoolSize {
get { return PoolGroupOptions.MaxPoolSize; }
}
private int MinPoolSize {
get { return PoolGroupOptions.MinPoolSize; }
}
internal int ObjectID {
get {
return _objectID;
}
}
internal DbConnectionPoolCounters PerformanceCounters {
get { return _connectionFactory.PerformanceCounters; }
}
internal DbConnectionPoolGroup PoolGroup {
get { return _connectionPoolGroup; }
}
internal DbConnectionPoolGroupOptions PoolGroupOptions {
get { return _connectionPoolGroupOptions; }
}
internal DbConnectionPoolProviderInfo ProviderInfo {
get { return _connectionPoolProviderInfo; }
}
/// <summary>
/// Return the pooled authentication contexts.
/// </summary>
internal ConcurrentDictionary<DbConnectionPoolAuthenticationContextKey, DbConnectionPoolAuthenticationContext> AuthenticationContexts
{
get
{
return _pooledDbAuthenticationContexts;
}
}
internal bool UseLoadBalancing {
get { return PoolGroupOptions.UseLoadBalancing; }
}
private bool UsingIntegrateSecurity {
get { return (null != _identity && DbConnectionPoolIdentity.NoIdentity != _identity); }
}
private void CleanupCallback(Object state) {
// Called when the cleanup-timer ticks over.
// This is the automatic prunning method. Every period, we will
// perform a two-step process:
//
// First, for each free object above MinPoolSize, we will obtain a
// semaphore representing one object and destroy one from old stack.
// We will continue this until we either reach MinPoolSize, we are
// unable to obtain a free object, or we have exhausted all the
// objects on the old stack.
//
// Second we move all free objects on the new stack to the old stack.
// So, every period the objects on the old stack are destroyed and
// the objects on the new stack are pushed to the old stack. All
// objects that are currently out and in use are not on either stack.
//
// With this logic, objects are pruned from the pool if unused for
// at least one period but not more than two periods.
Bid.PoolerTrace("<prov.DbConnectionPool.CleanupCallback|RES|INFO|CPOOL> %d#\n", ObjectID);
// Destroy free objects that put us above MinPoolSize from old stack.
while(Count > MinPoolSize) { // While above MinPoolSize...
if (_waitHandles.PoolSemaphore.WaitOne(0, false) /* != WAIT_TIMEOUT */) {
// We obtained a objects from the semaphore.
DbConnectionInternal obj;
if (_stackOld.TryPop(out obj)) {
Debug.Assert(obj != null, "null connection is not expected");
// If we obtained one from the old stack, destroy it.
#if !MOBILE
PerformanceCounters.NumberOfFreeConnections.Decrement();
#endif
// Transaction roots must survive even aging out (TxEnd event will clean them up).
bool shouldDestroy = true;
lock (obj) { // Lock to prevent race condition window between IsTransactionRoot and shouldDestroy assignment
if (obj.IsTransactionRoot) {
shouldDestroy = false;
}
}
// !!!!!!!!!! WARNING !!!!!!!!!!!!!
// ONLY touch obj after lock release if shouldDestroy is false!!! Otherwise, it may be destroyed
// by transaction-end thread!
// Note that there is a minor race condition between this task and the transaction end event, if the latter runs
// between the lock above and the SetInStasis call below. The reslult is that the stasis counter may be
// incremented without a corresponding decrement (the transaction end task is normally expected
// to decrement, but will only do so if the stasis flag is set when it runs). I've minimized the size
// of the window, but we aren't totally eliminating it due to SetInStasis needing to do bid tracing, which
// we don't want to do under this lock, if possible. It should be possible to eliminate this race condition with
// more substantial re-architecture of the pool, but we don't have the time to do that work for the current release.
if (shouldDestroy) {
DestroyObject(obj);
}
else {
obj.SetInStasis();
}
}
else {
// Else we exhausted the old stack (the object the
// semaphore represents is on the new stack), so break.
_waitHandles.PoolSemaphore.Release(1);
break;
}
}
else {
break;
}
}
// Push to the old-stack. For each free object, move object from
// new stack to old stack.
if(_waitHandles.PoolSemaphore.WaitOne(0, false) /* != WAIT_TIMEOUT */) {
for(;;) {
DbConnectionInternal obj;
if (!_stackNew.TryPop(out obj))
break;
Debug.Assert(obj != null, "null connection is not expected");
Bid.PoolerTrace("<prov.DbConnectionPool.CleanupCallback|RES|INFO|CPOOL> %d#, ChangeStacks=%d#\n", ObjectID, obj.ObjectID);
Debug.Assert(!obj.IsEmancipated, "pooled object not in pool");
Debug.Assert(obj.CanBePooled, "pooled object is not poolable");
_stackOld.Push(obj);
}
_waitHandles.PoolSemaphore.Release(1);
}
// Queue up a request to bring us up to MinPoolSize
QueuePoolCreateRequest();
}
internal void Clear() {
Bid.PoolerTrace("<prov.DbConnectionPool.Clear|RES|CPOOL> %d#, Clearing.\n", ObjectID);
DbConnectionInternal obj;
// First, quickly doom everything.
lock(_objectList) {
int count = _objectList.Count;
for (int i = 0; i < count; ++i) {
obj = _objectList[i];
if (null != obj) {
obj.DoNotPoolThisConnection();
}
}
}
// Second, dispose of all the free connections.
while (_stackNew.TryPop(out obj)) {
Debug.Assert(obj != null, "null connection is not expected");
#if !MOBILE
PerformanceCounters.NumberOfFreeConnections.Decrement();
#endif
DestroyObject(obj);
}
while (_stackOld.TryPop(out obj)) {
Debug.Assert(obj != null, "null connection is not expected");
#if !MOBILE
PerformanceCounters.NumberOfFreeConnections.Decrement();
#endif
DestroyObject(obj);
}
// Finally, reclaim everything that's emancipated (which, because
// it's been doomed, will cause it to be disposed of as well)
ReclaimEmancipatedObjects();
Bid.PoolerTrace("<prov.DbConnectionPool.Clear|RES|CPOOL> %d#, Cleared.\n", ObjectID);
}
private Timer CreateCleanupTimer() {
return (new Timer(new TimerCallback(this.CleanupCallback), null, _cleanupWait, _cleanupWait));
}
private DbConnectionInternal CreateObject(DbConnection owningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection) {
DbConnectionInternal newObj = null;
try {
newObj = _connectionFactory.CreatePooledConnection(this, owningObject, _connectionPoolGroup.ConnectionOptions, _connectionPoolGroup.PoolKey, userOptions);
if (null == newObj) {
throw ADP.InternalError(ADP.InternalErrorCode.CreateObjectReturnedNull); // CreateObject succeeded, but null object
}
if (!newObj.CanBePooled) {
throw ADP.InternalError(ADP.InternalErrorCode.NewObjectCannotBePooled); // CreateObject succeeded, but non-poolable object
}
newObj.PrePush(null);
lock (_objectList) {
if ((oldConnection != null) && (oldConnection.Pool == this)) {
_objectList.Remove(oldConnection);
}
_objectList.Add(newObj);
_totalObjects = _objectList.Count;
#if !MOBILE
PerformanceCounters.NumberOfPooledConnections.Increment(); //
#endif
}
// If the old connection belonged to another pool, we need to remove it from that
if (oldConnection != null) {
var oldConnectionPool = oldConnection.Pool;
if (oldConnectionPool != null && oldConnectionPool != this) {
Debug.Assert(oldConnectionPool._state == State.ShuttingDown, "Old connections pool should be shutting down");
lock (oldConnectionPool._objectList) {
oldConnectionPool._objectList.Remove(oldConnection);
oldConnectionPool._totalObjects = oldConnectionPool._objectList.Count;
}
}
}
Bid.PoolerTrace("<prov.DbConnectionPool.CreateObject|RES|CPOOL> %d#, Connection %d#, Added to pool.\n", ObjectID, newObj.ObjectID);
// Reset the error wait:
_errorWait = ERROR_WAIT_DEFAULT;
}
catch(Exception e) {
//
if (!ADP.IsCatchableExceptionType(e)) {
throw;
}
ADP.TraceExceptionForCapture(e);
newObj = null; // set to null, so we do not return bad new object
// Failed to create instance
_resError = e;
// VSTFDEVDIV 479561: Make sure the timer starts even if ThreadAbort occurs after setting the ErrorEvent.
// timer allocation has to be done out of CER block
Timer t = new Timer(new TimerCallback(this.ErrorCallback), null, Timeout.Infinite, Timeout.Infinite);
bool timerIsNotDisposed;
RuntimeHelpers.PrepareConstrainedRegions();
try{} finally {
_waitHandles.ErrorEvent.Set();
_errorOccurred = true;
// Enable the timer.
// Note that the timer is created to allow periodic invocation. If ThreadAbort occurs in the middle of ErrorCallback,
// the timer will restart. Otherwise, the timer callback (ErrorCallback) destroys the timer after resetting the error to avoid second callback.
_errorTimer = t;
timerIsNotDisposed = t.Change(_errorWait, _errorWait);
}
Debug.Assert(timerIsNotDisposed, "ErrorCallback timer has been disposed");
if (30000 < _errorWait) {
_errorWait = 60000;
}
else {
_errorWait *= 2;
}
throw;
}
return newObj;
}
private void DeactivateObject(DbConnectionInternal obj)
{
Bid.PoolerTrace("<prov.DbConnectionPool.DeactivateObject|RES|CPOOL> %d#, Connection %d#, Deactivating.\n", ObjectID, obj.ObjectID);
obj.DeactivateConnection(); // we presume this operation is safe outside of a lock...
bool returnToGeneralPool = false;
bool destroyObject = false;
bool rootTxn = false;
if ( obj.IsConnectionDoomed )
{
// the object is not fit for reuse -- just dispose of it.
destroyObject = true;
}
else
{
// NOTE: constructor should ensure that current state cannot be State.Initializing, so it can only
// be State.Running or State.ShuttingDown
Debug.Assert ( _state == State.Running || _state == State.ShuttingDown );
lock (obj)
{
// A connection with a delegated transaction cannot currently
// be returned to a different customer until the transaction
// actually completes, so we send it into Stasis -- the SysTx
// transaction object will ensure that it is owned (not lost),
// and it will be certain to put it back into the pool.
if ( _state == State.ShuttingDown )
{
if ( obj.IsTransactionRoot )
{
// SQLHotfix# 50003503 - connections that are affiliated with a
// root transaction and that also happen to be in a connection
// pool that is being shutdown need to be put in stasis so that
// the root transaction isn't effectively orphaned with no
// means to promote itself to a full delegated transaction or
// Commit or Rollback
obj.SetInStasis();
rootTxn = true;
}
else
{
// connection is being closed and the pool has been marked as shutting
// down, so destroy this object.
destroyObject = true;
}
}
else
{
if ( obj.IsNonPoolableTransactionRoot )
{
obj.SetInStasis();
rootTxn = true;
}
else if ( obj.CanBePooled )
{
// We must put this connection into the transacted pool
// while inside a lock to prevent a race condition with
// the transaction asyncronously completing on a second
// thread.
SysTx.Transaction transaction = obj.EnlistedTransaction;
if (null != transaction)
{
// NOTE: we're not locking on _state, so it's possible that its
// value could change between the conditional check and here.
// Although perhaps not ideal, this is OK because the
// DelegatedTransactionEnded event will clean up the
// connection appropriately regardless of the pool state.
Debug.Assert ( _transactedConnectionPool != null, "Transacted connection pool was not expected to be null.");
_transactedConnectionPool.PutTransactedObject(transaction, obj);
rootTxn = true;
}
else
{
// return to general pool
returnToGeneralPool = true;
}
}
else
{
if ( obj.IsTransactionRoot && !obj.IsConnectionDoomed )
{
// SQLHotfix# 50003503 - if the object cannot be pooled but is a transaction
// root, then we must have hit one of two race conditions:
// 1) PruneConnectionPoolGroups shutdown the pool and marked this connection
// as non-poolable while we were processing within this lock
// 2) The LoadBalancingTimeout expired on this connection and marked this
// connection as DoNotPool.
//
// This connection needs to be put in stasis so that the root transaction isn't
// effectively orphaned with no means to promote itself to a full delegated
// transaction or Commit or Rollback
obj.SetInStasis();
rootTxn = true;
}
else
{
// object is not fit for reuse -- just dispose of it
destroyObject = true;
}
}
}
}
}
if (returnToGeneralPool)
{
// Only push the connection into the general pool if we didn't
// already push it onto the transacted pool, put it into stasis,
// or want to destroy it.
Debug.Assert ( destroyObject == false );
PutNewObject(obj);
}
else if ( destroyObject )
{
// VSTFDEVDIV# 479556 - connections that have been marked as no longer
// poolable (e.g. exceeded their connection lifetime) are not, in fact,
// returned to the general pool
DestroyObject(obj);
QueuePoolCreateRequest();
}
//-------------------------------------------------------------------------------------
// postcondition
// ensure that the connection was processed
Debug.Assert ( rootTxn == true || returnToGeneralPool == true || destroyObject == true );
//
}
internal void DestroyObject(DbConnectionInternal obj) {
// A connection with a delegated transaction cannot be disposed of
// until the delegated transaction has actually completed. Instead,
// we simply leave it alone; when the transaction completes, it will
// come back through PutObjectFromTransactedPool, which will call us
// again.
if (obj.IsTxRootWaitingForTxEnd) {
Bid.PoolerTrace("<prov.DbConnectionPool.DestroyObject|RES|CPOOL> %d#, Connection %d#, Has Delegated Transaction, waiting to Dispose.\n", ObjectID, obj.ObjectID);
}
else {
Bid.PoolerTrace("<prov.DbConnectionPool.DestroyObject|RES|CPOOL> %d#, Connection %d#, Removing from pool.\n", ObjectID, obj.ObjectID);
bool removed = false;
lock (_objectList) {
removed = _objectList.Remove(obj);
Debug.Assert(removed, "attempt to DestroyObject not in list");
_totalObjects = _objectList.Count;
}
if (removed) {
Bid.PoolerTrace("<prov.DbConnectionPool.DestroyObject|RES|CPOOL> %d#, Connection %d#, Removed from pool.\n", ObjectID, obj.ObjectID);
#if !MOBILE
PerformanceCounters.NumberOfPooledConnections.Decrement();
#endif
}
obj.Dispose();
Bid.PoolerTrace("<prov.DbConnectionPool.DestroyObject|RES|CPOOL> %d#, Connection %d#, Disposed.\n", ObjectID, obj.ObjectID);
#if !MOBILE
PerformanceCounters.HardDisconnectsPerSecond.Increment();
#endif
}
}
private void ErrorCallback(Object state) {
Bid.PoolerTrace("<prov.DbConnectionPool.ErrorCallback|RES|CPOOL> %d#, Resetting Error handling.\n", ObjectID);
_errorOccurred = false;
_waitHandles.ErrorEvent.Reset();
// the error state is cleaned, destroy the timer to avoid periodic invocation
Timer t = _errorTimer;
_errorTimer = null;
if (t != null) {
t.Dispose(); // Cancel timer request.
}
}
private Exception TryCloneCachedException()
// Cached exception can be of any type, so is not always cloneable.
// This functions clones SqlException
// OleDb and Odbc connections are not passing throw this code
{
if (_resError==null)
return null;
if (_resError.GetType()==typeof(SqlClient.SqlException))
return ((SqlClient.SqlException)_resError).InternalClone();
return _resError;
}
void WaitForPendingOpen() {
Debug.Assert(!Thread.CurrentThread.IsThreadPoolThread, "This thread may block for a long time. Threadpool threads should not be used.");
PendingGetConnection next;
do {
bool started = false;
RuntimeHelpers.PrepareConstrainedRegions();
try {
RuntimeHelpers.PrepareConstrainedRegions();
try { }
finally {
started = Interlocked.CompareExchange(ref _pendingOpensWaiting, 1, 0) == 0;
}
if (!started) {
return;
}
while (_pendingOpens.TryDequeue(out next)) {
if (next.Completion.Task.IsCompleted) {
continue;
}
uint delay;
if (next.DueTime == Timeout.Infinite) {
delay = unchecked((uint)Timeout.Infinite);
}
else {
delay = (uint)Math.Max(ADP.TimerRemainingMilliseconds(next.DueTime), 0);
}
DbConnectionInternal connection = null;
bool timeout = false;
Exception caughtException = null;
RuntimeHelpers.PrepareConstrainedRegions();
try {
#if DEBUG
System.Data.SqlClient.TdsParser.ReliabilitySection tdsReliabilitySection = new System.Data.SqlClient.TdsParser.ReliabilitySection();
RuntimeHelpers.PrepareConstrainedRegions();
try {
tdsReliabilitySection.Start();
#else
{
#endif //DEBUG
bool allowCreate = true;
bool onlyOneCheckConnection = false;
ADP.SetCurrentTransaction(next.Completion.Task.AsyncState as Transactions.Transaction);
timeout = !TryGetConnection(next.Owner, delay, allowCreate, onlyOneCheckConnection, next.UserOptions, out connection);
}
#if DEBUG
finally {
tdsReliabilitySection.Stop();
}
#endif //DEBUG
}
catch (System.OutOfMemoryException) {
if (connection != null) { connection.DoomThisConnection(); }
throw;
}
catch (System.StackOverflowException) {
if (connection != null) { connection.DoomThisConnection(); }
throw;
}
catch (System.Threading.ThreadAbortException) {
if (connection != null) { connection.DoomThisConnection(); }
throw;
}
catch (Exception e) {
caughtException = e;
}
if (caughtException != null) {
next.Completion.TrySetException(caughtException);
}
else if (timeout) {
next.Completion.TrySetException(ADP.ExceptionWithStackTrace(ADP.PooledOpenTimeout()));
}
else {
Debug.Assert(connection != null, "connection should never be null in success case");
if (!next.Completion.TrySetResult(connection)) {
// if the completion was cancelled, lets try and get this connection back for the next try
PutObject(connection, next.Owner);
}
}
}
}
finally {
if (started) {
Interlocked.Exchange(ref _pendingOpensWaiting, 0);
}
}
} while (_pendingOpens.TryPeek(out next));
}
internal bool TryGetConnection(DbConnection owningObject, TaskCompletionSource<DbConnectionInternal> retry, DbConnectionOptions userOptions, out DbConnectionInternal connection) {
uint waitForMultipleObjectsTimeout = 0;
bool allowCreate = false;
if (retry == null) {
waitForMultipleObjectsTimeout = (uint)CreationTimeout;
// VSTFDEVDIV 445531: set the wait timeout to INFINITE (-1) if the SQL connection timeout is 0 (== infinite)
if (waitForMultipleObjectsTimeout == 0)
waitForMultipleObjectsTimeout = unchecked((uint)Timeout.Infinite);
allowCreate = true;
}
if (_state != State.Running) {
Bid.PoolerTrace("<prov.DbConnectionPool.GetConnection|RES|CPOOL> %d#, DbConnectionInternal State != Running.\n", ObjectID);
connection = null;
return true;
}
bool onlyOneCheckConnection = true;
if (TryGetConnection(owningObject, waitForMultipleObjectsTimeout, allowCreate, onlyOneCheckConnection, userOptions, out connection)) {
return true;
}
else if (retry == null) {
// timed out on a [....] call
return true;
}
var pendingGetConnection =
new PendingGetConnection(
CreationTimeout == 0 ? Timeout.Infinite : ADP.TimerCurrent() + ADP.TimerFromSeconds(CreationTimeout/1000),
owningObject,
retry,
userOptions);
_pendingOpens.Enqueue(pendingGetConnection);
// it is better to StartNew too many times than not enough
if (_pendingOpensWaiting == 0) {
Thread waitOpenThread = new Thread(WaitForPendingOpen);
waitOpenThread.IsBackground = true;
waitOpenThread.Start();
}
connection = null;
return false;
}
[SuppressMessage("Microsoft.Reliability", "CA2001:AvoidCallingProblematicMethods")] // copied from Triaged.cs
[ResourceExposure(ResourceScope.None)] // SxS: this method does not expose resources
[ResourceConsumption(ResourceScope.Machine, ResourceScope.Machine)]
private bool TryGetConnection(DbConnection owningObject, uint waitForMultipleObjectsTimeout, bool allowCreate, bool onlyOneCheckConnection, DbConnectionOptions userOptions, out DbConnectionInternal connection) {
DbConnectionInternal obj = null;
SysTx.Transaction transaction = null;
#if !MOBILE
PerformanceCounters.SoftConnectsPerSecond.Increment();
#endif
Bid.PoolerTrace("<prov.DbConnectionPool.GetConnection|RES|CPOOL> %d#, Getting connection.\n", ObjectID);
// If automatic transaction enlistment is required, then we try to
// get the connection from the transacted connection pool first.
if (HasTransactionAffinity) {
obj = GetFromTransactedPool(out transaction);
}
if (null == obj) {
Interlocked.Increment(ref _waitCount);
uint waitHandleCount = allowCreate ? 3u : 2u;
do {
int waitResult = BOGUS_HANDLE;
int releaseSemaphoreResult = 0;
bool mustRelease = false;
int waitForMultipleObjectsExHR = 0;
RuntimeHelpers.PrepareConstrainedRegions();
try {
_waitHandles.DangerousAddRef(ref mustRelease);
// We absolutely must have the value of waitResult set,
// or we may leak the mutex in async abort cases.
RuntimeHelpers.PrepareConstrainedRegions();
try {
Debug.Assert(2 == waitHandleCount || 3 == waitHandleCount, "unexpected waithandle count");
}
finally {
waitResult = SafeNativeMethods.WaitForMultipleObjectsEx(waitHandleCount, _waitHandles.DangerousGetHandle(), false, waitForMultipleObjectsTimeout, false);
#if !FULL_AOT_RUNTIME
// VSTFDEVDIV 479551 - call GetHRForLastWin32Error immediately after after the native call
if (waitResult == WAIT_FAILED) {
waitForMultipleObjectsExHR = Marshal.GetHRForLastWin32Error();
}
#endif
}
// From the WaitAny docs: "If more than one object became signaled during
// the call, this is the array index of the signaled object with the
// smallest index value of all the signaled objects." This is important
// so that the free object signal will be returned before a creation
// signal.
switch (waitResult) {
case WAIT_TIMEOUT:
Bid.PoolerTrace("<prov.DbConnectionPool.GetConnection|RES|CPOOL> %d#, Wait timed out.\n", ObjectID);
Interlocked.Decrement(ref _waitCount);
connection = null;
return false;
case ERROR_HANDLE:
// Throw the error that PoolCreateRequest stashed.
Bid.PoolerTrace("<prov.DbConnectionPool.GetConnection|RES|CPOOL> %d#, Errors are set.\n", ObjectID);
Interlocked.Decrement(ref _waitCount);
throw TryCloneCachedException();
case CREATION_HANDLE:
Bid.PoolerTrace("<prov.DbConnectionPool.GetConnection|RES|CPOOL> %d#, Creating new connection.\n", ObjectID);
try {
obj = UserCreateRequest(owningObject, userOptions);
}
catch {
if (null == obj) {
Interlocked.Decrement(ref _waitCount);
}
throw;
}
finally {
// SQLBUDT #386664 - ensure that we release this waiter, regardless
// of any exceptions that may be thrown.
if (null != obj) {
Interlocked.Decrement(ref _waitCount);
}
}
if (null == obj) {
// If we were not able to create an object, check to see if
// we reached MaxPoolSize. If so, we will no longer wait on
// the CreationHandle, but instead wait for a free object or
// the timeout.
//
if (Count >= MaxPoolSize && 0 != MaxPoolSize) {
if (!ReclaimEmancipatedObjects()) {
// modify handle array not to wait on creation mutex anymore
Debug.Assert(2 == CREATION_HANDLE, "creation handle changed value");
waitHandleCount = 2;
}
}
}
break;
case SEMAPHORE_HANDLE:
//
// guaranteed available inventory
//
Interlocked.Decrement(ref _waitCount);
obj = GetFromGeneralPool();
if ((obj != null) && (!obj.IsConnectionAlive())) {
Bid.PoolerTrace("<prov.DbConnectionPool.GetConnection|RES|CPOOL> %d#, Connection %d#, found dead and removed.\n", ObjectID, obj.ObjectID);
DestroyObject(obj);
obj = null; // Setting to null in case creating a new object fails
if (onlyOneCheckConnection) {
if (_waitHandles.CreationSemaphore.WaitOne(unchecked((int)waitForMultipleObjectsTimeout))) {
RuntimeHelpers.PrepareConstrainedRegions();
try {
Bid.PoolerTrace("<prov.DbConnectionPool.GetConnection|RES|CPOOL> %d#, Creating new connection.\n", ObjectID);
obj = UserCreateRequest(owningObject, userOptions);
}
finally {
_waitHandles.CreationSemaphore.Release(1);
}
}
else {
// Timeout waiting for creation semaphore - return null
Bid.PoolerTrace("<prov.DbConnectionPool.GetConnection|RES|CPOOL> %d#, Wait timed out.\n", ObjectID);
connection = null;
return false;
}
}
}
break;
case WAIT_FAILED:
Debug.Assert(waitForMultipleObjectsExHR != 0, "WaitForMultipleObjectsEx failed but waitForMultipleObjectsExHR remained 0");
Bid.PoolerTrace("<prov.DbConnectionPool.GetConnection|RES|CPOOL> %d#, Wait failed.\n", ObjectID);
Interlocked.Decrement(ref _waitCount);
Marshal.ThrowExceptionForHR(waitForMultipleObjectsExHR);
goto default; // if ThrowExceptionForHR didn't throw for some reason
case (WAIT_ABANDONED+SEMAPHORE_HANDLE):
Bid.PoolerTrace("<prov.DbConnectionPool.GetConnection|RES|CPOOL> %d#, Semaphore handle abandonded.\n", ObjectID);
Interlocked.Decrement(ref _waitCount);
throw new AbandonedMutexException(SEMAPHORE_HANDLE,_waitHandles.PoolSemaphore);
case (WAIT_ABANDONED+ERROR_HANDLE):
Bid.PoolerTrace("<prov.DbConnectionPool.GetConnection|RES|CPOOL> %d#, Error handle abandonded.\n", ObjectID);
Interlocked.Decrement(ref _waitCount);
throw new AbandonedMutexException(ERROR_HANDLE,_waitHandles.ErrorEvent);
case (WAIT_ABANDONED+CREATION_HANDLE):
Bid.PoolerTrace("<prov.DbConnectionPool.GetConnection|RES|CPOOL> %d#, Creation handle abandoned.\n", ObjectID);
Interlocked.Decrement(ref _waitCount);
throw new AbandonedMutexException(CREATION_HANDLE,_waitHandles.CreationSemaphore);
default:
Bid.PoolerTrace("<prov.DbConnectionPool.GetConnection|RES|CPOOL> %d#, WaitForMultipleObjects=%d\n", ObjectID, waitResult);
Interlocked.Decrement(ref _waitCount);
throw ADP.InternalError(ADP.InternalErrorCode.UnexpectedWaitAnyResult);
}
}
finally {
if (CREATION_HANDLE == waitResult) {
int result = SafeNativeMethods.ReleaseSemaphore(_waitHandles.CreationHandle.DangerousGetHandle(), 1, IntPtr.Zero);
if (0 == result) { // failure case
#if !FULL_AOT_RUNTIME
releaseSemaphoreResult = Marshal.GetHRForLastWin32Error();
#endif
}
}
if (mustRelease) {
_waitHandles.DangerousRelease();
}
}
if (0 != releaseSemaphoreResult) {
Marshal.ThrowExceptionForHR(releaseSemaphoreResult); // will only throw if (hresult < 0)
}
} while (null == obj);
}
if (null != obj)
{
PrepareConnection(owningObject, obj, transaction);
}
connection = obj;
return true;
}
private void PrepareConnection(DbConnection owningObject, DbConnectionInternal obj, SysTx.Transaction transaction) {
lock (obj)
{ // Protect against Clear and ReclaimEmancipatedObjects, which call IsEmancipated, which is affected by PrePush and PostPop
obj.PostPop(owningObject);
}
try
{
obj.ActivateConnection(transaction);
}
catch
{
// if Activate throws an exception
// put it back in the pool or have it properly disposed of
this.PutObject(obj, owningObject);
throw;
}
}
/// <summary>
/// Creates a new connection to replace an existing connection
/// </summary>
/// <param name="owningObject">Outer connection that currently owns <paramref name="oldConnection"/></param>
/// <param name="userOptions">Options used to create the new connection</param>
/// <param name="oldConnection">Inner connection that will be replaced</param>
/// <returns>A new inner connection that is attached to the <paramref name="owningObject"/></returns>
internal DbConnectionInternal ReplaceConnection(DbConnection owningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection) {
#if !MOBILE
PerformanceCounters.SoftConnectsPerSecond.Increment();
#endif
Bid.PoolerTrace("<prov.DbConnectionPool.ReplaceConnection|RES|CPOOL> %d#, replacing connection.\n", ObjectID);
DbConnectionInternal newConnection = UserCreateRequest(owningObject, userOptions, oldConnection);
if (newConnection != null) {
PrepareConnection(owningObject, newConnection, oldConnection.EnlistedTransaction);
oldConnection.PrepareForReplaceConnection();
oldConnection.DeactivateConnection();
oldConnection.Dispose();
}
return newConnection;
}
private DbConnectionInternal GetFromGeneralPool() {
DbConnectionInternal obj = null;
if (!_stackNew.TryPop(out obj)) {
if (!_stackOld.TryPop(out obj)) {
obj = null;
}
else {
Debug.Assert(obj != null, "null connection is not expected");
}
}
else {
Debug.Assert(obj != null, "null connection is not expected");
}
// SQLBUDT #356870 -- When another thread is clearing this pool,
// it will remove all connections in this pool which causes the
// following assert to fire, which really mucks up stress against
// checked bits. The assert is benign, so we're commenting it out.
//Debug.Assert(obj != null, "GetFromGeneralPool called with nothing in the pool!");
if (null != obj) {
Bid.PoolerTrace("<prov.DbConnectionPool.GetFromGeneralPool|RES|CPOOL> %d#, Connection %d#, Popped from general pool.\n", ObjectID, obj.ObjectID);
#if !MOBILE
PerformanceCounters.NumberOfFreeConnections.Decrement();
#endif
}
return(obj);
}
private DbConnectionInternal GetFromTransactedPool(out SysTx.Transaction transaction) {
transaction = ADP.GetCurrentTransaction();
DbConnectionInternal obj = null;
if (null != transaction && null != _transactedConnectionPool) {
obj = _transactedConnectionPool.GetTransactedObject(transaction);
if (null != obj) {
Bid.PoolerTrace("<prov.DbConnectionPool.GetFromTransactedPool|RES|CPOOL> %d#, Connection %d#, Popped from transacted pool.\n", ObjectID, obj.ObjectID);
#if !MOBILE
PerformanceCounters.NumberOfFreeConnections.Decrement();
#endif
if (obj.IsTransactionRoot) {
try {
obj.IsConnectionAlive(true);
}
catch {
Bid.PoolerTrace("<prov.DbConnectionPool.GetFromTransactedPool|RES|CPOOL> %d#, Connection %d#, found dead and removed.\n", ObjectID, obj.ObjectID);
DestroyObject(obj);
throw;
}
}
else if (!obj.IsConnectionAlive()) {
Bid.PoolerTrace("<prov.DbConnectionPool.GetFromTransactedPool|RES|CPOOL> %d#, Connection %d#, found dead and removed.\n", ObjectID, obj.ObjectID);
DestroyObject(obj);
obj = null;
}
}
}
return obj;
}
[ResourceExposure(ResourceScope.None)] // SxS: this method does not expose resources
[ResourceConsumption(ResourceScope.Machine, ResourceScope.Machine)]
private void PoolCreateRequest(object state) {
// called by pooler to ensure pool requests are currently being satisfied -
// creation mutex has not been obtained
IntPtr hscp;
Bid.PoolerScopeEnter(out hscp, "<prov.DbConnectionPool.PoolCreateRequest|RES|INFO|CPOOL> %d#\n", ObjectID);
try {
if (State.Running == _state) {
// in case WaitForPendingOpen ever failed with no subsequent OpenAsync calls,
// start it back up again
if (!_pendingOpens.IsEmpty && _pendingOpensWaiting == 0) {
Thread waitOpenThread = new Thread(WaitForPendingOpen);
waitOpenThread.IsBackground = true;
waitOpenThread.Start();
}
// Before creating any new objects, reclaim any released objects that were
// not closed.
ReclaimEmancipatedObjects();
if (!ErrorOccurred) {
if (NeedToReplenish) {
// Check to see if pool was created using integrated security and if so, make
// sure the identity of current user matches that of user that created pool.
// If it doesn't match, do not create any objects on the ThreadPool thread,
// since either Open will fail or we will open a object for this pool that does
// not belong in this pool. The side effect of this is that if using integrated
// security min pool size cannot be guaranteed.
if (UsingIntegrateSecurity && !_identity.Equals(DbConnectionPoolIdentity.GetCurrent())) {
return;
}
bool mustRelease = false;
int waitResult = BOGUS_HANDLE;
uint timeout = (uint)CreationTimeout;
RuntimeHelpers.PrepareConstrainedRegions();
try {
_waitHandles.DangerousAddRef(ref mustRelease);
// Obtain creation mutex so we're the only one creating objects
// and we must have the wait result
RuntimeHelpers.PrepareConstrainedRegions();
try { } finally {
waitResult = SafeNativeMethods.WaitForSingleObjectEx(_waitHandles.CreationHandle.DangerousGetHandle(), timeout, false);
}
if (WAIT_OBJECT_0 == waitResult) {
DbConnectionInternal newObj;
// Check ErrorOccurred again after obtaining mutex
if (!ErrorOccurred) {
while (NeedToReplenish) {
// Don't specify any user options because there is no outer connection associated with the new connection
newObj = CreateObject(owningObject: null, userOptions: null, oldConnection: null);
// We do not need to check error flag here, since we know if
// CreateObject returned null, we are in error case.
if (null != newObj) {
PutNewObject(newObj);
}
else {
break;
}
}
}
}
else if (WAIT_TIMEOUT == waitResult) {
// do not wait forever and potential block this worker thread
// instead wait for a period of time and just requeue to try again
QueuePoolCreateRequest();
}
else {
// trace waitResult and ignore the failure
Bid.PoolerTrace("<prov.DbConnectionPool.PoolCreateRequest|RES|CPOOL> %d#, PoolCreateRequest called WaitForSingleObject failed %d", ObjectID, waitResult);
}
}
catch (Exception e) {
//
if (!ADP.IsCatchableExceptionType(e)) {
throw;
}
// Now that CreateObject can throw, we need to catch the exception and discard it.
// There is no further action we can take beyond tracing. The error will be
// thrown to the user the next time they request a connection.
Bid.PoolerTrace("<prov.DbConnectionPool.PoolCreateRequest|RES|CPOOL> %d#, PoolCreateRequest called CreateConnection which threw an exception: %ls", ObjectID, e);
}
finally {
if (WAIT_OBJECT_0 == waitResult) {
// reuse waitResult and ignore its value
waitResult = SafeNativeMethods.ReleaseSemaphore(_waitHandles.CreationHandle.DangerousGetHandle(), 1, IntPtr.Zero);
}
if (mustRelease) {
_waitHandles.DangerousRelease();
}
}
}
}
}
}
finally {
Bid.ScopeLeave(ref hscp);
}
}
internal void PutNewObject(DbConnectionInternal obj) {
Debug.Assert(null != obj, "why are we adding a null object to the pool?");
// VSTFDEVDIV 742887 - When another thread is clearing this pool, it
// will set _cannotBePooled for all connections in this pool without prejudice which
// causes the following assert to fire, which really mucks up stress
// against checked bits.
// Debug.Assert(obj.CanBePooled, "non-poolable object in pool");
Bid.PoolerTrace("<prov.DbConnectionPool.PutNewObject|RES|CPOOL> %d#, Connection %d#, Pushing to general pool.\n", ObjectID, obj.ObjectID);
_stackNew.Push(obj);
_waitHandles.PoolSemaphore.Release(1);
#if !MOBILE
PerformanceCounters.NumberOfFreeConnections.Increment();
#endif
}
internal void PutObject(DbConnectionInternal obj, object owningObject) {
Debug.Assert(null != obj, "null obj?");
#if !MOBILE
PerformanceCounters.SoftDisconnectsPerSecond.Increment();
#endif
// Once a connection is closing (which is the state that we're in at
// this point in time) you cannot delegate a transaction to or enlist
// a transaction in it, so we can correctly presume that if there was
// not a delegated or enlisted transaction to start with, that there
// will not be a delegated or enlisted transaction once we leave the
// lock.
lock (obj) {
// Calling PrePush prevents the object from being reclaimed
// once we leave the lock, because it sets _pooledCount such
// that it won't appear to be out of the pool. What that
// means, is that we're now responsible for this connection:
// it won't get reclaimed if we drop the ball somewhere.
obj.PrePush(owningObject);
//
}
DeactivateObject(obj);
}
internal void PutObjectFromTransactedPool(DbConnectionInternal obj) {
Debug.Assert(null != obj, "null pooledObject?");
Debug.Assert(obj.EnlistedTransaction == null, "pooledObject is still enlisted?");
// called by the transacted connection pool , once it's removed the
// connection from it's list. We put the connection back in general
// circulation.
// NOTE: there is no locking required here because if we're in this
// method, we can safely presume that the caller is the only person
// that is using the connection, and that all pre-push logic has been
// done and all transactions are ended.
Bid.PoolerTrace("<prov.DbConnectionPool.PutObjectFromTransactedPool|RES|CPOOL> %d#, Connection %d#, Transaction has ended.\n", ObjectID, obj.ObjectID);
if (_state == State.Running && obj.CanBePooled) {
PutNewObject(obj);
}
else {
DestroyObject(obj);
QueuePoolCreateRequest();
}
}
private void QueuePoolCreateRequest() {
if (State.Running == _state) {
// Make sure we're at quota by posting a callback to the threadpool.
ThreadPool.QueueUserWorkItem(_poolCreateRequest);
}
}
private bool ReclaimEmancipatedObjects() {
bool emancipatedObjectFound = false;
Bid.PoolerTrace("<prov.DbConnectionPool.ReclaimEmancipatedObjects|RES|CPOOL> %d#\n", ObjectID);
List<DbConnectionInternal> reclaimedObjects = new List<DbConnectionInternal>();
int count;
lock(_objectList) {
count = _objectList.Count;
for (int i = 0; i < count; ++i) {
DbConnectionInternal obj = _objectList[i];
if (null != obj) {
bool locked = false;
try {
Monitor.TryEnter(obj, ref locked);
if (locked) { // avoid race condition with PrePush/PostPop and IsEmancipated
if (obj.IsEmancipated) {
// Inside the lock, we want to do as little
// as possible, so we simply mark the object
// as being in the pool, but hand it off to
// an out of pool list to be deactivated,
// etc.
obj.PrePush(null);
reclaimedObjects.Add(obj);
}
}
}
finally {
if (locked)
Monitor.Exit(obj);
}
}
}
}
// NOTE: we don't want to call DeactivateObject while we're locked,
// because it can make roundtrips to the server and this will block
// object creation in the pooler. Instead, we queue things we need
// to do up, and process them outside the lock.
count = reclaimedObjects.Count;
for (int i = 0; i < count; ++i) {
DbConnectionInternal obj = reclaimedObjects[i];
Bid.PoolerTrace("<prov.DbConnectionPool.ReclaimEmancipatedObjects|RES|CPOOL> %d#, Connection %d#, Reclaiming.\n", ObjectID, obj.ObjectID);
#if !MOBILE
PerformanceCounters.NumberOfReclaimedConnections.Increment();
#endif
emancipatedObjectFound = true;
obj.DetachCurrentTransactionIfEnded();
DeactivateObject(obj);
}
return emancipatedObjectFound;
}
internal void Startup() {
Bid.PoolerTrace("<prov.DbConnectionPool.Startup|RES|INFO|CPOOL> %d#, CleanupWait=%d\n", ObjectID, _cleanupWait);
_cleanupTimer = CreateCleanupTimer();
if (NeedToReplenish) {
QueuePoolCreateRequest();
}
}
internal void Shutdown() {
Bid.PoolerTrace("<prov.DbConnectionPool.Shutdown|RES|INFO|CPOOL> %d#\n", ObjectID);
_state = State.ShuttingDown;
// deactivate timer callbacks
Timer t = _cleanupTimer;
_cleanupTimer = null;
if (null != t) {
t.Dispose();
}
}
// TransactionEnded merely provides the plumbing for DbConnectionInternal to access the transacted pool
// that is implemented inside DbConnectionPool. This method's counterpart (PutTransactedObject) should
// only be called from DbConnectionPool.DeactivateObject and thus the plumbing to provide access to
// other objects is unnecessary (hence the asymmetry of Ended but no Begin)
internal void TransactionEnded(SysTx.Transaction transaction, DbConnectionInternal transactedObject) {
Debug.Assert(null != transaction, "null transaction?");
Debug.Assert(null != transactedObject, "null transactedObject?");
// Note: connection may still be associated with transaction due to Explicit Unbinding requirement.
Bid.PoolerTrace("<prov.DbConnectionPool.TransactionEnded|RES|CPOOL> %d#, Transaction %d#, Connection %d#, Transaction Completed\n", ObjectID, transaction.GetHashCode(), transactedObject.ObjectID);
// called by the internal connection when it get's told that the
// transaction is completed. We tell the transacted pool to remove
// the connection from it's list, then we put the connection back in
// general circulation.
TransactedConnectionPool transactedConnectionPool = _transactedConnectionPool;
if (null != transactedConnectionPool) {
transactedConnectionPool.TransactionEnded(transaction, transactedObject);
}
}
private DbConnectionInternal UserCreateRequest(DbConnection owningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection = null) {
// called by user when they were not able to obtain a free object but
// instead obtained creation mutex
DbConnectionInternal obj = null;
if (ErrorOccurred) {
throw TryCloneCachedException();
}
else {
if ((oldConnection != null) || (Count < MaxPoolSize) || (0 == MaxPoolSize)) {
// If we have an odd number of total objects, reclaim any dead objects.
// If we did not find any objects to reclaim, create a new one.
//
if ((oldConnection != null) || (Count & 0x1) == 0x1 || !ReclaimEmancipatedObjects())
obj = CreateObject(owningObject, userOptions, oldConnection);
}
return obj;
}
}
}
}
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