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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
using System;
using System.Runtime;
using System.Runtime.Diagnostics;
using System.Threading.Tasks;
namespace System.ServiceModel.Channels
{
// Helper class used to manage the lifetime of a connection relative to its pool.
internal abstract class ConnectionPoolHelper
{
private IConnectionInitiator _connectionInitiator;
private ConnectionPool _connectionPool;
private Uri _via;
private bool _closed;
// key for rawConnection in the connection pool
private string _connectionKey;
// did rawConnection originally come from connectionPool?
private bool _isConnectionFromPool;
// the "raw" connection that should be stored in the pool
private IConnection _rawConnection;
// the "upgraded" connection built on top of the "raw" connection to be used for I/O
private IConnection _upgradedConnection;
public ConnectionPoolHelper(ConnectionPool connectionPool, IConnectionInitiator connectionInitiator, Uri via)
{
_connectionInitiator = connectionInitiator;
_connectionPool = connectionPool;
_via = via;
}
private object ThisLock
{
get { return this; }
}
protected abstract IConnection AcceptPooledConnection(IConnection connection, ref TimeoutHelper timeoutHelper);
protected abstract Task<IConnection> AcceptPooledConnectionAsync(IConnection connection, ref TimeoutHelper timeoutHelper);
protected abstract TimeoutException CreateNewConnectionTimeoutException(TimeSpan timeout, TimeoutException innerException);
private IConnection TakeConnection(TimeSpan timeout)
{
return _connectionPool.TakeConnection(null, _via, timeout, out _connectionKey);
}
public async Task<IConnection> EstablishConnectionAsync(TimeSpan timeout)
{
TimeoutHelper timeoutHelper = new TimeoutHelper(timeout);
IConnection localRawConnection = null;
IConnection localUpgradedConnection = null;
bool localIsConnectionFromPool = true;
// first try and use a connection from our pool (and use it if we successfully receive an ACK)
while (localIsConnectionFromPool)
{
localRawConnection = this.TakeConnection(timeoutHelper.RemainingTime());
if (localRawConnection == null)
{
localIsConnectionFromPool = false;
}
else
{
bool preambleSuccess = false;
try
{
localUpgradedConnection = await AcceptPooledConnectionAsync(localRawConnection, ref timeoutHelper);
preambleSuccess = true;
break;
}
catch (CommunicationException)
{
// CommunicationException is ok since it was a cached connection of unknown state
}
catch (TimeoutException)
{
// ditto for TimeoutException
}
finally
{
if (!preambleSuccess)
{
// This cannot throw TimeoutException since isConnectionStillGood is false (doesn't attempt a Close).
_connectionPool.ReturnConnection(_connectionKey, localRawConnection, false, TimeSpan.Zero);
}
}
}
}
// if there isn't anything in the pool, we need to use a new connection
if (!localIsConnectionFromPool)
{
bool success = false;
TimeSpan connectTimeout = timeoutHelper.RemainingTime();
try
{
try
{
localRawConnection = await _connectionInitiator.ConnectAsync(_via, connectTimeout);
}
catch (TimeoutException e)
{
throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(CreateNewConnectionTimeoutException(
connectTimeout, e));
}
_connectionInitiator = null;
localUpgradedConnection = await AcceptPooledConnectionAsync(localRawConnection, ref timeoutHelper);
success = true;
}
finally
{
if (!success)
{
_connectionKey = null;
if (localRawConnection != null)
{
localRawConnection.Abort();
}
}
}
}
SnapshotConnection(localUpgradedConnection, localRawConnection, localIsConnectionFromPool);
return localUpgradedConnection;
}
public IConnection EstablishConnection(TimeSpan timeout)
{
TimeoutHelper timeoutHelper = new TimeoutHelper(timeout);
IConnection localRawConnection = null;
IConnection localUpgradedConnection = null;
bool localIsConnectionFromPool = true;
// first try and use a connection from our pool (and use it if we successfully receive an ACK)
while (localIsConnectionFromPool)
{
localRawConnection = this.TakeConnection(timeoutHelper.RemainingTime());
if (localRawConnection == null)
{
localIsConnectionFromPool = false;
}
else
{
bool preambleSuccess = false;
try
{
localUpgradedConnection = AcceptPooledConnection(localRawConnection, ref timeoutHelper);
preambleSuccess = true;
break;
}
catch (CommunicationException /*e*/)
{
// CommunicationException is ok since it was a cached connection of unknown state
}
catch (TimeoutException /*e*/)
{
// ditto for TimeoutException
}
finally
{
if (!preambleSuccess)
{
// This cannot throw TimeoutException since isConnectionStillGood is false (doesn't attempt a Close).
_connectionPool.ReturnConnection(_connectionKey, localRawConnection, false, TimeSpan.Zero);
}
}
}
}
// if there isn't anything in the pool, we need to use a new connection
if (!localIsConnectionFromPool)
{
bool success = false;
TimeSpan connectTimeout = timeoutHelper.RemainingTime();
try
{
try
{
localRawConnection = _connectionInitiator.Connect(_via, connectTimeout);
}
catch (TimeoutException e)
{
throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(CreateNewConnectionTimeoutException(
connectTimeout, e));
}
_connectionInitiator = null;
localUpgradedConnection = AcceptPooledConnection(localRawConnection, ref timeoutHelper);
success = true;
}
finally
{
if (!success)
{
_connectionKey = null;
if (localRawConnection != null)
{
localRawConnection.Abort();
}
}
}
}
SnapshotConnection(localUpgradedConnection, localRawConnection, localIsConnectionFromPool);
return localUpgradedConnection;
}
private void SnapshotConnection(IConnection upgradedConnection, IConnection rawConnection, bool isConnectionFromPool)
{
lock (ThisLock)
{
if (_closed)
{
upgradedConnection.Abort();
// cleanup our pool if necessary
if (isConnectionFromPool)
{
_connectionPool.ReturnConnection(_connectionKey, rawConnection, false, TimeSpan.Zero);
}
throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(
new CommunicationObjectAbortedException(
string.Format(SRServiceModel.OperationAbortedDuringConnectionEstablishment, _via)));
}
else
{
_upgradedConnection = upgradedConnection;
_rawConnection = rawConnection;
_isConnectionFromPool = isConnectionFromPool;
}
}
}
public void Abort()
{
ReleaseConnection(true, TimeSpan.Zero);
}
public void Close(TimeSpan timeout)
{
ReleaseConnection(false, timeout);
}
private void ReleaseConnection(bool abort, TimeSpan timeout)
{
string localConnectionKey;
IConnection localUpgradedConnection;
IConnection localRawConnection;
lock (ThisLock)
{
_closed = true;
localConnectionKey = _connectionKey;
localUpgradedConnection = _upgradedConnection;
localRawConnection = _rawConnection;
_upgradedConnection = null;
_rawConnection = null;
}
if (localUpgradedConnection == null)
{
return;
}
try
{
if (_isConnectionFromPool)
{
_connectionPool.ReturnConnection(localConnectionKey, localRawConnection, !abort, timeout);
}
else
{
if (abort)
{
localUpgradedConnection.Abort();
}
else
{
_connectionPool.AddConnection(localConnectionKey, localRawConnection, timeout);
}
}
}
catch (CommunicationException /*e*/)
{
localUpgradedConnection.Abort();
}
}
}
}
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