#region License
/*
* Copyright 2002-2008 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#endregion
using System;
using System.Collections;
using Spring.Messaging.Ems.Common;
using TIBCO.EMS;
using Common.Logging;
using Spring.Collections;
using Spring.Util;
namespace Spring.Messaging.Ems.Connections{
/// <summary>
/// <see cref="SingleConnectionFactory"/> subclass that adds
/// Session, MessageProducer, and MessageConsumer caching. This ConnectionFactory
/// also switches the ReconnectOnException property to true
/// by default, allowing for automatic recovery of the underlying
/// Connection.
/// </summary>
/// <remarks>
/// By default, only one single Session will be cached, with further requested
/// Sessions being created and disposed on demand. Consider raising the
/// SessionCacheSize property in case of a high-concurrency environment.
/// <para>
/// NOTE: This ConnectionFactory requires explicit closing of all Sessions
/// obtained from its shared Connection. This is the usual recommendation for
/// native EMS access code anyway. However, with this ConnectionFactory, its use
/// is mandatory in order to actually allow for Session reuse.
/// </para>
/// <para>
/// Note also that MessageConsumers obtained from a cached Session won't get
/// closed until the Session will eventually be removed from the pool. This may
/// lead to semantic side effects in some cases. For a durable subscriber, the
/// logical <code>Session.Close()</code> call will also close the subscription.
/// Re-registering a durable consumer for the same subscription on the same
/// Session handle is not supported; close and reobtain a cached Session first.
/// </para>
/// </remarks>
///
/// <author>Juergen Hoeller</author>
/// <author>Mark Pollack (.NET)</author>
public class CachingConnectionFactory : SingleConnectionFactory
{
#region Logging Definition
private static readonly ILog LOG = LogManager.GetLogger(typeof(CachingConnectionFactory));
#endregion
private int sessionCacheSize = 1;
private bool cacheProducers = true;
private bool cacheConsumers = true;
private volatile bool active = true;
private IDictionary cachedSessions = new Hashtable();
/// <summary>
/// Initializes a new instance of the <see cref="CachingConnectionFactory"/> class.
/// and sets the ReconnectOnException to true
/// </summary>
public CachingConnectionFactory()
{
ReconnectOnException = true;
}
/// <summary>
/// Initializes a new instance of the <see cref="CachingConnectionFactory"/> class for the given
/// IConnectionFactory
/// </summary>
/// <param name="targetConnectionFactory">The target connection factory.</param>
public CachingConnectionFactory(IConnectionFactory targetConnectionFactory) : base(targetConnectionFactory)
{
ReconnectOnException = true;
}
/// <summary>
/// Gets or sets the size of the session cache.
/// </summary>
/// <remarks>
/// This cache size is the maximum limit for the number of cached Sessions
/// per session acknowledgement type (auto, client, dups_ok, transacted).
/// As a consequence, the actual number of cached Sessions may be up to
/// four times as high as the specified value - in the unlikely case
/// of mixing and matching different acknowledgement types.
/// <para>
/// Default is 1: caching a single Session, (re-)creating further ones on
/// demand. Specify a number like 10 if you'd like to raise the number of cached
/// Sessions; that said, 1 may be sufficient for low-concurrency scenarios.
/// </para>
/// </remarks>
/// <value>The size of the session cache.</value>
public int SessionCacheSize
{
get { return sessionCacheSize; }
set
{
AssertUtils.IsTrue(value >= 1, "Session cache size must be 1 or higher");
sessionCacheSize = value;
}
}
/// <summary>
/// Gets or sets a value indicating whether to cache MessageProducers per
/// Session instance. (more specifically: one MessageProducer per Destination
/// and Session).
/// </summary>
/// <remarks>
/// <para>Default is "true". Switch this to "false" in order to always,
/// recreate MessageProducers on demand.
/// </para>
/// </remarks>
/// <value><c>true</c> if should cache message producers; otherwise, <c>false</c>.</value>
public bool CacheProducers
{
get { return cacheProducers; }
set { cacheProducers = value; }
}
/// <summary>
/// Gets or sets a value indicating whether o cache JMS MessageConsumers per
/// EMS Session instance.
/// </summary>
/// <remarks>
/// Mmore specifically: one MessageConsumer per Destination, selector String
/// and Session. Note that durable subscribers will only be cached until
/// logical closing of the Session handle.
/// <para>
/// Default is "true". Switch this to "false" in order to always
/// recreate MessageConsumers on demand.
/// </para>
/// </remarks>
/// <value><c>true</c> to cache consumers per session instance; otherwise, <c>false</c>.</value>
public bool CacheConsumers
{
get { return cacheConsumers; }
set { cacheConsumers = value; }
}
/// <summary>
/// Gets or sets a value indicating whether this instance is active.
/// </summary>
/// <value><c>true</c> if this instance is active; otherwise, <c>false</c>.</value>
public bool IsActive
{
get { return active; }
set { active = value; }
}
/// <summary>
/// Resets the Session cache as well as resetting the connection.
/// </summary>
public override void ResetConnection()
{
this.active = false;
lock (cachedSessions)
{
foreach (DictionaryEntry dictionaryEntry in cachedSessions)
{
LinkedList sessionList = (LinkedList) dictionaryEntry.Value;
lock (sessionList)
{
foreach (ISession session in sessionList)
{
try
{
session.Close();
}
catch (Exception ex)
{
LOG.Trace("Could not close cached EMS Session", ex);
}
}
}
}
cachedSessions.Clear();
}
this.active = true;
// Now proceed with actual closing of the shared Connection...
base.ResetConnection();
}
/// <summary>
/// Obtaining a cached Session.
/// </summary>
/// <param name="con">The connection to operate on.</param>
/// <param name="mode">The session ack mode.</param>
/// <returns>The Session to use
/// </returns>
public override ISession GetSession(IConnection con, SessionMode mode)
{
LinkedList sessionList;
lock (cachedSessions)
{
sessionList = (LinkedList) cachedSessions[mode];
if (sessionList == null)
{
sessionList = new LinkedList();
cachedSessions.Add(mode, sessionList);
}
}
ISession session = null;
lock (sessionList)
{
if (sessionList.Count > 0)
{
session = (ISession) sessionList[0];
sessionList.RemoveAt(0);
}
}
if (session != null)
{
if (LOG.IsDebugEnabled)
{
LOG.Debug("Found cached Session for mode " + mode + ": "
+ (session is IDecoratorSession ? ((IDecoratorSession) session).TargetSession : session));
}
} else
{
ISession targetSession = CreateSession(con, mode);
if (LOG.IsDebugEnabled)
{
LOG.Debug("Creating cached Session for mode " + mode + ": " + targetSession);
}
session = GetCachedSessionWrapper(targetSession, sessionList);
}
return session;
}
protected virtual ISession CreateSession(IConnection con, SessionMode mode)
{
bool transacted = (mode == SessionMode.SessionTransacted);
SessionMode ackMode = (transacted ? SessionMode.SessionTransacted : mode);
return con.CreateSession(transacted, ackMode);
}
/// <summary>
/// Wraps the given Session so that it delegates every method call to the target session but
/// adapts close calls. This is useful for allowing application code to
/// handle a special framework Session just like an ordinary Session.
/// </summary>
/// <param name="targetSession">The original Session to wrap.</param>
/// <param name="sessionList">The List of cached Sessions that the given Session belongs to.</param>
/// <returns>The wrapped Session</returns>
protected virtual ISession GetCachedSessionWrapper(ISession targetSession, LinkedList sessionList)
{
return new CachedSession(targetSession, sessionList, this);
}
}
}
|