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CacheInvalidatee.d

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00001 /*******************************************************************************
00002 
00003         @file CacheInvalidatee.d
00004         
00005         Copyright (C) 2004 Kris Bell
00006         
00007         This software is provided 'as-is', without any express or implied
00008         warranty. In no event will the authors be held liable for damages
00009         of any kind arising from the use of this software.
00010         
00011         Permission is hereby granted to anyone to use this software for any 
00012         purpose, including commercial applications, and to alter it and/or 
00013         redistribute it freely, subject to the following restrictions:
00014         
00015         1. The origin of this software must not be misrepresented; you must 
00016            not claim that you wrote the original software. If you use this 
00017            software in a product, an acknowledgment within documentation of 
00018            said product would be appreciated but is not required.
00019 
00020         2. Altered source versions must be plainly marked as such, and must 
00021            not be misrepresented as being the original software.
00022 
00023         3. This notice may not be removed or altered from any distribution
00024            of the source.
00025 
00026 
00027                         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
00028 
00029 
00030         @version        Initial version, July 2004      
00031         @author         Kris
00032 
00033 
00034 *******************************************************************************/
00035 
00036 module mango.cluster.CacheInvalidatee;
00037 
00038 private import  mango.log.Logger;
00039 
00040 private import  mango.cache.Payload;
00041 
00042 private import  mango.cache.model.ICache;
00043 
00044 private import  mango.cluster.model.ICluster;
00045 
00046 private import  mango.cluster.Client,
00047                 mango.cluster.CacheInvalidator;
00048                 
00049 /*******************************************************************************
00050 
00051         Wrapper around an ICache instance that attaches it to the network, 
00052         and ensures the former complies with cache invalidation requests. 
00053         Use this in conjunction with CacheInvalidator or NetworkCombo. The 
00054         ICache provided should typically be synchronized against thread 
00055         contention since it will potentially have entries removed from a 
00056         listener thread (you won't need synchronization if you're using
00057         the concurrent hash-map ICache implementation).
00058 
00059 *******************************************************************************/
00060 
00061 class CacheInvalidatee : Client, IEventListener
00062 {
00063         private IMutableCache   cache;
00064         private ILogger         logger;
00065         private IConsumer       consumer;
00066 
00067         /***********************************************************************
00068 
00069                 Construct a CacheInvalidatee upon the given cache, using
00070                 the named channel. This channel should be a name that's 
00071                 common to both the receiver and the sender.
00072 
00073         ***********************************************************************/
00074         
00075         this (ICluster cluster, char[] channel, IMutableCache cache)
00076         in {
00077            assert (cache);
00078            }
00079         body
00080         {
00081                 super (cluster, channel);
00082 
00083                 this.cache = cache;
00084                 this.logger = cluster.getLogger;
00085         
00086                 // make sure we have a logger configured
00087                 if (this.logger is null)
00088                     throw new ClusterException ("CacheInvalidatee requires the "
00089                                                 "cluster to have a logger configured");
00090         
00091                 // start listening for invalidation requests
00092                 consumer = getCluster.createConsumer (getChannel(), IEvent.Style.Bulletin, this);
00093         }
00094 
00095         /***********************************************************************
00096 
00097                 Detach from the network. The CacheInvalidatee is disabled
00098                 from this point forward.
00099 
00100         ***********************************************************************/
00101         
00102         void cancel ()
00103         {
00104                 consumer.cancel ();
00105         }
00106 
00107         /***********************************************************************
00108 
00109                 Return the IMutableCache instance provided during construction
00110 
00111         ***********************************************************************/
00112         
00113         IMutableCache getCache ()
00114         {
00115                 return cache;
00116         }
00117 
00118         /***********************************************************************
00119 
00120                 Notification callback from the listener. We remove the
00121                 indicated entry from our cache and destroy the payload
00122                 immediately in case it belongs on a freelist.
00123 
00124         ***********************************************************************/
00125         
00126         protected void notify (IEvent event, IPayload payload)
00127         {
00128                 assert (payload);
00129 
00130                 try {
00131                     InvalidatorPayload p = cast(InvalidatorPayload) payload;
00132 
00133                     // remove entry from our cache
00134                     if (cache.extract (p.getText, p.getTimeout))
00135                         if (logger.isEnabled (logger.Level.Trace))
00136                             logger.trace ("removed cache entry '"~p.getText~
00137                                           "' on channel '"~event.getChannel.getName~"'");
00138                     } finally
00139                             // place payload back on freelist?
00140                             payload.destroy ();
00141         }
00142 }
00143 

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