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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         4. Derivative works are permitted, but they must carry this notice
00027            in full and credit the original source.
00028 
00029 
00030                         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
00031 
00032 
00033         @version        Initial version, July 2004      
00034         @author         Kris
00035 
00036 
00037 *******************************************************************************/
00038 
00039 module mango.cluster.CacheInvalidatee;
00040 
00041 private import  mango.log.Logger;
00042 
00043 private import  mango.cache.Payload;
00044 
00045 private import  mango.cache.model.ICache;
00046 
00047 private import  mango.cluster.model.ICluster;
00048 
00049 private import  mango.cluster.Client,
00050                 mango.cluster.CacheInvalidator;
00051                 
00052 /*******************************************************************************
00053 
00054         Wrapper around an ICache instance that attaches it to the network, 
00055         and ensures the former complies with cache invalidation requests. 
00056         Use this in conjunction with CacheInvalidator or NetworkCombo. The 
00057         ICache provided should typically be synchronized against thread 
00058         contention since it will potentially have entries removed from a 
00059         listener thread (you won't need synchronization if you're using
00060         the concurrent hash-map ICache implementation).
00061 
00062 *******************************************************************************/
00063 
00064 class CacheInvalidatee : Client, IEventListener
00065 {
00066         private IMutableCache   cache;
00067         private ILogger         logger;
00068         private IConsumer       consumer;
00069 
00070         /***********************************************************************
00071 
00072                 Construct a CacheInvalidatee upon the given cache, using
00073                 the named channel. This channel should be a name that's 
00074                 common to both the receiver and the sender.
00075 
00076         ***********************************************************************/
00077         
00078         this (ICluster cluster, char[] channel, IMutableCache cache)
00079         in {
00080            assert (cache);
00081            }
00082         body
00083         {
00084                 super (cluster, channel);
00085 
00086                 this.cache = cache;
00087                 this.logger = cluster.getLogger;
00088         
00089                 // make sure we have a logger configured
00090                 if (this.logger is null)
00091                     throw new ClusterException ("CacheInvalidatee requires the "
00092                                                 "cluster to have a logger configured");
00093         
00094                 // start listening for invalidation requests
00095                 consumer = getCluster.createConsumer (getChannel(), IEvent.Style.Bulletin, this);
00096         }
00097 
00098         /***********************************************************************
00099 
00100                 Detach from the network. The CacheInvalidatee is disabled
00101                 from this point forward.
00102 
00103         ***********************************************************************/
00104         
00105         void cancel ()
00106         {
00107                 consumer.cancel ();
00108         }
00109 
00110         /***********************************************************************
00111 
00112                 Return the IMutableCache instance provided during construction
00113 
00114         ***********************************************************************/
00115         
00116         IMutableCache getCache ()
00117         {
00118                 return cache;
00119         }
00120 
00121         /***********************************************************************
00122 
00123                 Notification callback from the listener. We remove the
00124                 indicated entry from our cache and destroy the payload
00125                 immediately in case it belongs on a freelist.
00126 
00127         ***********************************************************************/
00128         
00129         protected void notify (IEvent event, IPayload payload)
00130         {
00131                 assert (payload);
00132 
00133                 try {
00134                     InvalidatorPayload p = cast(InvalidatorPayload) payload;
00135 
00136                     // remove entry from our cache
00137                     if (cache.extract (p.getText, p.getTimeout))
00138                         if (logger.isEnabled (logger.Level.Trace))
00139                             logger.trace ("removed cache entry '"~p.getText~
00140                                           "' on channel '"~event.getChannel.getName~"'");
00141                     } finally
00142                             // place payload back on freelist?
00143                             payload.destroy ();
00144         }
00145 }
00146 

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