Main Page | Class Hierarchy | Alphabetical List | Class List | File List | Class Members | File Members | Related Pages

CacheInvalidator.d

Go to the documentation of this file.
00001 /*******************************************************************************
00002 
00003         @file CacheInvalidator.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.CacheInvalidator;
00040 
00041 private import  mango.cache.Payload;
00042 
00043 public  import  mango.cluster.Client;
00044 
00045 /*******************************************************************************
00046 
00047         Utility class to invalidate specific cache entries across a 
00048         network. Any active CacheInvalidatee objects listening upon
00049         the channel specified for this class will "wake up" whenever
00050         the invalidate() method is invoked.
00051 
00052 *******************************************************************************/
00053 
00054 class CacheInvalidator : Client
00055 {
00056         private InvalidatorPayload filter;
00057 
00058         /***********************************************************************
00059 
00060                 Construct an invalidator on the specified channel. Only
00061                 those CacheInvalidatee instances configured for the same
00062                 channel will be listening to this invalidator.
00063 
00064         ***********************************************************************/
00065         
00066         this (ICluster cluster, char[] channel)
00067         in {
00068            assert (channel.length);
00069            }
00070         body
00071         {
00072                 super (cluster, channel);
00073 
00074                 // this is what we'll send as an invalidation notification ...
00075                 this.filter = new InvalidatorPayload;
00076         }
00077 
00078         /***********************************************************************
00079 
00080                 Invalidate all network cache instances on this channel
00081                 using the specified key. When 'timeLimit' is specified, 
00082                 only those cache entries with a time lesser or equal to
00083                 that specified will be removed. This is often useful if 
00084                 you wish to avoid invalidating a cache (local or remote)
00085                 that has just been updated; simply pass the time value
00086                 of the 'old' IPayload as the argument.
00087 
00088                 Note that this is asynchronous! An invalidation is just
00089                 a request to remove the item within a short time period.
00090                 If you need the entry removed synchronously, you should
00091                 use the NetworkCache extract() method instead.
00092 
00093         ***********************************************************************/
00094         
00095         void invalidate (char[] key, ulong timeLimit = ulong.max)
00096         in {
00097            assert (key.length);
00098            }
00099         body
00100         {
00101                 filter.setText (key);
00102                 filter.setTimeout (timeLimit);
00103 
00104                 // broadcast a message across the cluster
00105                 getCluster.broadcast (getChannel, filter);
00106         }
00107 }
00108 
00109 
00110 /*******************************************************************************
00111 
00112 *******************************************************************************/
00113 
00114 private class InvalidatorPayload : Payload
00115 {
00116         private char[]                    text;
00117         private ulong                     timeout;
00118 
00119         private InvalidatorPayload        next;   
00120         private static InvalidatorPayload freelist;
00121 
00122         private import mango.io.PickleRegistry;
00123 
00124         /***********************************************************************
00125         
00126                 Register this class for pickling, so we can resurrect
00127                 instances when they arrive on a network datagram.
00128 
00129         ***********************************************************************/
00130 
00131         static this ()
00132         {
00133                 PickleRegistry.enroll (new InvalidatorPayload);
00134         }
00135 
00136         /***********************************************************************
00137 
00138                 Allocate a Payload from a list rather than creating a new one
00139 
00140         ***********************************************************************/
00141 
00142         synchronized InvalidatorPayload create ()
00143         {  
00144                 InvalidatorPayload s;
00145         
00146                 if (freelist)
00147                    {
00148                    s = freelist;
00149                    freelist = s.next;
00150                    }
00151                 else
00152                    s = new InvalidatorPayload;
00153                 return s;
00154         }
00155 
00156         /***********************************************************************
00157 
00158         ***********************************************************************/
00159 
00160         char[] getText ()
00161         {
00162                 return text;
00163         }
00164 
00165         /***********************************************************************
00166 
00167         ***********************************************************************/
00168 
00169         void setText (char[] text)
00170         in {
00171            assert (text.length);
00172            }
00173         body
00174         {
00175                 this.text = text;
00176         }
00177 
00178         /***********************************************************************
00179 
00180                 Set the identifier of the cache that should not be touched
00181                 by an invalidation broadcast. This is typically a local
00182                 cache on the machine originating the invalidation; without
00183                 the ability to guard against local invalidation, the cache
00184                 entry that was just added locally would be removed along
00185                 with others across the cluster. The alternative would be
00186                 to invalidate before addding, but that approach can quickly 
00187                 become complicated by timing issues.
00188 
00189         ***********************************************************************/
00190 
00191         void setTimeout (ulong olderThan)
00192         {
00193                 timeout = olderThan;
00194         }
00195 
00196         /***********************************************************************
00197 
00198         ***********************************************************************/
00199 
00200         ulong getTimeout ()
00201         {
00202                 return timeout;
00203         }
00204 
00205         /***********************************************************************
00206 
00207                 Return this Payload to the free-list
00208 
00209         ***********************************************************************/
00210 
00211         synchronized void destroy ()
00212         {
00213                 next = freelist;
00214                 freelist = this;
00215         }
00216 
00217         /***********************************************************************
00218 
00219         ***********************************************************************/
00220 
00221         void write (IWriter writer)
00222         {
00223                 super.write (writer);
00224                 writer.put  (timeout).put(text);
00225         }
00226 
00227         /***********************************************************************
00228 
00229                 Read our attributes, after telling our superclass to do
00230                 likewise. The order of this is important with respect to
00231                 inheritance, such that a subclass and superclass may be 
00232                 populated in isolation where appropriate.
00233 
00234                 Note that we slice our text attribute, rather than copying
00235                 it. Since this class is temporal we can forego allocation
00236                 of memory, and just map it directly from the input buffer. 
00237 
00238         ***********************************************************************/
00239 
00240         void read (IReader reader)
00241         {
00242                 super.read (reader);
00243                 reader.get (timeout).get(text); 
00244         }
00245 
00246         /***********************************************************************
00247 
00248         ***********************************************************************/
00249 
00250         char[] getGuid ()
00251         {
00252                 return this.classinfo.name;
00253         }
00254 }
00255 
00256 

Generated on Tue Jan 25 21:18:20 2005 for Mango by doxygen 1.3.6