00001 /******************************************************************************* 00002 00003 @file PlainCache.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, April 2004 00034 @author Kris 00035 00036 00037 *******************************************************************************/ 00038 00039 module mango.cache.PlainCache; 00040 00041 public import mango.cache.HashMap; 00042 00043 public import mango.cache.model.ICache, 00044 mango.cache.model.IPayload; 00045 00046 /****************************************************************************** 00047 00048 A base-class for the cache framework, using a thread-aware hash map 00049 to contain the cache entries. Cache entries must be instances of the 00050 IPayload interface; this allows them to be moved around the network 00051 or serialized onto some external medium. 00052 00053 ******************************************************************************/ 00054 00055 class PlainCache : IMutableCache 00056 { 00057 private HashMap map; 00058 00059 /********************************************************************** 00060 00061 Construct a basic cache with the specified number of 00062 preallocated entries. The concurrency level indicates 00063 approximately how many threads will content for write 00064 access at one time. 00065 00066 **********************************************************************/ 00067 00068 this (uint capacity = 101, uint concurrency = 16) 00069 { 00070 map = new HashMap (capacity, 0.75, concurrency); 00071 } 00072 00073 /********************************************************************** 00074 00075 Get the cache entry identified by the given key 00076 00077 **********************************************************************/ 00078 00079 IPayload get (char[] key) 00080 { 00081 return cast (IPayload) map.get (key); 00082 } 00083 00084 /********************************************************************** 00085 00086 Place an entry into the cache and associate it with the 00087 provided key. Note that there can be only one entry for 00088 any particular key. If two keys entries are added with 00089 the same key, the second effectively overwrites the first. 00090 00091 Returns what it was given 00092 00093 **********************************************************************/ 00094 00095 IPayload put(char[] key, IPayload entry) 00096 { 00097 map.put (key, cast(Object) entry); 00098 return entry; 00099 } 00100 00101 /********************************************************************** 00102 00103 Remove (and return) the cache entry associated with the 00104 provided key. Returns null if there is no such entry. 00105 00106 **********************************************************************/ 00107 00108 IPayload extract (char[] key) 00109 { 00110 return cast(IPayload) map.remove (key); 00111 } 00112 00113 /********************************************************************** 00114 00115 Remove (and return) the cache entry associated with the 00116 provided key. Returns null if there is no such entry. 00117 00118 **********************************************************************/ 00119 00120 IPayload extract (char[] key, ulong timeLimit) 00121 { 00122 IPayload e = cast(IPayload) map.get (key); 00123 00124 if (e) 00125 { 00126 // ignore if existing entry is newer 00127 if (e.getTime > timeLimit) 00128 return null; 00129 00130 // remove the entry from array, and return it 00131 map.remove (key); 00132 } 00133 return e; 00134 } 00135 00136 /********************************************************************** 00137 00138 **********************************************************************/ 00139 00140 ICache bind (ICacheLoader loader) 00141 { 00142 class PlainLoader : ICache 00143 { 00144 IMutableCache cache; 00145 ICacheLoader loader; 00146 00147 /****************************************************** 00148 00149 ******************************************************/ 00150 00151 this (IMutableCache cache, ICacheLoader loader) 00152 { 00153 this.cache = cache; 00154 this.loader = loader; 00155 } 00156 00157 /****************************************************** 00158 00159 ******************************************************/ 00160 00161 IPayload get (char[] key) 00162 { 00163 long t; 00164 IPayload p = cache.get (key); 00165 00166 if (p) 00167 { 00168 if (loader.test (p)) 00169 return p; 00170 t = p.getTime (); 00171 } 00172 00173 p = loader.load (key, t); 00174 if (p) 00175 cache.put (key, p); 00176 return p; 00177 } 00178 } 00179 00180 return new PlainLoader (this, loader); 00181 } 00182 } 00183 00184