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 // cast to void* first to avoid overhead 00082 return cast (IPayload) cast(void*) map.get (key); 00083 } 00084 00085 /********************************************************************** 00086 00087 Place an entry into the cache and associate it with the 00088 provided key. Note that there can be only one entry for 00089 any particular key. If two keys entries are added with 00090 the same key, the second effectively overwrites the first. 00091 00092 Returns what it was given 00093 00094 **********************************************************************/ 00095 00096 IPayload put(char[] key, IPayload entry) 00097 { 00098 map.put (key, cast(Object) entry); 00099 return entry; 00100 } 00101 00102 /********************************************************************** 00103 00104 Remove (and return) the cache entry associated with the 00105 provided key. Returns null if there is no such entry. 00106 00107 **********************************************************************/ 00108 00109 IPayload extract (char[] key) 00110 { 00111 // cast to void* first to avoid overhead 00112 return cast(IPayload) cast(void*) map.remove (key); 00113 } 00114 00115 /********************************************************************** 00116 00117 Remove (and return) the cache entry associated with the 00118 provided key. Returns null if there is no such entry. 00119 00120 **********************************************************************/ 00121 00122 IPayload extract (char[] key, ulong timeLimit) 00123 { 00124 // cast to void* first to avoid overhead 00125 IPayload e = cast(IPayload) cast(void*) map.get (key); 00126 00127 if (e) 00128 { 00129 // ignore if existing entry is newer 00130 if (e.getTime > timeLimit) 00131 return null; 00132 00133 // remove the entry from array, and return it 00134 map.remove (key); 00135 } 00136 return e; 00137 } 00138 00139 /********************************************************************** 00140 00141 **********************************************************************/ 00142 00143 ICache bind (ICacheLoader loader) 00144 { 00145 class PlainLoader : ICache 00146 { 00147 IMutableCache cache; 00148 ICacheLoader loader; 00149 00150 /****************************************************** 00151 00152 ******************************************************/ 00153 00154 this (IMutableCache cache, ICacheLoader loader) 00155 { 00156 this.cache = cache; 00157 this.loader = loader; 00158 } 00159 00160 /****************************************************** 00161 00162 ******************************************************/ 00163 00164 IPayload get (char[] key) 00165 { 00166 long t; 00167 IPayload p = cache.get (key); 00168 00169 if (p) 00170 { 00171 if (loader.test (p)) 00172 return p; 00173 t = p.getTime (); 00174 } 00175 00176 p = loader.load (key, t); 00177 if (p) 00178 cache.put (key, p); 00179 return p; 00180 } 00181 } 00182 00183 return new PlainLoader (this, loader); 00184 } 00185 } 00186 00187