00001 /******************************************************************************* 00002 00003 @file PickleRegistry.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.io.PickleRegistry; 00040 00041 private import mango.io.Exception; 00042 00043 public import mango.io.model.IReader, 00044 mango.io.model.IPickle; 00045 00046 /******************************************************************************* 00047 00048 Bare framework for registering and creating serializable objects. 00049 Such objects are intended to be transported across a local network 00050 and re-instantiated at some destination node. 00051 00052 Each IPickle exposes the means to write, or freeze, its content. An 00053 IPickleFactory provides the means to create a new instance of itself 00054 populated with thawed data. Frozen objects are uniquely identified 00055 by a guid exposed via the interface. Responsibility of maintaining 00056 uniqueness across said identifiers lies in the hands of the developer. 00057 00058 See PickleReader for an example of how this is expected to operate. 00059 00060 *******************************************************************************/ 00061 00062 class PickleRegistry 00063 { 00064 private static Proxy[char[]] registry; 00065 00066 /*********************************************************************** 00067 00068 ***********************************************************************/ 00069 00070 alias Object function (IReader reader) SimpleProxyFnc; 00071 alias Object function (IReader reader, char[] guid) GuidProxyFnc; 00072 00073 /*********************************************************************** 00074 00075 This is a singleton: the constructor should not be exposed 00076 00077 ***********************************************************************/ 00078 00079 private this () 00080 { 00081 } 00082 00083 /*********************************************************************** 00084 00085 Base registrar entry 00086 00087 ***********************************************************************/ 00088 00089 private class Proxy 00090 { 00091 abstract Object create (IReader reader); 00092 } 00093 00094 /*********************************************************************** 00095 00096 Simple registrar entry 00097 00098 ***********************************************************************/ 00099 00100 private class SimpleProxy : Proxy 00101 { 00102 SimpleProxyFnc fnc; 00103 00104 /*************************************************************** 00105 00106 ***************************************************************/ 00107 00108 this (SimpleProxyFnc fnc) 00109 { 00110 this.fnc = fnc; 00111 } 00112 00113 /*************************************************************** 00114 00115 ***************************************************************/ 00116 00117 Object create (IReader reader) 00118 { 00119 return fnc (reader); 00120 } 00121 } 00122 00123 /*********************************************************************** 00124 00125 Guid registrar entry 00126 00127 ***********************************************************************/ 00128 00129 private class GuidProxy : Proxy 00130 { 00131 GuidProxyFnc fnc; 00132 char[] guid; 00133 00134 /*************************************************************** 00135 00136 ***************************************************************/ 00137 00138 this (GuidProxyFnc fnc, char[] guid) 00139 { 00140 this.fnc = fnc; 00141 this.guid = guid; 00142 } 00143 00144 /*************************************************************** 00145 00146 ***************************************************************/ 00147 00148 Object create (IReader reader) 00149 { 00150 return fnc (reader, guid); 00151 } 00152 } 00153 00154 /*********************************************************************** 00155 00156 IPickleFactory registrar entry 00157 00158 ***********************************************************************/ 00159 00160 private class PickleProxy : Proxy 00161 { 00162 IPickleFactory factory; 00163 00164 /*************************************************************** 00165 00166 ***************************************************************/ 00167 00168 this (IPickleFactory factory) 00169 { 00170 this.factory = factory; 00171 } 00172 00173 /*************************************************************** 00174 00175 ***************************************************************/ 00176 00177 Object create (IReader reader) 00178 { 00179 return factory.create (reader); 00180 } 00181 } 00182 00183 /*********************************************************************** 00184 00185 Add the provided class to the registry. Note that one 00186 cannot change a registration once it is placed. Neither 00187 can one remove registered item. This is done to avoid 00188 major issues when trying to synchronize servers across 00189 a farm, which may still have live instances of "old" 00190 objects waiting to be passed around the cluster. New 00191 versions of an object should be given a distinct guid 00192 from the prior version; appending an incremental number 00193 may well be sufficient for your needs. 00194 00195 ***********************************************************************/ 00196 00197 private static synchronized void enroll (Proxy proxy, char[] guid) 00198 { 00199 if (guid in registry) 00200 throw new PickleException ("Invalid attempt to re-register a guid"); 00201 00202 registry[guid] = proxy; 00203 } 00204 00205 /*********************************************************************** 00206 00207 do a synchronized Proxy lookup of the guid 00208 00209 ***********************************************************************/ 00210 00211 private final static synchronized Proxy lookup (char[] guid) 00212 { 00213 if (guid in registry) 00214 return registry [guid]; 00215 return null; 00216 } 00217 00218 /*********************************************************************** 00219 00220 Add the provided object to the registry. Note that one 00221 cannot change a registration once it is placed. Neither 00222 can one remove registered item. This is done to avoid 00223 major issues when trying to synchronize servers across 00224 a farm, which may still have live instances of "old" 00225 objects waiting to be passed around the cluster. New 00226 versions of an object should be given a distinct guid 00227 from the prior version; appending an incremental number 00228 may well be sufficient for your needs. 00229 00230 ***********************************************************************/ 00231 00232 static void enroll (IPickleFactory object) 00233 { 00234 enroll (new PickleProxy(object), object.getGuid); 00235 } 00236 00237 /*********************************************************************** 00238 00239 Add the provided function to the registry. Note that one 00240 cannot change a registration once it is placed. Neither 00241 can one remove registered item. This is done to avoid 00242 major issues when trying to synchronize servers across 00243 a farm, which may still have live instances of "old" 00244 objects waiting to be passed around the cluster. New 00245 versions of an object should be given a distinct guid 00246 from the prior version; appending an incremental number 00247 may well be sufficient for your needs. 00248 00249 ***********************************************************************/ 00250 00251 static void enroll (SimpleProxyFnc sp, char[] guid) 00252 { 00253 enroll (new SimpleProxy(sp), guid); 00254 } 00255 00256 /*********************************************************************** 00257 00258 Add the provided function to the registry. Note that one 00259 cannot change a registration once it is placed. Neither 00260 can one remove registered item. This is done to avoid 00261 major issues when trying to synchronize servers across 00262 a farm, which may still have live instances of "old" 00263 objects waiting to be passed around the cluster. New 00264 versions of an object should be given a distinct guid 00265 from the prior version; appending an incremental number 00266 may well be sufficient for your needs. 00267 00268 ***********************************************************************/ 00269 00270 static void enroll (GuidProxyFnc gp, char[] guid) 00271 { 00272 enroll (new GuidProxy(gp, guid), guid); 00273 } 00274 00275 /*********************************************************************** 00276 00277 Create a new instance of a registered class from the content 00278 made available via the given reader. The factory is located 00279 using the provided guid, which must match an enrolled class. 00280 00281 Note that only the factory lookup is synchronized, and not 00282 the instance construction itself. 00283 00284 ***********************************************************************/ 00285 00286 static Object create (IReader reader, char[] guid) 00287 { 00288 // locate the appropriate Proxy. 00289 Proxy p = lookup (guid); 00290 if (p) 00291 return p.create (reader); 00292 00293 throw new PickleException ("Attempt to unpickle via unregistered guid '"~guid~"'"); 00294 } 00295 } 00296