001 /* 002 * Copyright (C) 2012 eXo Platform SAS. 003 * 004 * This is free software; you can redistribute it and/or modify it 005 * under the terms of the GNU Lesser General Public License as 006 * published by the Free Software Foundation; either version 2.1 of 007 * the License, or (at your option) any later version. 008 * 009 * This software is distributed in the hope that it will be useful, 010 * but WITHOUT ANY WARRANTY; without even the implied warranty of 011 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 012 * Lesser General Public License for more details. 013 * 014 * You should have received a copy of the GNU Lesser General Public 015 * License along with this software; if not, write to the Free 016 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 017 * 02110-1301 USA, or see the FSF site: http://www.fsf.org. 018 */ 019 020 package org.crsh.util; 021 022 import org.crsh.shell.ErrorKind; 023 import org.crsh.shell.impl.command.spi.CommandException; 024 import org.crsh.plugin.PluginContext; 025 import org.crsh.plugin.ResourceKind; 026 import org.crsh.vfs.Resource; 027 028 import java.io.UnsupportedEncodingException; 029 import java.util.Map; 030 import java.util.concurrent.ConcurrentHashMap; 031 032 public class ClassCache<T> { 033 034 /** . */ 035 private final ClassFactory<T> classFactory; 036 037 /** . */ 038 private final Map<String, TimestampedObject<Class<? extends T>>> classes = new ConcurrentHashMap<String, TimestampedObject<Class<? extends T>>>(); 039 040 /** . */ 041 private final PluginContext context; 042 043 /** . */ 044 private final ResourceKind kind; 045 046 public ClassCache(PluginContext context, ClassFactory<T> classFactory, ResourceKind kind) { 047 this.classFactory = classFactory; 048 this.context = context; 049 this.kind = kind; 050 } 051 052 private TimestampedObject<Class<? extends T>> loadClass(String name) { 053 return classes.get(name); 054 } 055 056 private void saveClass(String name, TimestampedObject<Class<? extends T>> clazz) { 057 classes.put(name, clazz); 058 } 059 060 private Resource getResource(String name) { 061 return context.loadResource(name, kind); 062 } 063 064 public TimestampedObject<Class<? extends T>> getClass(String name) throws CommandException, NullPointerException { 065 if (name == null) { 066 throw new NullPointerException("No null argument allowed"); 067 } 068 069 TimestampedObject<Class<? extends T>> providerRef = loadClass(name); 070 071 // 072 Resource script = getResource(name); 073 074 // 075 if (script != null) { 076 if (providerRef != null) { 077 if (script.getTimestamp() != providerRef.getTimestamp()) { 078 providerRef = null; 079 } 080 } 081 082 // 083 if (providerRef == null) { 084 085 // 086 String source; 087 try { 088 source = new String(script.getContent(), "UTF-8"); 089 } 090 catch (UnsupportedEncodingException e) { 091 throw new CommandException(ErrorKind.INTERNAL, "Could not compile command script " + name, e); 092 } 093 094 // 095 Class<? extends T> clazz = classFactory.parse(name, source); 096 providerRef = new TimestampedObject<Class<? extends T>>(script.getTimestamp(), clazz); 097 saveClass(name, providerRef); 098 } 099 } 100 101 // 102 if (providerRef == null) { 103 return null; 104 } 105 106 // 107 return providerRef; 108 } 109 }