001// ***************************************************************************************************************************
002// * Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements.  See the NOTICE file *
003// * distributed with this work for additional information regarding copyright ownership.  The ASF licenses this file        *
004// * to you under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance            *
005// * with the License.  You may obtain a copy of the License at                                                              *
006// *                                                                                                                         *
007// *  http://www.apache.org/licenses/LICENSE-2.0                                                                             *
008// *                                                                                                                         *
009// * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an  *
010// * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the License for the        *
011// * specific language governing permissions and limitations under the License.                                              *
012// ***************************************************************************************************************************
013package org.apache.juneau.config.store;
014
015import static org.apache.juneau.internal.StringUtils.*;
016
017import java.io.*;
018import java.util.concurrent.*;
019
020import org.apache.juneau.*;
021import org.apache.juneau.annotation.*;
022import org.apache.juneau.collections.*;
023
024/**
025 * Filesystem-based storage location for configuration files.
026 *
027 * <p>
028 * Points to a file system directory containing configuration files.
029 */
030@ConfigurableContext
031public class ConfigMemoryStore extends ConfigStore {
032
033   //-------------------------------------------------------------------------------------------------------------------
034   // Configurable properties
035   //-------------------------------------------------------------------------------------------------------------------
036
037   static final String PREFIX = "ConfigMemoryStore";
038
039   //-------------------------------------------------------------------------------------------------------------------
040   // Predefined instances
041   //-------------------------------------------------------------------------------------------------------------------
042
043   /** Default memory store, all default values.*/
044   public static final ConfigMemoryStore DEFAULT = ConfigMemoryStore.create().build();
045
046
047   //-------------------------------------------------------------------------------------------------------------------
048   // Instance
049   //-------------------------------------------------------------------------------------------------------------------
050
051   /**
052    * Create a new builder for this object.
053    *
054    * @return A new builder for this object.
055    */
056   public static ConfigMemoryStoreBuilder create() {
057      return new ConfigMemoryStoreBuilder();
058   }
059
060   @Override /* Context */
061   public ConfigMemoryStoreBuilder builder() {
062      return new ConfigMemoryStoreBuilder(getPropertyStore());
063   }
064
065   private final ConcurrentHashMap<String,String> cache = new ConcurrentHashMap<>();
066
067   /**
068    * Constructor.
069    *
070    * @param ps The settings for this content store.
071    */
072   protected ConfigMemoryStore(PropertyStore ps) {
073      super(ps);
074   }
075
076   @Override /* ConfigStore */
077   public synchronized String read(String name) {
078      return emptyIfNull(cache.get(name));
079   }
080
081   @Override /* ConfigStore */
082   public synchronized String write(String name, String expectedContents, String newContents) {
083
084      // This is a no-op.
085      if (isEquals(expectedContents, newContents))
086         return null;
087
088      String currentContents = read(name);
089
090      if (expectedContents != null && ! isEquals(currentContents, expectedContents))
091         return currentContents;
092
093      update(name, newContents);
094
095      return null;
096   }
097
098   @Override /* ConfigStore */
099   public synchronized boolean exists(String name) {
100      return cache.containsKey(name);
101   }
102
103   @Override /* ConfigStore */
104   public synchronized ConfigMemoryStore update(String name, String newContents) {
105      if (newContents == null)
106         cache.remove(name);
107      else
108         cache.put(name, newContents);
109      super.update(name, newContents);  // Trigger any listeners.
110      return this;
111   }
112
113   /**
114    * No-op.
115    */
116   @Override /* Closeable */
117   public void close() throws IOException {
118      // No-op
119   }
120
121   //-----------------------------------------------------------------------------------------------------------------
122   // Other methods.
123   //-----------------------------------------------------------------------------------------------------------------
124
125   @Override /* Context */
126   public OMap toMap() {
127      return super.toMap()
128         .a("ConfigMemoryStore", new DefaultFilteringOMap()
129         );
130   }
131}