cvs commit: jakarta-turbine-jcs/auxiliary-builds/jdk15/yajcache/cache/src/net/sf/yajcache/core SafeCacheManager.java

[hc...@apache.org]

hchar       2005/01/19 02:59:19

  Added:       auxiliary-builds/jdk15/yajcache/cache/src/net/sf/yajcache/core
                        SafeCacheManager.java
  Log:
  no message
  
  Revision  Changes    Path
  1.1                  jakarta-turbine-jcs/auxiliary-builds/jdk15/yajcache/cache/src/net/sf/yajcache/core/SafeCacheManager.java
  
  Index: SafeCacheManager.java
  ===================================================================
  /*
   * SafeCacheManager.java
   */
  
  package net.sf.yajcache.core;
  
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.ConcurrentMap;
  
  
  
  import net.sf.yajcache.soft.SoftRefCacheSafe;
  
  /**
   * @author Hanson Char
   */
  public enum SafeCacheManager {
      inst;
      // Cache name to Cache mapping.
      private final ConcurrentMap<String,ICacheSafe> map = new ConcurrentHashMap<String, ICacheSafe>();
      /** 
       * Returns the cache for the specified name and value type;  
       * Creates the cache if necessary.
       *
       * @throws ClassCastException if the cache already exists for an
       * incompatible value type.
       */
      public <V> ICacheSafe<V> getCache(String name, Class<V> valueType)
      {
          ICacheSafe c = this.map.get(name);
                 
          if (c == null)
              c = this.createCache(name, valueType);
          else
              CacheManagerUtils.inst.checkValueType(c, valueType);
          return c;
      }
      /** 
       * Returns an existing cache for the specified name; or null if not found.
       */
      public ICacheSafe getCache(String name) {
          return this.map.get(name);
      }
      /**
       * Removes the specified cache, if it exists.
       */
      public ICacheSafe removeCache(String name) {
          ICacheSafe c = this.map.remove(name);
          
          if (c != null) {
              c.clear();
          }
          return c;
      }
      /** 
       * Creates the specified cache if not already created.
       * 
       * @return either the cache created by the current thread, or
       * an existing cache created earlier by another thread.
       */
      private <V> ICacheSafe<V> createCache(String name, Class<V> valueType) {
          ICacheSafe c = new SoftRefCacheSafe<V>(name, valueType);
          ICacheSafe old = this.map.putIfAbsent(name, c);
  
          if (old != null) {
              // race condition: cache already created by another thread.
              CacheManagerUtils.inst.checkValueType(old, valueType);
              c = old;
          }
          return c;
      }
      /**
       * This package private method is used soley to simluate a race condition 
       * during cache creation for testing purposes.
       */
      <V> ICacheSafe<V> testCreateCacheRaceCondition(String name, Class<V> valueType) 
      {
          return this.createCache(name, valueType);
      }
  }
  
  
  

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