content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you under the Apache License, Version 2.0 (the
   * "License"); you may not use this file except in compliance
   * with the License.  You may obtain a copy of the License at
   *
   * http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing,
   * software distributed under the License is distributed on an
   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
   * KIND, either express or implied.  See the License for the
   * specific language governing permissions and limitations
   * under the License.
   */
  package org.apache.chemistry.opencmis.bridge.lrucache;
  
  import java.io.Serializable;
  import java.util.LinkedHashMap;
  import java.util.Map;
  import java.util.concurrent.locks.ReentrantReadWriteLock;
  
  import org.apache.chemistry.opencmis.commons.server.CallContext;
  import org.apache.chemistry.opencmis.commons.spi.CmisBinding;
  
  /**
   * Simple LRU cache for {@link CmisBinding} objects. The cache key is consists
   * of the repository id and the user.
   */
  public class CmisBindingCache implements Serializable {
  
      private static final long serialVersionUID = 1L;
  
      private final ReentrantReadWriteLock lock = new ReentrantReadWriteLock();
      private final LinkedHashMap<String, CmisBinding> cache;
  
      public CmisBindingCache(final int size) {
          cache = new LinkedHashMap<String, CmisBinding>(size + 1, 0.70f, true) {
  
              private static final long serialVersionUID = 1L;
  
              @Override
              public boolean removeEldestEntry(Map.Entry<String, CmisBinding> eldest) {
                  return size() > size;
              }
          };
      }
  
      public CmisBinding getCmisBinding(CallContext context) {
          lock.writeLock().lock();
          try {
              return cache.get(getCacheKey(context));
          } finally {
              lock.writeLock().unlock();
          }
      }
  
      public CmisBinding putCmisBinding(CallContext context, CmisBinding binding) {
          lock.writeLock().lock();
          try {
              String key = getCacheKey(context);
              CmisBinding extistingBinding = cache.get(getCacheKey(context));
              if (extistingBinding == null) {
                  cache.put(key, binding);
              } else {
                  binding = extistingBinding;
              }
  
              return binding;
          } finally {
              lock.writeLock().unlock();
          }
      }
  
      protected String getCacheKey(CallContext context) {
          String repositoryId = context.getRepositoryId();
          String user = context.getUsername();
  
          String key = repositoryId == null ? "" : repositoryId;
          if (user != null) {
              key = key + "\n" + user;
          }
  
          return key;
      }
  }
  