001/**
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.apache.hadoop.hdfs.server.namenode;
019
020import java.util.List;
021
022import org.apache.hadoop.fs.permission.FsPermission;
023import org.apache.hadoop.fs.permission.PermissionStatus;
024import org.apache.hadoop.hdfs.protocol.QuotaExceededException;
025import org.apache.hadoop.hdfs.server.namenode.Quota.Counts;
026import org.apache.hadoop.hdfs.server.namenode.snapshot.Snapshot;
027import org.apache.hadoop.util.GSet;
028import org.apache.hadoop.util.LightWeightGSet;
029
030import com.google.common.base.Preconditions;
031
032/**
033 * Storing all the {@link INode}s and maintaining the mapping between INode ID
034 * and INode.  
035 */
036public class INodeMap {
037  
038  static INodeMap newInstance(INodeDirectory rootDir) {
039    // Compute the map capacity by allocating 1% of total memory
040    int capacity = LightWeightGSet.computeCapacity(1, "INodeMap");
041    GSet<INode, INodeWithAdditionalFields> map
042        = new LightWeightGSet<INode, INodeWithAdditionalFields>(capacity);
043    map.put(rootDir);
044    return new INodeMap(map);
045  }
046  
047  /** Synchronized by external lock. */
048  private final GSet<INode, INodeWithAdditionalFields> map;
049  
050  private INodeMap(GSet<INode, INodeWithAdditionalFields> map) {
051    Preconditions.checkArgument(map != null);
052    this.map = map;
053  }
054  
055  /**
056   * Add an {@link INode} into the {@link INode} map. Replace the old value if 
057   * necessary. 
058   * @param inode The {@link INode} to be added to the map.
059   */
060  public final void put(INode inode) {
061    if (inode instanceof INodeWithAdditionalFields) {
062      map.put((INodeWithAdditionalFields)inode);
063    }
064  }
065  
066  /**
067   * Remove a {@link INode} from the map.
068   * @param inode The {@link INode} to be removed.
069   */
070  public final void remove(INode inode) {
071    map.remove(inode);
072  }
073  
074  /**
075   * @return The size of the map.
076   */
077  public int size() {
078    return map.size();
079  }
080  
081  /**
082   * Get the {@link INode} with the given id from the map.
083   * @param id ID of the {@link INode}.
084   * @return The {@link INode} in the map with the given id. Return null if no 
085   *         such {@link INode} in the map.
086   */
087  public INode get(long id) {
088    INode inode = new INodeWithAdditionalFields(id, null, new PermissionStatus(
089        "", "", new FsPermission((short) 0)), 0, 0) {
090      
091      @Override
092      INode recordModification(Snapshot latest, INodeMap inodeMap)
093          throws QuotaExceededException {
094        return null;
095      }
096      
097      @Override
098      public void destroyAndCollectBlocks(BlocksMapUpdateInfo collectedBlocks,
099          List<INode> removedINodes) {
100        // Nothing to do
101      }
102      
103      @Override
104      public Counts computeQuotaUsage(Counts counts, boolean useCache,
105          int lastSnapshotId) {
106        return null;
107      }
108      
109      @Override
110      public ContentSummaryComputationContext computeContentSummary(
111          ContentSummaryComputationContext summary) {
112        return null;
113      }
114      
115      @Override
116      public Counts cleanSubtree(Snapshot snapshot, Snapshot prior,
117          BlocksMapUpdateInfo collectedBlocks, List<INode> removedINodes,
118          boolean countDiffChange) throws QuotaExceededException {
119        return null;
120      }
121    };
122      
123    return map.get(inode);
124  }
125  
126  /**
127   * Clear the {@link #map}
128   */
129  public void clear() {
130    map.clear();
131  }
132}