Line data    Source code

       1             : // Copyright (C) 2013 The Android Open Source Project
       2             : //
       3             : // Licensed under the Apache License, Version 2.0 (the "License");
       4             : // you may not use this file except in compliance with the License.
       5             : // You may obtain a copy of the License at
       6             : //
       7             : // http://www.apache.org/licenses/LICENSE-2.0
       8             : //
       9             : // Unless required by applicable law or agreed to in writing, software
      10             : // distributed under the License is distributed on an "AS IS" BASIS,
      11             : // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
      12             : // See the License for the specific language governing permissions and
      13             : // limitations under the License.
      14             : 
      15             : package com.google.gerrit.index;
      16             : 
      17             : import com.google.common.annotations.VisibleForTesting;
      18             : import com.google.common.collect.Lists;
      19             : import com.google.gerrit.extensions.events.LifecycleListener;
      20             : import java.util.Collection;
      21             : import java.util.Collections;
      22             : import java.util.concurrent.CopyOnWriteArrayList;
      23             : import java.util.concurrent.atomic.AtomicReference;
      24             : 
      25             : /** Dynamic pointers to the index versions used for searching and writing. */
      26             : public abstract class IndexCollection<K, V, I extends Index<K, V>> implements LifecycleListener {
      27             :   private final CopyOnWriteArrayList<I> writeIndexes;
      28             :   private final AtomicReference<I> searchIndex;
      29             : 
      30         151 :   protected IndexCollection() {
      31         151 :     this.writeIndexes = Lists.newCopyOnWriteArrayList();
      32         151 :     this.searchIndex = new AtomicReference<>();
      33         151 :   }
      34             : 
      35             :   /** Returns the current search index version. */
      36             :   public I getSearchIndex() {
      37         151 :     return searchIndex.get();
      38             :   }
      39             : 
      40             :   public void setSearchIndex(I index) {
      41         151 :     setSearchIndex(index, true);
      42         151 :   }
      43             : 
      44             :   @VisibleForTesting
      45             :   public void setSearchIndex(I index, boolean closeOld) {
      46         151 :     I old = searchIndex.getAndSet(index);
      47         151 :     if (closeOld && old != null && old != index && !writeIndexes.contains(old)) {
      48           1 :       old.close();
      49             :     }
      50         151 :   }
      51             : 
      52             :   public Collection<I> getWriteIndexes() {
      53         151 :     return Collections.unmodifiableCollection(writeIndexes);
      54             :   }
      55             : 
      56             :   public synchronized I addWriteIndex(I index) {
      57         151 :     int version = index.getSchema().getVersion();
      58         151 :     for (int i = 0; i < writeIndexes.size(); i++) {
      59          10 :       if (writeIndexes.get(i).getSchema().getVersion() == version) {
      60           9 :         return writeIndexes.set(i, index);
      61             :       }
      62             :     }
      63         151 :     writeIndexes.add(index);
      64         151 :     return null;
      65             :   }
      66             : 
      67             :   public synchronized void removeWriteIndex(int version) {
      68           1 :     int removeIndex = -1;
      69           1 :     for (int i = 0; i < writeIndexes.size(); i++) {
      70           1 :       if (writeIndexes.get(i).getSchema().getVersion() == version) {
      71           1 :         removeIndex = i;
      72           1 :         break;
      73             :       }
      74             :     }
      75           1 :     if (removeIndex >= 0) {
      76             :       try {
      77           1 :         writeIndexes.get(removeIndex).close();
      78             :       } finally {
      79           1 :         writeIndexes.remove(removeIndex);
      80             :       }
      81             :     }
      82           1 :   }
      83             : 
      84             :   public I getWriteIndex(int version) {
      85           2 :     for (I i : writeIndexes) {
      86           2 :       if (i.getSchema().getVersion() == version) {
      87           2 :         return i;
      88             :       }
      89           0 :     }
      90           0 :     return null;
      91             :   }
      92             : 
      93             :   @Override
      94         151 :   public void start() {}
      95             : 
      96             :   @Override
      97             :   public void stop() {
      98         151 :     I read = searchIndex.get();
      99         151 :     if (read != null) {
     100         151 :       read.close();
     101             :     }
     102         151 :     for (I write : writeIndexes) {
     103         151 :       if (write != read) {
     104           0 :         write.close();
     105             :       }
     106         151 :     }
     107         151 :   }
     108             : }