tachyon.worker.eviction.EvictLRUBase.java Source code

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Here is the source code for tachyon.worker.eviction.EvictLRUBase.java

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/*
 * Licensed to the University of California, Berkeley 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 tachyon.worker.eviction;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.Map.Entry;
import java.util.Set;

import com.google.common.collect.HashMultimap;
import com.google.common.collect.Multimap;
import com.google.common.collect.Multimaps;

import tachyon.Pair;
import tachyon.worker.tiered.BlockInfo;
import tachyon.worker.tiered.StorageDir;

/**
 * Base class for evicting blocks by LRU strategy.
 */
public abstract class EvictLRUBase implements EvictStrategy {
    private final boolean mLastTier;
    private final Multimap<StorageDir, Long> mEvictingBlockIds;

    protected EvictLRUBase(boolean lastTier) {
        mLastTier = lastTier;
        mEvictingBlockIds = Multimaps.synchronizedMultimap(HashMultimap.<StorageDir, Long>create());
    }

    /**
     * Check if the current block can be evicted
     *
     * @param blockId the Id of the block
     * @param pinList the list of the pinned files
     * @return true if the block can be evicted, false otherwise
     */
    protected boolean blockEvictable(long blockId, Set<Integer> pinList) {
        return !mLastTier || !pinList.contains(tachyon.master.BlockInfo.computeInodeId(blockId));
    }

    /**
     * Clean the blocks that have been evicted from evicting list in each StorageDir
     */
    protected void cleanEvictingBlockIds() {
        Iterator<Entry<StorageDir, Long>> iterator = mEvictingBlockIds.entries().iterator();
        while (iterator.hasNext()) {
            Entry<StorageDir, Long> block = iterator.next();
            StorageDir dir = block.getKey();
            long blockId = block.getValue();
            if (!dir.containsBlock(blockId)) {
                iterator.remove();
            }
        }
    }

    /**
     * Update the blocks that are being evicted in each StorageDir
     * 
     * @param blockList The list of blocks that will be added in to evicting list
     */
    protected void updateEvictingBlockIds(Collection<BlockInfo> blockList) {
        for (BlockInfo block : blockList) {
            StorageDir dir = block.getStorageDir();
            long blockId = block.getBlockId();
            if (dir.containsBlock(blockId)) {
                mEvictingBlockIds.put(dir, blockId);
            }
        }
    }

    /**
     * Get the oldest access information from a StorageDir
     *
     * @param curDir current StorageDir
     * @param toEvictBlockIds the Ids of blocks that have been selected to evict
     * @param pinList list of pinned files
     * @return the oldest access information of current StorageDir
     */
    protected Pair<Long, Long> getLRUBlock(StorageDir curDir, Collection<Long> toEvictBlockIds,
            Set<Integer> pinList) {
        long lruBlockId = -1;
        long oldestTime = Long.MAX_VALUE;
        Set<Long> evictingBlockIds = (Set<Long>) mEvictingBlockIds.get(curDir);

        for (Entry<Long, Long> accessInfo : curDir.getLastBlockAccessTimeMs()) {
            long blockId = accessInfo.getKey();
            long accessTime = accessInfo.getValue();
            if (toEvictBlockIds.contains(blockId) || evictingBlockIds.contains(blockId)) {
                continue;
            }
            if (accessTime < oldestTime && !curDir.isBlockLocked(blockId) && blockEvictable(blockId, pinList)) {
                lruBlockId = blockId;
                oldestTime = accessTime;
            }
        }

        return new Pair<Long, Long>(lruBlockId, oldestTime);
    }
}