io.hops.resolvingcache.PathMemcache.java Source code

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Here is the source code for io.hops.resolvingcache.PathMemcache.java

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/*
 * Copyright (C) 2015 hops.io.
 *
 * Licensed 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 io.hops.resolvingcache;

import net.spy.memcached.MemcachedClient;
import net.spy.memcached.internal.OperationCompletionListener;
import net.spy.memcached.internal.OperationFuture;
import org.apache.commons.codec.digest.DigestUtils;
import org.apache.hadoop.hdfs.server.namenode.INode;

import java.io.IOException;
import java.io.Serializable;
import java.util.Arrays;
import java.util.List;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;

public class PathMemcache extends Memcache {

    public static class CacheEntry implements Serializable {

        private int[] inodeIds;

        public CacheEntry(int[] inodeIds) {
            this.inodeIds = inodeIds;
        }

        public int[] getInodeIds() {
            return inodeIds;
        }

        @Override
        public String toString() {
            return "CacheEntry{" + "inodeIds=" + Arrays.toString(inodeIds) + '}';
        }
    }

    @Override
    protected void setInternal(final MemcachedClient mc, final String path, final List<INode> inodes) {
        if (INode.getPathNames(path).length != inodes.size()) {
            return;
        }
        final String key = getKey(path);
        final int[] inodeIds = getINodeIds(inodes);
        final long startTime = System.currentTimeMillis();
        mc.set(key, keyExpiry, new CacheEntry(inodeIds)).addListener(new OperationCompletionListener() {
            @Override
            public void onComplete(OperationFuture<?> f) throws Exception {
                long elapsed = System.currentTimeMillis() - startTime;
                LOG.debug("SET for path (" + path + ")  " + key + "=" + Arrays.toString(inodeIds) + " in " + elapsed
                        + " msec");
            }
        });
    }

    @Override
    protected void setInternal(MemcachedClient mc, INode inode) {
        throw new UnsupportedOperationException();
    }

    @Override
    protected int[] getInternal(final MemcachedClient mc, String path) throws IOException {
        Object ce = null;
        Future<Object> f = mc.asyncGet(getKey(path));
        try {
            ce = f.get(1, TimeUnit.SECONDS);
        } catch (Exception ex) {
            LOG.error(ex);
            f.cancel(true);
        }
        if (ce != null && ce instanceof CacheEntry) {
            return ((CacheEntry) ce).getInodeIds();
        }
        return null;
    }

    @Override
    protected void deleteInternal(final MemcachedClient mc, final String path) {
        final String key = getKey(path);
        mc.delete(key).addListener(new OperationCompletionListener() {
            @Override
            public void onComplete(OperationFuture<?> f) throws Exception {
                LOG.debug("DELETE for path (" + path + ")  " + key);
            }
        });
    }

    @Override
    protected void deleteInternal(MemcachedClient mc, INode inode) {
        throw new UnsupportedOperationException();
    }

    private String getKey(String path) {
        return keyPrefix + DigestUtils.sha256Hex(path);
    }

    private int[] getINodeIds(List<INode> inodes) {
        int[] inodeIds = new int[inodes.size()];
        for (int i = 0; i < inodes.size(); i++) {
            inodeIds[i] = inodes.get(i).getId();
        }
        return inodeIds;
    }

    @Override
    protected int getRoundTrips(String path) {
        return 1;
    }

    @Override
    protected int getRoundTrips(List<INode> inodes) {
        return 1;
    }
}