io.hops.memcache.PathMemcache.java Source code

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Here is the source code for io.hops.memcache.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.memcache;

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.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hdfs.DFSConfigKeys;
import org.apache.hadoop.hdfs.server.namenode.INode;

import java.io.IOException;
import java.util.Arrays;
import java.util.List;

public class PathMemcache {

    private static final Log LOG = LogFactory.getLog(PathMemcache.class);
    private static PathMemcache instance = null;
    private MemcachedClientPool mcpool;
    private boolean isEnabled;
    private int keyExpiry;
    private String keyPrefix;

    private boolean isStarted;
    private int numberOfConnections;
    private String server;

    private PathMemcache() {
    }

    public static PathMemcache getInstance() {
        if (instance == null) {
            instance = new PathMemcache();
        }
        return instance;
    }

    public void setConfiguration(Configuration conf) throws IOException {
        numberOfConnections = conf.getInt(DFSConfigKeys.DFS_MEMCACHE_CONNECTION_POOL_SIZE,
                DFSConfigKeys.DFS_MEMCACHE_CONNECTION_POOL_SIZE_DEFAULT);
        server = conf.get(DFSConfigKeys.DFS_MEMCACHE_SERVER, DFSConfigKeys.DFS_MEMCACHE_SERVER_DEFAULT);
        keyExpiry = conf.getInt(DFSConfigKeys.DFS_MEMCACHE_KEY_EXPIRY_IN_SECONDS,
                DFSConfigKeys.DFS_MEMCACHE_KEY_EXPIRY_IN_SECONDS_DEFAULT);
        keyPrefix = conf.get(DFSConfigKeys.DFS_MEMCACHE_KEY_PREFIX, DFSConfigKeys.DFS_MEMCACHE_KEY_PREFIX_DEFAULT);
        isEnabled = conf.getBoolean(DFSConfigKeys.DFS_MEMCACHE_ENABLED, DFSConfigKeys.DFS_MEMCACHE_ENABLED_DEFAULT);
        if (isEnabled) {
            start();
        }
    }

    public void enableOrDisable(boolean forceEnable) throws IOException {
        if (forceEnable) {
            start();
        } else {
            stop();
        }
        isEnabled = forceEnable;
    }

    private void start() throws IOException {
        if (!isStarted) {
            LOG.info("starting PathMemcached");
            mcpool = new MemcachedClientPool(numberOfConnections, server);
            isStarted = true;
        }
    }

    private void stop() {
        if (isStarted) {
            LOG.info("stoping PathMemcached");
            mcpool.shutdown();
            isStarted = false;
        }
    }

    public void set(final String path, final INode[] inodes) {
        set(path, Arrays.asList(inodes));
    }

    public void set(final String path, final List<INode> inodes) {
        if (isStarted) {
            if (INode.getPathNames(path).length != inodes.size()) {
                return;
            }
            MemcachedClient mc = mcpool.poll();
            if (mc == null) {
                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");
                }
            });
        }
    }

    public int[] get(String path) throws IOException {
        if (isStarted) {
            MemcachedClient mc = mcpool.poll();
            if (mc == null) {
                return null;
            }
            final long startTime = System.currentTimeMillis();
            Object ce = null;
            try {
                ce = mc.get(getKey(path));
            } catch (Exception ex) {
                LOG.error(ex);
            }
            if (ce != null && ce instanceof CacheEntry) {
                LOG.debug("GET for path (" + path + ")  got value = " + ce + " in "
                        + (System.currentTimeMillis() - startTime) + " msec");
                return ((CacheEntry) ce).getInodeIds();
            }
        }
        return null;
    }

    public void delete(final String path) {
        if (isStarted) {
            MemcachedClient mc = mcpool.poll();
            if (mc == null) {
                return;
            }
            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);
                }
            });
        }
    }

    public void flush() {
        if (isStarted) {
            MemcachedClient mc = mcpool.poll();
            if (mc == null) {
                return;
            }
            mc.flush().addListener(new OperationCompletionListener() {

                @Override
                public void onComplete(OperationFuture<?> f) throws Exception {
                    LOG.debug("Memcache flushed");
                }
            });
        }
    }

    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;
    }
}