io.hops.resolvingcache.Cache.java Source code

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

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/**
 * Licensed to the Apache Software Foundation (ASF) 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 io.hops.resolvingcache;

import io.hops.transaction.context.TransactionsStats;
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;
import static io.hops.transaction.context.TransactionsStats.ResolvingCacheStat;

public abstract class Cache {

    private static Cache instance = null;

    protected static final Log LOG = LogFactory.getLog(PathMemcache.class);

    private boolean isStarted;
    private boolean isEnabled;

    protected Cache() {
    }

    public static Cache getInstance(Configuration conf) throws IOException {
        if (instance == null) {
            String memType = conf
                    .get(DFSConfigKeys.DFS_RESOLVING_CACHE_TYPE, DFSConfigKeys.DFS_RESOLVING_CACHE_TYPE_DEFAULT)
                    .toLowerCase();
            if (memType.equals("inode")) {
                instance = new INodeMemcache();
            } else if (memType.equals("path")) {
                instance = new PathMemcache();
            } else if (memType.equals("inmemory")) {
                instance = new InMemoryCache();
            } else if (memType.equals("optimal")) {
                instance = new OptimalMemcache();
            } else {
                throw new IllegalArgumentException("Cache has only two "
                        + "Memcache implementations, Inode based and Path based: wrong " + "parameter " + memType);
            }
            instance.setConfiguration(conf);
        }
        return instance;
    }

    public static Cache getInstance() {
        if (instance == null) {
            throw new IllegalStateException("Memcache should have started first " + "with configuration");
        }
        return instance;
    }

    protected void setConfiguration(Configuration conf) throws IOException {
        isEnabled = conf.getBoolean(DFSConfigKeys.DFS_RESOLVING_CACHE_ENABLED,
                DFSConfigKeys.DFS_RESOLVING_CACHE_ENABLED_DEFAULT);

        if (isEnabled) {
            start();
        }
    }

    private void start() throws IOException {
        if (!isStarted) {
            LOG.info("starting Resolving Cache [" + instance.getClass().getSimpleName() + "]");
            startInternal();
            isStarted = true;
        }
    }

    private void stop() {
        if (isStarted) {
            LOG.info("stopping Resolving Cache [" + instance.getClass().getSimpleName() + "]");
            stopInternal();
            isStarted = false;
        }
    }

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

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

    public final void set(final String path, final List<INode> inodes) {
        if (isStarted) {
            setInternal(path, inodes);
            if (TransactionsStats.getInstance().isEnabled()) {
                TransactionsStats.getInstance().pushResolvingCacheStats(
                        new ResolvingCacheStat(ResolvingCacheStat.Op.SET, 0, getRoundTrips(inodes)));
            }
        }
    }

    public final void set(final INode inode) {
        if (isStarted) {

        }
    }

    public final int[] get(final String path) throws IOException {
        if (isStarted) {
            final long startTime = System.currentTimeMillis();
            int[] result = getInternal(path);
            final long elapsed = (System.currentTimeMillis() - startTime);
            LOG.debug("GET for path (" + path + ")  got value = " + Arrays.toString(result) + " in " + elapsed + " "
                    + "msec");
            if (TransactionsStats.getInstance().isEnabled()) {
                TransactionsStats.getInstance().pushResolvingCacheStats(
                        new ResolvingCacheStat(ResolvingCacheStat.Op.GET, elapsed, getRoundTrips(path)));
            }
            return result;
        }
        return null;
    }

    public final void delete(final String path) {
        if (isStarted) {
            deleteInternal(path);
        }
    }

    public final void delete(final INode inode) {
        if (isStarted) {
            deleteInternal(inode);
        }
    }

    public final void flush() {
        if (isStarted) {
            flushInternal();
        }
    }

    protected abstract void startInternal() throws IOException;

    protected abstract void stopInternal();

    protected abstract void setInternal(final String path, final List<INode> inodes);

    protected abstract void setInternal(final INode inode);

    protected abstract int[] getInternal(final String path) throws IOException;

    protected abstract void deleteInternal(final String path);

    protected abstract void deleteInternal(final INode inode);

    protected abstract void flushInternal();

    protected abstract int getRoundTrips(String path);

    protected abstract int getRoundTrips(List<INode> inodes);
}