com.alibaba.wasp.fserver.GlobalEntityGroup.java Source code

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Here is the source code for com.alibaba.wasp.fserver.GlobalEntityGroup.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 com.alibaba.wasp.fserver;

import com.alibaba.wasp.EntityGroupInfo;
import com.alibaba.wasp.GlobalEntityGroupInfo;
import com.alibaba.wasp.NotServingEntityGroupException;
import com.alibaba.wasp.plan.action.ScanAction;
import com.alibaba.wasp.storage.StorageTableNotFoundException;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;

import java.io.Closeable;
import java.io.IOException;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.locks.ReentrantReadWriteLock;

/**
 * Execute global query plan.
 * 
 */
public class GlobalEntityGroup implements Closeable, EntityGroupServices {

    public static final Log LOG = LogFactory.getLog(GlobalEntityGroup.class);

    protected final FServerServices services;

    protected Configuration configuration;

    private final ReentrantReadWriteLock lock = new ReentrantReadWriteLock();

    final AtomicBoolean close = new AtomicBoolean(false);

    final GlobalEntityGroupInfo entityGroupInfo;

    public GlobalEntityGroup(FServerServices service) {
        this.services = service;
        this.configuration = service.getConfiguration();
        this.entityGroupInfo = new GlobalEntityGroupInfo();
    }

    /**
     * Return an iterator that scans over the EntityGroup, returning the indicated
     * columns and rows specified by the
     * 
     * <p>
     * This Iterator must be closed by the caller.
     * 
     * @param action
     * @return
     * @throws java.io.IOException
     * @throws com.alibaba.wasp.storage.StorageTableNotFoundException
     */
    public EntityGroupScanner getScanner(ScanAction action) throws IOException, StorageTableNotFoundException {
        startEntityGroupOperation();
        try {
            return instantiateEntityGroupScanner(action);
        } finally {
            closeEntityGroupOperation();
        }
    }

    /**
     * return EntityGroupScanner.
     *
     * @param action
     * @return
     * @throws java.io.IOException
     * @throws com.alibaba.wasp.storage.StorageTableNotFoundException
     */
    protected EntityGroupScanner instantiateEntityGroupScanner(ScanAction action)
            throws StorageTableNotFoundException, IOException {
        return new EntityGroupScanner(this, action, System.currentTimeMillis());
    }

    /**
     * This method needs to be called before any public call that reads or
     * modifies data. It has to be called just before a try. Acquires checks if
     * the entityGroup is close.
     *
     * @throws com.alibaba.wasp.NotServingEntityGroupException
     *           when the entityGroup is closing or closed
     */
    private void startEntityGroupOperation() throws NotServingEntityGroupException {
        lock.readLock().lock();
        if (this.close.get()) {
            lock.readLock().unlock();
            throw new NotServingEntityGroupException("GlobalEntityGroup is closed");
        }
    }

    private void closeEntityGroupOperation() {
        lock.readLock().unlock();
    }

    @Override
    public void close() {
        close.set(true);
    }

    /**
     * @see org.apache.hadoop.conf.Configurable#getConf()
     */
    @Override
    public Configuration getConf() {
        return this.configuration;
    }

    /**
     * @see com.alibaba.wasp.fserver.EntityGroupServices#getFServerServices()
     */
    @Override
    public FServerServices getFServerServices() {
        return this.services;
    }

    /**
     * @see com.alibaba.wasp.fserver.EntityGroupServices#getEntityGroupInfo()
     */
    @Override
    public EntityGroupInfo getEntityGroupInfo() {
        return entityGroupInfo;
    }
}