com.qwazr.utils.cassandra.CassandraSession.java Source code

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Here is the source code for com.qwazr.utils.cassandra.CassandraSession.java

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/**
 * Copyright 2014-2016 Emmanuel Keller / QWAZR
 * <p>
 * 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
 * <p>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p>
 * 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.qwazr.utils.cassandra;

import com.datastax.driver.core.Cluster;
import com.datastax.driver.core.ResultSet;
import com.datastax.driver.core.Session;
import com.datastax.driver.core.SimpleStatement;
import com.datastax.driver.core.exceptions.DriverException;
import com.datastax.driver.core.exceptions.NoHostAvailableException;
import com.qwazr.utils.LockUtils;
import org.apache.commons.io.IOUtils;
import org.apache.commons.lang3.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.Closeable;

public class CassandraSession implements Closeable {

    private static final Logger logger = LoggerFactory.getLogger(CassandraSession.class);

    private final LockUtils.ReadWriteLock rwl = new LockUtils.ReadWriteLock();

    private volatile long lastUse;

    private final Cluster cluster;
    private final String keySpace;
    private Session session;

    public CassandraSession(Cluster cluster) {
        this(cluster, null);
    }

    public CassandraSession(Cluster cluster, String keySpace) {
        this.cluster = cluster;
        this.keySpace = keySpace;
        session = null;
        lastUse = System.currentTimeMillis();
    }

    @Override
    public void finalize() throws Throwable {
        closeNoLock();
        super.finalize();
    }

    private void closeNoLock() {
        if (session != null) {
            if (!session.isClosed())
                IOUtils.closeQuietly(session);
            session = null;
        }
    }

    @Override
    public void close() {
        rwl.w.lock();
        try {
            closeNoLock();
        } finally {
            rwl.w.unlock();
        }
    }

    public boolean isClosed() {
        rwl.r.lock();
        try {
            return session == null || session.isClosed();
        } finally {
            rwl.r.unlock();
        }
    }

    private Session checkSession() {
        rwl.r.lock();
        try {
            lastUse = System.currentTimeMillis();
            if (session != null && !session.isClosed())
                return session;
        } finally {
            rwl.r.unlock();
        }
        rwl.w.lock();
        try {
            if (session != null && !session.isClosed())
                return session;
            if (cluster == null || cluster.isClosed())
                throw new DriverException("The cluster is closed");
            if (logger.isDebugEnabled())
                logger.debug("Create session " + keySpace == null ? StringUtils.EMPTY : keySpace);
            session = keySpace == null ? cluster.connect() : cluster.connect(keySpace);
            return session;
        } finally {
            rwl.w.unlock();
        }
    }

    private SimpleStatement getStatement(Session session, String cql, Integer fetchSize, Object... values) {
        SimpleStatement statement = values != null && values.length > 0 ? new SimpleStatement(cql, values)
                : new SimpleStatement(cql);
        if (fetchSize != null)
            statement.setFetchSize(fetchSize);
        return statement;
    }

    private ResultSet executeStatement(Session session, SimpleStatement statement) {
        try {
            return session.execute(statement);
        } catch (NoHostAvailableException e1) {
            if (cluster == null || !cluster.isClosed())
                throw e1;
            try {
                return session.execute(statement);
            } catch (DriverException e2) {
                logger.warn(e2.getMessage(), e2);
                throw e1;
            }
        }

    }

    public ResultSet executeWithFetchSize(String cql, int fetchSize, Object... values) {
        if (logger.isDebugEnabled())
            logger.debug("Execute " + cql);
        Session session = checkSession();
        SimpleStatement statement = getStatement(session, cql, fetchSize, values);
        return executeStatement(session, statement);
    }

    public ResultSet execute(String cql, Object... values) {
        if (logger.isDebugEnabled())
            logger.debug("Execute " + cql);
        Session session = checkSession();
        SimpleStatement statement = getStatement(session, cql, null, values);
        return executeStatement(session, statement);
    }

    long getLastUse() {
        return lastUse;
    }

}