curator-master/curator-framework/src/main/java/org/apache/curator/framework/imps/CuratorTempFrameworkImpl.java
/*
 * 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 org.apache.curator.framework.imps;

import com.google.common.annotations.VisibleForTesting;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.TimeUnit;
import org.apache.curator.framework.CuratorFrameworkFactory;
import org.apache.curator.framework.CuratorTempFramework;
import org.apache.curator.framework.api.TempGetDataBuilder;
import org.apache.curator.framework.api.transaction.CuratorTransaction;
import org.apache.curator.utils.CloseableUtils;
import org.apache.curator.utils.ThreadUtils;

public class CuratorTempFrameworkImpl implements CuratorTempFramework {
    private final CuratorFrameworkFactory.Builder factory;
    private final long inactiveThresholdMs;

    // guarded by sync
    private CuratorFrameworkImpl client;

    // guarded by sync
    private ScheduledExecutorService cleanup;

    // guarded by sync
    private long lastAccess;

    public CuratorTempFrameworkImpl(CuratorFrameworkFactory.Builder factory, long inactiveThresholdMs) {
        this.factory = factory;
        this.inactiveThresholdMs = inactiveThresholdMs;
    }

    @Override
    public void close() {
        closeClient();
    }

    @Override
    public CuratorTransaction inTransaction() throws Exception {
        openConnectionIfNeeded();
        return new CuratorTransactionImpl(client);
    }

    @Override
    public TempGetDataBuilder getData() throws Exception {
        openConnectionIfNeeded();
        return new TempGetDataBuilderImpl(client);
    }

    @VisibleForTesting
    synchronized CuratorFrameworkImpl getClient() {
        return client;
    }

    @VisibleForTesting
    synchronized ScheduledExecutorService getCleanup() {
        return cleanup;
    }

    @VisibleForTesting
    synchronized void updateLastAccess() {
        lastAccess = System.currentTimeMillis();
    }

    private synchronized void openConnectionIfNeeded() throws Exception {
        if (client == null) {
            client = (CuratorFrameworkImpl) factory.build(); // cast is safe - we control both sides of this
            client.start();
        }

        if (cleanup == null) {
            ThreadFactory threadFactory = factory.getThreadFactory();

            if (threadFactory == null) {
                threadFactory = ThreadUtils.newGenericThreadFactory("CuratorTempFrameworkImpl");
            }

            cleanup = Executors.newScheduledThreadPool(1, threadFactory);

            Runnable command = new Runnable() {
                @Override
                public void run() {
                    checkInactive();
                }
            };
            cleanup.scheduleAtFixedRate(command, inactiveThresholdMs, inactiveThresholdMs, TimeUnit.MILLISECONDS);
        }

        updateLastAccess();
    }

    private synchronized void checkInactive() {
        long elapsed = System.currentTimeMillis() - lastAccess;
        if (elapsed >= inactiveThresholdMs) {
            closeClient();
        }
    }

    private synchronized void closeClient() {
        if (cleanup != null) {
            cleanup.shutdownNow();
            cleanup = null;
        }

        if (client != null) {
            CloseableUtils.closeQuietly(client);
            client = null;
        }
    }
}
