/*
 * 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.jackrabbit.core.cluster;

import java.util.ArrayList;

import javax.jcr.RepositoryException;

import org.apache.jackrabbit.core.cluster.SimpleEventListener.LockEvent;
import org.apache.jackrabbit.core.config.ClusterConfig;
import org.apache.jackrabbit.core.id.NodeId;
import org.apache.jackrabbit.core.journal.Journal;
import org.apache.jackrabbit.core.journal.JournalFactory;
import org.apache.jackrabbit.core.journal.MemoryJournal;
import org.apache.jackrabbit.core.journal.Record;
import org.apache.jackrabbit.core.journal.RecordConsumer;
import org.apache.jackrabbit.core.journal.MemoryJournal.MemoryRecord;
import org.apache.jackrabbit.spi.commons.namespace.NamespaceResolver;
import org.apache.jackrabbit.test.JUnitTest;

import EDU.oswego.cs.dl.util.concurrent.Latch;

/**
 * Test cases for cluster synchronization.
 */
public class ClusterSyncTest extends JUnitTest {

    /** Defaut workspace name. */
    private static final String DEFAULT_WORKSPACE = "default";

    /** Default sync delay: 5 seconds. */
    private static final long SYNC_DELAY = 5000;

    /** Master node. */
    private ClusterNode master;

    /** Slave node. */
    /* avoid synthetic accessor */ ClusterNode slave;

    /** Records shared among multiple memory journals. */
    private final ArrayList<MemoryRecord> records = new ArrayList<MemoryRecord>();
    
    /**
     * {@inheritDoc}
     */
    @Override
    protected void setUp() throws Exception {
        master = createClusterNode("master", false);
        master.start();

        slave = createClusterNode("slave", true);
        slave.start();

        super.setUp();
    }

    /**
     * {@inheritDoc}
     */
    @Override
    protected void tearDown() throws Exception {
        if (slave != null) {
            slave.stop();
        }
        if (master != null) {
            master.stop();
        }
        super.tearDown();
    }

    /**
     * Verify that sync() on a cluster node will continue fetching results until no more
     * changes are detected. 
     * 
     * @throws Exception
     */
    public void testSyncAllChanges() throws Exception {
        // create channel on master and slave
        LockEventChannel channel = master.createLockChannel(DEFAULT_WORKSPACE);
        slave.createLockChannel(DEFAULT_WORKSPACE).setListener(new SimpleEventListener());
        
        // add blocking consumer to slave, this will block on the first non-empty sync()
        BlockingConsumer consumer = new BlockingConsumer();
        slave.getJournal().register(consumer);
        
        // add first entry
        LockEvent event = new LockEvent(NodeId.randomId(), true, "admin");
        channel.create(event.getNodeId(), event.isDeep(), event.getUserId()).ended(true);
        
        // start a manual sync on the slave and ...
        Thread syncOnce = new Thread(new Runnable() {
            public void run() {
                try {
                    slave.sync();
                } catch (ClusterException e) {
                    /* ignore */
                }
            }
        });
        syncOnce.start();

        // ... wait until it blocks
        consumer.waitUntilBlocked();
        
        // add second entry
        event = new LockEvent(NodeId.randomId(), true, "admin");
        channel.create(event.getNodeId(), event.isDeep(), event.getUserId()).ended(true);
        
        // now unblock slave
        consumer.unblock();

        // wait for the sync to finish
        syncOnce.join();
        
        assertEquals(master.getRevision(), slave.getRevision());
    }

    /**
     * Create a cluster node, with a memory journal referencing a list of records.
     *
     * @param id cluster node id
     * @param records memory journal's list of records
     * @param disableAutoSync if <code>true</code> background synchronization is disabled
     */
    private ClusterNode createClusterNode(String id, boolean disableAutoSync) throws Exception {
        final MemoryJournal journal = new MemoryJournal() {
            protected boolean syncAgainOnNewRecords() {
                return true;
            }
        };
        JournalFactory jf = new JournalFactory() {
            public Journal getJournal(NamespaceResolver resolver)
                    throws RepositoryException {
                return journal;
            }
        };
        ClusterConfig cc = new ClusterConfig(id, SYNC_DELAY, jf);
        SimpleClusterContext context = new SimpleClusterContext(cc);

        journal.setRepositoryHome(context.getRepositoryHome());
        journal.init(id, context.getNamespaceResolver());
        journal.setRecords(records);
        
        ClusterNode clusterNode = new ClusterNode();
        clusterNode.init(context);
        if (disableAutoSync) {
            clusterNode.disableAutoSync();
        }
        return clusterNode;
    }
    
    /**
     * Custom consumer that will block inside the journal's sync() method
     * until it is unblocked.
     */
    static class BlockingConsumer implements RecordConsumer {

        private final Latch blockLatch = new Latch();
        private final Latch unblockLatch = new Latch();
        private long revision;
        
        public String getId() {
            return "CUSTOM";
        }

        public long getRevision() {
            return revision;
        }

        public void consume(Record record) {
            /* nothing to be done here */
        }

        public void setRevision(long revision) {
            blockLatch.release();
            
            try {
                unblockLatch.acquire();
            } catch (InterruptedException e) {
                /* ignore */
            }
            this.revision = revision;
        }
        
        public void waitUntilBlocked() throws InterruptedException {
            blockLatch.acquire();
        }
        
        public void unblock() {
            unblockLatch.release();
        }
    }
}