
org.neo4j.io.fs.watcher.DatabaseLayoutWatcher Maven / Gradle / Ivy
/*
* Copyright (c) "Neo4j"
* Neo4j Sweden AB [http://neo4j.com]
*
* This file is part of Neo4j.
*
* Neo4j is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see .
*/
package org.neo4j.io.fs.watcher;
import java.io.IOException;
import java.io.UncheckedIOException;
import java.nio.file.Path;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import org.neo4j.io.IOUtils;
import org.neo4j.io.fs.watcher.resource.WatchedResource;
import org.neo4j.io.layout.DatabaseLayout;
import org.neo4j.io.layout.Neo4jLayout;
import org.neo4j.kernel.lifecycle.LifecycleAdapter;
import static java.util.Objects.requireNonNull;
/**
* File system fileWatcher that will remember all the files that it was asked to watch
* and will register them in real file watcher during {@link #startWatching()} call.
* When watcher will be stopped all registered resources will be closed.
*
* Described pattern allows to perform repeatable startWatching/stopWatching cycle for pre-configured set of files provided by {@link DatabaseLayout}.
*/
public class DatabaseLayoutWatcher extends LifecycleAdapter
{
private final FileWatcher fileWatcher;
private final DatabaseLayout databaseLayout;
private final FileWatchEventListenerFactory listenerFactory;
private final Set filesToWatch = ConcurrentHashMap.newKeySet();
private final Set watchedResources = ConcurrentHashMap.newKeySet();
private FileWatchEventListener eventListener;
public DatabaseLayoutWatcher( FileWatcher fileWatcher, DatabaseLayout databaseLayout, FileWatchEventListenerFactory listenerFactory )
{
requireNonNull( fileWatcher );
requireNonNull( databaseLayout );
requireNonNull( listenerFactory );
this.fileWatcher = fileWatcher;
this.databaseLayout = databaseLayout;
this.listenerFactory = listenerFactory;
}
@Override
public void start() throws Exception
{
watchDirectories();
eventListener = listenerFactory.createListener( watchedResources );
fileWatcher.addFileWatchEventListener( eventListener );
}
@Override
public void stop() throws Exception
{
stopWatching();
fileWatcher.removeFileWatchEventListener( eventListener );
}
private void watchDirectories()
{
Neo4jLayout layout = databaseLayout.getNeo4jLayout();
watch( databaseLayout.databaseDirectory() );
watch( databaseLayout.getTransactionLogsDirectory() );
watch( layout.databasesDirectory() );
watch( layout.transactionLogsRootDirectory() );
watch( layout.homeDirectory() );
startWatching();
}
private void watch( Path file )
{
filesToWatch.add( file );
}
private void stopWatching()
{
try
{
IOUtils.closeAll( watchedResources );
watchedResources.clear();
}
catch ( IOException e )
{
throw new UncheckedIOException( e );
}
}
private void startWatching()
{
for ( Path fileToWatch : filesToWatch )
{
watchFile( fileToWatch );
}
}
private void watchFile( Path fileToWatch )
{
try
{
watchedResources.add( fileWatcher.watch( fileToWatch ) );
}
catch ( IOException e )
{
throw new UncheckedIOException( e );
}
}
}
© 2015 - 2025 Weber Informatics LLC | Privacy Policy