rhelp/org.eclipse.statet.rhelp.server/src/main/java/org/eclipse/statet/internal/rhelp/server/update/RLibPathsMonitor.java

/*=============================================================================#
 # Copyright (c) 2018, 2019 Stephan Wahlbrink and others.
 # 
 # This program and the accompanying materials are made available under the
 # terms of the Eclipse Public License 2.0 which is available at
 # https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
 # which is available at https://www.apache.org/licenses/LICENSE-2.0.
 # 
 # SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
 # 
 # Contributors:
 #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
 #=============================================================================*/

package org.eclipse.statet.internal.rhelp.server.update;

import static org.eclipse.statet.rhelp.server.Application.BUNDLE_ID;

import java.io.IOException;
import java.nio.file.ClosedWatchServiceException;
import java.nio.file.FileSystems;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.StandardWatchEventKinds;
import java.nio.file.WatchEvent;
import java.nio.file.WatchKey;
import java.nio.file.WatchService;
import java.util.List;
import java.util.concurrent.TimeUnit;

import org.eclipse.statet.jcommons.runtime.CommonsRuntime;
import org.eclipse.statet.jcommons.status.ErrorStatus;
import org.eclipse.statet.jcommons.status.InfoStatus;

import org.eclipse.statet.rj.renv.core.RLibLocation;
import org.eclipse.statet.rj.renv.core.RLibPaths;


public class RLibPathsMonitor implements Runnable {
	
	
	private final REnvIndexer indexer;
	
	private WatchService watchService;
	
	
	public RLibPathsMonitor(final REnvIndexer indexer) {
		this.indexer= indexer;
	}
	
	
	public void check(final RLibPaths rLibPaths) {
		try {
			ensureService();
			
			for (final RLibLocation location : rLibPaths.getRLibLocations()) {
				final Path path= location.getDirectoryPath();
				if (path != null && Files.isDirectory(path)) {
					path.register(this.watchService,
							StandardWatchEventKinds.ENTRY_CREATE,
							StandardWatchEventKinds.ENTRY_DELETE,
							StandardWatchEventKinds.OVERFLOW );
				}
			}
			
		}
		catch (final IOException e) {
			CommonsRuntime.log(new ErrorStatus(BUNDLE_ID,
					String.format("%1$sAn error occurred when setting up R lib paths monitor.",
							this.indexer.getLogPrefix() ),
					e ));
		}
	}
	
	public void stop() {
		try {
			stopService();
		}
		catch (final IOException e) {
			CommonsRuntime.log(new ErrorStatus(BUNDLE_ID,
					String.format("%1$sAn error occurred when stopping R lib paths monitor.",
							this.indexer.getLogPrefix() ),
					e ));
		}
	}
	
	private synchronized void ensureService() throws IOException {
		if (this.watchService == null) {
			this.watchService= FileSystems.getDefault().newWatchService();
			
			this.indexer.getController().startMonitor(this);
		}
	}
	
	private synchronized void stopService() throws IOException {
		if (this.watchService != null) {
			this.watchService.close();
		}
	}
	
	
	private boolean isTempFolder(final String fileName) {
		if (fileName.length() >= 5) {
			if (fileName.startsWith("_test_") || fileName.startsWith("_TEST_")) { //$NON-NLS-1$ //$NON-NLS-2$
				return true;
			}
			if (fileName.startsWith("file") || fileName.startsWith("FILE")) { //$NON-NLS-1$ //$NON-NLS-2$
				final char c= fileName.charAt(4);
				return (c >= '0' && c <= '9');
			}
		}
		return false;
	}
	
	@Override
	public void run() {
		try {
			CommonsRuntime.log(new InfoStatus(BUNDLE_ID,
					String.format("%1$sR lib paths monitor started.",
							this.indexer.getLogPrefix() )));
			
			boolean update= false;
			while (true) {
				try {
					final WatchKey key= (update) ?
							this.watchService.poll(1000, TimeUnit.MILLISECONDS) :
							this.watchService.take();
					if (key == null) {
						assert(update);
						update= false;
						this.indexer.schedule(REnvIndexer.LIB_PATHS_MONITOR);
						continue;
					}
					else {
						final List<WatchEvent<?>> events= key.pollEvents();
						for (final WatchEvent<?> event : events) {
							if (event.kind() == StandardWatchEventKinds.OVERFLOW) {
								update= true;
								break;
							}
							final Path path= (Path) event.context();
							if (path != null && !isTempFolder(path.getFileName().toString())) {
								update= true;
								break;
							}
						}
						key.reset();
					}
				}
				catch (final InterruptedException e) {
				}
				catch (final ClosedWatchServiceException e) {
					synchronized (this) {
						this.watchService= null;
					}
					return;
				}
			}
		}
		catch (final Throwable e) {
			CommonsRuntime.log(new ErrorStatus(BUNDLE_ID,
					String.format("%1$sR lib paths monitor did not complete normally.",
							this.indexer.getLogPrefix() ),
					e ));
		}
	}
	
}