// License: GPL. For details, see LICENSE file.
package org.openstreetmap.josm.io;
import java.io.File;
import java.io.IOException;
import java.nio.file.FileSystems;
import java.nio.file.Path;
import java.nio.file.StandardWatchEventKinds;
import java.nio.file.WatchEvent;
import java.nio.file.WatchEvent.Kind;
import java.nio.file.WatchKey;
import java.nio.file.WatchService;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import org.openstreetmap.josm.Main;
import org.openstreetmap.josm.data.validation.OsmValidator;
import org.openstreetmap.josm.data.validation.tests.MapCSSTagChecker;
import org.openstreetmap.josm.gui.mappaint.MapPaintStyles.MapPaintStyleLoader;
import org.openstreetmap.josm.gui.mappaint.StyleSource;
import org.openstreetmap.josm.gui.mappaint.mapcss.parsergen.ParseException;
import org.openstreetmap.josm.gui.preferences.SourceEntry;
import org.openstreetmap.josm.tools.CheckParameterUtil;
/**
* Background thread that monitors certain files and perform relevant actions when they change.
* @since 7185
*/
public class FileWatcher {
private WatchService watcher;
private Thread thread;
private final Map<Path, StyleSource> styleMap = new HashMap<>();
private final Map<Path, SourceEntry> ruleMap = new HashMap<>();
/**
* Constructs a new {@code FileWatcher}.
*/
public FileWatcher() {
try {
watcher = FileSystems.getDefault().newWatchService();
thread = new Thread((Runnable) this::processEvents, "File Watcher");
} catch (IOException e) {
Main.error(e);
}
}
/**
* Starts the File Watcher thread.
*/
public final void start() {
if (thread != null && !thread.isAlive()) {
thread.start();
}
}
/**
* Registers a map paint style for local file changes, allowing dynamic reloading.
* @param style The style to watch
* @throws IllegalArgumentException if {@code style} is null or if it does not provide a local file
* @throws IllegalStateException if the watcher service failed to start
* @throws IOException if an I/O error occurs
*/
public void registerStyleSource(StyleSource style) throws IOException {
register(style, styleMap);
}
/**
* Registers a validator rule for local file changes, allowing dynamic reloading.
* @param rule The rule to watch
* @throws IllegalArgumentException if {@code rule} is null or if it does not provide a local file
* @throws IllegalStateException if the watcher service failed to start
* @throws IOException if an I/O error occurs
* @since 7276
*/
public void registerValidatorRule(SourceEntry rule) throws IOException {
register(rule, ruleMap);
}
private <T extends SourceEntry> void register(T obj, Map<Path, T> map) throws IOException {
CheckParameterUtil.ensureParameterNotNull(obj, "obj");
if (watcher == null) {
throw new IllegalStateException("File watcher is not available");
}
// Get local file, as this method is only called for local style sources
File file = new File(obj.url);
// Get parent directory as WatchService allows only to monitor directories, not single files
File dir = file.getParentFile();
if (dir == null) {
throw new IllegalArgumentException("Resource "+obj+" does not have a parent directory");
}
synchronized (this) {
// Register directory. Can be called several times for a same directory without problem
// (it returns the same key so it should not send events several times)
dir.toPath().register(watcher, StandardWatchEventKinds.ENTRY_MODIFY, StandardWatchEventKinds.ENTRY_CREATE);
map.put(file.toPath(), obj);
}
}
/**
* Process all events for the key queued to the watcher.
*/
private void processEvents() {
if (Main.isDebugEnabled()) {
Main.debug("File watcher thread started");
}
while (true) {
// wait for key to be signaled
WatchKey key;
try {
key = watcher.take();
} catch (InterruptedException ex) {
Thread.currentThread().interrupt();
return;
}
for (WatchEvent<?> event: key.pollEvents()) {
Kind<?> kind = event.kind();
if (StandardWatchEventKinds.OVERFLOW.equals(kind)) {
continue;
}
// The filename is the context of the event.
@SuppressWarnings("unchecked")
WatchEvent<Path> ev = (WatchEvent<Path>) event;
Path filename = ev.context();
if (filename == null) {
continue;
}
// Only way to get full path (http://stackoverflow.com/a/7802029/2257172)
Path fullPath = ((Path) key.watchable()).resolve(filename);
synchronized (this) {
StyleSource style = styleMap.get(fullPath);
SourceEntry rule = ruleMap.get(fullPath);
if (style != null) {
Main.info("Map style "+style.getDisplayString()+" has been modified. Reloading style...");
Main.worker.submit(new MapPaintStyleLoader(Collections.singleton(style)));
} else if (rule != null) {
Main.info("Validator rule "+rule.getDisplayString()+" has been modified. Reloading rule...");
MapCSSTagChecker tagChecker = OsmValidator.getTest(MapCSSTagChecker.class);
if (tagChecker != null) {
try {
tagChecker.addMapCSS(rule.url);
} catch (IOException | ParseException e) {
Main.warn(e);
}
}
} else if (Main.isDebugEnabled()) {
Main.debug("Received "+kind.name()+" event for unregistered file: "+fullPath);
}
}
}
// Reset the key -- this step is critical to receive
// further watch events. If the key is no longer valid, the directory
// is inaccessible so exit the loop.
if (!key.reset()) {
break;
}
}
}
}