/*
* Copyright 2016 Red Hat, Inc. and/or its affiliates.
*
* Licensed 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.uberfire.backend.server.plugins.engine;
import java.io.IOException;
import java.nio.file.FileSystems;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.WatchEvent;
import java.nio.file.WatchEvent.Kind;
import java.nio.file.WatchKey;
import java.nio.file.WatchService;
import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.TimeUnit;
import javax.enterprise.context.Dependent;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import static java.nio.file.StandardWatchEventKinds.ENTRY_CREATE;
import static java.nio.file.StandardWatchEventKinds.ENTRY_DELETE;
import static java.nio.file.StandardWatchEventKinds.ENTRY_MODIFY;
import static java.nio.file.StandardWatchEventKinds.OVERFLOW;
/**
* Monitors the plugins directory for changes and loads/removes plugins using the
* {@link PluginJarProcessor}.
*/
@Dependent
public class PluginWatcher {
private static final Logger LOG = LoggerFactory.getLogger(PluginWatcher.class);
volatile boolean active;
private ExecutorService executor;
private PluginJarProcessor pluginJarProcessor;
/**
* Starts the plugins watcher iff the provided plugin directory exists and
* the watcher hasn't already been started.
* @param pluginDir the plugin directory to monitor
* @param executor the executor service to submit the watch thread to
* @param pluginJarProcessor the plugin loader for registering and removing plugins
*/
void start(final String pluginDir,
final ExecutorService executor,
final PluginJarProcessor pluginJarProcessor) throws IOException {
final Path pluginsRootPath = Paths.get(pluginDir);
if (active || !Files.exists(pluginsRootPath)) {
return;
}
this.active = true;
this.executor = executor;
this.pluginJarProcessor = pluginJarProcessor;
final WatchService watchService = FileSystems.getDefault().newWatchService();
pluginsRootPath.register(watchService,
ENTRY_CREATE,
ENTRY_MODIFY,
ENTRY_DELETE);
startWatchService(watchService);
}
private void startWatchService(final WatchService watchService) {
executor.submit(() -> {
while (active) {
try {
final WatchKey watchKey = watchService.poll(5,
TimeUnit.SECONDS);
if (watchKey != null && active) {
final List<WatchEvent<?>> events = watchKey.pollEvents();
for (WatchEvent<?> event : events) {
final Kind<?> kind = event.kind();
if (kind == OVERFLOW) {
continue;
}
final Path file = (Path) event.context();
if (kind == ENTRY_CREATE || kind == ENTRY_MODIFY) {
loadPlugins(file);
} else if (kind == ENTRY_DELETE) {
reloadPlugins(file);
}
}
boolean valid = watchKey.reset();
if (!valid) {
break;
}
}
} catch (InterruptedException e) {
active = false;
Thread.currentThread().interrupt();
}
}
});
}
void stop() {
active = false;
if (executor != null) {
executor.shutdown();
}
}
void loadPlugins(final Path file) {
if (file.getFileName().toString().endsWith(".jar")) {
try {
pluginJarProcessor.loadPlugins(file,
true);
} catch (Exception e) {
logPluginsWatcherError("Failed to process new plugin " + file.getFileName().toString(),
e,
!active);
}
}
}
void reloadPlugins(final Path file) {
try {
pluginJarProcessor.reload();
} catch (Exception e) {
logPluginsWatcherError("Failed to delete plugin " + file.getFileName().toString(),
e,
!active);
}
}
void logPluginsWatcherError(final String message,
final Exception e,
final boolean debug) {
if (debug) {
// Debug level is sufficient in case application is stopping
LOG.debug(message);
} else {
LOG.error(message);
}
}
}