| /* |
| * 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.cassandra.utils; |
| |
| import java.io.File; |
| import java.util.concurrent.TimeUnit; |
| |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| import org.apache.cassandra.concurrent.ScheduledExecutors; |
| |
| public class ResourceWatcher |
| { |
| public static void watch(String resource, Runnable callback, int period) |
| { |
| ScheduledExecutors.scheduledTasks.scheduleWithFixedDelay(new WatchedResource(resource, callback), period, period, TimeUnit.MILLISECONDS); |
| } |
| |
| public static class WatchedResource implements Runnable |
| { |
| private static final Logger logger = LoggerFactory.getLogger(WatchedResource.class); |
| private final String resource; |
| private final Runnable callback; |
| private long lastLoaded; |
| |
| public WatchedResource(String resource, Runnable callback) |
| { |
| this.resource = resource; |
| this.callback = callback; |
| lastLoaded = 0; |
| } |
| |
| public void run() |
| { |
| try |
| { |
| String filename = FBUtilities.resourceToFile(resource); |
| long lastModified = new File(filename).lastModified(); |
| if (lastModified > lastLoaded) |
| { |
| callback.run(); |
| lastLoaded = lastModified; |
| } |
| } |
| catch (Throwable t) |
| { |
| JVMStabilityInspector.inspectThrowable(t); |
| logger.error(String.format("Timed run of %s failed.", callback.getClass()), t); |
| } |
| } |
| } |
| } |