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Diffstat (limited to 'src/java/nginx/unit/websocket/BackgroundProcessManager.java')
-rw-r--r-- | src/java/nginx/unit/websocket/BackgroundProcessManager.java | 149 |
1 files changed, 149 insertions, 0 deletions
diff --git a/src/java/nginx/unit/websocket/BackgroundProcessManager.java b/src/java/nginx/unit/websocket/BackgroundProcessManager.java new file mode 100644 index 00000000..d8b1b950 --- /dev/null +++ b/src/java/nginx/unit/websocket/BackgroundProcessManager.java @@ -0,0 +1,149 @@ +/* + * 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 nginx.unit.websocket; + +import java.util.HashSet; +import java.util.Set; + +import org.apache.juli.logging.Log; +import org.apache.juli.logging.LogFactory; +import org.apache.tomcat.util.ExceptionUtils; +import org.apache.tomcat.util.res.StringManager; + +/** + * Provides a background processing mechanism that triggers roughly once a + * second. The class maintains a thread that only runs when there is at least + * one instance of {@link BackgroundProcess} registered. + */ +public class BackgroundProcessManager { + + private final Log log = + LogFactory.getLog(BackgroundProcessManager.class); + private static final StringManager sm = + StringManager.getManager(BackgroundProcessManager.class); + private static final BackgroundProcessManager instance; + + + static { + instance = new BackgroundProcessManager(); + } + + + public static BackgroundProcessManager getInstance() { + return instance; + } + + private final Set<BackgroundProcess> processes = new HashSet<>(); + private final Object processesLock = new Object(); + private WsBackgroundThread wsBackgroundThread = null; + + private BackgroundProcessManager() { + // Hide default constructor + } + + + public void register(BackgroundProcess process) { + synchronized (processesLock) { + if (processes.size() == 0) { + wsBackgroundThread = new WsBackgroundThread(this); + wsBackgroundThread.setContextClassLoader( + this.getClass().getClassLoader()); + wsBackgroundThread.setDaemon(true); + wsBackgroundThread.start(); + } + processes.add(process); + } + } + + + public void unregister(BackgroundProcess process) { + synchronized (processesLock) { + processes.remove(process); + if (wsBackgroundThread != null && processes.size() == 0) { + wsBackgroundThread.halt(); + wsBackgroundThread = null; + } + } + } + + + private void process() { + Set<BackgroundProcess> currentProcesses = new HashSet<>(); + synchronized (processesLock) { + currentProcesses.addAll(processes); + } + for (BackgroundProcess process : currentProcesses) { + try { + process.backgroundProcess(); + } catch (Throwable t) { + ExceptionUtils.handleThrowable(t); + log.error(sm.getString( + "backgroundProcessManager.processFailed"), t); + } + } + } + + + /* + * For unit testing. + */ + int getProcessCount() { + synchronized (processesLock) { + return processes.size(); + } + } + + + void shutdown() { + synchronized (processesLock) { + processes.clear(); + if (wsBackgroundThread != null) { + wsBackgroundThread.halt(); + wsBackgroundThread = null; + } + } + } + + + private static class WsBackgroundThread extends Thread { + + private final BackgroundProcessManager manager; + private volatile boolean running = true; + + public WsBackgroundThread(BackgroundProcessManager manager) { + setName("WebSocket background processing"); + this.manager = manager; + } + + @Override + public void run() { + while (running) { + try { + Thread.sleep(1000); + } catch (InterruptedException e) { + // Ignore + } + manager.process(); + } + } + + public void halt() { + setName("WebSocket background processing - stopping"); + running = false; + } + } +} |