150 lines
4.5 KiB
Java
150 lines
4.5 KiB
Java
/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.apache.tomcat.websocket;
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import java.util.HashSet;
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import java.util.Set;
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import org.apache.juli.logging.Log;
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import org.apache.juli.logging.LogFactory;
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import org.apache.tomcat.util.ExceptionUtils;
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import org.apache.tomcat.util.res.StringManager;
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/**
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* Provides a background processing mechanism that triggers roughly once a
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* second. The class maintains a thread that only runs when there is at least
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* one instance of {@link BackgroundProcess} registered.
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*/
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public class BackgroundProcessManager {
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private final Log log =
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LogFactory.getLog(BackgroundProcessManager.class);
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private static final StringManager sm =
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StringManager.getManager(BackgroundProcessManager.class);
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private static final BackgroundProcessManager instance;
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static {
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instance = new BackgroundProcessManager();
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}
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public static BackgroundProcessManager getInstance() {
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return instance;
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}
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private final Set<BackgroundProcess> processes = new HashSet<>();
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private final Object processesLock = new Object();
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private WsBackgroundThread wsBackgroundThread = null;
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private BackgroundProcessManager() {
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// Hide default constructor
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}
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public void register(BackgroundProcess process) {
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synchronized (processesLock) {
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if (processes.size() == 0) {
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wsBackgroundThread = new WsBackgroundThread(this);
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wsBackgroundThread.setContextClassLoader(
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this.getClass().getClassLoader());
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wsBackgroundThread.setDaemon(true);
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wsBackgroundThread.start();
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}
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processes.add(process);
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}
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}
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public void unregister(BackgroundProcess process) {
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synchronized (processesLock) {
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processes.remove(process);
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if (wsBackgroundThread != null && processes.size() == 0) {
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wsBackgroundThread.halt();
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wsBackgroundThread = null;
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}
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}
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}
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private void process() {
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Set<BackgroundProcess> currentProcesses = new HashSet<>();
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synchronized (processesLock) {
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currentProcesses.addAll(processes);
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}
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for (BackgroundProcess process : currentProcesses) {
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try {
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process.backgroundProcess();
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} catch (Throwable t) {
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ExceptionUtils.handleThrowable(t);
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log.error(sm.getString(
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"backgroundProcessManager.processFailed"), t);
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}
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}
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}
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/*
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* For unit testing.
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*/
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int getProcessCount() {
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synchronized (processesLock) {
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return processes.size();
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}
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}
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void shutdown() {
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synchronized (processesLock) {
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processes.clear();
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if (wsBackgroundThread != null) {
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wsBackgroundThread.halt();
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wsBackgroundThread = null;
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}
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}
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}
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private static class WsBackgroundThread extends Thread {
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private final BackgroundProcessManager manager;
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private volatile boolean running = true;
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public WsBackgroundThread(BackgroundProcessManager manager) {
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setName("WebSocket background processing");
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this.manager = manager;
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}
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@Override
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public void run() {
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while (running) {
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try {
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Thread.sleep(1000);
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} catch (InterruptedException e) {
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// Ignore
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}
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manager.process();
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}
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}
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public void halt() {
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setName("WebSocket background processing - stopping");
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running = false;
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}
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}
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}
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