Java tutorial
/* * Copyright 2013 the original author or authors. * * 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.springframework.xd.batch.hsqldb.server; import java.lang.management.ManagementFactory; import java.lang.management.OperatingSystemMXBean; import java.net.SocketException; import java.util.Properties; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.hsqldb.persist.HsqlProperties; import org.hsqldb.server.ServerConfiguration; import org.hsqldb.server.ServerConstants; import org.springframework.beans.factory.DisposableBean; import org.springframework.beans.factory.InitializingBean; import com.sun.management.UnixOperatingSystemMXBean; /** * HSQL server mode * * @author Thomas Risberg * @author Ilayaperumal Gopinathan */ public class HSQLServerBean implements InitializingBean, DisposableBean { /** * Commons Logging instance. */ private static final Log logger = LogFactory.getLog(HSQLServerBean.class); /** * Properties used to customize instance. */ private Properties serverProperties; /** * The actual server instance. */ private org.hsqldb.Server server; public Properties getServerProperties() { return serverProperties; } public void setServerProperties(Properties serverProperties) { this.serverProperties = serverProperties; } @Override public void afterPropertiesSet() throws Exception { HsqlProperties configProps = serverProperties != null ? new HsqlProperties(serverProperties) : new HsqlProperties(); ServerConfiguration.translateDefaultDatabaseProperty(configProps); // finished setting up properties - set some important behaviors as well; server = new org.hsqldb.Server(); server.setLogWriter(null); server.setRestartOnShutdown(false); server.setNoSystemExit(true); server.setProperties(configProps); logger.debug("HSQL Database path: " + server.getDatabasePath(0, true)); startServer(); } private void startServer() throws Exception { logger.info("Starting HSQL Server database '" + server.getDatabaseName(0, true) + "' listening on port: " + server.getPort()); int tries = 0; boolean started; Throwable t = null; do { server.start(); started = server.getState() == ServerConstants.SERVER_STATE_ONLINE; if (!started) { // The JavaDoc for server.start() claims to start the server synchronously; // however it only guarantees a transition to state SERVER_STATE_OPENING. // It is possible that the server is still starting up normally so // wait to see if it does. Thread.sleep(1000); started = server.getState() == ServerConstants.SERVER_STATE_ONLINE; } if (!started) { // On occasion the server will fail to start due to exception // "java.net.SocketException: Invalid argument" // when it calls socket.accept(). This exception mostly occurs // on Java 1.7 on OS X. This appears to be caused by having // > 1024 file descriptors open. Multiple attempts // will be made to start HSQLDB before giving up. An attempt // will be made every five seconds or sooner if the file // descriptor count drops below 1024. // // This Stack Overflow thread indicates that it happens on // Tomcat as well: // // http://stackoverflow.com/questions/16191236/ // tomcat-startup-fails-due-to-java-net-socketexception-invalid-argument-on-mac-o // // This will be fixed in Java 7u60: // // https://bugs.openjdk.java.net/browse/JDK-8021820 t = server.getServerError(); if (t instanceof SocketException && "Invalid argument".equals(t.getMessage())) { long fileCount = getOpenFileDescriptorCount(); logger.debug(String.format( "Caught SocketException (likely due to excessive file descriptors open; current count: %d)", fileCount), t); long timeout = System.currentTimeMillis() + 5000; while (System.currentTimeMillis() < timeout && fileCount > 1024) { Thread.sleep(500); fileCount = getOpenFileDescriptorCount(); } logger.debug(String.format("Open files: %d", getOpenFileDescriptorCount())); } else { // if the server fails to start for any other reason, // break out of this loop instead of continuing to try // a restart break; } } } while (!started && ++tries < 5); if (started) { logger.info("Started HSQL Server"); } else { String msg = String.format("HSQLDB could not be started on %s:%d, state: %s", server.getAddress(), server.getPort(), server.getStateDescriptor()); if (t == null) { throw new IllegalStateException(msg); } else { throw new IllegalStateException(msg, t); } } } /** * On UNIX operating systems, return the number of open file descriptors. On non UNIX operating systems this returns * -1. * * @return number of open file descriptors if this is executing on a UNIX operating system */ private long getOpenFileDescriptorCount() { OperatingSystemMXBean osStats = ManagementFactory.getOperatingSystemMXBean(); return osStats instanceof UnixOperatingSystemMXBean ? ((UnixOperatingSystemMXBean) osStats).getOpenFileDescriptorCount() : -1; } @Override public void destroy() { shutdownServer(); } private void shutdownServer() { logger.info("HSQL Server Shutdown sequence initiated"); if (server != null) { server.signalCloseAllServerConnections(); server.stop(); server.shutdown(); // Wait until the server shuts down or timeout after 5 seconds. int attempts = 0; while (server.getState() != ServerConstants.SERVER_STATE_SHUTDOWN && attempts++ < 50) { try { Thread.sleep(100); } catch (InterruptedException e) { Thread.currentThread().interrupt(); break; } } if (server.getState() == ServerConstants.SERVER_STATE_SHUTDOWN) { logger.info("HSQL Server Shutdown completed."); } else { logger.warn( "HSQL Server Shutdown timed out or was interrupted. Server State: " + server.getState()); } server = null; } } }