Java tutorial
/* * Copyright 2010 LinkedIn, Inc * * 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 azkaban.jobs.builtin; import azkaban.common.utils.Props; import org.apache.log4j.ConsoleAppender; import org.apache.log4j.Layout; import org.apache.log4j.Logger; import org.apache.log4j.PatternLayout; import java.io.BufferedOutputStream; import java.io.BufferedReader; import java.io.FileOutputStream; import java.io.FileReader; import java.io.IOException; import java.io.OutputStream; import java.lang.reflect.Constructor; import java.lang.reflect.Method; import java.util.LinkedHashMap; import java.util.Map; import java.util.Properties; public class JavaJobRunnerMain { public static final String JOB_CLASS = "job.class"; public static final String DEFAULT_RUN_METHOD = "run"; public static final String DEFAULT_CANCEL_METHOD = "cancel"; // This is the Job interface method to get the properties generated by the job. public static final String GET_GENERATED_PROPERTIES_METHOD = "getJobGeneratedProperties"; public static final String CANCEL_METHOD_PARAM = "method.cancel"; public static final String RUN_METHOD_PARAM = "method.run"; public static final String PROPS_CLASS = "azkaban.common.utils.Props"; private static final Layout DEFAULT_LAYOUT = new PatternLayout("%p %m\n"); public final Logger _logger; public String _cancelMethod; public String _jobName; public Object _javaObject; private boolean _isFinished = false; public static void main(String[] args) throws Exception { @SuppressWarnings("unused") JavaJobRunnerMain wrapper = new JavaJobRunnerMain(); } public JavaJobRunnerMain() throws Exception { Runtime.getRuntime().addShutdownHook(new Thread() { public void run() { cancelJob(); } }); try { _jobName = System.getenv(ProcessJob.JOB_NAME_ENV); String propsFile = System.getenv(ProcessJob.JOB_PROP_ENV); _logger = Logger.getRootLogger(); _logger.removeAllAppenders(); ConsoleAppender appender = new ConsoleAppender(DEFAULT_LAYOUT); appender.activateOptions(); _logger.addAppender(appender); Properties prop = new Properties(); prop.load(new BufferedReader(new FileReader(propsFile))); _logger.info("Running job " + _jobName); String className = prop.getProperty(JOB_CLASS); if (className == null) { throw new Exception("Class name is not set."); } _logger.info("Class name " + className); // Create the object. _javaObject = getObject(_jobName, className, prop); if (_javaObject == null) { _logger.info("Could not create java object to run job: " + className); throw new Exception("Could not create running object"); } _cancelMethod = prop.getProperty(CANCEL_METHOD_PARAM, DEFAULT_CANCEL_METHOD); String runMethod = prop.getProperty(RUN_METHOD_PARAM, DEFAULT_RUN_METHOD); _logger.info("Invoking method " + runMethod); _javaObject.getClass().getMethod(runMethod, new Class<?>[] {}).invoke(_javaObject); _isFinished = true; // Get the generated properties and store them to disk, to be read by ProcessJob. try { final Method generatedPropertiesMethod = _javaObject.getClass() .getMethod(GET_GENERATED_PROPERTIES_METHOD, new Class<?>[] {}); Props outputGendProps = (Props) generatedPropertiesMethod.invoke(_javaObject, new Object[] {}); outputGeneratedProperties(outputGendProps); } catch (NoSuchMethodException e) { _logger.info(String.format( "Apparently there isn't a method[%s] on object[%s], using empty Props object instead.", GET_GENERATED_PROPERTIES_METHOD, _javaObject)); outputGeneratedProperties(new Props()); } } catch (Exception e) { _isFinished = true; throw e; } } private void outputGeneratedProperties(Props outputProperties) { _logger.info("Outputting generated properties to " + ProcessJob.JOB_OUTPUT_PROP_FILE); if (outputProperties == null) { _logger.info(" no gend props"); return; } for (String key : outputProperties.keySet()) { _logger.info(" gend prop " + key + " value:" + outputProperties.get(key)); } String outputFileStr = System.getenv(ProcessJob.JOB_OUTPUT_PROP_FILE); if (outputFileStr == null) { return; } Map<String, String> properties = new LinkedHashMap<String, String>(); for (String key : outputProperties.keySet()) { properties.put(key, outputProperties.get(key)); } OutputStream writer = null; try { writer = new BufferedOutputStream(new FileOutputStream(outputFileStr)); // Manually serialize into JSON instead of adding org.json to external classpath writer.write("{\n".getBytes()); for (Map.Entry<String, String> entry : properties.entrySet()) { writer.write(String.format(" '%s':'%s',\n", entry.getKey().replace("'", "\\'"), entry.getValue().replace("'", "\\'")).getBytes()); } writer.write("}".getBytes()); } catch (Exception e) { new RuntimeException("Unable to store output properties to: " + outputFileStr); } finally { try { writer.close(); } catch (IOException e) { } } } public void cancelJob() { if (_isFinished) { return; } _logger.info("Attempting to call cancel on this job"); if (_javaObject != null) { Method method = null; try { method = _javaObject.getClass().getMethod(_cancelMethod); } catch (SecurityException e) { } catch (NoSuchMethodException e) { } if (method != null) try { method.invoke(_javaObject); } catch (Exception e) { if (_logger != null) { _logger.error("Cancel method failed! ", e); } } else { throw new RuntimeException("Job " + _jobName + " does not have cancel method " + _cancelMethod); } } } private static Object getObject(String jobName, String className, Properties properties) throws Exception { Class<?> runningClass = JavaJobRunnerMain.class.getClassLoader().loadClass(className); if (runningClass == null) { throw new Exception("Class " + className + " was not found. Cannot run job."); } Class<?> propsClass = JavaJobRunnerMain.class.getClassLoader().loadClass(PROPS_CLASS); Object obj = null; if (propsClass != null && getConstructor(runningClass, String.class, propsClass) != null) { // This case covers the use of azkaban.common.utils.Props with the Constructor<?> con = getConstructor(propsClass, propsClass, Properties[].class); Object props = con.newInstance(null, new Properties[] { properties }); obj = getConstructor(runningClass, String.class, propsClass).newInstance(jobName, props); } else if (getConstructor(runningClass, String.class, Properties.class) != null) { obj = getConstructor(runningClass, String.class, Properties.class).newInstance(jobName, properties); } else if (getConstructor(runningClass, String.class) != null) { obj = getConstructor(runningClass, String.class).newInstance(jobName); } else if (getConstructor(runningClass) != null) { obj = getConstructor(runningClass).newInstance(); } return obj; } private static Constructor<?> getConstructor(Class<?> c, Class<?>... args) { try { Constructor<?> cons = c.getConstructor(args); return cons; } catch (NoSuchMethodException e) { return null; } } }