001 /**
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements. See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership. The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License. You may obtain a copy of the License at
009 *
010 * http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018 package org.apache.oozie;
019
020 import org.apache.oozie.util.XLog;
021
022 /**
023 * Fault Injection support class. <p/> Concrete classes should be available only during testing, not in production. <p/>
024 * To activate fault injection the {@link #FAULT_INJECTION} system property must be set to true. <p/> When fault
025 * injection is activated, the concrete class (specified by name) will be call for activation. <p/> Concrete classes
026 * should be activated by presense of a second system property. <p/> This fault injection pattern provides 3 levels of
027 * safeguard: a general 'fault injection' system property, the availabity of of the concrete 'fault injection' class in
028 * the classpath, a specifi 'fault injection' system property. <p/> Refer to the <code>SkipCommitFaultInjection</code>
029 * class in the test classes for an example.
030 */
031 public abstract class FaultInjection {
032
033 public static final String FAULT_INJECTION = "oozie.fault.injection";
034
035 private static FaultInjection getFaultInjection(String className) {
036 if (Boolean.parseBoolean(System.getProperty(FAULT_INJECTION, "false"))) {
037 try {
038 Class klass = Thread.currentThread().getContextClassLoader().loadClass(className);
039 return (FaultInjection) klass.newInstance();
040 }
041 catch (ClassNotFoundException ex) {
042 XLog.getLog(FaultInjection.class).warn("Trying to activate fault injection in production", ex);
043 }
044 catch (IllegalAccessException ex) {
045 throw new RuntimeException(XLog.format("Could not initialize [{0}]", className, ex), ex);
046 }
047 catch (InstantiationException ex) {
048 throw new RuntimeException(XLog.format("Could not initialize [{0}]", className, ex), ex);
049 }
050 }
051 return null;
052 }
053
054 public static boolean activate(String className) {
055 FaultInjection fi = getFaultInjection(className);
056 if (fi != null) {
057 className = className.substring(className.lastIndexOf(".") + 1);
058 if (fi.activate()) {
059 XLog.getLog(FaultInjection.class).warn("FAULT INJECTION, ACTIVATING [{0}]", className);
060 return true;
061 }
062 else {
063 XLog.getLog(FaultInjection.class).warn("FAULT INJECTION, DID NOT ACTIVATE [{0}]", className);
064 }
065 }
066 return false;
067 }
068
069 public static void deactivate(String className) {
070 FaultInjection fi = getFaultInjection(className);
071 if (fi != null) {
072 className = className.substring(className.lastIndexOf(".") + 1);
073 if (fi.isActive()) {
074 XLog.getLog(FaultInjection.class).warn("FAULT INJECTION, DEACTIVATING [{0}]", className);
075 fi.deactivate();
076 }
077 else {
078 XLog.getLog(FaultInjection.class).warn("FAULT INJECTION, CANNOT DEACTIVATE, NOT ACTIVE [{0}]",
079 className);
080 }
081 }
082 }
083
084 public static boolean isActive(String className) {
085 FaultInjection fi = getFaultInjection(className);
086 if (fi != null) {
087 className = className.substring(className.lastIndexOf(".") + 1);
088 if (fi.isActive()) {
089 XLog.getLog(FaultInjection.class).warn("FAULT INJECTION, ACTIVE [{0}]", className);
090 return true;
091 }
092 else {
093 XLog.getLog(FaultInjection.class).warn("FAULT INJECTION, NOT ACTIVE [{0}]", className);
094 }
095 }
096 return false;
097 }
098
099 public abstract boolean activate();
100
101 public abstract void deactivate();
102
103 public abstract boolean isActive();
104
105 }