001/* 002 * Copyright 2002-2019 the original author or authors. 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); 005 * you may not use this file except in compliance with the License. 006 * You may obtain a copy of the License at 007 * 008 * https://www.apache.org/licenses/LICENSE-2.0 009 * 010 * Unless required by applicable law or agreed to in writing, software 011 * distributed under the License is distributed on an "AS IS" BASIS, 012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 013 * See the License for the specific language governing permissions and 014 * limitations under the License. 015 */ 016 017package org.springframework.scheduling.support; 018 019import java.util.concurrent.Future; 020 021import org.apache.commons.logging.Log; 022import org.apache.commons.logging.LogFactory; 023 024import org.springframework.lang.Nullable; 025import org.springframework.util.ErrorHandler; 026import org.springframework.util.ReflectionUtils; 027 028/** 029 * Utility methods for decorating tasks with error handling. 030 * 031 * <p><b>NOTE:</b> This class is intended for internal use by Spring's scheduler 032 * implementations. It is only public so that it may be accessed from impl classes 033 * within other packages. It is <i>not</i> intended for general use. 034 * 035 * @author Mark Fisher 036 * @author Juergen Hoeller 037 * @since 3.0 038 */ 039public abstract class TaskUtils { 040 041 /** 042 * An ErrorHandler strategy that will log the Exception but perform 043 * no further handling. This will suppress the error so that 044 * subsequent executions of the task will not be prevented. 045 */ 046 public static final ErrorHandler LOG_AND_SUPPRESS_ERROR_HANDLER = new LoggingErrorHandler(); 047 048 /** 049 * An ErrorHandler strategy that will log at error level and then 050 * re-throw the Exception. Note: this will typically prevent subsequent 051 * execution of a scheduled task. 052 */ 053 public static final ErrorHandler LOG_AND_PROPAGATE_ERROR_HANDLER = new PropagatingErrorHandler(); 054 055 056 /** 057 * Decorate the task for error handling. If the provided {@link ErrorHandler} 058 * is not {@code null}, it will be used. Otherwise, repeating tasks will have 059 * errors suppressed by default whereas one-shot tasks will have errors 060 * propagated by default since those errors may be expected through the 061 * returned {@link Future}. In both cases, the errors will be logged. 062 */ 063 public static DelegatingErrorHandlingRunnable decorateTaskWithErrorHandler( 064 Runnable task, @Nullable ErrorHandler errorHandler, boolean isRepeatingTask) { 065 066 if (task instanceof DelegatingErrorHandlingRunnable) { 067 return (DelegatingErrorHandlingRunnable) task; 068 } 069 ErrorHandler eh = (errorHandler != null ? errorHandler : getDefaultErrorHandler(isRepeatingTask)); 070 return new DelegatingErrorHandlingRunnable(task, eh); 071 } 072 073 /** 074 * Return the default {@link ErrorHandler} implementation based on the boolean 075 * value indicating whether the task will be repeating or not. For repeating tasks 076 * it will suppress errors, but for one-time tasks it will propagate. In both 077 * cases, the error will be logged. 078 */ 079 public static ErrorHandler getDefaultErrorHandler(boolean isRepeatingTask) { 080 return (isRepeatingTask ? LOG_AND_SUPPRESS_ERROR_HANDLER : LOG_AND_PROPAGATE_ERROR_HANDLER); 081 } 082 083 084 /** 085 * An {@link ErrorHandler} implementation that logs the Throwable at error 086 * level. It does not perform any additional error handling. This can be 087 * useful when suppression of errors is the intended behavior. 088 */ 089 private static class LoggingErrorHandler implements ErrorHandler { 090 091 private final Log logger = LogFactory.getLog(LoggingErrorHandler.class); 092 093 @Override 094 public void handleError(Throwable t) { 095 logger.error("Unexpected error occurred in scheduled task", t); 096 } 097 } 098 099 100 /** 101 * An {@link ErrorHandler} implementation that logs the Throwable at error 102 * level and then propagates it. 103 */ 104 private static class PropagatingErrorHandler extends LoggingErrorHandler { 105 106 @Override 107 public void handleError(Throwable t) { 108 super.handleError(t); 109 ReflectionUtils.rethrowRuntimeException(t); 110 } 111 } 112 113}