001/** 002 * Logback: the reliable, generic, fast and flexible logging framework. 003 * Copyright (C) 1999-2015, QOS.ch. All rights reserved. 004 * 005 * This program and the accompanying materials are dual-licensed under 006 * either the terms of the Eclipse Public License v1.0 as published by 007 * the Eclipse Foundation 008 * 009 * or (per the licensee's choosing) 010 * 011 * under the terms of the GNU Lesser General Public License version 2.1 012 * as published by the Free Software Foundation. 013 */ 014package ch.qos.logback.core; 015 016import java.util.List; 017 018import ch.qos.logback.core.filter.Filter; 019import ch.qos.logback.core.spi.ContextAwareBase; 020import ch.qos.logback.core.spi.FilterAttachableImpl; 021import ch.qos.logback.core.spi.FilterReply; 022import ch.qos.logback.core.status.WarnStatus; 023 024/** 025 * Sets a skeleton implementation for appenders. 026 * 027 * <p> 028 * For more information about this appender, please refer to the online manual 029 * at http://logback.qos.ch/manual/appenders.html#AppenderBase 030 * 031 * @author Ceki Gülcü 032 */ 033abstract public class AppenderBase<E> extends ContextAwareBase implements Appender<E> { 034 035 protected volatile boolean started = false; 036 037 /** 038 * The guard prevents an appender from repeatedly calling its own doAppend 039 * method. 040 */ 041 private boolean guard = false; 042 043 /** 044 * Appenders are named. 045 */ 046 protected String name; 047 048 private FilterAttachableImpl<E> fai = new FilterAttachableImpl<E>(); 049 050 public String getName() { 051 return name; 052 } 053 054 private int statusRepeatCount = 0; 055 private int exceptionCount = 0; 056 057 static final int ALLOWED_REPEATS = 5; 058 059 public synchronized void doAppend(E eventObject) { 060 // WARNING: The guard check MUST be the first statement in the 061 // doAppend() method. 062 063 // prevent re-entry. 064 if (guard) { 065 return; 066 } 067 068 try { 069 guard = true; 070 071 if (!this.started) { 072 if (statusRepeatCount++ < ALLOWED_REPEATS) { 073 addStatus(new WarnStatus("Attempted to append to non started appender [" + name + "].", this)); 074 } 075 return; 076 } 077 078 if (getFilterChainDecision(eventObject) == FilterReply.DENY) { 079 return; 080 } 081 082 // ok, we now invoke derived class' implementation of append 083 this.append(eventObject); 084 085 } catch (Exception e) { 086 if (exceptionCount++ < ALLOWED_REPEATS) { 087 addError("Appender [" + name + "] failed to append.", e); 088 } 089 } finally { 090 guard = false; 091 } 092 } 093 094 abstract protected void append(E eventObject); 095 096 /** 097 * Set the name of this appender. 098 */ 099 public void setName(String name) { 100 this.name = name; 101 } 102 103 public void start() { 104 started = true; 105 } 106 107 public void stop() { 108 started = false; 109 } 110 111 public boolean isStarted() { 112 return started; 113 } 114 115 public String toString() { 116 return this.getClass().getName() + "[" + name + "]"; 117 } 118 119 public void addFilter(Filter<E> newFilter) { 120 fai.addFilter(newFilter); 121 } 122 123 public void clearAllFilters() { 124 fai.clearAllFilters(); 125 } 126 127 public List<Filter<E>> getCopyOfAttachedFiltersList() { 128 return fai.getCopyOfAttachedFiltersList(); 129 } 130 131 public FilterReply getFilterChainDecision(E event) { 132 return fai.getFilterChainDecision(event); 133 } 134 135}