Logback: the reliable, generic, fast and flexible logging framework.
Copyright (C) 1999-2015, QOS.ch. All rights reserved.
This program and the accompanying materials are dual-licensed under
either the terms of the Eclipse Public License v1.0 as published by
the Eclipse Foundation
  or (per the licensee's choosing)
under the terms of the GNU Lesser General Public License version 2.1
as published by the Free Software Foundation.
/**
 * Logback: the reliable, generic, fast and flexible logging framework.
 * Copyright (C) 1999-2015, QOS.ch. All rights reserved.
 *
 * This program and the accompanying materials are dual-licensed under
 * either the terms of the Eclipse Public License v1.0 as published by
 * the Eclipse Foundation
 *
 *   or (per the licensee's choosing)
 *
 * under the terms of the GNU Lesser General Public License version 2.1
 * as published by the Free Software Foundation.
 */
package ch.qos.logback.core;

import java.util.List;

import ch.qos.logback.core.filter.Filter;
import ch.qos.logback.core.spi.ContextAwareBase;
import ch.qos.logback.core.spi.FilterAttachableImpl;
import ch.qos.logback.core.spi.FilterReply;
import ch.qos.logback.core.status.WarnStatus;

Sets a skeleton implementation for appenders.
 For more information about this appender, please refer to the online
manual at http://logback.qos.ch/manual/appenders.html#AppenderBase
Author:
Ceki Gülcü/**
 * Sets a skeleton implementation for appenders.
 * 
 * <p> For more information about this appender, please refer to the online
 * manual at http://logback.qos.ch/manual/appenders.html#AppenderBase
 * 
 * @author Ceki G&uuml;lc&uuml;
 */
abstract public class AppenderBase<E> extends ContextAwareBase implements Appender<E> {

    protected volatile boolean started = false;

    
The guard prevents an appender from repeatedly calling its own doAppend
method.
/**
     * The guard prevents an appender from repeatedly calling its own doAppend
     * method.
     */
    private boolean guard = false;

    
Appenders are named.
/**
     * Appenders are named.
     */
    protected String name;

    private FilterAttachableImpl<E> fai = new FilterAttachableImpl<E>();

    public String getName() {
        return name;
    }

    private int statusRepeatCount = 0;
    private int exceptionCount = 0;

    static final int ALLOWED_REPEATS = 5;

    public synchronized void doAppend(E eventObject) {
        // WARNING: The guard check MUST be the first statement in the
        // doAppend() method.

        // prevent re-entry.
        if (guard) {
            return;
        }

        try {
            guard = true;

            if (!this.started) {
                if (statusRepeatCount++ < ALLOWED_REPEATS) {
                    addStatus(new WarnStatus("Attempted to append to non started appender [" + name + "].", this));
                }
                return;
            }

            if (getFilterChainDecision(eventObject) == FilterReply.DENY) {
                return;
            }

            // ok, we now invoke derived class' implementation of append
            this.append(eventObject);

        } catch (Exception e) {
            if (exceptionCount++ < ALLOWED_REPEATS) {
                addError("Appender [" + name + "] failed to append.", e);
            }
        } finally {
            guard = false;
        }
    }

    abstract protected void append(E eventObject);

    
Set the name of this appender.
/**
     * Set the name of this appender.
     */
    public void setName(String name) {
        this.name = name;
    }

    public void start() {
        started = true;
    }

    public void stop() {
        started = false;
    }

    public boolean isStarted() {
        return started;
    }

    public String toString() {
        return this.getClass().getName() + "[" + name + "]";
    }

    public void addFilter(Filter<E> newFilter) {
        fai.addFilter(newFilter);
    }

    public void clearAllFilters() {
        fai.clearAllFilters();
    }

    public List<Filter<E>> getCopyOfAttachedFiltersList() {
        return fai.getCopyOfAttachedFiltersList();
    }

    public FilterReply getFilterChainDecision(E event) {
        return fai.getFilterChainDecision(event);
    }

}