log4j-core/src/main/java/org/apache/logging/log4j/core/appender/RandomAccessFileAppender.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.logging.log4j.core.appender;

import java.io.Serializable;
import java.util.HashMap;
import java.util.Map;

import org.apache.logging.log4j.core.Filter;
import org.apache.logging.log4j.core.Layout;
import org.apache.logging.log4j.core.LogEvent;
import org.apache.logging.log4j.core.config.Configuration;
import org.apache.logging.log4j.core.config.plugins.Plugin;
import org.apache.logging.log4j.core.config.plugins.PluginAttribute;
import org.apache.logging.log4j.core.config.plugins.PluginConfiguration;
import org.apache.logging.log4j.core.config.plugins.PluginElement;
import org.apache.logging.log4j.core.config.plugins.PluginFactory;
import org.apache.logging.log4j.core.helpers.Booleans;
import org.apache.logging.log4j.core.helpers.Integers;
import org.apache.logging.log4j.core.layout.PatternLayout;
import org.apache.logging.log4j.core.net.Advertiser;

/**
 * File Appender.
 */
@Plugin(name = "RandomAccessFile", category = "Core", elementType = "appender", printObject = true)
public final class RandomAccessFileAppender extends AbstractOutputStreamAppender<RandomAccessFileManager> {

    private final String fileName;
    private Object advertisement;
    private final Advertiser advertiser;

    private RandomAccessFileAppender(final String name, final Layout<? extends Serializable> layout, final Filter filter,
            final RandomAccessFileManager manager, final String filename, final boolean ignoreExceptions,
            final boolean immediateFlush, final Advertiser advertiser) {
        super(name, layout, filter, ignoreExceptions, immediateFlush, manager);
        if (advertiser != null) {
            final Map<String, String> configuration = new HashMap<String, String>(
                    layout.getContentFormat());
            configuration.putAll(manager.getContentFormat());
            configuration.put("contentType", layout.getContentType());
            configuration.put("name", name);
            advertisement = advertiser.advertise(configuration);
        }
        this.fileName = filename;
        this.advertiser = advertiser;
    }

    @Override
    public void stop() {
        super.stop();
        if (advertiser != null) {
            advertiser.unadvertise(advertisement);
        }
    }

    /**
     * Write the log entry rolling over the file when required.
     *
     * @param event The LogEvent.
     */
    @Override
    public void append(final LogEvent event) {

        // Leverage the nice batching behaviour of async Loggers/Appenders:
        // we can signal the file manager that it needs to flush the buffer
        // to disk at the end of a batch.
        // From a user's point of view, this means that all log events are
        // _always_ available in the log file, without incurring the overhead
        // of immediateFlush=true.
        getManager().setEndOfBatch(event.isEndOfBatch());
        super.append(event);
    }

    /**
     * Returns the file name this appender is associated with.
     *
     * @return The File name.
     */
    public String getFileName() {
        return this.fileName;
    }

    // difference from standard File Appender:
    // locking is not supported and buffering cannot be switched off
    /**
     * Create a File Appender.
     *
     * @param fileName The name and path of the file.
     * @param append "True" if the file should be appended to, "false" if it
     *            should be overwritten. The default is "true".
     * @param name The name of the Appender.
     * @param immediateFlush "true" if the contents should be flushed on every
     *            write, "false" otherwise. The default is "true".
     * @param bufferSizeStr The buffer size, defaults to {@value RandomAccessFileManager#DEFAULT_BUFFER_SIZE}.
     * @param ignore If {@code "true"} (default) exceptions encountered when appending events are logged; otherwise
     *               they are propagated to the caller.
     * @param layout The layout to use to format the event. If no layout is
     *            provided the default PatternLayout will be used.
     * @param filter The filter, if any, to use.
     * @param advertise "true" if the appender configuration should be
     *            advertised, "false" otherwise.
     * @param advertiseURI The advertised URI which can be used to retrieve the
     *            file contents.
     * @param config The Configuration.
     * @return The FileAppender.
     */
    @PluginFactory
    public static RandomAccessFileAppender createAppender(
            @PluginAttribute("fileName") final String fileName,
            @PluginAttribute("append") final String append,
            @PluginAttribute("name") final String name,
            @PluginAttribute("immediateFlush") final String immediateFlush,
            @PluginAttribute("bufferSize") final String bufferSizeStr,
            @PluginAttribute("ignoreExceptions") final String ignore,
            @PluginElement("Layout") Layout<? extends Serializable> layout,
            @PluginElement("Filters") final Filter filter,
            @PluginAttribute("advertise") final String advertise,
            @PluginAttribute("advertiseURI") final String advertiseURI,
            @PluginConfiguration final Configuration config) {

        final boolean isAppend = Booleans.parseBoolean(append, true);
        final boolean isFlush = Booleans.parseBoolean(immediateFlush, true);
        final boolean ignoreExceptions = Booleans.parseBoolean(ignore, true);
        final boolean isAdvertise = Boolean.parseBoolean(advertise);
        final int bufferSize = Integers.parseInt(bufferSizeStr, RandomAccessFileManager.DEFAULT_BUFFER_SIZE);

        if (name == null) {
            LOGGER.error("No name provided for FileAppender");
            return null;
        }

        if (fileName == null) {
            LOGGER.error("No filename provided for FileAppender with name "
                    + name);
            return null;
        }
        if (layout == null) {
            layout = PatternLayout.createLayout(null, null, null, null, null, null);
        }
        final RandomAccessFileManager manager = RandomAccessFileManager.getFileManager(
                fileName, isAppend, isFlush, bufferSize, advertiseURI, layout
        );
        if (manager == null) {
            return null;
        }

        return new RandomAccessFileAppender(
                name, layout, filter, manager, fileName, ignoreExceptions, isFlush,
                isAdvertise ? config.getAdvertiser() : null
        );
    }
}