org.springframework.boot.logging.DeferredLog.java Source code

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Here is the source code for org.springframework.boot.logging.DeferredLog.java

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/*
 * Copyright 2012-2019 the original author or authors.
 *
 * Licensed 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
 *
 *      https://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.springframework.boot.logging;

import java.util.ArrayList;
import java.util.List;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * Deferred {@link Log} that can be used to store messages that shouldn't be written until
 * the logging system is fully initialized.
 *
 * @author Phillip Webb
 * @since 1.3.0
 */
public class DeferredLog implements Log {

    private volatile Log destination;

    private final List<Line> lines = new ArrayList<>();

    @Override
    public boolean isTraceEnabled() {
        synchronized (this.lines) {
            return (this.destination == null) || this.destination.isTraceEnabled();
        }
    }

    @Override
    public boolean isDebugEnabled() {
        synchronized (this.lines) {
            return (this.destination == null) || this.destination.isDebugEnabled();
        }
    }

    @Override
    public boolean isInfoEnabled() {
        synchronized (this.lines) {
            return (this.destination == null) || this.destination.isInfoEnabled();
        }
    }

    @Override
    public boolean isWarnEnabled() {
        synchronized (this.lines) {
            return (this.destination == null) || this.destination.isWarnEnabled();
        }
    }

    @Override
    public boolean isErrorEnabled() {
        synchronized (this.lines) {
            return (this.destination == null) || this.destination.isErrorEnabled();
        }
    }

    @Override
    public boolean isFatalEnabled() {
        synchronized (this.lines) {
            return (this.destination == null) || this.destination.isFatalEnabled();
        }
    }

    @Override
    public void trace(Object message) {
        log(LogLevel.TRACE, message, null);
    }

    @Override
    public void trace(Object message, Throwable t) {
        log(LogLevel.TRACE, message, t);
    }

    @Override
    public void debug(Object message) {
        log(LogLevel.DEBUG, message, null);
    }

    @Override
    public void debug(Object message, Throwable t) {
        log(LogLevel.DEBUG, message, t);
    }

    @Override
    public void info(Object message) {
        log(LogLevel.INFO, message, null);
    }

    @Override
    public void info(Object message, Throwable t) {
        log(LogLevel.INFO, message, t);
    }

    @Override
    public void warn(Object message) {
        log(LogLevel.WARN, message, null);
    }

    @Override
    public void warn(Object message, Throwable t) {
        log(LogLevel.WARN, message, t);
    }

    @Override
    public void error(Object message) {
        log(LogLevel.ERROR, message, null);
    }

    @Override
    public void error(Object message, Throwable t) {
        log(LogLevel.ERROR, message, t);
    }

    @Override
    public void fatal(Object message) {
        log(LogLevel.FATAL, message, null);
    }

    @Override
    public void fatal(Object message, Throwable t) {
        log(LogLevel.FATAL, message, t);
    }

    private void log(LogLevel level, Object message, Throwable t) {
        synchronized (this.lines) {
            if (this.destination != null) {
                logTo(this.destination, level, message, t);
            } else {
                this.lines.add(new Line(level, message, t));
            }
        }
    }

    /**
     * Switch from deferred logging to immediate logging to the specified destination.
     * @param destination the new log destination
     * @since 2.1.0
     */
    public void switchTo(Class<?> destination) {
        switchTo(LogFactory.getLog(destination));
    }

    /**
     * Switch from deferred logging to immediate logging to the specified destination.
     * @param destination the new log destination
     * @since 2.1.0
     */
    public void switchTo(Log destination) {
        synchronized (this.lines) {
            replayTo(destination);
            this.destination = destination;
        }
    }

    /**
     * Replay deferred logging to the specified destination.
     * @param destination the destination for the deferred log messages
     */
    public void replayTo(Class<?> destination) {
        replayTo(LogFactory.getLog(destination));
    }

    /**
     * Replay deferred logging to the specified destination.
     * @param destination the destination for the deferred log messages
     */
    public void replayTo(Log destination) {
        synchronized (this.lines) {
            for (Line line : this.lines) {
                logTo(destination, line.getLevel(), line.getMessage(), line.getThrowable());
            }
            this.lines.clear();
        }
    }

    /**
     * Replay from a source log to a destination log when the source is deferred.
     * @param source the source logger
     * @param destination the destination logger class
     * @return the destination
     */
    public static Log replay(Log source, Class<?> destination) {
        return replay(source, LogFactory.getLog(destination));
    }

    /**
     * Replay from a source log to a destination log when the source is deferred.
     * @param source the source logger
     * @param destination the destination logger
     * @return the destination
     */
    public static Log replay(Log source, Log destination) {
        if (source instanceof DeferredLog) {
            ((DeferredLog) source).replayTo(destination);
        }
        return destination;
    }

    private static void logTo(Log log, LogLevel level, Object message, Throwable throwable) {
        switch (level) {
        case TRACE:
            log.trace(message, throwable);
            return;
        case DEBUG:
            log.debug(message, throwable);
            return;
        case INFO:
            log.info(message, throwable);
            return;
        case WARN:
            log.warn(message, throwable);
            return;
        case ERROR:
            log.error(message, throwable);
            return;
        case FATAL:
            log.fatal(message, throwable);
            return;
        }
    }

    private static class Line {

        private final LogLevel level;

        private final Object message;

        private final Throwable throwable;

        Line(LogLevel level, Object message, Throwable throwable) {
            this.level = level;
            this.message = message;
            this.throwable = throwable;
        }

        LogLevel getLevel() {
            return this.level;
        }

        Object getMessage() {
            return this.message;
        }

        Throwable getThrowable() {
            return this.throwable;
        }

    }

}