/*
 * Copyright 2012 The Netty Project
 *
 * The Netty Project 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 io.netty.util.internal.logging;

Creates an InternalLogger or changes the default factory implementation. This factory allows you to choose what logging framework Netty should use. The default factory is Slf4JLoggerFactory. If SLF4J is not available, Log4JLoggerFactory is used. If Log4J is not available, JdkLoggerFactory is used. You can change it to your preferred logging framework before other Netty classes are loaded: 
InternalLoggerFactory.setDefaultFactory(Log4JLoggerFactory.INSTANCE); 
 Please note that the new default factory is effective only for the classes which were loaded after the default factory is changed. Therefore, setDefaultFactory(InternalLoggerFactory) should be called as early as possible and shouldn't be called more than once. /**
 * Creates an {@link InternalLogger} or changes the default factory
 * implementation.  This factory allows you to choose what logging framework
 * Netty should use.  The default factory is {@link Slf4JLoggerFactory}.  If SLF4J
 * is not available, {@link Log4JLoggerFactory} is used.  If Log4J is not available,
 * {@link JdkLoggerFactory} is used.  You can change it to your preferred
 * logging framework before other Netty classes are loaded:
 * <pre>
 * {@link InternalLoggerFactory}.setDefaultFactory({@link Log4JLoggerFactory}.INSTANCE);
 * </pre>
 * Please note that the new default factory is effective only for the classes
 * which were loaded after the default factory is changed.  Therefore,
 * {@link #setDefaultFactory(InternalLoggerFactory)} should be called as early
 * as possible and shouldn't be called more than once.
 */
public abstract class InternalLoggerFactory {

    private static volatile InternalLoggerFactory defaultFactory;

    @SuppressWarnings("UnusedCatchParameter")
    private static InternalLoggerFactory newDefaultFactory(String name) {
        InternalLoggerFactory f;
        try {
            f = new Slf4JLoggerFactory(true);
            f.newInstance(name).debug("Using SLF4J as the default logging framework");
        } catch (Throwable t1) {
            try {
                f = Log4JLoggerFactory.INSTANCE;
                f.newInstance(name).debug("Using Log4J as the default logging framework");
            } catch (Throwable t2) {
                f = JdkLoggerFactory.INSTANCE;
                f.newInstance(name).debug("Using java.util.logging as the default logging framework");
            }
        }
        return f;
    }

    
Returns the default factory. The initial default factory is JdkLoggerFactory. /**
     * Returns the default factory.  The initial default factory is
     * {@link JdkLoggerFactory}.
     */
    public static InternalLoggerFactory getDefaultFactory() {
        if (defaultFactory == null) {
            defaultFactory = newDefaultFactory(InternalLoggerFactory.class.getName());
        }
        return defaultFactory;
    }

    
Changes the default factory.
/**
     * Changes the default factory.
     */
    public static void setDefaultFactory(InternalLoggerFactory defaultFactory) {
        if (defaultFactory == null) {
            throw new NullPointerException("defaultFactory");
        }
        InternalLoggerFactory.defaultFactory = defaultFactory;
    }

    
Creates a new logger instance with the name of the specified class.
/**
     * Creates a new logger instance with the name of the specified class.
     */
    public static InternalLogger getInstance(Class<?> clazz) {
        return getInstance(clazz.getName());
    }

    
Creates a new logger instance with the specified name.
/**
     * Creates a new logger instance with the specified name.
     */
    public static InternalLogger getInstance(String name) {
        return getDefaultFactory().newInstance(name);
    }

    
Creates a new logger instance with the specified name.
/**
     * Creates a new logger instance with the specified name.
     */
    protected abstract InternalLogger newInstance(String name);

}