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The Apache Log4j Implementation
/*
* 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.util;
import org.apache.logging.log4j.status.StatusLogger;
import org.apache.logging.log4j.util.PropertiesUtil;
/**
* Factory for {@code Clock} objects.
*/
public final class ClockFactory {
/**
* Name of the system property that can be used to specify a {@code Clock}
* implementation class. The value of this property is {@value}.
*/
public static final String PROPERTY_NAME = "log4j.Clock";
private static final StatusLogger LOGGER = StatusLogger.getLogger();
// private static final Clock clock = createClock();
private ClockFactory() {
}
/**
* Returns a {@code Clock} instance depending on the value of system
* property {@link #PROPERTY_NAME}.
*
* If system property {@code log4j.Clock=CachedClock} is specified,
* this method returns an instance of {@link CachedClock}. If system
* property {@code log4j.Clock=CoarseCachedClock} is specified, this
* method returns an instance of {@link CoarseCachedClock}.
*
*
* If another value is specified, this value is taken as the fully qualified
* class name of a class that implements the {@code Clock} interface. An
* object of this class is instantiated and returned.
*
*
* If no value is specified, or if the specified value could not correctly
* be instantiated or did not implement the {@code Clock} interface, then an
* instance of {@link SystemClock} is returned.
*
*
* @return a {@code Clock} instance
*/
public static Clock getClock() {
return createClock();
}
private static Clock createClock() {
final String userRequest = PropertiesUtil.getProperties().getStringProperty(PROPERTY_NAME);
if (userRequest == null || "SystemClock".equals(userRequest)) {
LOGGER.trace("Using default SystemClock for timestamps.");
return new SystemClock();
}
if (CachedClock.class.getName().equals(userRequest)
|| "CachedClock".equals(userRequest)) {
LOGGER.trace("Using specified CachedClock for timestamps.");
return CachedClock.instance();
}
if (CoarseCachedClock.class.getName().equals(userRequest)
|| "CoarseCachedClock".equals(userRequest)) {
LOGGER.trace("Using specified CoarseCachedClock for timestamps.");
return CoarseCachedClock.instance();
}
try {
final Clock result = Loader.newCheckedInstanceOf(userRequest, Clock.class);
LOGGER.trace("Using {} for timestamps.", result.getClass().getName());
return result;
} catch (final Exception e) {
final String fmt = "Could not create {}: {}, using default SystemClock for timestamps.";
LOGGER.error(fmt, userRequest, e);
return new SystemClock();
}
}
}