001 /* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache license, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the license for the specific language governing permissions and 015 * limitations under the license. 016 */ 017 package org.apache.logging.log4j.core.helpers; 018 019 import org.apache.logging.log4j.status.StatusLogger; 020 021 /** 022 * Factory for {@code Clock} objects. 023 */ 024 public final class ClockFactory { 025 026 /** 027 * Name of the system property that can be used to specify a {@code Clock} 028 * implementation class. 029 */ 030 public static final String PROPERTY_NAME = "log4j.Clock"; 031 private static final StatusLogger LOGGER = StatusLogger.getLogger(); 032 033 // private static final Clock clock = createClock(); 034 035 private ClockFactory() { 036 } 037 038 /** 039 * Returns a {@code Clock} instance depending on the value of system 040 * property {@code "AsyncLogger.Clock"}. 041 * <p> 042 * If system property {@code AsyncLogger.Clock=CachedClock} is specified, 043 * this method returns an instance of {@link CachedClock}. If system 044 * property {@code AsyncLogger.Clock=CoarseCachedClock} is specified, this 045 * method returns an instance of {@link CoarseCachedClock}. 046 * <p> 047 * If another value is specified, this value is taken as the fully qualified 048 * class name of a class that implements the {@code Clock} interface. An 049 * object of this class is instantiated and returned. 050 * <p> 051 * If no value is specified, or if the specified value could not correctly 052 * be instantiated or did not implement the {@code Clock} interface, then an 053 * instance of {@link SystemClock} is returned. 054 * 055 * @return a {@code Clock} instance 056 */ 057 public static Clock getClock() { 058 return createClock(); 059 } 060 061 private static Clock createClock() { 062 String userRequest = System.getProperty(PROPERTY_NAME); 063 if (userRequest == null || "SystemClock".equals(userRequest)) { 064 LOGGER.debug("Using default SystemClock for timestamps"); 065 return new SystemClock(); 066 } 067 if (CachedClock.class.getName().equals(userRequest) // 068 || "CachedClock".equals(userRequest)) { 069 LOGGER.debug("Using specified CachedClock for timestamps"); 070 return CachedClock.instance(); 071 } 072 if (CoarseCachedClock.class.getName().equals(userRequest) // 073 || "CoarseCachedClock".equals(userRequest)) { 074 LOGGER.debug("Using specified CoarseCachedClock for timestamps"); 075 return CoarseCachedClock.instance(); 076 } 077 try { 078 Clock result = (Clock) Class.forName(userRequest).newInstance(); 079 LOGGER.debug("Using {} for timestamps", userRequest); 080 return result; 081 } catch (Exception e) { 082 String fmt = "Could not create {}: {}, using default SystemClock for timestamps"; 083 LOGGER.error(fmt, userRequest, e); 084 return new SystemClock(); 085 } 086 } 087 }