com.hazelcast.util.Clock Maven / Gradle / Ivy
/*
* Copyright (c) 2008-2015, Hazelcast, Inc. All Rights Reserved.
*
* 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
*
* 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 com.hazelcast.util;
import com.hazelcast.nio.ClassLoaderUtil;
/**
* Utility class to be able to simulate different time zones.
* Time offset can be configured with the property com.hazelcast.clock.offset
*/
public final class Clock {
/**
* Clock offset property in milliseconds. When it is set to a non-zero value,
* {@link Clock#currentTimeMillis()} will return a shifted {@link System#currentTimeMillis()}
* time by the given offset value.
*/
public static final String HAZELCAST_CLOCK_OFFSET = "com.hazelcast.clock.offset";
/**
* Classname of a {@link com.hazelcast.util.Clock.ClockImpl} implementation.
* When this property is set, {@link Clock#currentTimeMillis()}
* will call the currentTimeMillis() method of given ClockImpl.
*/
public static final String HAZELCAST_CLOCK_IMPL = "com.hazelcast.clock.impl";
private static final ClockImpl CLOCK;
private Clock() {
}
public static long currentTimeMillis() {
return CLOCK.currentTimeMillis();
}
static {
CLOCK = initClock();
}
private static ClockImpl initClock() {
String clockImplClassName = System.getProperty(HAZELCAST_CLOCK_IMPL);
if (clockImplClassName != null) {
try {
return ClassLoaderUtil.newInstance(null, clockImplClassName);
} catch (Exception e) {
throw ExceptionUtil.rethrow(e);
}
}
String clockOffset = System.getProperty(HAZELCAST_CLOCK_OFFSET);
long offset = 0L;
if (clockOffset != null) {
try {
offset = Long.parseLong(clockOffset);
} catch (NumberFormatException e) {
throw ExceptionUtil.rethrow(e);
}
}
if (offset != 0L) {
return new SystemOffsetClock(offset);
}
return new SystemClock();
}
/**
* Clock abstraction to be able to simulate different clocks
* without changing actual system time.
*/
public abstract static class ClockImpl {
protected abstract long currentTimeMillis();
}
private static final class SystemClock extends ClockImpl {
@Override
protected long currentTimeMillis() {
return System.currentTimeMillis();
}
@Override
public String toString() {
return "SystemClock";
}
}
private static final class SystemOffsetClock extends ClockImpl {
private final long offset;
private SystemOffsetClock(final long offset) {
this.offset = offset;
}
@Override
protected long currentTimeMillis() {
return System.currentTimeMillis() + offset;
}
@Override
public String toString() {
final StringBuilder sb = new StringBuilder();
sb.append("SystemOffsetClock");
sb.append("{offset=").append(offset);
sb.append('}');
return sb.toString();
}
}
}