/*
* Copyright (c) 2008-2013, 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;
/**
* @author mdogan 4/10/12
*/
public final class
Clock {
public static long
currentTimeMillis() {
return
CLOCK.
currentTimeMillis();
}
private static final
ClockImpl CLOCK;
static {
final
String clockOffset =
System.
getProperty("com.hazelcast.clock.offset");
long
offset = 0L;
if (
clockOffset != null) {
try {
offset =
Long.
parseLong(
clockOffset);
} catch (
NumberFormatException ignore) {
}
}
if (
offset == 0L) {
CLOCK = new
SystemClock();
} else {
CLOCK = new
SystemOffsetClock(
offset);
}
}
private static abstract class
ClockImpl {
protected abstract long
currentTimeMillis();
}
private static final class
SystemClock extends
ClockImpl {
protected final long
currentTimeMillis() {
return
System.
currentTimeMillis();
}
public
String toString() {
return "SystemClock";
}
}
private static final class
SystemOffsetClock extends
ClockImpl {
private final long
offset;
private
SystemOffsetClock(final long
offset) {
this.
offset =
offset;
}
protected final 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();
}
}
private
Clock() {}
}