/*
* Copyright Terracotta, Inc.
*
* 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 org.ehcache.expiry;
import java.util.concurrent.
TimeUnit;
/**
* A time duration in a given {@link TimeUnit}.
*/
public final class
Duration {
/**
* The infinite {@code Duration}.
* <p>
* This constant should be used to express a lack of a concrete expiration time (ie. "eternal").
*/
public static final
Duration INFINITE = new
Duration(0, null, true);
/**
* The zero {@code Duration}.
*/
public static final
Duration ZERO = new
Duration(0,
TimeUnit.
NANOSECONDS, false);
/**
* Convenience method to create a {@code Duration} with the specified values.
*
* @param length the duration length
* @param timeUnit the time unit
* @return a new {@code Duration}
*
* @see #Duration(long, TimeUnit)
*/
public static
Duration of(long
length,
TimeUnit timeUnit) {
return new
Duration(
length,
timeUnit);
}
private final
TimeUnit timeUnit;
private final long
length;
/**
* Instantiates a new {@code Duration} of the given length and {@link TimeUnit}.
*
* @param length the duration length
* @param timeUnit the time unit
*
* @throws NullPointerException if the given time unit is null
* @throws IllegalArgumentException if the given length is less than zero
*/
public
Duration(long
length,
TimeUnit timeUnit) {
this(
length,
timeUnit, false);
}
private
Duration(long
length,
TimeUnit timeUnit, boolean
forever) {
if (!
forever) {
if (
length < 0) {
throw new
IllegalArgumentException("length must be greater than or equal to zero: " +
length);
}
if (
timeUnit == null) {
throw new
NullPointerException("TimeUnit must not be null");
}
}
this.
length =
length;
this.
timeUnit =
timeUnit;
}
/**
* Gets the length of time this {@code Duration} represents.
*
* @return the length of this instance
* @throws IllegalStateException if this instance is {@link #INFINITE}
*
* @see #getTimeUnit()
*/
public long
getLength() {
checkInfinite();
return
length;
}
/**
* Gets the {@link TimeUnit} of this {@code Duration}.
*
* @return the {@link TimeUnit} of this instance
* @throws IllegalStateException if this instance is {@link #INFINITE}
*
* @see #getLength()
*/
public
TimeUnit getTimeUnit() {
checkInfinite();
return
timeUnit;
}
private void
checkInfinite() {
if (
isInfinite()) {
throw new
IllegalStateException(
"The calling code should be checking explicitly for Duration#INFINITE or isInfinite()");
}
}
/**
* Indicates if this duration represents {@link Duration#INFINITE} or an <i>infinite</i> {@code Duration}.
*
* @return {@code true} if this instance is the special {@code Forever} value
*/
public boolean
isInfinite() {
return
timeUnit == null;
}
/**
* {@inheritDoc}
*/
@
Override
public int
hashCode() {
final int
prime = 31;
int
result = 1;
result =
prime *
result + (int) (
length ^ (
length >>> 32));
if (
length != 0) {
result =
prime *
result + ((
timeUnit == null) ? 0 :
timeUnit.
hashCode());
} else {
// Differentiate zero from forever
result =
prime *
result + ((
timeUnit == null) ? 0 : 1);
}
return
result;
}
/**
* {@inheritDoc}
*/
@
Override
public boolean
equals(
Object obj) {
if (this ==
obj) {
return true;
}
if (
obj == null) {
return false;
}
if (
getClass() !=
obj.
getClass()) {
return false;
}
Duration other = (
Duration)
obj;
if (
length !=
other.
length) {
return false;
}
if (
timeUnit == null ||
other.
timeUnit == null) {
return
timeUnit ==
other.
timeUnit;
}
if (
timeUnit !=
other.
timeUnit) {
if (
length == 0) {
return true;
}
return false;
}
return true;
}
/**
* {@inheritDoc}
*/
@
Override
public
String toString() {
if (
isInfinite()) {
return "Duration[INFINITE]";
}
if (
length == 0) {
return "Duration[ZERO]";
}
return "Duration[length=" +
length + ", timeUnit=" +
timeUnit.
name() + "]";
}
}