/*
* 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.config.units;
import org.ehcache.config.ResourceUnit;
/**
* A {@link ResourceUnit} that designates memory quantity.
*/
public enum MemoryUnit implements ResourceUnit {
/**
* Bytes.
*/
B("B", 0),
/**
* Kilobytes.
*/
KB("kB", 10),
/**
* Megabytes.
*/
MB("MB", 20),
/**
* Gigabytes.
*/
GB("GB", 30),
/**
* Terabytes.
*/
TB("TB", 40),
/**
* Petabytes.
*/
PB("PB", 50);
/** the index of this unit */
private final int index;
private final String stringForm;
/** Internal constructor */
MemoryUnit(String stringForm, int index) {
this.stringForm = stringForm;
this.index = index;
}
/**
* Computes <pre>amount * 2^delta</pre>.
*
* The result is always rounded toward zero.
*
* @param delta log<sub>2</sub>(divisor)
* @param amount dividend
* @throws ArithmeticException if the result overflows
*/
private static long doConvert(int delta, long amount) throws ArithmeticException {
if (delta == 0 || amount == 0) {
return amount;
} else if (delta < 0) {
// Hacker's Delight : 10-1
long t = amount >> (-delta - 1);
t >>>= 64 + delta;
t += amount;
return t >> -delta;
} else if (delta >= Long.numberOfLeadingZeros(amount < 0 ? ~amount : amount)) {
throw new ArithmeticException("Conversion overflows");
} else {
return amount << delta;
}
}
/**
* Converts {@code quantity} in this unit to bytes.
*
* @param quantity the quantity
* @return the quantity in bytes
*/
public long toBytes(long quantity) {
return doConvert(index - B.index, quantity);
}
/**
* Converts {@code quantity} in {@code unit} into this unit.
*
* @param quantity quantity to convert
* @param unit {@code quantity}'s unit
* @return the quantity in this unit
*/
public long convert(long quantity, MemoryUnit unit) {
return doConvert(unit.index - index, quantity);
}
/**
* {@inheritDoc}
*/
@Override
public String toString() {
return stringForm;
}
/**
* {@inheritDoc}
*/
@Override
public int compareTo(long thisSize, long thatSize, ResourceUnit thatUnit) throws IllegalArgumentException {
if (thatUnit instanceof MemoryUnit) {
MemoryUnit mThatUnit = (MemoryUnit) thatUnit;
if (index < mThatUnit.index) {
try {
return Long.signum(thisSize - convert(thatSize, mThatUnit));
} catch (ArithmeticException e) {
return Long.signum(mThatUnit.convert(thisSize, this) - thatSize);
}
} else {
try {
return Long.signum(mThatUnit.convert(thisSize, this) - thatSize);
} catch (ArithmeticException e) {
return Long.signum(thisSize - convert(thatSize, mThatUnit));
}
}
} else {
throw new IllegalArgumentException();
}
}
}