com.hazelcast.internal.util.hashslot.impl.CapacityUtil Maven / Gradle / Ivy
/*
* Copyright (c) 2008-2020, 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.internal.util.hashslot.impl;
import com.hazelcast.internal.util.QuickMath;
/**
* Utility functions related to data structure capacity calculation.
*/
public final class CapacityUtil {
/** Maximum length of a Java array that is a power of two. */
@SuppressWarnings("checkstyle:magicnumber")
public static final int MAX_INT_CAPACITY = 1 << 30;
/** Maximum length of an off-heap array that is a power of two. */
@SuppressWarnings("checkstyle:magicnumber")
public static final long MAX_LONG_CAPACITY = 1L << 62;
/** Minimum capacity for a hash container. */
public static final int MIN_CAPACITY = 4;
/** Default capacity for a hash container. */
public static final int DEFAULT_CAPACITY = 16;
/** Default load factor. */
public static final float DEFAULT_LOAD_FACTOR = 0.6f;
private CapacityUtil() { }
/** Round the capacity to the next allowed value. */
public static long roundCapacity(long requestedCapacity) {
if (requestedCapacity > MAX_LONG_CAPACITY) {
throw new IllegalArgumentException(requestedCapacity + " is greater than max allowed capacity["
+ MAX_LONG_CAPACITY + "].");
}
return Math.max(MIN_CAPACITY, QuickMath.nextPowerOfTwo(requestedCapacity));
}
/** Round the capacity to the next allowed value. */
public static int roundCapacity(int requestedCapacity) {
if (requestedCapacity > MAX_INT_CAPACITY) {
throw new IllegalArgumentException(requestedCapacity + " is greater than max allowed capacity["
+ MAX_INT_CAPACITY + "].");
}
return Math.max(MIN_CAPACITY, QuickMath.nextPowerOfTwo(requestedCapacity));
}
/** Returns the next possible capacity, counting from the current buffers' size. */
public static int nextCapacity(int current) {
assert current > 0 && Long.bitCount(current) == 1 : "Capacity must be a power of two.";
if (current < MIN_CAPACITY / 2) {
current = MIN_CAPACITY / 2;
}
current <<= 1;
if (current < 0) {
throw new RuntimeException("Maximum capacity exceeded.");
}
return current;
}
/** Returns the next possible capacity, counting from the current buffers' size. */
public static long nextCapacity(long current) {
assert current > 0 && Long.bitCount(current) == 1 : "Capacity must be a power of two, but was " + current;
if (current < MIN_CAPACITY / 2) {
current = MIN_CAPACITY / 2;
}
current <<= 1;
if (current < 0) {
throw new RuntimeException("Maximum capacity exceeded.");
}
return current;
}
}