com.datastax.oss.driver.shaded.netty.buffer.LongLongHashMap Maven / Gradle / Ivy
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/*
* Copyright 2020 The Netty Project
*
* The Netty Project licenses this file to you 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:
*
* https://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.datastax.oss.driver.shaded.netty.buffer;
/**
* Internal primitive map implementation that is specifically optimised for the runs availability map use case in {@link
* PoolChunk}.
*/
final class LongLongHashMap {
private static final int MASK_TEMPLATE = ~1;
private int mask;
private long[] array;
private int maxProbe;
private long zeroVal;
private final long emptyVal;
LongLongHashMap(long emptyVal) {
this.emptyVal = emptyVal;
zeroVal = emptyVal;
int initialSize = 32;
array = new long[initialSize];
mask = initialSize - 1;
computeMaskAndProbe();
}
public long put(long key, long value) {
if (key == 0) {
long prev = zeroVal;
zeroVal = value;
return prev;
}
for (;;) {
int index = index(key);
for (int i = 0; i < maxProbe; i++) {
long existing = array[index];
if (existing == key || existing == 0) {
long prev = existing == 0? emptyVal : array[index + 1];
array[index] = key;
array[index + 1] = value;
for (; i < maxProbe; i++) { // Nerf any existing misplaced entries.
index = index + 2 & mask;
if (array[index] == key) {
array[index] = 0;
prev = array[index + 1];
break;
}
}
return prev;
}
index = index + 2 & mask;
}
expand(); // Grow array and re-hash.
}
}
public void remove(long key) {
if (key == 0) {
zeroVal = emptyVal;
return;
}
int index = index(key);
for (int i = 0; i < maxProbe; i++) {
long existing = array[index];
if (existing == key) {
array[index] = 0;
break;
}
index = index + 2 & mask;
}
}
public long get(long key) {
if (key == 0) {
return zeroVal;
}
int index = index(key);
for (int i = 0; i < maxProbe; i++) {
long existing = array[index];
if (existing == key) {
return array[index + 1];
}
index = index + 2 & mask;
}
return emptyVal;
}
private int index(long key) {
// Hash with murmur64, and mask.
key ^= key >>> 33;
key *= 0xff51afd7ed558ccdL;
key ^= key >>> 33;
key *= 0xc4ceb9fe1a85ec53L;
key ^= key >>> 33;
return (int) key & mask;
}
private void expand() {
long[] prev = array;
array = new long[prev.length * 2];
computeMaskAndProbe();
for (int i = 0; i < prev.length; i += 2) {
long key = prev[i];
if (key != 0) {
long val = prev[i + 1];
put(key, val);
}
}
}
private void computeMaskAndProbe() {
int length = array.length;
mask = length - 1 & MASK_TEMPLATE;
maxProbe = (int) Math.log(length);
}
}