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QuestDB is High Performance Time Series Database
/*******************************************************************************
* ___ _ ____ ____
* / _ \ _ _ ___ ___| |_| _ \| __ )
* | | | | | | |/ _ \/ __| __| | | | _ \
* | |_| | |_| | __/\__ \ |_| |_| | |_) |
* \__\_\\__,_|\___||___/\__|____/|____/
*
* Copyright (c) 2014-2019 Appsicle
* Copyright (c) 2019-2020 QuestDB
*
* 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 io.questdb.cutlass.http;
import io.questdb.std.Misc;
import io.questdb.std.Mutable;
import java.io.Closeable;
public class LocalValueMap implements Closeable, Mutable {
private static final int INITIAL_CAPACITY = 32;
private Entry[] table;
private int size;
private int threshold;
public LocalValueMap() {
table = new Entry[INITIAL_CAPACITY];
size = 0;
setThreshold(INITIAL_CAPACITY);
}
private static int nextIndex(int i, int mod) {
return ((i + 1 < mod) ? i + 1 : 0);
}
private static int prevIndex(int i, int mod) {
return ((i - 1 > -1) ? i - 1 : mod - 1);
}
@Override
public void clear() {
for (int i = 0, n = table.length; i < n; i++) {
Entry e = table[i];
if (e != null && e.value instanceof Mutable) {
((Mutable) e.value).clear();
}
}
}
@Override
public void close() {
for (int i = 0, n = table.length; i < n; i++) {
Entry e = table[i];
if (e != null) {
e.value = Misc.free(e.value);
e.k = null;
}
table[i] = null;
}
}
@SuppressWarnings("unchecked")
public T get(LocalValue key) {
int i = key.hashCode & (table.length - 1);
Entry e = table[i];
return e != null && e.k == key ? (T) e.value : get0(key, i, e);
}
public void set(LocalValue key, T value) {
Entry[] tab = table;
int len = tab.length;
int i = key.hashCode & (len - 1);
for (Entry e = tab[i];
e != null;
e = tab[i = nextIndex(i, len)]) {
LocalValue k = e.k;
if (k == key) {
Misc.free(e.value);
e.value = value;
return;
}
if (k == null) {
replaceNull(key, value, i);
return;
}
}
tab[i] = new Entry(key, value);
int sz = ++size;
if (!removeNullKeys(i, sz) && sz >= threshold) {
rehash();
}
}
@SuppressWarnings("unchecked")
private T get0(LocalValue key, int i, Entry e) {
Entry[] tab = table;
int len = tab.length;
while (e != null) {
LocalValue k = e.k;
if (k == key) {
return (T) e.value;
}
if (k == null) {
removeNull(i);
} else {
i = nextIndex(i, len);
}
e = tab[i];
}
return null;
}
private void rehash() {
removeNulls();
if (size >= threshold - threshold / 4) {
resize();
}
}
private int removeNull(int index) {
Entry[] tab = table;
int len = tab.length;
tab[index].value = Misc.free(tab[index].value);
tab[index] = null;
size--;
Entry e;
int i;
for (i = nextIndex(index, len); (e = tab[i]) != null; i = nextIndex(i, len)) {
LocalValue k = e.k;
if (k == null) {
e.value = Misc.free(e.value);
tab[i] = null;
size--;
} else {
int h = k.hashCode & (len - 1);
if (h != i) {
tab[i] = null;
while (tab[h] != null) {
h = nextIndex(h, len);
}
tab[h] = e;
}
}
}
return i;
}
private boolean removeNullKeys(int i, int n) {
boolean removed = false;
Entry[] tab = table;
int len = tab.length;
do {
i = nextIndex(i, len);
Entry e = tab[i];
if (e != null && e.k == null) {
n = len;
removed = true;
i = removeNull(i);
}
} while ((n >>>= 1) != 0);
return removed;
}
private void removeNulls() {
Entry[] tab = table;
int len = tab.length;
for (int j = 0; j < len; j++) {
Entry e = tab[j];
if (e != null && e.k == null) {
removeNull(j);
}
}
}
private void replaceNull(LocalValue key, Object value, int index) {
Entry[] tab = table;
int len = tab.length;
Entry e;
int slotToExpunge = index;
for (int i = prevIndex(index, len);
(e = tab[i]) != null;
i = prevIndex(i, len))
if (e.k == null) {
slotToExpunge = i;
}
for (int i = nextIndex(index, len); (e = tab[i]) != null; i = nextIndex(i, len)) {
LocalValue k = e.k;
if (k == key) {
Misc.free(e.value);
e.value = value;
tab[i] = tab[index];
tab[index] = e;
if (slotToExpunge == index) {
slotToExpunge = i;
}
removeNullKeys(removeNull(slotToExpunge), len);
return;
}
if (k == null && slotToExpunge == index) {
slotToExpunge = i;
}
}
tab[index].value = Misc.free(tab[index].value);
tab[index] = new Entry(key, value);
if (slotToExpunge != index) {
removeNullKeys(removeNull(slotToExpunge), len);
}
}
private void resize() {
Entry[] oldTab = table;
int oldLen = oldTab.length;
int newLen = oldLen * 2;
Entry[] newTab = new Entry[newLen];
int count = 0;
for (int j = 0; j < oldLen; ++j) {
Entry e = oldTab[j];
if (e != null) {
LocalValue k = e.k;
if (k == null) {
e.value = Misc.free(e.value);
} else {
int h = k.hashCode & (newLen - 1);
while (newTab[h] != null) {
h = nextIndex(h, newLen);
}
newTab[h] = e;
count++;
}
}
}
setThreshold(newLen);
size = count;
table = newTab;
}
private void setThreshold(int len) {
threshold = len * 2 / 3;
}
static class Entry {
Object value;
LocalValue k;
Entry(LocalValue k, Object v) {
value = v;
this.k = k;
}
}
}
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