htop/Hashtable.c

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/*
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htop - Hashtable.c
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(C) 2004-2011 Hisham H. Muhammad
Released under the GNU GPLv2, see the COPYING file
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in the source distribution for its full text.
*/
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#include "config.h" // IWYU pragma: keep
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#include "Hashtable.h"
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#include <assert.h>
#include <stdint.h>
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#include <stdio.h>
#include <stdlib.h>
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#include "Macros.h"
#include "XUtils.h"
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#ifndef NDEBUG
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static void Hashtable_dump(const Hashtable* this) {
fprintf(stderr, "Hashtable %p: size=%u items=%u owner=%s\n",
(const void*)this,
this->size,
this->items,
this->owner ? "yes" : "no");
unsigned int items = 0;
for (unsigned int i = 0; i < this->size; i++) {
fprintf(stderr, " item %5u: key = %5u probe = %2u value = %p\n",
i,
this->buckets[i].key,
this->buckets[i].probe,
this->buckets[i].value ? (const void*)this->buckets[i].value : "(nil)");
if (this->buckets[i].value)
items++;
}
fprintf(stderr, "Hashtable %p: items=%u counted=%u\n",
(const void*)this,
this->items,
items);
}
static bool Hashtable_isConsistent(const Hashtable* this) {
unsigned int items = 0;
for (unsigned int i = 0; i < this->size; i++) {
if (this->buckets[i].value)
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items++;
}
bool res = items == this->items;
if (!res)
Hashtable_dump(this);
return res;
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}
unsigned int Hashtable_count(const Hashtable* this) {
unsigned int items = 0;
for (unsigned int i = 0; i < this->size; i++) {
if (this->buckets[i].value)
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items++;
}
assert(items == this->items);
return items;
}
#endif /* NDEBUG */
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/* https://oeis.org/A014234 */
static const uint64_t OEISprimes[] = {
2, 3, 7, 13, 31, 61, 127, 251, 509, 1021, 2039, 4093, 8191,
16381, 32749, 65521, 131071, 262139, 524287, 1048573,
2097143, 4194301, 8388593, 16777213, 33554393,
67108859, 134217689, 268435399, 536870909, 1073741789,
2147483647, 4294967291, 8589934583, 17179869143,
34359738337, 68719476731, 137438953447
};
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static uint64_t nextPrime(unsigned int n) {
assert(n <= OEISprimes[ARRAYSIZE(OEISprimes) - 1]);
for (unsigned int i = 0; i < ARRAYSIZE(OEISprimes); i++) {
if (n <= OEISprimes[i])
return OEISprimes[i];
}
return OEISprimes[ARRAYSIZE(OEISprimes) - 1];
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}
Hashtable* Hashtable_new(unsigned int size, bool owner) {
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Hashtable* this;
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this = xMalloc(sizeof(Hashtable));
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this->items = 0;
this->size = size ? nextPrime(size) : 13;
this->buckets = (HashtableItem*) xCalloc(this->size, sizeof(HashtableItem));
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this->owner = owner;
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assert(Hashtable_isConsistent(this));
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return this;
}
void Hashtable_delete(Hashtable* this) {
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assert(Hashtable_isConsistent(this));
if (this->owner) {
for (unsigned int i = 0; i < this->size; i++)
free(this->buckets[i].value);
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}
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free(this->buckets);
free(this);
}
static void insert(Hashtable* this, hkey_t key, void* value) {
unsigned int index = key % this->size;
unsigned int probe = 0;
#ifndef NDEBUG
unsigned int origIndex = index;
#endif
for (;;) {
if (!this->buckets[index].value) {
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this->items++;
this->buckets[index].key = key;
this->buckets[index].probe = probe;
this->buckets[index].value = value;
return;
}
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if (this->buckets[index].key == key) {
if (this->owner && this->buckets[index].value != value)
free(this->buckets[index].value);
this->buckets[index].value = value;
return;
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}
/* Robin Hood swap */
if (probe > this->buckets[index].probe) {
HashtableItem tmp = this->buckets[index];
this->buckets[index].key = key;
this->buckets[index].probe = probe;
this->buckets[index].value = value;
key = tmp.key;
probe = tmp.probe;
value = tmp.value;
}
index = (index + 1) % this->size;
probe++;
assert(index != origIndex);
}
}
void Hashtable_setSize(Hashtable* this, unsigned int size) {
assert(Hashtable_isConsistent(this));
if (size <= this->items)
return;
HashtableItem* oldBuckets = this->buckets;
unsigned int oldSize = this->size;
this->size = nextPrime(size);
this->buckets = (HashtableItem*) xCalloc(this->size, sizeof(HashtableItem));
this->items = 0;
/* rehash */
for (unsigned int i = 0; i < oldSize; i++) {
if (!oldBuckets[i].value)
continue;
insert(this, oldBuckets[i].key, oldBuckets[i].value);
}
free(oldBuckets);
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assert(Hashtable_isConsistent(this));
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}
void Hashtable_put(Hashtable* this, hkey_t key, void* value) {
assert(Hashtable_isConsistent(this));
assert(this->size > 0);
assert(value);
/* grow on load-factor > 0.7 */
if (10 * this->items > 7 * this->size)
Hashtable_setSize(this, 2 * this->size);
insert(this, key, value);
assert(Hashtable_isConsistent(this));
assert(Hashtable_get(this, key) != NULL);
assert(this->size > this->items);
}
void* Hashtable_remove(Hashtable* this, hkey_t key) {
unsigned int index = key % this->size;
unsigned int probe = 0;
#ifndef NDEBUG
unsigned int origIndex = index;
#endif
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assert(Hashtable_isConsistent(this));
void* res = NULL;
while (this->buckets[index].value) {
if (this->buckets[index].key == key) {
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if (this->owner) {
free(this->buckets[index].value);
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} else {
res = this->buckets[index].value;
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}
unsigned int next = (index + 1) % this->size;
while (this->buckets[next].value && this->buckets[next].probe > 0) {
this->buckets[index] = this->buckets[next];
this->buckets[index].probe -= 1;
index = next;
next = (index + 1) % this->size;
}
/* set empty after backward shifting */
this->buckets[index].value = NULL;
this->items--;
break;
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}
if (this->buckets[index].probe < probe)
break;
index = (index + 1) % this->size;
probe++;
assert(index != origIndex);
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}
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assert(Hashtable_isConsistent(this));
assert(Hashtable_get(this, key) == NULL);
/* shrink on load-factor < 0.125 */
if (8 * this->items < this->size)
Hashtable_setSize(this, this->size / 2);
return res;
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}
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void* Hashtable_get(Hashtable* this, hkey_t key) {
unsigned int index = key % this->size;
unsigned int probe = 0;
void* res = NULL;
#ifndef NDEBUG
unsigned int origIndex = index;
#endif
assert(Hashtable_isConsistent(this));
while (this->buckets[index].value) {
if (this->buckets[index].key == key) {
res = this->buckets[index].value;
break;
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}
if (this->buckets[index].probe < probe)
break;
index = (index + 1) != this->size ? (index + 1) : 0;
probe++;
assert(index != origIndex);
}
return res;
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}
void Hashtable_foreach(Hashtable* this, Hashtable_PairFunction f, void* userData) {
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assert(Hashtable_isConsistent(this));
for (unsigned int i = 0; i < this->size; i++) {
HashtableItem* walk = &this->buckets[i];
if (walk->value)
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f(walk->key, walk->value, userData);
}
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assert(Hashtable_isConsistent(this));
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}