htop/Hashtable.c

331 lines
7.7 KiB
C

/*
htop - Hashtable.c
(C) 2004-2011 Hisham H. Muhammad
Released under the GNU GPLv2+, see the COPYING file
in the source distribution for its full text.
*/
#include "config.h" // IWYU pragma: keep
#include "Hashtable.h"
#include <assert.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include "CRT.h"
#include "Macros.h"
#include "XUtils.h"
#ifndef NDEBUG
#include <stdio.h>
#endif
typedef struct HashtableItem_ {
ht_key_t key;
size_t probe;
void* value;
} HashtableItem;
struct Hashtable_ {
size_t size;
HashtableItem* buckets;
size_t items;
bool owner;
};
#ifndef NDEBUG
static void Hashtable_dump(const Hashtable* this) {
fprintf(stderr, "Hashtable %p: size=%zu items=%zu owner=%s\n",
(const void*)this,
this->size,
this->items,
this->owner ? "yes" : "no");
size_t items = 0;
for (size_t i = 0; i < this->size; i++) {
fprintf(stderr, " item %5zu: key = %5u probe = %2zu value = %p\n",
i,
this->buckets[i].key,
this->buckets[i].probe,
this->buckets[i].value);
if (this->buckets[i].value)
items++;
}
fprintf(stderr, "Hashtable %p: items=%zu counted=%zu\n",
(const void*)this,
this->items,
items);
}
static bool Hashtable_isConsistent(const Hashtable* this) {
size_t items = 0;
for (size_t i = 0; i < this->size; i++) {
if (this->buckets[i].value)
items++;
}
bool res = items == this->items;
if (!res)
Hashtable_dump(this);
return res;
}
size_t Hashtable_count(const Hashtable* this) {
size_t items = 0;
for (size_t i = 0; i < this->size; i++) {
if (this->buckets[i].value)
items++;
}
assert(items == this->items);
return items;
}
#endif /* NDEBUG */
/* https://oeis.org/A014234 */
static const uint64_t OEISprimes[] = {
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
};
static size_t nextPrime(size_t n) {
/* on 32-bit make sure we do not return primes not fitting in size_t */
for (size_t i = 0; i < ARRAYSIZE(OEISprimes) && OEISprimes[i] < SIZE_MAX; i++) {
if (n <= OEISprimes[i])
return OEISprimes[i];
}
CRT_fatalError("Hashtable: no prime found");
}
Hashtable* Hashtable_new(size_t size, bool owner) {
Hashtable* this;
this = xMalloc(sizeof(Hashtable));
this->items = 0;
this->size = size ? nextPrime(size) : 13;
this->buckets = (HashtableItem*) xCalloc(this->size, sizeof(HashtableItem));
this->owner = owner;
assert(Hashtable_isConsistent(this));
return this;
}
void Hashtable_delete(Hashtable* this) {
Hashtable_clear(this);
free(this->buckets);
free(this);
}
void Hashtable_clear(Hashtable* this) {
assert(Hashtable_isConsistent(this));
if (this->owner)
for (size_t i = 0; i < this->size; i++)
free(this->buckets[i].value);
memset(this->buckets, 0, this->size * sizeof(HashtableItem));
this->items = 0;
assert(Hashtable_isConsistent(this));
}
static void insert(Hashtable* this, ht_key_t key, void* value) {
size_t index = key % this->size;
size_t probe = 0;
#ifndef NDEBUG
size_t origIndex = index;
#endif
for (;;) {
if (!this->buckets[index].value) {
this->items++;
this->buckets[index].key = key;
this->buckets[index].probe = probe;
this->buckets[index].value = value;
return;
}
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;
}
/* 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, size_t size) {
assert(Hashtable_isConsistent(this));
if (size <= this->items)
return;
size_t newSize = nextPrime(size);
if (newSize == this->size)
return;
HashtableItem* oldBuckets = this->buckets;
size_t oldSize = this->size;
this->size = newSize;
this->buckets = (HashtableItem*) xCalloc(this->size, sizeof(HashtableItem));
this->items = 0;
/* rehash */
for (size_t i = 0; i < oldSize; i++) {
if (!oldBuckets[i].value)
continue;
insert(this, oldBuckets[i].key, oldBuckets[i].value);
}
free(oldBuckets);
assert(Hashtable_isConsistent(this));
}
void Hashtable_put(Hashtable* this, ht_key_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) {
if (SIZE_MAX / 2 < this->size)
CRT_fatalError("Hashtable: size overflow");
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, ht_key_t key) {
size_t index = key % this->size;
size_t probe = 0;
#ifndef NDEBUG
size_t origIndex = index;
#endif
assert(Hashtable_isConsistent(this));
void* res = NULL;
while (this->buckets[index].value) {
if (this->buckets[index].key == key) {
if (this->owner) {
free(this->buckets[index].value);
} else {
res = this->buckets[index].value;
}
size_t 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;
}
if (this->buckets[index].probe < probe)
break;
index = (index + 1) % this->size;
probe++;
assert(index != origIndex);
}
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 / 3); /* account for nextPrime rounding up */
return res;
}
void* Hashtable_get(Hashtable* this, ht_key_t key) {
size_t index = key % this->size;
size_t probe = 0;
void* res = NULL;
#ifndef NDEBUG
size_t origIndex = index;
#endif
assert(Hashtable_isConsistent(this));
while (this->buckets[index].value) {
if (this->buckets[index].key == key) {
res = this->buckets[index].value;
break;
}
if (this->buckets[index].probe < probe)
break;
index = (index + 1) != this->size ? (index + 1) : 0;
probe++;
assert(index != origIndex);
}
return res;
}
void Hashtable_foreach(Hashtable* this, Hashtable_PairFunction f, void* userData) {
assert(Hashtable_isConsistent(this));
for (size_t i = 0; i < this->size; i++) {
HashtableItem* walk = &this->buckets[i];
if (walk->value)
f(walk->key, walk->value, userData);
}
assert(Hashtable_isConsistent(this));
}