Copy hashtable implementation from another project

This commit is contained in:
Vftdan 2024-10-23 14:03:51 +02:00
parent bf9677f2ae
commit 9df451de61
5 changed files with 456 additions and 1 deletions

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@ -2,7 +2,7 @@ include common.mk
all: server all: server
server: $(BUILD_DIR)/server/main.o server: $(BUILD_DIR)/server/main.o $(BUILD_DIR)/common/util/hash_table.o
$(COMPILE_EXE) $(COMPILE_EXE)
run: server run: server

23
src/common/defs.h Normal file
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@ -0,0 +1,23 @@
#ifndef COMMON_DEFS_H_
#define COMMON_DEFS_H_
#include <stddef.h>
#include <stdlib.h>
#include <stdint.h>
#include <stdbool.h>
#define lengthof(arr) (sizeof(arr) / sizeof(*arr))
#define containerof(ptr, contype, membpath) ((contype*)(0 ? (void)(((contype*)NULL)->membpath = *(ptr)) : (void)0, ((char *)(ptr)) - offsetof(contype, membpath)))
// Assuming child type has a field for the base type
// So for structs it is usually actual downcast, but for unions it is an upcast
#define DOWNCAST(contype, basename, ptr) containerof(ptr, contype, as_##basename)
#define T_ALLOC(count, T) ((T*)calloc((count), sizeof(T)))
#define HEADER_FN __attribute__((unused)) inline static
#ifdef DEBUG
# define DEBUG_PRINT_VALUE(x, fmt) (void) (fprintf(stderr, #x " = " fmt "\n", x), fflush(stderr))
#else
# define DEBUG_PRINT_VALUE(...) (void) (0)
#endif
#endif /* end of include guard: COMMON_DEFS_H_ */

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@ -0,0 +1,360 @@
#include <stdlib.h>
#include "hash_table.h"
#define FNV_OFFSET_BASIS 0xCBF29CE484222325
#define FNV_PRIME 0x00000100000001B3
inline static uint64_t
fnv_1a(uint8_t *bytes, size_t length)
{
uint64_t hash = FNV_OFFSET_BASIS;
for (size_t i = 0; i < length; ++i) {
uint8_t b = bytes[i];
hash ^= b;
hash *= FNV_PRIME;
}
return hash;
}
#define NULL_KEY ((HashTableKey){.length = 0, .bytes = NULL, .pre_hash = 0})
HashTableKey
hash_table_key_from_bytes(const char *bytes, size_t size)
{
if (!bytes) {
return NULL_KEY;
}
HashTableKey key = {
.length = size,
.bytes = bytes,
.pre_hash = fnv_1a((uint8_t*) bytes, size),
};
return key;
}
HashTableKey
hash_table_key_copy(const HashTableKey old)
{
if (!old.bytes) {
return NULL_KEY;
}
char *new_bytes = malloc(old.length + 1);
if (!new_bytes) {
return NULL_KEY;
}
memcpy(new_bytes, old.bytes, old.length);
new_bytes[old.length] = 0;
return (HashTableKey) {
.length = old.length,
.bytes = new_bytes,
.pre_hash = old.pre_hash,
};
}
void
hash_table_key_deinit_copied(HashTableKey *key)
{
if (key->bytes) {
free((char*) key->bytes);
key->bytes = NULL;
}
key->length = 0;
key->pre_hash = 0;
}
#define FAMILY_PRIME 0x1FFFFFFFFFFFFFFF
inline static HashFamilyMember
family_random_member()
{
uint64_t n[2];
for (int i = 0; i < 2; ++i) {
n[i] = (uint64_t)((rand() / (double) RAND_MAX) * (FAMILY_PRIME - RAND_MAX) + rand()) % FAMILY_PRIME;
}
if (!n[0]) {
n[0] = 1;
}
return (HashFamilyMember) {
.a = n[0],
.b = n[1],
};
}
inline static size_t
family_map(HashFamilyMember member, uint64_t pre_hash)
{
if (!member.a)
++member.a;
uint64_t hash = (pre_hash * member.a + member.b) % FAMILY_PRIME; // Integer overflows may influence the properties of this family
return hash;
}
bool
hash_table_key_equals(const HashTableKey lhs, const HashTableKey rhs)
{
if (lhs.pre_hash != rhs.pre_hash) {
return false;
}
if (lhs.length != rhs.length) {
return false;
}
if (lhs.bytes == rhs.bytes) {
return true;
}
if (!lhs.bytes || !rhs.bytes) {
return false;
}
size_t length = lhs.length;
return memcmp(lhs.bytes, rhs.bytes, length) == 0;
}
inline static size_t
initial_position(const HashTableKey key, const HashTableDynamicData * ht)
{
uint64_t hash = family_map(ht->family_member, key.pre_hash);
return hash % ht->capacity;
}
inline static size_t
probe_next(size_t current_index, size_t base_index, size_t iteration, size_t modulo)
{
(void) base_index;
(void) iteration;
++current_index;
current_index %= modulo;
return current_index;
}
static HashTableDynamicData
create_table(size_t capacity, size_t value_size, HashFamilyMember family_member)
{
HashTableDynamicData data = {
.value_array = NULL,
.capacity = 0,
.length = 0,
.key_array = NULL,
.family_member = family_member,
.value_size = value_size,
};
void *value_array = calloc(capacity, value_size);
if (!value_array) {
return data;
}
HashTableKeyEntry *key_array = T_ALLOC(capacity, HashTableKeyEntry);
if (!key_array) {
free(value_array);
return data;
}
data.value_array = value_array;
data.capacity = capacity;
data.key_array = key_array;
return data;
}
void
hash_table_init_impl(HashTableDynamicData * data, size_t value_size, void (*value_deinit)(void*))
{
*data = create_table(5, value_size, family_random_member());
data->value_deinit = value_deinit;
}
void
hash_table_deinit_impl(HashTableDynamicData * data)
{
if (data->key_array && data->value_array && data->length) {
void (*value_deinit)(void*) = data->value_deinit;
for (HashTableIndex i = 0; i < (ssize_t) data->capacity; ++i) {
if (data->key_array[i].key.bytes) {
if (value_deinit) {
value_deinit(data->value_array + (data->value_size * (size_t) i));
}
hash_table_key_deinit_copied(&data->key_array[i].key);
}
}
}
if (data->key_array) {
free(data->key_array);
data->key_array = NULL;
}
if (data->value_array) {
free(data->value_array);
data->value_array = NULL;
}
data->capacity = 0;
data->length = 0;
}
static void
hash_table_grow(HashTableDynamicData * old_ht)
{
size_t capacity = old_ht->capacity;
capacity += (capacity >> 1) + 1;
const size_t value_size = old_ht->value_size;
HashTableDynamicData new_ht = create_table(capacity, value_size, old_ht->family_member);
if (!new_ht.key_array) {
return;
}
for (size_t i = 0; i < old_ht->capacity; ++i) {
if (!old_ht->key_array[i].key.bytes) {
continue;
}
if (hash_table_insert_impl(&new_ht, old_ht->key_array[i].key, old_ht->value_array + (i * value_size)) < 0) {
hash_table_deinit_impl(&new_ht);
return;
}
}
new_ht.value_deinit = old_ht->value_deinit;
old_ht->value_deinit = NULL;
// TODO avoid duplication-deletion of the keys
hash_table_deinit_impl(old_ht);
*old_ht = new_ht;
}
static void
hash_table_change_hash(HashTableDynamicData * old_ht)
{
const size_t capacity = old_ht->capacity;
const size_t value_size = old_ht->value_size;
HashTableDynamicData new_ht = create_table(capacity, value_size, family_random_member());
if (!new_ht.key_array) {
return;
}
for (size_t i = 0; i < old_ht->capacity; ++i) {
if (!old_ht->key_array[i].key.bytes) {
continue;
}
if (hash_table_insert_impl(&new_ht, old_ht->key_array[i].key, old_ht->value_array + (i * value_size)) < 0) {
hash_table_deinit_impl(&new_ht);
return;
}
}
new_ht.value_deinit = old_ht->value_deinit;
old_ht->value_deinit = NULL;
// TODO avoid duplication-deletion of the keys
hash_table_deinit_impl(old_ht);
*old_ht = new_ht;
}
HashTableIndex
hash_table_insert_impl(HashTableDynamicData * ht, const HashTableKey key, const void * value_ptr)
{
if (!key.bytes) {
return -1;
}
size_t length = ht->length;
size_t capacity = ht->capacity;
if (length + (length >> 1) >= ht->capacity) {
hash_table_grow(ht);
capacity = ht->capacity;
}
if (length >= capacity) {
return -1;
}
const size_t base_index = initial_position(key, ht);
size_t current_index = base_index;
size_t collision_offset = 0;
bool found = false;
bool overwrite = false;
bool pre_hash_collision = false;
for (; collision_offset < capacity; current_index = probe_next(current_index, base_index, ++collision_offset, capacity)) {
if (!ht->key_array[current_index].key.bytes) {
found = true;
break;
}
if (hash_table_key_equals(key, ht->key_array[current_index].key)) {
overwrite = true;
found = true;
break;
}
if (!pre_hash_collision) {
pre_hash_collision = key.pre_hash == ht->key_array[current_index].key.pre_hash;
}
}
if (!found) {
return -1;
}
void *value_target_ptr = ht->value_array + (ht->value_size * current_index);
if (ht->key_array[base_index].max_collision_offset < collision_offset) {
ht->key_array[base_index].max_collision_offset = collision_offset;
}
if (overwrite) {
// Deinitialize the old value
void (*value_deinit)(void*) = ht->value_deinit;
if (value_deinit) {
value_deinit(value_target_ptr);
}
} else {
// Make a local copy of the key
ht->key_array[current_index].key = hash_table_key_copy(key);
}
memcpy(value_target_ptr, value_ptr, ht->value_size); // Assign the value
ht->length = ++length;
if (!pre_hash_collision && (collision_offset << 1) > capacity + 6) {
hash_table_change_hash(ht);
}
return current_index;
}
HashTableIndex
hash_table_find_impl(const HashTableDynamicData * ht, const HashTableKey key)
{
if (!key.bytes) {
return -1;
}
const size_t capacity = ht->capacity;
const size_t base_index = initial_position(key, ht);
const size_t max_collision_offset = ht->key_array[base_index].max_collision_offset;
size_t collision_offset = 0;
size_t current_index = base_index;
for (; collision_offset <= max_collision_offset; current_index = probe_next(current_index, base_index, ++collision_offset, capacity)) {
if (hash_table_key_equals(key, ht->key_array[current_index].key)) {
return current_index;
break;
}
}
return -1;
}
bool
hash_table_delete_at_index_impl(HashTableDynamicData * ht, const HashTableIndex index)
{
if (!ht) {
return false;
}
if (index < 0 || (size_t) index > ht->capacity) {
return false;
}
HashTableKeyEntry *key_entry_ptr = ht->key_array + index;
void *value_ptr = ht->value_array + (ht->value_size * index);
if (!key_entry_ptr->key.bytes) {
// No entry at index
return false;
}
// TODO find base_index and reduce its max_collision_offset when provably justified
hash_table_key_deinit_copied(&key_entry_ptr->key);
ht->length -= 1;
void (*value_deinit)(void*) = ht->value_deinit;
if (value_deinit) {
value_deinit(value_ptr);
}
memset(value_ptr, 0, ht->value_size);
return true;
}

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#ifndef COMMON_UTIL_HASH_TABLE_H_
#define COMMON_UTIL_HASH_TABLE_H_
#include <string.h>
#include "common/defs.h"
#define HASH_TABLE_INTERFACE_FIELDS \
size_t capacity; \
size_t length; \
HashTableKeyEntry *key_array; \
HashFamilyMember family_member; \
;
#define TYPED_HASH_TABLE(T) union { HashTableDynamicData as_HashTableDynamicData; struct { typeof(T) *value_array; HASH_TABLE_INTERFACE_FIELDS; void (*value_deinit)(typeof(T)*); }; }
typedef ptrdiff_t HashTableIndex; // Invalidated after hashtable modification
typedef struct {
size_t length;
const char *bytes;
uint64_t pre_hash;
} HashTableKey;
typedef struct {
HashTableKey key;
size_t max_collision_offset;
} HashTableKeyEntry;
typedef struct {
uint64_t a, b;
} HashFamilyMember;
typedef struct {
void *value_array;
HASH_TABLE_INTERFACE_FIELDS;
void (*value_deinit)(void*);
size_t value_size;
} HashTableDynamicData;
HashTableKey hash_table_key_from_bytes(const char *bytes, size_t size);
HashTableKey hash_table_key_copy(const HashTableKey old);
void hash_table_key_deinit_copied(HashTableKey *key);
bool hash_table_key_equals(const HashTableKey lhs, const HashTableKey rhs);
__attribute__((unused)) inline static HashTableKey
hash_table_key_from_cstr(const char *s)
{
size_t length = strlen(s);
return hash_table_key_from_bytes(s, length);
}
void hash_table_init_impl(HashTableDynamicData * dyndata, size_t value_size, void (*value_deinit)(void*));
void hash_table_deinit_impl(HashTableDynamicData * dyndata);
HashTableIndex hash_table_insert_impl(HashTableDynamicData * dyndata, const HashTableKey key, const void * value_ptr);
HashTableIndex hash_table_find_impl(const HashTableDynamicData * dyndata, const HashTableKey key);
bool hash_table_delete_at_index_impl(HashTableDynamicData * dyndata, const HashTableIndex index);
__attribute__((unused)) inline static bool
hash_table_delete_by_key_impl(HashTableDynamicData * dyndata, const HashTableKey key)
{
return hash_table_delete_at_index_impl(dyndata, hash_table_find_impl(dyndata, key));
}
#define hash_table_init(ht, value_deinit) hash_table_init_impl(&(ht)->as_HashTableDynamicData, sizeof(*(ht)->value_array), IMPLICIT_CAST(void(void*), void(typeof((ht)->value_array)), value_deinit))
#define hash_table_deinit(ht) hash_table_deinit_impl(&(ht)->as_HashTableDynamicData)
#define hash_table_insert(ht, key, value_ptr) hash_table_insert_impl(&(ht)->as_HashTableDynamicData, key, IMPLICIT_CAST(const void, const typeof(*(ht)->value_array), value_ptr))
#define hash_table_find(ht, key) hash_table_find_impl(&(ht)->as_HashTableDynamicData, key)
#define hash_table_delete_at_index(ht, index) hash_table_delete_at_index_impl(&(ht)->as_HashTableDynamicData, index)
#define hash_table_delete_by_key(ht, key) hash_table_delete_by_key_impl(&(ht)->as_HashTableDynamicData, key)
#endif /* end of include guard: COMMON_UTIL_HASH_TABLE_H_ */

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@ -1,6 +1,7 @@
#include "main.h" #include "main.h"
#include <stdio.h> #include <stdio.h>
#include "common/util/hash_table.h"
int int
main(int argc, char **argv) main(int argc, char **argv)