/*
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
*
* Copyright 2021 Mike Becker, Olaf Wintermann All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include "cx/hash_map.h"
#include "cx/utils.h"
#include <string.h>
#include <assert.h>
struct cx_hash_map_element_s {
/** A pointer to the next element in the current bucket. */
struct cx_hash_map_element_s *next;
/** The corresponding key. */
CxHashKey key;
/** The value data. */
char data[];
};
static void cx_hash_map_clear(struct cx_map_s *map) {
struct cx_hash_map_s *hash_map = (struct cx_hash_map_s *) map;
cx_for_n(i, hash_map->bucket_count) {
struct cx_hash_map_element_s *elem = hash_map->buckets[i];
if (elem != NULL) {
do {
struct cx_hash_map_element_s *next = elem->next;
// invoke the destructor
cx_invoke_destructor(map, elem->data);
// free the key data
cxFree(map->collection.allocator, (void *) elem->key.data);
// free the node
cxFree(map->collection.allocator, elem);
// proceed
elem = next;
} while (elem != NULL);
// do not leave a dangling pointer
hash_map->buckets[i] = NULL;
}
}
map->collection.size = 0;
}
static void cx_hash_map_destructor(struct cx_map_s *map) {
struct cx_hash_map_s *hash_map = (struct cx_hash_map_s *) map;
// free the buckets
cx_hash_map_clear(map);
cxFree(map->collection.allocator, hash_map->buckets);
// free the map structure
cxFree(map->collection.allocator, map);
}
static int cx_hash_map_put(
CxMap *map,
CxHashKey key,
void *value
) {
struct cx_hash_map_s *hash_map = (struct cx_hash_map_s *) map;
const CxAllocator *allocator = map->collection.allocator;
unsigned hash = key.hash;
if (hash == 0) {
cx_hash_murmur(&key);
hash = key.hash;
}
size_t slot = hash % hash_map->bucket_count;
struct cx_hash_map_element_s *elm = hash_map->buckets[slot];
struct cx_hash_map_element_s *prev = NULL;
while (elm != NULL && elm->key.hash < hash) {
prev = elm;
elm = elm->next;
}
if (elm != NULL && elm->key.hash == hash && elm->key.len == key.len &&
memcmp(elm->key.data, key.data, key.len) == 0) {
// overwrite existing element
if (map->collection.store_pointer) {
memcpy(elm->data, &value, sizeof(void *));
} else {
memcpy(elm->data, value, map->collection.elem_size);
}
} else {
// allocate new element
struct cx_hash_map_element_s *e = cxMalloc(
allocator,
sizeof(struct cx_hash_map_element_s) + map->collection.elem_size
);
if (e == NULL) {
return -1;
}
// write the value
if (map->collection.store_pointer) {
memcpy(e->data, &value, sizeof(void *));
} else {
memcpy(e->data, value, map->collection.elem_size);
}
// copy the key
void *kd = cxMalloc(allocator, key.len);
if (kd == NULL) {
return -1;
}
memcpy(kd, key.data, key.len);
e->key.data = kd;
e->key.len = key.len;
e->key.hash = hash;
// insert the element into the linked list
if (prev == NULL) {
hash_map->buckets[slot] = e;
} else {
prev->next = e;
}
e->next = elm;
// increase the size
map->collection.size++;
}
return 0;
}
static void cx_hash_map_unlink(
struct cx_hash_map_s *hash_map,
size_t slot,
struct cx_hash_map_element_s *prev,
struct cx_hash_map_element_s *elm
) {
// unlink
if (prev == NULL) {
hash_map->buckets[slot] = elm->next;
} else {
prev->next = elm->next;
}
// free element
cxFree(hash_map->base.collection.allocator, (void *) elm->key.data);
cxFree(hash_map->base.collection.allocator, elm);
// decrease size
hash_map->base.collection.size--;
}
/**
* Helper function to avoid code duplication.
*
* @param map the map
* @param key the key to look up
* @param remove flag indicating whether the looked up entry shall be removed
* @param destroy flag indicating whether the destructor shall be invoked
* @return a pointer to the value corresponding to the key or \c NULL
*/
static void *cx_hash_map_get_remove(
CxMap *map,
CxHashKey key,
bool remove,
bool destroy
) {
struct cx_hash_map_s *hash_map = (struct cx_hash_map_s *) map;
unsigned hash = key.hash;
if (hash == 0) {
cx_hash_murmur(&key);
hash = key.hash;
}
size_t slot = hash % hash_map->bucket_count;
struct cx_hash_map_element_s *elm = hash_map->buckets[slot];
struct cx_hash_map_element_s *prev = NULL;
while (elm && elm->key.hash <= hash) {
if (elm->key.hash == hash && elm->key.len == key.len) {
if (memcmp(elm->key.data, key.data, key.len) == 0) {
void *data = NULL;
if (destroy) {
cx_invoke_destructor(map, elm->data);
} else {
if (map->collection.store_pointer) {
data = *(void **) elm->data;
} else {
data = elm->data;
}
}
if (remove) {
cx_hash_map_unlink(hash_map, slot, prev, elm);
}
return data;
}
}
prev = elm;
elm = prev->next;
}
return NULL;
}
static void *cx_hash_map_get(
const CxMap *map,
CxHashKey key
) {
// we can safely cast, because we know the map stays untouched
return cx_hash_map_get_remove((CxMap *) map, key, false, false);
}
static void *cx_hash_map_remove(
CxMap *map,
CxHashKey key,
bool destroy
) {
return cx_hash_map_get_remove(map, key, true, destroy);
}
static void *cx_hash_map_iter_current_entry(const void *it) {
const struct cx_iterator_s *iter = it;
// struct has to have a compatible signature
return (struct cx_map_entry_s *) &(iter->kv_data);
}
static void *cx_hash_map_iter_current_key(const void *it) {
const struct cx_iterator_s *iter = it;
struct cx_hash_map_element_s *elm = iter->elem_handle;
return &elm->key;
}
static void *cx_hash_map_iter_current_value(const void *it) {
const struct cx_iterator_s *iter = it;
const struct cx_hash_map_s *map = iter->src_handle.c;
struct cx_hash_map_element_s *elm = iter->elem_handle;
if (map->base.collection.store_pointer) {
return *(void **) elm->data;
} else {
return elm->data;
}
}
static bool cx_hash_map_iter_valid(const void *it) {
const struct cx_iterator_s *iter = it;
return iter->elem_handle != NULL;
}
static void cx_hash_map_iter_next(void *it) {
struct cx_iterator_s *iter = it;
struct cx_hash_map_element_s *elm = iter->elem_handle;
struct cx_hash_map_s *map = iter->src_handle.m;
// remove current element, if asked
if (iter->base.remove) {
// clear the flag
iter->base.remove = false;
// determine the next element
struct cx_hash_map_element_s *next = elm->next;
// search the previous element
struct cx_hash_map_element_s *prev = NULL;
if (map->buckets[iter->slot] != elm) {
prev = map->buckets[iter->slot];
while (prev->next != elm) {
prev = prev->next;
}
}
// destroy
cx_invoke_destructor((struct cx_map_s *) map, elm->data);
// unlink
cx_hash_map_unlink(map, iter->slot, prev, elm);
// advance
elm = next;
} else {
// just advance
elm = elm->next;
iter->index++;
}
// search the next bucket, if required
while (elm == NULL && ++iter->slot < map->bucket_count) {
elm = map->buckets[iter->slot];
}
// fill the struct with the next element
iter->elem_handle = elm;
if (elm == NULL) {
iter->kv_data.key = NULL;
iter->kv_data.value = NULL;
} else {
iter->kv_data.key = &elm->key;
if (map->base.collection.store_pointer) {
iter->kv_data.value = *(void **) elm->data;
} else {
iter->kv_data.value = elm->data;
}
}
}
static CxIterator cx_hash_map_iterator(
const CxMap *map,
enum cx_map_iterator_type type
) {
CxIterator iter;
iter.src_handle.c = map;
iter.elem_count = map->collection.size;
switch (type) {
case CX_MAP_ITERATOR_PAIRS:
iter.elem_size = sizeof(CxMapEntry);
iter.base.current = cx_hash_map_iter_current_entry;
break;
case CX_MAP_ITERATOR_KEYS:
iter.elem_size = sizeof(CxHashKey);
iter.base.current = cx_hash_map_iter_current_key;
break;
case CX_MAP_ITERATOR_VALUES:
iter.elem_size = map->collection.elem_size;
iter.base.current = cx_hash_map_iter_current_value;
break;
default:
assert(false);
}
iter.base.valid = cx_hash_map_iter_valid;
iter.base.next = cx_hash_map_iter_next;
iter.base.remove = false;
iter.base.mutating = false;
iter.slot = 0;
iter.index = 0;
if (map->collection.size > 0) {
struct cx_hash_map_s *hash_map = (struct cx_hash_map_s *) map;
struct cx_hash_map_element_s *elm = hash_map->buckets[0];
while (elm == NULL) {
elm = hash_map->buckets[++iter.slot];
}
iter.elem_handle = elm;
iter.kv_data.key = &elm->key;
if (map->collection.store_pointer) {
iter.kv_data.value = *(void **) elm->data;
} else {
iter.kv_data.value = elm->data;
}
} else {
iter.elem_handle = NULL;
iter.kv_data.key = NULL;
iter.kv_data.value = NULL;
}
return iter;
}
static cx_map_class cx_hash_map_class = {
cx_hash_map_destructor,
cx_hash_map_clear,
cx_hash_map_put,
cx_hash_map_get,
cx_hash_map_remove,
cx_hash_map_iterator,
};
CxMap *cxHashMapCreate(
const CxAllocator *allocator,
size_t itemsize,
size_t buckets
) {
if (buckets == 0) {
// implementation defined default
buckets = 16;
}
struct cx_hash_map_s *map = cxCalloc(allocator, 1,
sizeof(struct cx_hash_map_s));
if (map == NULL) return NULL;
// initialize hash map members
map->bucket_count = buckets;
map->buckets = cxCalloc(allocator, buckets,
sizeof(struct cx_hash_map_element_s *));
if (map->buckets == NULL) {
cxFree(allocator, map);
return NULL;
}
// initialize base members
map->base.cl = &cx_hash_map_class;
map->base.collection.allocator = allocator;
if (itemsize > 0) {
map->base.collection.store_pointer = false;
map->base.collection.elem_size = itemsize;
} else {
map->base.collection.store_pointer = true;
map->base.collection.elem_size = sizeof(void *);
}
return (CxMap *) map;
}
int cxMapRehash(CxMap *map) {
struct cx_hash_map_s *hash_map = (struct cx_hash_map_s *) map;
if (map->collection.size > ((hash_map->bucket_count * 3) >> 2)) {
size_t new_bucket_count = (map->collection.size * 5) >> 1;
struct cx_hash_map_element_s **new_buckets = cxCalloc(
map->collection.allocator,
new_bucket_count, sizeof(struct cx_hash_map_element_s *)
);
if (new_buckets == NULL) {
return 1;
}
// iterate through the elements and assign them to their new slots
cx_for_n(slot, hash_map->bucket_count) {
struct cx_hash_map_element_s *elm = hash_map->buckets[slot];
while (elm != NULL) {
struct cx_hash_map_element_s *next = elm->next;
size_t new_slot = elm->key.hash % new_bucket_count;
// find position where to insert
struct cx_hash_map_element_s *bucket_next = new_buckets[new_slot];
struct cx_hash_map_element_s *bucket_prev = NULL;
while (bucket_next != NULL &&
bucket_next->key.hash < elm->key.hash) {
bucket_prev = bucket_next;
bucket_next = bucket_next->next;
}
// insert
if (bucket_prev == NULL) {
elm->next = new_buckets[new_slot];
new_buckets[new_slot] = elm;
} else {
bucket_prev->next = elm;
elm->next = bucket_next;
}
// advance
elm = next;
}
}
// assign result to the map
hash_map->bucket_count = new_bucket_count;
cxFree(map->collection.allocator, hash_map->buckets);
hash_map->buckets = new_buckets;
}
return 0;
}