ucx: src/hash_map.c@69a83fad8a35 (annotated)

src/hash_map.c@69a83fad8a35 (annotated)

src/hash_map.c

Wed, 08 Jun 2022 21:33:31 +0200

author: Mike Becker <universe@uap-core.de>
date: Wed, 08 Jun 2022 21:33:31 +0200
changeset 563: 69a83fad8a35
parent 562: fd3368c20413
child 573: 3f3a0d19db58
permissions: -rw-r--r--

improve hash key handling

 /*
  * 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 <string.h>
 #include "cx/hash_map.h"
 #include "cx/utils.h"
 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;
                 // free the key data
                 cxFree(map->allocator, elem->key.data.obj);
                 // free the node
                 cxFree(map->allocator, elem);
                 // proceed
                 elem = next;
             } while (elem != NULL);
             // do not leave a dangling pointer
             hash_map->buckets[i] = NULL;
         }
     }
     map->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->allocator, hash_map->buckets);
     // free the map structure
     cxFree(map->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;
     CxAllocator *allocator = map->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) {
         struct cx_hash_map_element_s *e = cxMalloc(allocator, sizeof(struct cx_hash_map_element_s));
         if (e == NULL) {
             return -1;
         }
         // write the value
         // TODO: depending on future map features, we may want to copy here
         e->data = value;
         // copy the key
         void *kd = cxMalloc(allocator, key.len);
         if (kd == NULL) {
             return -1;
         }
         memcpy(kd, key.data.obj, key.len);
         e->key.data.obj = 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->size++;
     } else {
         // (elem != NULL && elem->key.hash == hash) - overwrite value of existing element
         elm->data = value;
     }
     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.allocator, elm->key.data.obj);
     cxFree(hash_map->base.allocator, elm);
     // decrease size
     hash_map->base.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
  * @return the value corresponding to the key or \c NULL
  */
 static void *cx_hash_map_get_remove(
         CxMap *map,
         CxHashKey key,
         bool remove
 ) {
     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.obj, key.data.obj, key.len) == 0) {
                 void *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(
         CxMap const *map,
         CxHashKey key
 ) {
     // we can safely cast, because we know when remove=false, the map stays untouched
     return cx_hash_map_get_remove((CxMap *) map, key, false);
 }
 static void *cx_hash_map_remove(
         CxMap *map,
         CxHashKey key
 ) {
     return cx_hash_map_get_remove(map, key, true);
 }
 static void *cx_hash_map_iter_current_entry(CxIterator const *iter) {
     // struct has to have a compatible signature
     struct cx_map_entry_s *entry = (struct cx_map_entry_s *) &(iter->kv_data);
     return entry;
 }
 static void *cx_hash_map_iter_current_key(CxIterator const *iter) {
     struct cx_hash_map_element_s *elm = iter->elem_handle;
     return &elm->key;
 }
 static void *cx_hash_map_iter_current_value(CxIterator const *iter) {
     struct cx_hash_map_element_s *elm = iter->elem_handle;
     // TODO: return a pointer to data if this map is storing copies
     return elm->data;
 }
 static bool cx_hash_map_iter_valid(CxIterator const *iter) {
     return iter->elem_handle != NULL;
 }
 static void cx_hash_map_iter_next(CxIterator *iter) {
     struct cx_hash_map_s *map = iter->src_handle;
     struct cx_hash_map_element_s *elm = iter->elem_handle;
     // remove current element, if asked
     if (iter->remove) {
         // clear the flag
         iter->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;
             }
         }
         // 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;
         // TODO: pointer to data if this map is storing copies
         iter->kv_data.value = elm->data;
     }
 }
 static CxIterator cx_hash_map_iterator(CxMap *map) {
     CxIterator iter;
     iter.src_handle = map;
     iter.valid = cx_hash_map_iter_valid;
     iter.next = cx_hash_map_iter_next;
     iter.current = cx_hash_map_iter_current_entry;
     iter.slot = 0;
     iter.index = 0;
     iter.remove = false;
     if (map->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];
         for (; elm == NULL; iter.slot++) {
             elm = hash_map->buckets[iter.slot];
         }
         iter.elem_handle = elm;
         iter.kv_data.key = &elm->key;
         // TODO: pointer to data if this map is storing copies
         iter.kv_data.value = elm->data;
     } else {
         iter.elem_handle = NULL;
         iter.kv_data.key = NULL;
         iter.kv_data.value = NULL;
     }
     return iter;
 }
 static CxIterator cx_hash_map_iterator_keys(CxMap *map) {
     CxIterator iter = cx_hash_map_iterator(map);
     iter.current = cx_hash_map_iter_current_key;
     return iter;
 }
 static CxIterator cx_hash_map_iterator_values(CxMap *map) {
     CxIterator iter = cx_hash_map_iterator(map);
     iter.current = cx_hash_map_iter_current_value;
     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,
         cx_hash_map_iterator_keys,
         cx_hash_map_iterator_values,
 };
 CxMap *cxHashMapCreate(
         CxAllocator *allocator,
         size_t buckets
 ) {
     if (buckets == 0) {
         // implementation defined default
         buckets = 16;
     }
     struct cx_hash_map_s *map = cxMalloc(allocator, 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.allocator = allocator;
     map->base.size = 0;
     return (CxMap *) map;
 }
 int cxMapRehash(CxMap *map) {
     struct cx_hash_map_s *hash_map = (struct cx_hash_map_s *) map;
     if (map->size > ((hash_map->bucket_count * 3) >> 2)) {
         size_t new_bucket_count = (map->size * 5) >> 1;
         struct cx_hash_map_element_s **new_buckets = cxCalloc(map->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->allocator, hash_map->buckets);
         hash_map->buckets = new_buckets;
     }
     return 0;
 }

Mercurial > hg > ucx / annotate

src/hash_map.c@69a83fad8a35 (annotated)

src/hash_map.c