data/hashtable.[hc]: Implement intrusive hashtable structure.

README.md

@@ -4,7 +4,6 @@
 
 
 
-
 # C Reusables Readme
 
 Home: https://github.com/mity/c-reusables
@@ -39,6 +38,8 @@ The following rules apply:
  * `data/buffer.[hc]`: Simple growing buffer. It offers also a stack-like
    interface (push, pop operations) and array-like interface.
 
+ * `data/htable.[hc]`: Simple growing intrusive hash table.
+
  * `data/list.h`: Intrusive double-linked and single-linked lists.
 
  * `data/rbtree.[hc]`: Intrusive red-black tree.
@@ -59,7 +60,7 @@ The following rules apply:
 
  * `hash/crc32.[hc]`: 32-bit cyclic redundancy check function.
 
- * `hash/fnv1a.[hc]`: 32-bit and 64-bit Fowler–Noll–Vo (variant 1a) hash
+ * `hash/fnv1a.[hc]`: 32-bit and 64-bit Fowler-Noll-Vo (variant 1a) hash
    functions.
 
 ### Directory `mem`

data/htable.c

@@ -0,0 +1,251 @@
+/*
+ * C Reusables
+ * <http://github.com/mity/c-reusables>
+ *
+ * Copyright (c) 2023 Martin Mitas
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#include "htable.h"
+
+#include <string.h>
+
+
+#define HTABLE_PLANE_SIZE(plane_index)  (59 << (plane_index))
+#define HTABLE_SLOT_COUNT(htable)       (HTABLE_PLANE_SIZE(0) * ((1 << (htable)->n_planes) - 1))
+#define HTABLE_TOO_FULL(htable)         ((htable)->n >= HTABLE_SLOT_COUNT(htable))
+#define HTABLE_TOO_EMPTY(htable)        ((htable)->n < (HTABLE_SLOT_COUNT(htable) / 4))
+
+
+static int
+htable_grow(HTABLE* htable)
+{
+    HTABLE_NODE** new_planes;
+
+    /* Grow by appending one more plane, twice the size the previous one. */
+    new_planes = (HTABLE_NODE**) realloc(htable->planes, (htable->n_planes+1) * sizeof(HTABLE_NODE*));
+    if(new_planes == NULL) {
+        if(htable->n_planes > 0) {
+            /* It may be suboptimal, but we can still add the new stuff into
+             * the current planes. */
+            return 0;
+        }
+        return -1;
+    }
+    htable->planes = (void**) new_planes;
+
+    new_planes[htable->n_planes] = (HTABLE_NODE*) malloc(HTABLE_PLANE_SIZE(htable->n_planes) * sizeof(HTABLE_NODE*));
+    if(new_planes[htable->n_planes] == NULL)
+        return -1;
+    memset(new_planes[htable->n_planes], 0, HTABLE_PLANE_SIZE(htable->n_planes) * sizeof(HTABLE_NODE*));
+    htable->n_planes++;
+
+    return 0;
+}
+
+static void
+htable_free_all_planes(HTABLE* htable)
+{
+    int i;
+
+    for(i = 0; i < htable->n_planes; i++)
+        free(htable->planes[i]);
+    free(htable->planes);
+
+    htable->planes = NULL;
+    htable->n_planes = 0;
+}
+
+static void
+htable_shrink(HTABLE* htable)
+{
+    HTABLE_NODE** prev_plane;
+    size_t prev_plane_size;
+    HTABLE_NODE** plane;
+    size_t plane_size;
+    size_t i;
+
+    if(htable->n == 0) {
+        htable_free_all_planes(htable);
+        return;
+    }
+
+    if(htable->n_planes <= 1)
+        return;
+
+    /* We shrink by merging the largest plane into the previous one. */
+    prev_plane = (HTABLE_NODE**) htable->planes[htable->n_planes-2];
+    prev_plane_size = HTABLE_PLANE_SIZE(htable->n_planes-2);
+    plane = (HTABLE_NODE**) htable->planes[htable->n_planes-1];
+    plane_size = HTABLE_PLANE_SIZE(htable->n_planes-1);
+    for(i = 0; i < plane_size; i++) {
+        if(plane[i] != NULL) {
+            if(prev_plane[i % prev_plane_size] != NULL) {
+                /* Join the slot in the previous plane to our tail. */
+                HTABLE_NODE* tail = plane[i];
+                while(tail->next != NULL)
+                    tail = tail->next;
+                tail->next = prev_plane[i % prev_plane_size];
+            }
+
+            /* Move it to the previous plane. */
+            prev_plane[i % prev_plane_size] = plane[i];
+        }
+    }
+
+    free(plane);
+    htable->n_planes--;
+}
+
+static HTABLE_NODE*
+htable_lookup_internal(HTABLE* htable, uint32_t hash, const HTABLE_NODE* key,
+                       HTABLE_NODE*** p_ref, HTABLE_CMP_FUNC cmp_func)
+{
+    HTABLE_NODE* node;
+    HTABLE_NODE** ref;
+    int i;
+
+    /* It's better to lookup the biggest planes first, as much more stuff is
+     * stored there, and also because it's moire recently inserted stuff which
+     * is arguably more likely to accessed soon. */
+    for(i = htable->n_planes-1; i >= 0; i--) {
+        HTABLE_NODE** plane;
+        size_t index;
+
+        plane = (HTABLE_NODE**) htable->planes[i];
+        index = hash % HTABLE_PLANE_SIZE(i);
+
+        ref = &plane[index];
+        node = plane[index];
+
+        while(node != NULL) {
+            if(cmp_func(key, node) == 0) {
+                if(p_ref != NULL)
+                    *p_ref = ref;
+                return node;
+            }
+
+            ref = &node->next;
+            node = node->next;
+        }
+    }
+
+    return NULL;
+}
+
+void
+htable_fini(HTABLE* htable, void (*dtor_func)(HTABLE_NODE*))
+{
+    if(dtor_func != NULL  &&  htable->n > 0) {
+        unsigned i;
+        size_t index;
+
+        for(i = 0; i < htable->n_planes; i++) {
+            HTABLE_NODE** plane = (HTABLE_NODE**) htable->planes[i];
+            for(index = 0; index < HTABLE_PLANE_SIZE(i); index++) {
+                while(plane[index] != NULL) {
+                    HTABLE_NODE* node;
+
+                    node = plane[index];
+                    plane[index] = node->next;
+                    dtor_func(node);
+                }
+            }
+        }
+    }
+    htable->n = 0;
+
+    htable_free_all_planes(htable);
+}
+
+static int
+htable_insert_internal(HTABLE* htable, HTABLE_NODE* node,
+                       HTABLE_CMP_FUNC cmp_func, HTABLE_HASH_FUNC hash_func,
+                       int skip_lookup)
+{
+    uint32_t hash;
+    HTABLE_NODE** plane;
+
+    hash = hash_func(node);
+    if(!skip_lookup) {
+        if(htable_lookup_internal(htable, hash, node, NULL, cmp_func) != NULL)
+            return -1;
+    }
+
+    /* When we are too populated, grow by adding a new plane. */
+    if(HTABLE_TOO_FULL(htable)) {
+        if(htable_grow(htable) != 0)
+            return -1;
+    }
+
+    plane = (HTABLE_NODE**) htable->planes[htable->n_planes - 1];
+
+    node->next = plane[hash % HTABLE_PLANE_SIZE(htable->n_planes - 1)];
+    plane[hash % HTABLE_PLANE_SIZE(htable->n_planes - 1)] = node;
+
+    htable->n++;
+    return 0;
+}
+
+int
+htable_insert(HTABLE* htable, HTABLE_NODE* node,
+              HTABLE_CMP_FUNC cmp_func, HTABLE_HASH_FUNC hash_func)
+{
+    return htable_insert_internal(htable, node, cmp_func, hash_func, 0);
+}
+
+int
+htable_insert_unsafe(HTABLE* htable, HTABLE_NODE* node,
+                     HTABLE_CMP_FUNC cmp_func, HTABLE_HASH_FUNC hash_func)
+{
+    return htable_insert_internal(htable, node, cmp_func, hash_func, 1);
+}
+
+HTABLE_NODE*
+htable_remove(HTABLE* htable, const HTABLE_NODE* key,
+              HTABLE_CMP_FUNC cmp_func, HTABLE_HASH_FUNC hash_func)
+{
+    uint32_t hash;
+    HTABLE_NODE* node;
+    HTABLE_NODE** p_ref;
+
+    hash = hash_func(key);
+    node = htable_lookup_internal(htable, hash, key, &p_ref, cmp_func);
+    if(node == NULL)
+        return NULL;
+
+    *p_ref = node->next;
+    htable->n--;
+
+    if(HTABLE_TOO_EMPTY(htable))
+        htable_shrink(htable);
+
+    return node;
+}
+
+HTABLE_NODE*
+htable_lookup(HTABLE* htable, const HTABLE_NODE* key,
+              HTABLE_CMP_FUNC cmp_func, HTABLE_HASH_FUNC hash_func)
+{
+    uint32_t hash;
+
+    hash = hash_func(key);
+    return htable_lookup_internal(htable, hash, key, NULL, cmp_func);
+}