New hash table implementation based on open addressing and linear pro…

…bing. Seems significantly faster than existing chained hash table implementation.

benchmark.c

@@ -66,6 +66,7 @@ main(int argc, char **argv)
 	fprintf(stderr, "   w: weight-balanced tree\n");
 	fprintf(stderr, "   S: skiplist\n");
 	fprintf(stderr, "   H: hashtable\n");
+	fprintf(stderr, "   2: hashtable 2\n");
 	fprintf(stderr, "input: text file consisting of newline-separated keys\n");
 	exit(EXIT_FAILURE);
     }
@@ -129,7 +130,7 @@ main(int argc, char **argv)
 	   comp_count, hash_count);
     total_comp += comp_count; comp_count = 0;
     total_hash += hash_count; hash_count = 0;
-    if (type != 'H' && type != 'S') {
+    if (type != 'H' && type != '2' && type != 'S') {
 	tree_base *tree = dict_private(dct);
 	printf("insert rotations: %zu\n", tree->rotation_count);
 	total_rotations += tree->rotation_count;
@@ -193,7 +194,7 @@ main(int argc, char **argv)
 	   comp_count, hash_count);
     total_comp += comp_count; comp_count = 0;
     total_hash += hash_count; hash_count = 0;
-    if (type != 'H' && type != 'S') {
+    if (type != 'H' && type != '2' && type != 'S') {
 	tree_base *tree = dict_private(dct);
 	printf("search rotations: %zu\n", tree->rotation_count);
 	total_rotations += tree->rotation_count;
@@ -229,7 +230,7 @@ main(int argc, char **argv)
 	   comp_count, hash_count);
     total_comp += comp_count; comp_count = 0;
     total_hash += hash_count; hash_count = 0;
-    if (type != 'H' && type != 'S') {
+    if (type != 'H' && type != '2' && type != 'S') {
 	tree_base *tree = dict_private(dct);
 	printf("remove rotations: %zu\n", tree->rotation_count);
 	total_rotations += tree->rotation_count;
@@ -248,7 +249,7 @@ main(int argc, char **argv)
 	   (total.tv_sec * 1000000 + total.tv_usec) * 1e-6,
 	   total_comp, total_hash);
 
-    if (type != 'H' && type != 'S') {
+    if (type != 'H' && type != '2' && type != 'S') {
 	printf(" total rotations: %zu\n", total_rotations);
     }
 
@@ -296,6 +297,10 @@ create_dictionary(char type, const char **container_name)
 	    *container_name = "ht";
 	    return hashtable_dict_new(cmp_func, hash_func, key_str_free, HASHTABLE_SIZE);
 
+	case '2':
+	    *container_name = "h2";
+	    return hashtable2_dict_new(cmp_func, hash_func, key_str_free, HASHTABLE_SIZE);
+
 	default:
 	    quit("type must be one of h, p, r, t, s, w or H");
     }

demo.c

@@ -72,6 +72,11 @@ main(int argc, char **argv)
 				     dict_str_hash,
 				     key_val_free, HSIZE);
 	    break;
+	case '2':
+	    dct = hashtable2_dict_new((dict_compare_func)strcmp,
+				      dict_str_hash,
+				      key_val_free, HSIZE);
+	    break;
 	default:
 	    quit("type must be one of h, p, r, t, s, w, or H");
     }

include/dict.h

@@ -197,6 +197,7 @@ unsigned dict_str_hash(const void* str);
 END_DECL
 
 #include "hashtable.h"
+#include "hashtable2.h"
 #include "hb_tree.h"
 #include "pr_tree.h"
 #include "rb_tree.h"

include/hashtable2.h

@@ -0,0 +1,79 @@
+/*
+ * libdict -- open-addressing hash-table interface.
+ *
+ * Copyright (c) 2001-2014, Farooq Mela
+ * 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 OWNER 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.
+ */
+
+#ifndef _HASHTABLE2_H_
+#define _HASHTABLE2_H_
+
+#include "dict.h"
+
+BEGIN_DECL
+
+typedef struct hashtable2 hashtable2;
+
+hashtable2*	hashtable2_new(dict_compare_func cmp_func,
+			       dict_hash_func hash_func,
+			       dict_delete_func del_func, unsigned size);
+dict*		hashtable2_dict_new(dict_compare_func cmp_func,
+				    dict_hash_func hash_func,
+				    dict_delete_func del_func, unsigned size);
+size_t		hashtable2_free(hashtable2* table);
+hashtable2*	hashtable2_clone(hashtable2* table,
+				 dict_key_datum_clone_func clone_func);
+
+void**		hashtable2_insert(hashtable2* table, void* key, bool* inserted);
+void*		hashtable2_search(hashtable2* table, const void* key);
+bool		hashtable2_remove(hashtable2* table, const void* key);
+size_t		hashtable2_clear(hashtable2* table);
+size_t		hashtable2_traverse(hashtable2* table, dict_visit_func visit);
+size_t		hashtable2_count(const hashtable2* table);
+size_t		hashtable2_size(const hashtable2* table);
+size_t		hashtable2_slots_used(const hashtable2* table);
+bool		hashtable2_verify(const hashtable2* table);
+bool		hashtable2_resize(hashtable2* table, unsigned size);
+
+typedef struct hashtable2_itor hashtable2_itor;
+
+hashtable2_itor* hashtable2_itor_new(hashtable2* table);
+dict_itor*	hashtable2_dict_itor_new(hashtable2* table);
+void		hashtable2_itor_free(hashtable2_itor* itor);
+
+bool		hashtable2_itor_valid(const hashtable2_itor* itor);
+void		hashtable2_itor_invalidate(hashtable2_itor* itor);
+bool		hashtable2_itor_next(hashtable2_itor* itor);
+bool		hashtable2_itor_prev(hashtable2_itor* itor);
+bool		hashtable2_itor_nextn(hashtable2_itor* itor, size_t count);
+bool		hashtable2_itor_prevn(hashtable2_itor* itor, size_t count);
+bool		hashtable2_itor_first(hashtable2_itor* itor);
+bool		hashtable2_itor_last(hashtable2_itor* itor);
+bool		hashtable2_itor_search(hashtable2_itor* itor, const void* key);
+const void*	hashtable2_itor_key(const hashtable2_itor* itor);
+void**		hashtable2_itor_data(hashtable2_itor* itor);
+bool		hashtable2_itor_remove(hashtable2_itor* itor);
+
+END_DECL
+
+#endif /* !_HASHTABLE2_H_ */