X-Git-Url: https://git.ozlabs.org/?a=blobdiff_plain;f=ccan%2Fhtable%2Fhtable.c;h=59048dc0ada0df95b23583e0dfbba65d3c96768c;hb=c23a40c7f1ac9fad0146b46988a41f196aae933f;hp=ba5f0de530a1a68d7acd5649cfeca6a67e64142b;hpb=45f24da35118db441e6153f02f6ddd937da1fa1c;p=ccan

diff --git a/ccan/htable/htable.c b/ccan/htable/htable.c
index ba5f0de5..59048dc0 100644
--- a/ccan/htable/htable.c
+++ b/ccan/htable/htable.c
@@ -1,7 +1,6 @@
 /* Licensed under LGPLv2+ - see LICENSE file for details */
 #include <ccan/htable/htable.h>
 #include <ccan/compiler/compiler.h>
-#include <stdint.h>
 #include <stdlib.h>
 #include <limits.h>
 #include <stdbool.h>
@@ -10,17 +9,6 @@
 /* We use 0x1 as deleted marker. */
 #define HTABLE_DELETED (0x1)
 
-struct htable {
-	size_t (*rehash)(const void *elem, void *priv);
-	void *priv;
-	unsigned int bits;
-	size_t elems, deleted, max, max_with_deleted;
-	/* These are the bits which are the same in all pointers. */
-	uintptr_t common_mask, common_bits;
-	uintptr_t perfect_bit;
-	uintptr_t *table;
-};
-
 /* We clear out the bits which are always the same, and put metadata there. */
 static inline uintptr_t get_extra_ptr_bits(const struct htable *ht,
 					   uintptr_t e)
@@ -54,33 +42,44 @@ static inline uintptr_t get_hash_ptr_bits(const struct htable *ht,
 		& ht->common_mask & ~ht->perfect_bit;
 }
 
-struct htable *htable_new(size_t (*rehash)(const void *elem, void *priv),
-			  void *priv)
+void htable_init(struct htable *ht,
+		 size_t (*rehash)(const void *elem, void *priv), void *priv)
 {
-	struct htable *ht = malloc(sizeof(struct htable));
-	if (ht) {
-		ht->bits = 0;
-		ht->rehash = rehash;
-		ht->priv = priv;
-		ht->elems = 0;
-		ht->deleted = 0;
-		ht->max = 0;
-		ht->max_with_deleted = 0;
-		/* This guarantees we enter update_common first add. */
-		ht->common_mask = -1;
-		ht->common_bits = 0;
-		ht->perfect_bit = 0;
-		/* Dummy table until first insert. */
+	struct htable empty = HTABLE_INITIALIZER(empty, NULL, NULL);
+	*ht = empty;
+	ht->rehash = rehash;
+	ht->priv = priv;
+	ht->table = &ht->perfect_bit;
+}
+
+bool htable_init_sized(struct htable *ht,
+		       size_t (*rehash)(const void *, void *),
+		       void *priv, size_t expect)
+{
+	htable_init(ht, rehash, priv);
+
+	/* Don't go insane with sizing. */
+	for (ht->bits = 1; ((size_t)3 << ht->bits) / 4 < expect; ht->bits++) {
+		if (ht->bits == 30)
+			break;
+	}
+
+	ht->table = calloc(1 << ht->bits, sizeof(size_t));
+	if (!ht->table) {
 		ht->table = &ht->perfect_bit;
+		return false;
 	}
-	return ht;
-}
+	ht->max = ((size_t)3 << ht->bits) / 4;
+	ht->max_with_deleted = ((size_t)9 << ht->bits) / 10;
 
-void htable_free(const struct htable *ht)
+	return true;
+}
+	
+void htable_clear(struct htable *ht)
 {
 	if (ht->table != &ht->perfect_bit)
 		free((void *)ht->table);
-	free((void *)ht);
+	htable_init(ht, ht->rehash, ht->priv);
 }
 
 static size_t hash_bucket(const struct htable *ht, size_t h)
@@ -221,8 +220,17 @@ static COLD void update_common(struct htable *ht, const void *p)
 	uintptr_t maskdiff, bitsdiff;
 
 	if (ht->elems == 0) {
-		ht->common_mask = -1;
-		ht->common_bits = (uintptr_t)p;
+		/* Always reveal one bit of the pointer in the bucket,
+		 * so it's not zero or HTABLE_DELETED (1), even if
+		 * hash happens to be 0.  Assumes (void *)1 is not a
+		 * valid pointer. */
+		for (i = sizeof(uintptr_t)*CHAR_BIT - 1; i > 0; i--) {
+			if ((uintptr_t)p & ((uintptr_t)1 << i))
+				break;
+		}
+
+		ht->common_mask = ~((uintptr_t)1 << i);
+		ht->common_bits = ((uintptr_t)p & ht->common_mask);
 		ht->perfect_bit = 1;
 		return;
 	}