X-Git-Url: http://git.ozlabs.org/?a=blobdiff_plain;f=ccan%2Fhtable%2Fhtable.c;h=e1d13699ea85811fe2f61adbb1ce4eca942406c8;hb=5ff76d983c62c8fc489672a1f89927ee3ba58e5d;hp=f3e529211d5b2456bad5165d3baa848de4314d3d;hpb=0c3590dc33d644f73bb8587db454c491830aaf26;p=ccan

diff --git a/ccan/htable/htable.c b/ccan/htable/htable.c
index f3e52921..e1d13699 100644
--- a/ccan/htable/htable.c
+++ b/ccan/htable/htable.c
@@ -5,6 +5,7 @@
 #include <limits.h>
 #include <stdbool.h>
 #include <assert.h>
+#include <string.h>
 
 /* We use 0x1 as deleted marker. */
 #define HTABLE_DELETED (0x1)
@@ -45,21 +46,41 @@ static inline uintptr_t get_hash_ptr_bits(const struct htable *ht,
 void htable_init(struct htable *ht,
 		 size_t (*rehash)(const void *elem, void *priv), void *priv)
 {
-	ht->bits = 0;
+	struct htable empty = HTABLE_INITIALIZER(empty, NULL, NULL);
+	*ht = empty;
 	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. */
 	ht->table = &ht->perfect_bit;
 }
 
+/* We've changed ht->bits, update ht->max and ht->max_with_deleted */
+static void htable_adjust_capacity(struct htable *ht)
+{
+	ht->max = ((size_t)3 << ht->bits) / 4;
+	ht->max_with_deleted = ((size_t)9 << ht->bits) / 10;
+}
+
+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;
+	}
+	htable_adjust_capacity(ht);
+	return true;
+}
+	
 void htable_clear(struct htable *ht)
 {
 	if (ht->table != &ht->perfect_bit)
@@ -67,6 +88,19 @@ void htable_clear(struct htable *ht)
 	htable_init(ht, ht->rehash, ht->priv);
 }
 
+bool htable_copy(struct htable *dst, const struct htable *src)
+{
+	uintptr_t *htable = malloc(sizeof(size_t) << src->bits);
+
+	if (!htable)
+		return false;
+
+	*dst = *src;
+	dst->table = htable;
+	memcpy(dst->table, src->table, sizeof(size_t) << src->bits);
+	return true;
+}
+
 static size_t hash_bucket(const struct htable *ht, size_t h)
 {
 	return h & ((1 << ht->bits)-1);
@@ -120,6 +154,17 @@ void *htable_next(const struct htable *ht, struct htable_iter *i)
 	return NULL;
 }
 
+void *htable_prev(const struct htable *ht, struct htable_iter *i)
+{
+	for (;;) {
+		if (!i->off)
+			return NULL;
+		i->off --;
+		if (entry_is_valid(ht->table[i->off]))
+			return get_raw_ptr(ht, ht->table[i->off]);
+	}
+}
+
 /* This does not expand the hash table, that's up to caller. */
 static void ht_add(struct htable *ht, const void *new, size_t h)
 {
@@ -148,8 +193,7 @@ static COLD bool double_table(struct htable *ht)
 		return false;
 	}
 	ht->bits++;
-	ht->max = ((size_t)3 << ht->bits) / 4;
-	ht->max_with_deleted = ((size_t)9 << ht->bits) / 10;
+	htable_adjust_capacity(ht);
 
 	/* If we lost our "perfect bit", get it back now. */
 	if (!ht->perfect_bit && ht->common_mask) {
@@ -205,8 +249,17 @@ 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;
 	}