htable: add allocator hooks.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

ccan/htable/htable.c

@@ -11,6 +11,30 @@
 /* We use 0x1 as deleted marker. */
 #define HTABLE_DELETED (0x1)
 
+static void *htable_default_alloc(struct htable *ht, size_t len)
+{
+	return calloc(len, 1);
+}
+
+static void htable_default_free(struct htable *ht, void *p)
+{
+	free(p);
+}
+
+static void *(*htable_alloc)(struct htable *, size_t) = htable_default_alloc;
+static void (*htable_free)(struct htable *, void *) = htable_default_free;
+
+void htable_set_allocator(void *(*alloc)(struct htable *, size_t len),
+			  void (*free)(struct htable *, void *p))
+{
+	if (!alloc)
+		alloc = htable_default_alloc;
+	if (!free)
+		free = htable_default_free;
+	htable_alloc = alloc;
+	htable_free = free;
+}
+
 /* 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)
@@ -73,7 +97,7 @@ bool htable_init_sized(struct htable *ht,
 			break;
 	}
 
-	ht->table = calloc(1 << ht->bits, sizeof(size_t));
+	ht->table = htable_alloc(ht, sizeof(size_t) << ht->bits);
 	if (!ht->table) {
 		ht->table = &ht->perfect_bit;
 		return false;
@@ -86,13 +110,13 @@ bool htable_init_sized(struct htable *ht,
 void htable_clear(struct htable *ht)
 {
 	if (ht->table != &ht->perfect_bit)
-		free((void *)ht->table);
+		htable_free(ht, (void *)ht->table);
 	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);
+	uintptr_t *htable = htable_alloc(dst, sizeof(size_t) << src->bits);
 
 	if (!htable)
 		return false;
@@ -189,7 +213,7 @@ static COLD bool double_table(struct htable *ht)
 	uintptr_t *oldtable, e;
 
 	oldtable = ht->table;
-	ht->table = calloc(1 << (ht->bits+1), sizeof(size_t));
+	ht->table = htable_alloc(ht, sizeof(size_t) << (ht->bits+1));
 	if (!ht->table) {
 		ht->table = oldtable;
 		return false;
@@ -214,7 +238,7 @@ static COLD bool double_table(struct htable *ht)
 				ht_add(ht, p, ht->rehash(p, ht->priv));
 			}
 		}
-		free(oldtable);
+		htable_free(ht, oldtable);
 	}
 	ht->deleted = 0;
 

ccan/htable/htable.h

@@ -259,4 +259,11 @@ void *htable_prev_(const struct htable *htable, struct htable_iter *i);
 	htable_delval_(htable_debug(htable, HTABLE_LOC), i)
 void htable_delval_(struct htable *ht, struct htable_iter *i);
 
+/**
+ * htable_set_allocator - set calloc/free functions.
+ * @alloc: allocator to use, must zero memory!
+ * @free: unallocator to use (@p is NULL or a return from @alloc)
+ */
+void htable_set_allocator(void *(*alloc)(struct htable *, size_t len),
+			  void (*free)(struct htable *, void *p));
 #endif /* CCAN_HTABLE_H */

ccan/htable/test/run-allocator.c

+/* Include the C files directly. */
+#include <ccan/htable/htable.h>
+#include <ccan/htable/htable.c>
+#include <ccan/tap/tap.h>
+#include <stdbool.h>
+#include <string.h>
+
+struct htable_with_counters {
+	struct htable ht;
+	size_t num_alloc, num_free;
+};
+
+static void *test_alloc(struct htable *ht, size_t len)
+{
+	((struct htable_with_counters *)ht)->num_alloc++;
+	return calloc(len, 1);
+}
+
+	
+static void test_free(struct htable *ht, void *p)
+{
+	if (p) {
+		((struct htable_with_counters *)ht)->num_free++;
+		free(p);
+	}
+}
+
+static size_t hash(const void *elem, void *unused UNNEEDED)
+{
+	return *(size_t *)elem;
+}
+
+int main(void)
+{
+	struct htable_with_counters htc;
+	size_t val[] = { 0, 1 };
+
+	htc.num_alloc = htc.num_free = 0;
+	plan_tests(12);
+
+	htable_set_allocator(test_alloc, test_free);
+	htable_init(&htc.ht, hash, NULL);
+	htable_add(&htc.ht, hash(&val[0], NULL), &val[0]);
+	ok1(htc.num_alloc == 1);
+	ok1(htc.num_free == 0);
+	/* Adding another increments, then frees old */
+	htable_add(&htc.ht, hash(&val[1], NULL), &val[1]);
+	ok1(htc.num_alloc == 2);
+	ok1(htc.num_free == 1);
+	htable_clear(&htc.ht);
+	ok1(htc.num_alloc == 2);
+	ok1(htc.num_free == 2);
+
+	/* Should restore defaults */
+	htable_set_allocator(NULL, NULL);
+	ok1(htable_alloc == htable_default_alloc);
+	ok1(htable_free == htable_default_free);
+
+	htable_init(&htc.ht, hash, NULL);
+	htable_add(&htc.ht, hash(&val[0], NULL), &val[0]);
+	ok1(htc.num_alloc == 2);
+	ok1(htc.num_free == 2);
+	htable_add(&htc.ht, hash(&val[1], NULL), &val[1]);
+	ok1(htc.num_alloc == 2);
+	ok1(htc.num_free == 2);
+	htable_clear(&htc.ht);
+
+	/* This exits depending on whether all tests passed */
+	return exit_status();
+}