htable: add and integrate htable_check function.

Trying to debug what looked like an htable fail in my own code (but seems
it's not), I added htable_check a-la list_check et al.

This means we now depend on ccan/str (for stringify), which breaks the
_info example which also defined streq, and played nasty with const pointers.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

ccan/htable/_info

@@ -41,7 +41,7 @@
  *	}
  *
  *	// Comparison function.
- *	static bool streq(const void *e, void *string)
+ *	static bool nameeq(const void *e, void *string)
  *	{
  *		return strcmp(((struct name_to_digit *)e)->name, string) == 0;
  *	}
@@ -49,13 +49,13 @@
  *	// We let them add their own aliases, eg. --alias=v=5
  *	static void add_alias(struct htable *ht, const char *alias)
  *	{
- *		char *eq;
+ *		char *eq, *name;
  *		struct name_to_digit *n;
  *
  *		n = malloc(sizeof(*n));
- *		n->name = strdup(alias);
+ *		n->name = name = strdup(alias);
  *
- *		eq = strchr(n->name, '=');
+ *		eq = strchr(name, '=');
  *		if (!eq || ((n->val = atoi(eq+1)) == 0 && !strcmp(eq+1, "0")))
  *			errx(1, "Usage: --alias=<name>=<value>");
  *		*eq = '\0';
@@ -89,7 +89,7 @@
  *		for (val = 0; i < argc; i++) {
  *			struct name_to_digit *n;
  *			n = htable_get(&ht, hash_string(argv[i]),
- *				       streq, argv[i]);
+ *				       nameeq, argv[i]);
  *			if (!n)
  *				errx(1, "Invalid digit name %s", argv[i]);
  *			// Append it to the value we are building up.
@@ -110,6 +110,7 @@ int main(int argc, char *argv[])
 
 	if (strcmp(argv[1], "depends") == 0) {
 		printf("ccan/compiler\n");
+		printf("ccan/str\n");
 		return 0;
 	}
 

ccan/htable/htable.c

@@ -2,6 +2,7 @@
 #include <ccan/htable/htable.h>
 #include <ccan/compiler/compiler.h>
 #include <stdlib.h>
+#include <stdio.h>
 #include <limits.h>
 #include <stdbool.h>
 #include <assert.h>
@@ -78,6 +79,7 @@ bool htable_init_sized(struct htable *ht,
 		return false;
 	}
 	htable_adjust_capacity(ht);
+	(void)htable_debug(ht, HTABLE_LOC);
 	return true;
 }
 	
@@ -88,7 +90,7 @@ void htable_clear(struct htable *ht)
 	htable_init(ht, ht->rehash, ht->priv);
 }
 
-bool htable_copy(struct htable *dst, const struct htable *src)
+bool htable_copy_(struct htable *dst, const struct htable *src)
 {
 	uintptr_t *htable = malloc(sizeof(size_t) << src->bits);
 
@@ -122,21 +124,21 @@ static void *htable_val(const struct htable *ht,
 	return NULL;
 }
 
-void *htable_firstval(const struct htable *ht,
-		      struct htable_iter *i, size_t hash)
+void *htable_firstval_(const struct htable *ht,
+		       struct htable_iter *i, size_t hash)
 {
 	i->off = hash_bucket(ht, hash);
 	return htable_val(ht, i, hash, ht->perfect_bit);
 }
 
-void *htable_nextval(const struct htable *ht,
-		     struct htable_iter *i, size_t hash)
+void *htable_nextval_(const struct htable *ht,
+		      struct htable_iter *i, size_t hash)
 {
 	i->off = (i->off + 1) & ((1 << ht->bits)-1);
 	return htable_val(ht, i, hash, 0);
 }
 
-void *htable_first(const struct htable *ht, struct htable_iter *i)
+void *htable_first_(const struct htable *ht, struct htable_iter *i)
 {
 	for (i->off = 0; i->off < (size_t)1 << ht->bits; i->off++) {
 		if (entry_is_valid(ht->table[i->off]))
@@ -145,7 +147,7 @@ void *htable_first(const struct htable *ht, struct htable_iter *i)
 	return NULL;
 }
 
-void *htable_next(const struct htable *ht, struct htable_iter *i)
+void *htable_next_(const struct htable *ht, struct htable_iter *i)
 {
 	for (i->off++; i->off < (size_t)1 << ht->bits; i->off++) {
 		if (entry_is_valid(ht->table[i->off]))
@@ -154,7 +156,7 @@ void *htable_next(const struct htable *ht, struct htable_iter *i)
 	return NULL;
 }
 
-void *htable_prev(const struct htable *ht, struct htable_iter *i)
+void *htable_prev_(const struct htable *ht, struct htable_iter *i)
 {
 	for (;;) {
 		if (!i->off)
@@ -215,6 +217,8 @@ static COLD bool double_table(struct htable *ht)
 		free(oldtable);
 	}
 	ht->deleted = 0;
+
+	(void)htable_debug(ht, HTABLE_LOC);
 	return true;
 }
 
@@ -240,6 +244,7 @@ static COLD void rehash_table(struct htable *ht)
 		}
 	}
 	ht->deleted = 0;
+	(void)htable_debug(ht, HTABLE_LOC);
 }
 
 /* We stole some bits, now we need to put them back... */
@@ -261,6 +266,7 @@ static COLD void update_common(struct htable *ht, const void *p)
 		ht->common_mask = ~((uintptr_t)1 << i);
 		ht->common_bits = ((uintptr_t)p & ht->common_mask);
 		ht->perfect_bit = 1;
+		(void)htable_debug(ht, HTABLE_LOC);
 		return;
 	}
 
@@ -283,9 +289,10 @@ static COLD void update_common(struct htable *ht, const void *p)
 	ht->common_mask &= ~maskdiff;
 	ht->common_bits &= ~maskdiff;
 	ht->perfect_bit &= ~maskdiff;
+	(void)htable_debug(ht, HTABLE_LOC);
 }
 
-bool htable_add(struct htable *ht, size_t hash, const void *p)
+bool htable_add_(struct htable *ht, size_t hash, const void *p)
 {
 	if (ht->elems+1 > ht->max && !double_table(ht))
 		return false;
@@ -300,7 +307,7 @@ bool htable_add(struct htable *ht, size_t hash, const void *p)
 	return true;
 }
 
-bool htable_del(struct htable *ht, size_t h, const void *p)
+bool htable_del_(struct htable *ht, size_t h, const void *p)
 {
 	struct htable_iter i;
 	void *c;
@@ -314,7 +321,7 @@ bool htable_del(struct htable *ht, size_t h, const void *p)
 	return false;
 }
 
-void htable_delval(struct htable *ht, struct htable_iter *i)
+void htable_delval_(struct htable *ht, struct htable_iter *i)
 {
 	assert(i->off < (size_t)1 << ht->bits);
 	assert(entry_is_valid(ht->table[i->off]));
@@ -323,3 +330,53 @@ void htable_delval(struct htable *ht, struct htable_iter *i)
 	ht->table[i->off] = HTABLE_DELETED;
 	ht->deleted++;
 }
+
+struct htable *htable_check(const struct htable *ht, const char *abortstr)
+{
+	void *p;
+	struct htable_iter i;
+	size_t n = 0;
+
+	/* Use non-DEBUG versions here, to avoid infinite recursion with
+	 * CCAN_HTABLE_DEBUG! */
+	for (p = htable_first_(ht, &i); p; p = htable_next_(ht, &i)) {
+		struct htable_iter i2;
+		void *c;
+		size_t h = ht->rehash(p, ht->priv);
+		bool found = false;
+
+		n++;
+
+		/* Open-code htable_get to avoid CCAN_HTABLE_DEBUG */
+		for (c = htable_firstval_(ht, &i2, h);
+		     c;
+		     c = htable_nextval_(ht, &i2, h)) {
+			if (c == p) {
+				found = true;
+				break;
+			}
+		}
+
+		if (!found) {
+			if (abortstr) {
+				fprintf(stderr,
+					"%s: element %p in position %zu"
+					" cannot find itself\n",
+					abortstr, p, i.off);
+				abort();
+			}
+			return NULL;
+		}
+	}
+	if (n != ht->elems) {
+		if (abortstr) {
+			fprintf(stderr,
+				"%s: found %zu elems, expected %zu\n",
+				abortstr, n, ht->elems);
+			abort();
+		}
+		return NULL;
+	}
+
+	return (struct htable *)ht;
+}

ccan/htable/htable.h

@@ -2,10 +2,19 @@
 #ifndef CCAN_HTABLE_H
 #define CCAN_HTABLE_H
 #include "config.h"
+#include <ccan/str/str.h>
 #include <stdint.h>
 #include <stdbool.h>
 #include <stdlib.h>
 
+/* Define CCAN_HTABLE_DEBUG for expensive debugging checks on each call. */
+#define HTABLE_LOC __FILE__ ":" stringify(__LINE__)
+#ifdef CCAN_HTABLE_DEBUG
+#define htable_debug(h, loc) htable_check((h), loc)
+#else
+#define htable_debug(h, loc) ((void)loc, h)
+#endif
+
 /**
  * struct htable - private definition of a htable.
  *
@@ -75,6 +84,22 @@ bool htable_init_sized(struct htable *ht,
  */
 void htable_clear(struct htable *ht);
 
+
+/**
+ * htable_check - check hash table for consistency
+ * @ht: the htable
+ * @abortstr: the location to print on aborting, or NULL.
+ *
+ * Because hash tables have redundant information, consistency checking that
+ * each element is in the correct location can be done.  This is useful as a
+ * debugging check.  If @abortstr is non-NULL, that will be printed in a
+ * diagnostic if the htable is inconsistent, and the function will abort.
+ *
+ * Returns the htable if it is consistent, NULL if not (it can never return
+ * NULL if @abortstr is set).
+ */
+struct htable *htable_check(const struct htable *ht, const char *abortstr);
+
 /**
  * htable_copy - duplicate a hash table.
  * @dst: the hash table to overwrite
@@ -92,14 +117,8 @@ void htable_clear(struct htable *ht);
  *    }
  *    return true;
  */
-bool htable_copy(struct htable *dst, const struct htable *src);
-
-/**
- * htable_rehash - use a hashtree's rehash function
- * @elem: the argument to rehash()
- *
- */
-size_t htable_rehash(const void *elem);
+#define htable_copy(dst, src) htable_copy_(dst, htable_debug(src, HTABLE_LOC))
+bool htable_copy_(struct htable *dst, const struct htable *src);
 
 /**
  * htable_add - add a pointer into a hash table.
@@ -110,7 +129,9 @@ size_t htable_rehash(const void *elem);
  * Also note that this can only fail due to allocation failure.  Otherwise, it
  * returns true.
  */
-bool htable_add(struct htable *ht, size_t hash, const void *p);
+#define htable_add(ht, hash, p) \
+	htable_add_(htable_debug(ht, HTABLE_LOC), hash, p)
+bool htable_add_(struct htable *ht, size_t hash, const void *p);
 
 /**
  * htable_del - remove a pointer from a hash table
@@ -120,7 +141,9 @@ bool htable_add(struct htable *ht, size_t hash, const void *p);
  *
  * Returns true if the pointer was found (and deleted).
  */
-bool htable_del(struct htable *ht, size_t hash, const void *p);
+#define htable_del(ht, hash, p) \
+	htable_del_(htable_debug(ht, HTABLE_LOC), hash, p)
+bool htable_del_(struct htable *ht, size_t hash, const void *p);
 
 /**
  * struct htable_iter - iterator or htable_first or htable_firstval etc.
@@ -141,8 +164,11 @@ struct htable_iter {
  * See Also:
  *	htable_delval()
  */
-void *htable_firstval(const struct htable *htable,
-		      struct htable_iter *i, size_t hash);
+#define htable_firstval(htable, i, hash) \
+	htable_firstval_(htable_debug(htable, HTABLE_LOC), i, hash)
+
+void *htable_firstval_(const struct htable *htable,
+		       struct htable_iter *i, size_t hash);
 
 /**
  * htable_nextval - find another candidate for a given hash value
@@ -152,8 +178,10 @@ void *htable_firstval(const struct htable *htable,
  *
  * You'll need to check the value is what you want; returns NULL if no more.
  */
-void *htable_nextval(const struct htable *htable,
-		     struct htable_iter *i, size_t hash);
+#define htable_nextval(htable, i, hash) \
+	htable_nextval_(htable_debug(htable, HTABLE_LOC), i, hash)
+void *htable_nextval_(const struct htable *htable,
+		      struct htable_iter *i, size_t hash);
 
 /**
  * htable_get - find an entry in the hash table
@@ -186,7 +214,9 @@ static inline void *htable_get(const struct htable *ht,
  *
  * Get an entry in the hashtable; NULL if empty.
  */
-void *htable_first(const struct htable *htable, struct htable_iter *i);
+#define htable_first(htable, i) \
+	htable_first_(htable_debug(htable, HTABLE_LOC), i)
+void *htable_first_(const struct htable *htable, struct htable_iter *i);
 
 /**
  * htable_next - find another entry in the hash table
@@ -196,7 +226,9 @@ void *htable_first(const struct htable *htable, struct htable_iter *i);
  * Get another entry in the hashtable; NULL if all done.
  * This is usually used after htable_first or prior non-NULL htable_next.
  */
-void *htable_next(const struct htable *htable, struct htable_iter *i);
+#define htable_next(htable, i) \
+	htable_next_(htable_debug(htable, HTABLE_LOC), i)
+void *htable_next_(const struct htable *htable, struct htable_iter *i);
 
 /**
  * htable_prev - find the previous entry in the hash table
@@ -211,7 +243,9 @@ void *htable_next(const struct htable *htable, struct htable_iter *i);
  * This is usually used in the middle of (or after) a htable_next iteration and
  * to "unwind" actions taken.
  */
-void *htable_prev(const struct htable *htable, struct htable_iter *i);
+#define htable_prev(htable, i) \
+	htable_prev_(htable_debug(htable, HTABLE_LOC), i)
+void *htable_prev_(const struct htable *htable, struct htable_iter *i);
 
 /**
  * htable_delval - remove an iterated pointer from a hash table
@@ -221,6 +255,8 @@ void *htable_prev(const struct htable *htable, struct htable_iter *i);
  * Usually used to delete a hash entry after it has been found with
  * htable_firstval etc.
  */
-void htable_delval(struct htable *ht, struct htable_iter *i);
+#define htable_delval(htable, i) \
+	htable_delval_(htable_debug(htable, HTABLE_LOC), i)
+void htable_delval_(struct htable *ht, struct htable_iter *i);
 
 #endif /* CCAN_HTABLE_H */