util/hash_table: Rework the API to know about hashing

Previously, the hash_table API required the user to do all of the hashing
of keys as it passed them in.  Since the hashing function is intrinsically
tied to the comparison function, it makes sense for the hash table to know
about it.  Also, it makes for a somewhat clumsy API as the user is
constantly calling hashing functions many of which have long names.  This
is especially bad when the standard call looks something like

_mesa_hash_table_insert(ht, _mesa_pointer_hash(key), key, data);

In the above case, there is no reason why the hash table shouldn't do the
hashing for you.  We leave the option for you to do your own hashing if
it's more efficient, but it's no longer needed.  Also, if you do do your
own hashing, the hash table will assert that your hash matches what it
expects out of the hashing function.  This should make it harder to mess up
your hashing.

v2: change to call the old entrypoint "pre_hashed" rather than
    "with_hash", like cworth's equivalent change upstream (change by
    anholt, acked-in-general by Jason).

Signed-off-by: Jason Ekstrand <[email protected]>
Signed-off-by: Eric Anholt <[email protected]>
Reviewed-by: Eric Anholt <[email protected]>

1 files changed, 15 insertions, 4 deletions

diff --git a/src/util/hash_table.h b/src/util/hash_table.h
index d6b6ebf4069..5561e158454 100644
--- a/src/util/hash_table.h
+++ b/src/util/hash_table.h
@@ -46,6 +46,7 @@ struct hash_entry {
 
 struct hash_table {
    struct hash_entry *table;
+   uint32_t (*key_hash_function)(const void *key);
    bool (*key_equals_function)(const void *a, const void *b);
    const void *deleted_key;
    uint32_t size;
@@ -58,6 +59,7 @@ struct hash_table {
 
 struct hash_table *
 _mesa_hash_table_create(void *mem_ctx,
+                        uint32_t (*key_hash_function)(const void *key),
                         bool (*key_equals_function)(const void *a,
                                                     const void *b));
 void _mesa_hash_table_destroy(struct hash_table *ht,
@@ -66,11 +68,15 @@ void _mesa_hash_table_set_deleted_key(struct hash_table *ht,
                                       const void *deleted_key);
 
 struct hash_entry *
-_mesa_hash_table_insert(struct hash_table *ht, uint32_t hash,
-                        const void *key, void *data);
+_mesa_hash_table_insert(struct hash_table *ht, const void *key, void *data);
 struct hash_entry *
-_mesa_hash_table_search(struct hash_table *ht, uint32_t hash,
-                        const void *key);
+_mesa_hash_table_insert_with_hash(struct hash_table *ht, uint32_t hash,
+                                  const void *key, void *data);
+struct hash_entry *
+_mesa_hash_table_search(struct hash_table *ht, const void *key);
+struct hash_entry *
+_mesa_hash_table_search_pre_hashed(struct hash_table *ht, uint32_t hash,
+                                  const void *key);
 void _mesa_hash_table_remove(struct hash_table *ht,
                              struct hash_entry *entry);
 
@@ -85,6 +91,11 @@ uint32_t _mesa_hash_string(const char *key);
 bool _mesa_key_string_equal(const void *a, const void *b);
 bool _mesa_key_pointer_equal(const void *a, const void *b);
 
+static inline uint32_t _mesa_key_hash_string(const void *key)
+{
+   return _mesa_hash_string((const char *)key);
+}
+
 static inline uint32_t _mesa_hash_pointer(const void *pointer)
 {
    return _mesa_hash_data(&pointer, sizeof(pointer));