MDEV-5675 - Performance: my_hash_sort_bin is called too often

Reduced number of my_hash_sort_bin() calls from 4 to 1 per query.
Reduced number of memory accesses done by my_hash_sort_bin().

Details:
- let MDL subsystem use pre-calculated hash value for hash
  inserts and deletes
- let table cache use pre-calculated MDL hash value
- MDL namespace is excluded from hash value calculation, so that
  hash value can be used by table cache as is
- hash value for MDL is calculated as resulting hash value + MDL
  namespace
- extended hash implementation to accept user defined hash function

1 files changed, 2 insertions, 2 deletions

diff --git a/mysys/thr_mutex.c b/mysys/thr_mutex.c
index c70aa342802..18af5f47b10 100644
--- a/mysys/thr_mutex.c
+++ b/mysys/thr_mutex.c
@@ -174,12 +174,12 @@ static int safe_mutex_lazy_init_deadlock_detection(safe_mutex_t *mp)
              128,
              offsetof(safe_mutex_deadlock_t, id),
              sizeof(mp->id),
-             0, 0, HASH_UNIQUE);
+             0, 0, 0, HASH_UNIQUE);
   my_hash_init2(mp->used_mutex, 64, &my_charset_bin,
              128,
              offsetof(safe_mutex_t, id),
              sizeof(mp->id),
-             0, 0, HASH_UNIQUE);
+             0, 0, 0, HASH_UNIQUE);
   return 0;
 }