MDEV-32899 instrumentation

In debug builds, let us declare dict_sys.latch as index_lock instead of
srw_lock, so that we will benefit from the full tracking of lock ownership.

lock_table_for_trx(): Assert that the current thread is not holding
dict_sys.latch. If the dict_sys.unfreeze() call were moved to the end of
lock_table_children(), this assertion would fail in the test innodb.innodb
and many other tests that use FOREIGN KEY.

mysql-test/suite/perfschema/r/sxlock_func,debug.rdiff

@@ -0,0 +1,22 @@
+@@ -7,7 +7,6 @@
+ WHERE name LIKE 'wait/synch/rwlock/innodb/%'
+ AND name!='wait/synch/rwlock/innodb/btr_search_latch' ORDER BY name;
+ name
+-wait/synch/rwlock/innodb/dict_operation_lock
+ wait/synch/rwlock/innodb/fil_space_latch
+ wait/synch/rwlock/innodb/lock_latch
+ wait/synch/rwlock/innodb/trx_i_s_cache_lock
+@@ -19,11 +18,13 @@
+ select name from performance_schema.setup_instruments
+ where name like "wait/synch/sxlock/%" order by name;
+ name
++wait/synch/sxlock/innodb/dict_operation_lock
+ wait/synch/sxlock/innodb/index_tree_rw_lock
+ SELECT DISTINCT name FROM performance_schema.rwlock_instances
+ WHERE name LIKE 'wait/synch/sxlock/innodb/%'
+ ORDER BY name;
+ name
++wait/synch/sxlock/innodb/dict_operation_lock
+ wait/synch/sxlock/innodb/index_tree_rw_lock
+ create table t1(a int) engine=innodb;
+ begin;

mysql-test/suite/perfschema/t/sxlock_func.test

@@ -5,6 +5,7 @@
 --source include/not_embedded.inc
 --source include/have_perfschema.inc
 --source include/have_innodb.inc
+--source include/maybe_debug.inc
 
 UPDATE performance_schema.setup_instruments SET enabled = 'NO', timed = 'YES';
 

storage/innobase/dict/dict0dict.cc

@@ -958,11 +958,12 @@ void dict_sys_t::lock_wait(SRW_LOCK_ARGS(const char *file, unsigned line))
   if (latch_ex_wait_start.compare_exchange_strong
       (old, now, std::memory_order_relaxed, std::memory_order_relaxed))
   {
+#ifdef UNIV_DEBUG
+    latch.x_lock(SRW_LOCK_ARGS(file, line));
+#else
     latch.wr_lock(SRW_LOCK_ARGS(file, line));
+#endif
     latch_ex_wait_start.store(0, std::memory_order_relaxed);
-    ut_ad(!latch_readers);
-    ut_ad(!latch_ex);
-    ut_d(latch_ex= pthread_self());
     return;
   }
 
@@ -977,33 +978,39 @@ void dict_sys_t::lock_wait(SRW_LOCK_ARGS(const char *file, unsigned line))
   if (waited > threshold / 4)
     ib::warn() << "A long wait (" << waited
                << " seconds) was observed for dict_sys.latch";
+#ifdef UNIV_DEBUG
+  latch.x_lock(SRW_LOCK_ARGS(file, line));
+#else
   latch.wr_lock(SRW_LOCK_ARGS(file, line));
-  ut_ad(!latch_readers);
+#endif
-  ut_ad(!latch_ex);
-  ut_d(latch_ex= pthread_self());
 }
 
 #ifdef UNIV_PFS_RWLOCK
 ATTRIBUTE_NOINLINE void dict_sys_t::unlock()
 {
-  ut_ad(latch_ex == pthread_self());
+# ifdef UNIV_DEBUG
-  ut_ad(!latch_readers);
+  latch.x_unlock();
-  ut_d(latch_ex= 0);
+# else
   latch.wr_unlock();
+# endif
 }
 
 ATTRIBUTE_NOINLINE void dict_sys_t::freeze(const char *file, unsigned line)
 {
+# ifdef UNIV_DEBUG
+  latch.s_lock(file, line);
+# else
   latch.rd_lock(file, line);
-  ut_ad(!latch_ex);
+# endif
-  ut_d(latch_readers++);
 }
 
 ATTRIBUTE_NOINLINE void dict_sys_t::unfreeze()
 {
-  ut_ad(!latch_ex);
+# ifdef UNIV_DEBUG
-  ut_ad(latch_readers--);
+  latch.s_unlock();
+# else
   latch.rd_unlock();
+# endif
 }
 #endif /* UNIV_PFS_RWLOCK */
 
@@ -4533,7 +4540,11 @@ void dict_sys_t::close()
   temp_id_hash.free();
 
   unlock();
+#ifdef UNIV_DEBUG
+  latch.free();
+#else
   latch.destroy();
+#endif
 
   mysql_mutex_destroy(&dict_foreign_err_mutex);
 

storage/innobase/handler/ha_innodb.cc

@@ -598,7 +598,13 @@ static PSI_rwlock_info all_innodb_rwlocks[] =
 #  ifdef BTR_CUR_HASH_ADAPT
   { &btr_search_latch_key, "btr_search_latch", 0 },
 #  endif
-  { &dict_operation_lock_key, "dict_operation_lock", 0 },
+  { &dict_operation_lock_key, "dict_operation_lock",
+#  ifdef UNIV_DEBUG
+    PSI_RWLOCK_FLAG_SX
+#  else
+    0
+#  endif
+  },
   { &fil_space_latch_key, "fil_space_latch", 0 },
   { &trx_i_s_cache_lock_key, "trx_i_s_cache_lock", 0 },
   { &trx_purge_latch_key, "trx_purge_latch", 0 },

storage/innobase/include/dict0dict.h

@@ -1316,14 +1316,14 @@ class dict_sys_t
   /** The my_hrtime_coarse().val of the oldest lock_wait() start, or 0 */
   std::atomic<ulonglong> latch_ex_wait_start;
 
-  /** the rw-latch protecting the data dictionary cache */
-  alignas(CPU_LEVEL1_DCACHE_LINESIZE) srw_lock latch;
 #ifdef UNIV_DEBUG
-  /** whether latch is being held in exclusive mode (by any thread) */
+  typedef index_lock dict_lock;
-  Atomic_relaxed<pthread_t> latch_ex;
+#else
-  /** number of S-latch holders */
+  typedef srw_lock dict_lock;
-  Atomic_counter<uint32_t> latch_readers;
 #endif
+
+  /** the rw-latch protecting the data dictionary cache */
+  alignas(CPU_LEVEL1_DCACHE_LINESIZE) dict_lock latch;
 public:
   /** Indexes of SYS_TABLE[] */
   enum
@@ -1491,15 +1491,12 @@ public:
   }
 
 #ifdef UNIV_DEBUG
-  /** @return whether any thread (not necessarily the current thread)
+  /** @return whether the current thread is holding the latch */
-  is holding the latch; that is, this check may return false
+  bool frozen() const { return latch.have_any(); }
-  positives */
+  /** @return whether the current thread is holding a shared latch */
-  bool frozen() const { return latch_readers || latch_ex; }
+  bool frozen_not_locked() const { return latch.have_s(); }
-  /** @return whether any thread (not necessarily the current thread)
-  is holding a shared latch */
-  bool frozen_not_locked() const { return latch_readers; }
   /** @return whether the current thread holds the exclusive latch */
-  bool locked() const { return latch_ex == pthread_self(); }
+  bool locked() const { return latch.have_x(); }
 #endif
 private:
   /** Acquire the exclusive latch */
@@ -1514,13 +1511,11 @@ public:
   /** Exclusively lock the dictionary cache. */
   void lock(SRW_LOCK_ARGS(const char *file, unsigned line))
   {
-    if (latch.wr_lock_try())
+#ifdef UNIV_DEBUG
-    {
+    if (!latch.x_lock_try())
-      ut_ad(!latch_readers);
+#else
-      ut_ad(!latch_ex);
+    if (!latch.wr_lock_try())
-      ut_d(latch_ex= pthread_self());
+#endif
-    }
-    else
       lock_wait(SRW_LOCK_ARGS(file, line));
   }
 
@@ -1535,24 +1530,29 @@ public:
   /** Unlock the data dictionary cache. */
   void unlock()
   {
-    ut_ad(latch_ex == pthread_self());
+# ifdef UNIV_DEBUG
-    ut_ad(!latch_readers);
+    latch.x_unlock();
-    ut_d(latch_ex= 0);
+# else
     latch.wr_unlock();
+# endif
   }
   /** Acquire a shared lock on the dictionary cache. */
   void freeze()
   {
+# ifdef UNIV_DEBUG
+    latch.s_lock();
+# else
     latch.rd_lock();
-    ut_ad(!latch_ex);
+# endif
-    ut_d(latch_readers++);
   }
   /** Release a shared lock on the dictionary cache. */
   void unfreeze()
   {
-    ut_ad(!latch_ex);
+# ifdef UNIV_DEBUG
-    ut_ad(latch_readers--);
+    latch.s_unlock();
+# else
     latch.rd_unlock();
+# endif
   }
 #endif
 

storage/innobase/lock/lock0lock.cc

@@ -3940,6 +3940,8 @@ static void lock_table_dequeue(lock_t *in_lock, bool owns_wait_mutex)
 dberr_t lock_table_for_trx(dict_table_t *table, trx_t *trx, lock_mode mode,
                            bool no_wait)
 {
+  ut_ad(!dict_sys.frozen());
+
   mem_heap_t *heap= mem_heap_create(512);
   sel_node_t *node= sel_node_create(heap);
   que_thr_t *thr= pars_complete_graph_for_exec(node, trx, heap, nullptr);