MDEV-12121 Introduce build option WITH_INNODB_AHI to disable innodb_adaptive_hash_index

The InnoDB adaptive hash index is sometimes degrading the performance of
InnoDB, and it is sometimes disabled to get more consistent performance.
We should have a compile-time option to disable the adaptive hash index.

Let us introduce two options:

OPTION(WITH_INNODB_AHI "Include innodb_adaptive_hash_index" ON)
OPTION(WITH_INNODB_ROOT_GUESS "Cache index root block descriptors" ON)

where WITH_INNODB_AHI always implies WITH_INNODB_ROOT_GUESS.

As part of this change, the misleadingly named function
trx_search_latch_release_if_reserved(trx) will be replaced with the macro
trx_assert_no_search_latch(trx) that will be empty unless
BTR_CUR_HASH_ADAPT is defined (cmake -DWITH_INNODB_AHI=ON).

We will also remove the unused column
INFORMATION_SCHEMA.INNODB_TRX.TRX_ADAPTIVE_HASH_TIMEOUT.
In MariaDB Server 10.1, it used to reflect the value of
trx_t::search_latch_timeout which could be adjusted during
row_search_for_mysql(). In 10.2, there is no such field.

Other than the removal of the unused column TRX_ADAPTIVE_HASH_TIMEOUT,
this is an almost non-functional change to the server when using the
default build options.

Some tests are adjusted so that they will work with both
-DWITH_INNODB_AHI=ON and -DWITH_INNODB_AHI=OFF. The test
innodb.innodb_monitor has been renamed to innodb.monitor
in order to track MySQL 5.7, and the duplicate tests
sys_vars.innodb_monitor_* are removed.

2 files changed, 8 insertions, 2 deletions

diff --git a/storage/innobase/ha/ha0ha.cc b/storage/innobase/ha/ha0ha.cc
index cf92f22ac15..1f90738c75f 100644
--- a/storage/innobase/ha/ha0ha.cc
+++ b/storage/innobase/ha/ha0ha.cc
@@ -146,7 +146,9 @@ ha_clear(
 	hash_table_t*	table)	/*!< in, own: hash table */
 {
 	ut_ad(table->magic_n == HASH_TABLE_MAGIC_N);
+#ifdef BTR_CUR_HASH_ADAPT
 	ut_ad(!table->adaptive || btr_search_own_all(RW_LOCK_X));
+#endif /* BTR_CUR_HASH_ADAPT */
 
 	for (ulint i = 0; i < table->n_sync_obj; i++) {
 		mem_heap_free(table->heaps[i]);
@@ -189,6 +191,7 @@ ha_clear(
 	}
 }
 
+#ifdef BTR_CUR_HASH_ADAPT
 /*************************************************************//**
 Inserts an entry into a hash table. If an entry with the same fold number
 is found, its node is updated to point to the new data, and no new node
@@ -536,3 +539,4 @@ builds, see http://bugs.mysql.com/36941 */
 			(ulong) n_bufs);
 	}
 }
+#endif /* BTR_CUR_HASH_ADAPT */
diff --git a/storage/innobase/ha/hash0hash.cc b/storage/innobase/ha/hash0hash.cc
index 7c5798ae254..ef1339ff47b 100644
--- a/storage/innobase/ha/hash0hash.cc
+++ b/storage/innobase/ha/hash0hash.cc
@@ -273,9 +273,11 @@ hash_create(
 	table->type = HASH_TABLE_SYNC_NONE;
 	table->array = array;
 	table->n_cells = prime;
-#if defined UNIV_AHI_DEBUG || defined UNIV_DEBUG
+#ifdef BTR_CUR_HASH_ADAPT
+# if defined UNIV_AHI_DEBUG || defined UNIV_DEBUG
 	table->adaptive = FALSE;
-#endif /* UNIV_AHI_DEBUG || UNIV_DEBUG */
+# endif /* UNIV_AHI_DEBUG || UNIV_DEBUG */
+#endif /* BTR_CUR_HASH_ADAPT */
 	table->n_sync_obj = 0;
 	table->sync_obj.mutexes = NULL;
 	table->heaps = NULL;