MDEV-28542 Useless output in SHOW ENGINE INNODB STATUS

srv_printf_innodb_monitor(): Only display an ADAPTIVE HASH INDEX
section if the adaptive hash index is enabled.

ibuf_print(): Only display an INSERT BUFFER section if the
change buffer is not empty.

mysql-test/suite/innodb/r/innodb-change-buffer-recovery.result

@@ -39,19 +39,13 @@ Table	Op	Msg_type	Msg_text
 test.t1	check	Error	Unknown storage engine 'InnoDB'
 test.t1	check	error	Corrupt
 FOUND 1 /innodb_read_only prevents crash recovery/ in mysqld.1.err
-# restart: --innodb-force-recovery=5
+# restart: --innodb-force-recovery=5 --debug-dbug=d,crash_after_log_ibuf_upd_inplace
 SELECT * FROM t1 LIMIT 1;
 a	b	c
 1	X	1
-SHOW ENGINE INNODB STATUS;
-Type	Name	Status
-InnoDB		insert 0, delete mark 0
 SET GLOBAL innodb_fast_shutdown=0;
 # restart
 CHECK TABLE t1;
 Table	Op	Msg_type	Msg_text
 test.t1	check	status	OK
-SHOW ENGINE INNODB STATUS;
-Type	Name	Status
-InnoDB		
 DROP TABLE t1;

mysql-test/suite/innodb/t/innodb-change-buffer-recovery.test

@@ -67,16 +67,12 @@ CHECK TABLE t1;
 let SEARCH_PATTERN=innodb_read_only prevents crash recovery;
 --source include/search_pattern_in_file.inc
 
---let $restart_parameters= --innodb-force-recovery=5
+--let $restart_parameters= --innodb-force-recovery=5 --debug-dbug=d,crash_after_log_ibuf_upd_inplace
 --source include/start_mysqld.inc
 SELECT * FROM t1 LIMIT 1;
-replace_regex /.*operations:.* (insert.*), delete \d.*discarded .*/\1/;
-SHOW ENGINE INNODB STATUS;
 # Slow shutdown will not merge the changes due to innodb_force_recovery=5.
 SET GLOBAL innodb_fast_shutdown=0;
 --let $restart_parameters=
 --source include/restart_mysqld.inc
 CHECK TABLE t1;
-replace_regex /.*operations:.* insert [1-9][0-9]*, delete mark [1-9][0-9]*, delete \d.*discarded .*//;
-SHOW ENGINE INNODB STATUS;
 DROP TABLE t1;

storage/innobase/ibuf/ibuf0ibuf.cc

@@ -1218,6 +1218,7 @@ static
 void
 ibuf_print_ops(
 /*===========*/
+	const char*			op_name,/*!< in: operation name */
 	const Atomic_counter<ulint>*	ops,	/*!< in: operation counts */
 	FILE*				file)	/*!< in: file where to print */
 {
@@ -1226,11 +1227,11 @@ ibuf_print_ops(
 		"delete mark",
 		"delete"
 	};
-	ulint	i;
 
-	ut_a(UT_ARR_SIZE(op_names) == IBUF_OP_COUNT);
+	static_assert(array_elements(op_names) == IBUF_OP_COUNT, "");
+	fputs(op_name, file);
 
-	for (i = 0; i < IBUF_OP_COUNT; i++) {
+	for (ulint i = 0; i < IBUF_OP_COUNT; i++) {
 		fprintf(file, "%s " ULINTPF "%s", op_names[i],
 			ulint{ops[i]}, (i < (IBUF_OP_COUNT - 1)) ? ", " : "");
 	}
@@ -4547,23 +4548,28 @@ ibuf_print(
 /*=======*/
 	FILE*	file)	/*!< in: file where to print */
 {
-	mysql_mutex_lock(&ibuf_mutex);
-
-	fprintf(file,
-		"Ibuf: size " ULINTPF ", free list len " ULINTPF ","
-		" seg size " ULINTPF ", " ULINTPF " merges\n",
-		ibuf.size,
-		ibuf.free_list_len,
-		ibuf.seg_size,
-		ulint{ibuf.n_merges});
 
-	fputs("merged operations:\n ", file);
-	ibuf_print_ops(ibuf.n_merged_ops, file);
-
-	fputs("discarded operations:\n ", file);
-	ibuf_print_ops(ibuf.n_discarded_ops, file);
-
-	mysql_mutex_unlock(&ibuf_mutex);
+  mysql_mutex_lock(&ibuf_mutex);
+  if (ibuf.empty)
+  {
+    mysql_mutex_unlock(&ibuf_mutex);
+    return;
+  }
+
+  const ulint size= ibuf.size;
+  const ulint free_list_len= ibuf.free_list_len;
+  const ulint seg_size= ibuf.seg_size;
+  mysql_mutex_unlock(&ibuf_mutex);
+
+  fprintf(file,
+          "-------------\n"
+          "INSERT BUFFER\n"
+          "-------------\n"
+          "size " ULINTPF ", free list len " ULINTPF ","
+          " seg size " ULINTPF ", " ULINTPF " merges\n",
+          size, free_list_len, seg_size, ulint{ibuf.n_merges});
+  ibuf_print_ops("merged operations:\n", ibuf.n_merged_ops, file);
+  ibuf_print_ops("discarded operations:\n", ibuf.n_discarded_ops, file);
 }
 
 /** Check the insert buffer bitmaps on IMPORT TABLESPACE.

storage/innobase/srv/srv0srv.cc

@@ -828,34 +828,36 @@ srv_printf_innodb_monitor(
 	      "--------\n", file);
 	os_aio_print(file);
 
-	fputs("-------------------------------------\n"
-	      "INSERT BUFFER AND ADAPTIVE HASH INDEX\n"
-	      "-------------------------------------\n", file);
 	ibuf_print(file);
 
 #ifdef BTR_CUR_HASH_ADAPT
-	for (ulint i = 0; i < btr_ahi_parts && btr_search_enabled; ++i) {
-		const auto part= &btr_search_sys.parts[i];
-		part->latch.rd_lock(SRW_LOCK_CALL);
-		ut_ad(part->heap->type == MEM_HEAP_FOR_BTR_SEARCH);
-		fprintf(file, "Hash table size " ULINTPF
-			", node heap has " ULINTPF " buffer(s)\n",
-			part->table.n_cells,
-			part->heap->base.count - !part->heap->free_block);
-		part->latch.rd_unlock();
-	}
+	if (btr_search_enabled) {
+		fputs("-------------------\n"
+		      "ADAPTIVE HASH INDEX\n"
+		      "-------------------\n", file);
+		for (ulint i = 0; i < btr_ahi_parts; ++i) {
+			const auto part= &btr_search_sys.parts[i];
+			part->latch.rd_lock(SRW_LOCK_CALL);
+			ut_ad(part->heap->type == MEM_HEAP_FOR_BTR_SEARCH);
+			fprintf(file, "Hash table size " ULINTPF
+				", node heap has " ULINTPF " buffer(s)\n",
+				part->table.n_cells,
+				part->heap->base.count
+				- !part->heap->free_block);
+			part->latch.rd_unlock();
+		}
 
-	/* btr_cur_n_sea_old and btr_cur_n_non_sea_old are protected by
-	srv_innodb_monitor_mutex (srv_refresh_innodb_monitor_stats) */
-	const ulint with_ahi = btr_cur_n_sea, without_ahi = btr_cur_n_non_sea;
-	fprintf(file,
-		"%.2f hash searches/s, %.2f non-hash searches/s\n",
-		static_cast<double>(with_ahi - btr_cur_n_sea_old)
-		/ time_elapsed,
-		static_cast<double>(without_ahi - btr_cur_n_non_sea_old)
-		/ time_elapsed);
-	btr_cur_n_sea_old = with_ahi;
-	btr_cur_n_non_sea_old = without_ahi;
+		const ulint with_ahi = btr_cur_n_sea;
+		const ulint without_ahi = btr_cur_n_non_sea;
+		fprintf(file,
+			"%.2f hash searches/s, %.2f non-hash searches/s\n",
+			static_cast<double>(with_ahi - btr_cur_n_sea_old)
+			/ time_elapsed,
+			static_cast<double>(without_ahi - btr_cur_n_non_sea_old)
+			/ time_elapsed);
+		btr_cur_n_sea_old = with_ahi;
+		btr_cur_n_non_sea_old = without_ahi;
+	}
 #endif /* BTR_CUR_HASH_ADAPT */
 
 	fputs("---\n"