MDEV-11455: create status variable innodb_buffer_pool_load_incomplete

This status variable indicates that an innodb buffer pool load never
completed and dumping at shutdown would result in an incomplete dump file.

This status variable is set to 1 once a buffer pool loads. Upon a successful
load this status variable returns to 0.

With this status variable set, the system variable
innodb_buffer_pool_dump_at_shutdown==1 will have no effect as dumping after
an incomplete load will generate a less complete dump file than the current
one.

If a user aborts a buffer pool load by changing the system variable
innodb_buffer_pool_load_abort=1 will cause the the status variable
innodb_buffer_pool_load_incomplete to remain set to 1.

A shutdown that occurs while innodb is loading the buffer pool will
not save the buffer pool on shutdown.

A user may indirectly set innodb_buffer_pool_load_incomplete
to 0 by:
* Forcing a load, by setting innodb_buffer_pool_load_now=ON, or
* Forcing a dump, by setting innodb_buffer_pool_dump_now=ON

This will enable the next dump on shutdown to complete.
Signed-off-by: Daniel Black <daniel.black@au.ibm.com>

storage/innobase/buf/buf0dump.cc

@@ -413,6 +413,11 @@ buf_dump(
 
 	buf_dump_status(STATUS_INFO,
 			"Buffer pool(s) dump completed at %s", now);
+
+	/* Though dumping doesn't related to an incomplete load,
+	 we reset this to 0 here to indicate that a shutdown can also perform
+	 a dump */
+	export_vars.innodb_buffer_pool_load_incomplete = 0;
 }
 
 /*****************************************************************//**
@@ -576,6 +581,8 @@ buf_load()
 
 	rewind(f);
 
+	export_vars.innodb_buffer_pool_load_incomplete = 1;
+
 	for (i = 0; i < dump_n && !SHUTTING_DOWN(); i++) {
 		fscanf_ret = fscanf(f, ULINTPF "," ULINTPF,
 				    &space_id, &page_no);
@@ -723,8 +730,23 @@ buf_load()
 
 	ut_sprintf_timestamp(now);
 
-	buf_load_status(STATUS_INFO,
+	if (i == dump_n) {
+		buf_load_status(STATUS_INFO,
 			"Buffer pool(s) load completed at %s", now);
+		export_vars.innodb_buffer_pool_load_incomplete = 0;
+	} else if (!buf_load_abort_flag) {
+		buf_load_status(STATUS_INFO,
+			"Buffer pool(s) load aborted due to user instigated abort at %s",
+			now);
+		/* intentionally don't reset innodb_buffer_pool_load_incomplete
+                   as we don't want a shutdown to save the buffer pool */
+	} else {
+		buf_load_status(STATUS_INFO,
+			"Buffer pool(s) load aborted due to shutdown at %s",
+			now);
+		/* intentionally don't reset innodb_buffer_pool_load_incomplete
+                   as we want to abort without saving the buffer pool */
+	}
 
 	/* Make sure that estimated = completed when we end. */
 	/* mysql_stage_set_work_completed(pfs_stage_progress, dump_n); */
@@ -793,15 +815,16 @@ DECLARE_THREAD(buf_dump_thread)(void*)
 	}
 
 	if (srv_buffer_pool_dump_at_shutdown && srv_fast_shutdown != 2) {
+		if (export_vars.innodb_buffer_pool_load_incomplete) {
+			buf_dump_status(STATUS_INFO,
+				"Dumping of buffer pool not started"
+				" as load was incomplete");
 #ifdef WITH_WSREP
-		if (!wsrep_recovery) {
+		} else if (wsrep_recovery) {
 #endif /* WITH_WSREP */
-
-		buf_dump(FALSE /* ignore shutdown down flag,
-		keep going even if we are in a shutdown state */);
-#ifdef WITH_WSREP
+		} else {
+			buf_dump(FALSE/* do complete dump at shutdown */);
 		}
-#endif /* WITH_WSREP */
 	}
 
 	srv_buf_dump_thread_active = false;

storage/innobase/handler/ha_innodb.cc

@@ -931,6 +931,8 @@ static SHOW_VAR innodb_status_variables[]= {
   (char*) &export_vars.innodb_buffer_pool_load_status,	  SHOW_CHAR},
   {"buffer_pool_resize_status",
   (char*) &export_vars.innodb_buffer_pool_resize_status,  SHOW_CHAR},
+  {"buffer_pool_load_incomplete",
+  &export_vars.innodb_buffer_pool_load_incomplete,        SHOW_BOOL},
   {"buffer_pool_pages_data",
   (char*) &export_vars.innodb_buffer_pool_pages_data,	  SHOW_LONG},
   {"buffer_pool_bytes_data",

storage/innobase/include/srv0srv.h

@@ -946,6 +946,7 @@ struct export_var_t{
 	char  innodb_buffer_pool_dump_status[OS_FILE_MAX_PATH + 128];/*!< Buf pool dump status */
 	char  innodb_buffer_pool_load_status[OS_FILE_MAX_PATH + 128];/*!< Buf pool load status */
 	char  innodb_buffer_pool_resize_status[512];/*!< Buf pool resize status */
+	my_bool innodb_buffer_pool_load_incomplete;/*!< Buf pool load incomplete */
 	ulint innodb_buffer_pool_pages_total;	/*!< Buffer pool size */
 	ulint innodb_buffer_pool_pages_data;	/*!< Data pages */
 	ulint innodb_buffer_pool_bytes_data;	/*!< File bytes used */