MDEV-16264 Use threadpool for Innodb background work.

Almost all threads have gone
- the "ticking" threads, that sleep a while then do some work)
(srv_monitor_thread, srv_error_monitor_thread, srv_master_thread)
were replaced with timers. Some timers are periodic,
e.g the "master" timer.

- The btr_defragment_thread is also replaced by a timer , which
reschedules it self when current defragment "item" needs throttling

- the buf_resize_thread and buf_dump_threads are substitutes with tasks
Ditto with page cleaner workers.

- purge workers threads are not tasks as well, and purge cleaner
coordinator is a combination of a task and timer.

- All AIO is outsourced to tpool, Innodb just calls thread_pool::submit_io()
and provides the callback.

- The srv_slot_t was removed, and innodb_debug_sync used in purge
is currently not working, and needs reimplementation.

1 files changed, 1 insertions, 3 deletions

diff --git a/storage/innobase/include/buf0flu.h b/storage/innobase/include/buf0flu.h
index 3753cb05651..ea26dbe9106 100644
--- a/storage/innobase/include/buf0flu.h
+++ b/storage/innobase/include/buf0flu.h
@@ -269,9 +269,7 @@ buf_flush_free_flush_rbt(void);
 
 /********************************************************************//**
 Writes a flushable page asynchronously from the buffer pool to a file.
-NOTE: in simulated aio we must call
-os_aio_simulated_wake_handler_threads after we have posted a batch of
-writes! NOTE: buf_pool->mutex and buf_page_get_mutex(bpage) must be
+NOTE: buf_pool->mutex and buf_page_get_mutex(bpage) must be
 held upon entering this function, and they will be released by this
 function.
 @return TRUE if page was flushed */