Problem:
========
InnoDB FTS requesting the fts sync of the table once the fts
cache size reaches 1/10 of innodb_ft_cache_size. But fts_sync()
releases cache lock when writing the word. By doing this, InnoDB
insert thread increases the innodb fts cache memory and
SYNC operation will take more time to complete.
Solution:
=========
Remove the fts sync operation(FTS_MSG_SYNC_TABLE) from
the fts optimize background thread. Instead of that,
allow user thread to sync the InnoDB fts cache when
the cache size exceeds 512 kb. User thread holds
cache lock while doing cache syncing, it make sure that
other threads doesn't add the docs into the cache.
Removed FTS_MSG_SYNC_TABLE and its related function
because we do remove the FTS_MSG_SYNC_TABLE message
itself.
Removed fts_sync_index_check() and all related
function because other threads doesn't add while
cache operation going on.
Problem:
=======
During dropping of fts index, InnoDB waits for fts_optimize_remove_table()
and it holds dict_sys->mutex and dict_operaiton_lock even though the
table id is not present in the queue. But fts_optimize_thread does wait
for dict_sys->mutex to process the unrelated table id from the slot.
Solution:
========
Whenever table is added to fts_optimize_wq, update the fts_status
of in-memory fts subsystem to TABLE_IN_QUEUE. Whenever drop index
wants to remove table from the queue, it can check the fts_status
to decide whether it should send the MSG_DELETE_TABLE to the queue.
Removed the following functions because these are all deadcode.
dict_table_wait_for_bg_threads_to_exit(),
fts_wait_for_background_thread_to_start(),fts_start_shutdown(), fts_shudown().
fts_get_next_doc_id(): Assign the first and subsequent FTS_DOC_ID
in the same way: by post-incrementing the cached value.
If there is a user-specified FTS_DOC_ID, do not touch the internal
sequence.
