mirror of
https://github.com/MariaDB/server.git
synced 2025-02-01 11:31:51 +01:00
53cc9aa5be
Take snapshot of registered read-write transaction identifiers directly from rw_trx_hash. It immediately saves one trx_sys.mutex lock, reduces size of another critical section protected by this mutex, and makes further optimisations like removing trx_sys_t::serialisation_list possible. Downside of this approach is bigger overhead for view opening, because iterating LF_HASH is more expensive compared to taking snapshot of an array. However for low concurrency overhead difference is negligible, while for high concurrency mutex is much bigger evil. Currently we still take trx_sys.mutex to serialise ReadView creation. This is required to keep serialisation_list ordered by trx->no as well as not to let purge thread to create more recent snapshot while another thread gets suspended during creation of older snapshot. This will become completely mutex free along with serialisation_list removal. Compared to previous implementation removing element from rw_trx_hash and serialisation_list is not atomic. We disregard all possible bad consequences (if there're any) since it will be solved along with serialisation_list removal. |
||
|---|---|---|
| .. | ||
| ut0crc32.cc | ||
| ut0dbg.cc | ||
| ut0list.cc | ||
| ut0mem.cc | ||
| ut0new.cc | ||
| ut0rbt.cc | ||
| ut0rnd.cc | ||
| ut0timer.cc | ||
| ut0ut.cc | ||
| ut0vec.cc | ||
| ut0wqueue.cc | ||