Hi Sergei, On Fri, Jun 23, 2017 at 12:47:46PM +0200, Sergei Golubchik wrote: > Hi, Sergey! > > On Jun 22, Sergey Vojtovich wrote: > > revision-id: 62021f391a42c5577190aa43cb8ad91e56235b46 > > (mariadb-10.2.6-57-g62021f3) > > parent(s): 557e1bd472612848a42e772c1fb6f8ed32ab33b4 > > committer: Sergey Vojtovich > > timestamp: 2017-06-22 17:15:10 +0400 > > message: > > > > MDEV-12070 - Introduce thd_query_safe() from MySQL 5.7 > > > > Merged relevant part of MySQL revision: > > https://github.com/mysql/mysql-server/commit/565d20b44f24fcc855dc616164d87b03cfad10bc > > > > diff --git a/sql/sql_class.cc b/sql/sql_class.cc > > index f8cf829..db65eb3 100644 > > --- a/sql/sql_class.cc > > +++ b/sql/sql_class.cc > > @@ -4529,6 +4529,32 @@ extern "C" LEX_STRING * thd_query_string (MYSQL_THD > > thd) > > return(&thd->query_string.string); > > } > > > > + > > +/** > > + Get the current query string for the thread. > > + > > + @param thd The MySQL internal thread pointer > > + @param buf Buffer where the query string will be copied > > + @param buflen Length of the buffer > > + > > + @return Length of the query > > + > > + @note This function is thread safe as the query string is > > + accessed under mutex protection and the string is copied > > + into the provided buffer. @see thd_query_string(). > > +*/ > > + > > +extern "C" size_t thd_query_safe(MYSQL_THD thd, char *buf, size_t buflen) > > +{ > > + mysql_mutex_lock(&thd->LOCK_thd_data); > > + size_t len= MY_MIN(buflen - 1, thd->query_length()); > > + memcpy(buf, thd->query(), len); > > + mysql_mutex_unlock(&thd->LOCK_thd_data); > > + buf[len]= '\0'; > > + return len; > > +} > > Okay. But as neither thd_query_string() nor thd_query() are part of the > plugin API, I'd suggest to remove them, they're inherently unsafe and > should not be used. Few other engines use thd_query_string() need to be > fixed too (but they bypass the plugin API and we don't promise stability > for internal functions). thd_query() - yes, this looks fairly broken. thd_query_string() - I'd say this one should stay, because in most cases we need to access query_string from the same thread; in this case we better avoid mutex for performance reasons.
Thanks, Sergey _______________________________________________ Mailing list: https://launchpad.net/~maria-developers Post to : maria-developers@lists.launchpad.net Unsubscribe : https://launchpad.net/~maria-developers More help : https://help.launchpad.net/ListHelp
