/* Copyright (c) 2010, 2011, Oracle and/or its affiliates. All rights reserved. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; version 2 of the License. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1335 USA */ #ifndef MYSQL_SERVICE_THD_WAIT_INCLUDED #define MYSQL_SERVICE_THD_WAIT_INCLUDED /** @file include/mysql/service_thd_wait.h This service provides functions for plugins and storage engines to report when they are going to sleep/stall. SYNOPSIS thd_wait_begin() - call just before a wait begins thd Thread object Use NULL if the thd is NOT known. wait_type Type of wait 1 -- short wait (e.g. for mutex) 2 -- medium wait (e.g. for disk io) 3 -- large wait (e.g. for locked row/table) NOTES This is used by the threadpool to have better knowledge of which threads that currently are actively running on CPUs. When a thread reports that it's going to sleep/stall, the threadpool scheduler is free to start another thread in the pool most likely. The expected wait time is simply an indication of how long the wait is expected to become, the real wait time could be very different. thd_wait_end() called immediately after the wait is complete thd_wait_end() MUST be called if thd_wait_begin() was called. Using thd_wait_...() service is optional but recommended. Using it will improve performance as the thread pool will be more active at managing the thread workload. */ #ifdef __cplusplus extern "C" { #endif /* One should only report wait events that could potentially block for a long time. A mutex wait is too short of an event to report. The reason is that an event which is reported leads to a new thread starts executing a query and this has a negative impact of usage of CPU caches and thus the expected gain of starting a new thread must be higher than the expected cost of lost performance due to starting a new thread. Good examples of events that should be reported are waiting for row locks that could easily be for many milliseconds or even seconds and the same holds true for global read locks, table locks and other meta data locks. Another event of interest is going to sleep for an extended time. */ typedef enum _thd_wait_type_e { THD_WAIT_SLEEP= 1, THD_WAIT_DISKIO= 2, THD_WAIT_ROW_LOCK= 3, THD_WAIT_GLOBAL_LOCK= 4, THD_WAIT_META_DATA_LOCK= 5, THD_WAIT_TABLE_LOCK= 6, THD_WAIT_USER_LOCK= 7, THD_WAIT_BINLOG= 8, THD_WAIT_GROUP_COMMIT= 9, THD_WAIT_SYNC= 10, THD_WAIT_NET= 11, THD_WAIT_LAST= 12 } thd_wait_type; extern struct thd_wait_service_st { void (*thd_wait_begin_func)(MYSQL_THD, int); void (*thd_wait_end_func)(MYSQL_THD); } *thd_wait_service; #ifdef MYSQL_DYNAMIC_PLUGIN #define thd_wait_begin(_THD, _WAIT_TYPE) \ thd_wait_service->thd_wait_begin_func(_THD, _WAIT_TYPE) #define thd_wait_end(_THD) thd_wait_service->thd_wait_end_func(_THD) #else void thd_wait_begin(MYSQL_THD thd, int wait_type); void thd_wait_end(MYSQL_THD thd); #endif #ifdef __cplusplus } #endif #endif