mariadb/include/mysql/service_thd_wait.h
Mats Kindahl b1dcf448ea WL#5363: Thread Pool Service Interface
In order to allow thread schedulers to be dynamically loaded,
it is necessary to make the following changes to the server:

- Two new service interfaces

- Modifications to InnoDB to inform the thread scheduler of state changes.

- Changes to the VIO subsystem for checking if data is available on a socket.

- Elimination of remains of the old thread pool implementation.

The two new service interfaces introduces are:

my_thread_scheduler
  A service interface to register a thread
  scheduler.

thd_wait
  A service interface to inform thread scheduler
  that the thread is about to start waiting.

In addition, the patch adds code that:

- Add a call to thd_wait for table locks in mysys
  thd_lock.c by introducing a set function that
  can be used to set a callback to be used when
  waiting on a lock and resuming from waiting.

- Calling the mysys set function from the server
  to set the callbacks correctly.
2010-06-07 16:01:39 +02:00

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C

/* Copyright (C) 2010, 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 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
typedef enum _thd_wait_type_e {
THD_WAIT_MUTEX= 1,
THD_WAIT_DISKIO= 2,
THD_WAIT_ROW_TABLE_LOCK= 3,
THD_WAIT_GLOBAL_LOCK= 4
} thd_wait_type;
extern struct thd_wait_service_st {
void (*thd_wait_begin_func)(MYSQL_THD, thd_wait_type);
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, thd_wait_type wait_type);
void thd_wait_end(MYSQL_THD thd);
#endif
#ifdef __cplusplus
}
#endif
#endif