~drizzle-trunk/drizzle/development

/*****************************************************************************

Copyright (c) 1995, 2009, Innobase Oy. All Rights Reserved.

Copyright (c) 2008, Google Inc.

Portions of this file contain modifications contributed and copyrighted by

Google, Inc. Those modifications are gratefully acknowledged and are described

briefly in the InnoDB documentation. The contributions by Google are

incorporated with their permission, and subject to the conditions contained in

the file COPYING.Google.

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

*****************************************************************************/

/******************************************************

The interface to the operating system

synchronization primitives.

Created 9/6/1995 Heikki Tuuri

*******************************************************/

#ifndef os0sync_h

#define os0sync_h

#include "univ.i"

#include "ut0lst.h"

#ifdef __WIN__

#define os_fast_mutex_t CRITICAL_SECTION

typedef HANDLE		os_native_event_t;

typedef struct os_event_struct	os_event_struct_t;

typedef os_event_struct_t*	os_event_t;

struct os_event_struct {

	os_native_event_t		  handle;

					/* Windows event */

	UT_LIST_NODE_T(os_event_struct_t) os_event_list;

					/* list of all created events */

};

#else

typedef pthread_mutex_t	os_fast_mutex_t;

typedef struct os_event_struct	os_event_struct_t;

typedef os_event_struct_t*	os_event_t;

struct os_event_struct {

	os_fast_mutex_t	os_mutex;	/* this mutex protects the next

					fields */

	ibool		is_set;		/* this is TRUE when the event is

					in the signaled state, i.e., a thread

					does not stop if it tries to wait for

					this event */

	ib_int64_t	signal_count;	/* this is incremented each time

					the event becomes signaled */

	pthread_cond_t	cond_var;	/* condition variable is used in

					waiting for the event */

	UT_LIST_NODE_T(os_event_struct_t) os_event_list;

					/* list of all created events */

};

#endif

typedef struct os_mutex_struct	os_mutex_str_t;

typedef os_mutex_str_t*		os_mutex_t;

#define OS_SYNC_INFINITE_TIME	((ulint)(-1))

#define OS_SYNC_TIME_EXCEEDED	1

/* Mutex protecting counts and the event and OS 'slow' mutex lists */

extern os_mutex_t	os_sync_mutex;

/* This is incremented by 1 in os_thread_create and decremented by 1 in

os_thread_exit */

extern ulint		os_thread_count;

extern ulint		os_event_count;

extern ulint		os_mutex_count;

extern ulint		os_fast_mutex_count;

/*************************************************************

Initializes global event and OS 'slow' mutex lists. */

UNIV_INTERN

void

os_sync_init(void);

/*==============*/

/*************************************************************

Frees created events and OS 'slow' mutexes. */

UNIV_INTERN

void

os_sync_free(void);

/*==============*/

/*************************************************************

Creates an event semaphore, i.e., a semaphore which may just have two states:

signaled and nonsignaled. The created event is manual reset: it must be reset

explicitly by calling sync_os_reset_event. */

UNIV_INTERN

os_event_t

os_event_create(

/*============*/

				/* out: the event handle */

	const char*	name);	/* in: the name of the event, if NULL

				the event is created without a name */

#ifdef __WIN__

/*************************************************************

Creates an auto-reset event semaphore, i.e., an event which is automatically

reset when a single thread is released. Works only in Windows. */

UNIV_INTERN

os_event_t

os_event_create_auto(

/*=================*/

				/* out: the event handle */

	const char*	name);	/* in: the name of the event, if NULL

				the event is created without a name */

#endif

/**************************************************************

Sets an event semaphore to the signaled state: lets waiting threads

proceed. */

UNIV_INTERN

void

os_event_set(

/*=========*/

	os_event_t	event);	/* in: event to set */

/**************************************************************

Resets an event semaphore to the nonsignaled state. Waiting threads will

stop to wait for the event.

The return value should be passed to os_even_wait_low() if it is desired

that this thread should not wait in case of an intervening call to

os_event_set() between this os_event_reset() and the

os_event_wait_low() call. See comments for os_event_wait_low(). */

UNIV_INTERN

ib_int64_t

os_event_reset(

/*===========*/

	os_event_t	event);	/* in: event to reset */

/**************************************************************

Frees an event object. */

UNIV_INTERN

void

os_event_free(

/*==========*/

	os_event_t	event);	/* in: event to free */

/**************************************************************

Waits for an event object until it is in the signaled state. If

srv_shutdown_state == SRV_SHUTDOWN_EXIT_THREADS this also exits the

waiting thread when the event becomes signaled (or immediately if the

event is already in the signaled state).

Typically, if the event has been signalled after the os_event_reset()

we'll return immediately because event->is_set == TRUE.

There are, however, situations (e.g.: sync_array code) where we may

lose this information. For example:

thread A calls os_event_reset()

thread B calls os_event_set()   [event->is_set == TRUE]

thread C calls os_event_reset() [event->is_set == FALSE]

thread A calls os_event_wait()  [infinite wait!]

thread C calls os_event_wait()  [infinite wait!]

Where such a scenario is possible, to avoid infinite wait, the

value returned by os_event_reset() should be passed in as

reset_sig_count. */

UNIV_INTERN

void

os_event_wait_low(

/*==============*/

	os_event_t	event,		/* in: event to wait */

	ib_int64_t	reset_sig_count);/* in: zero or the value

					returned by previous call of

					os_event_reset(). */

#define os_event_wait(event) os_event_wait_low(event, 0)

/**************************************************************

Waits for an event object until it is in the signaled state or

a timeout is exceeded. In Unix the timeout is always infinite. */

UNIV_INTERN

ulint

os_event_wait_time(

/*===============*/

				/* out: 0 if success,

				OS_SYNC_TIME_EXCEEDED if timeout

				was exceeded */

	os_event_t	event,	/* in: event to wait */

	ulint		time);	/* in: timeout in microseconds, or

				OS_SYNC_INFINITE_TIME */

#ifdef __WIN__

/**************************************************************

Waits for any event in an OS native event array. Returns if even a single

one is signaled or becomes signaled. */

UNIV_INTERN

ulint

os_event_wait_multiple(

/*===================*/

					/* out: index of the event

					which was signaled */

	ulint			n,	/* in: number of events in the

					array */

	os_native_event_t*	native_event_array);

					/* in: pointer to an array of event

					handles */

#endif

/*************************************************************

Creates an operating system mutex semaphore. Because these are slow, the

mutex semaphore of InnoDB itself (mutex_t) should be used where possible. */

UNIV_INTERN

os_mutex_t

os_mutex_create(

/*============*/

				/* out: the mutex handle */

	const char*	name);	/* in: the name of the mutex, if NULL

				the mutex is created without a name */

/**************************************************************

Acquires ownership of a mutex semaphore. */

UNIV_INTERN

void

os_mutex_enter(

/*===========*/

	os_mutex_t	mutex);	/* in: mutex to acquire */

/**************************************************************

Releases ownership of a mutex. */

UNIV_INTERN

void

os_mutex_exit(

/*==========*/

	os_mutex_t	mutex);	/* in: mutex to release */

/**************************************************************

Frees an mutex object. */

UNIV_INTERN

void

os_mutex_free(

/*==========*/

	os_mutex_t	mutex);	/* in: mutex to free */

/**************************************************************

Acquires ownership of a fast mutex. Currently in Windows this is the same

as os_fast_mutex_lock! */

UNIV_INLINE

ulint

os_fast_mutex_trylock(

/*==================*/

						/* out: 0 if success, != 0 if

						was reserved by another

						thread */

	os_fast_mutex_t*	fast_mutex);	/* in: mutex to acquire */

/**************************************************************

Releases ownership of a fast mutex. */

UNIV_INTERN

void

os_fast_mutex_unlock(

/*=================*/

	os_fast_mutex_t*	fast_mutex);	/* in: mutex to release */

/*************************************************************

Initializes an operating system fast mutex semaphore. */

UNIV_INTERN

void

os_fast_mutex_init(

/*===============*/

	os_fast_mutex_t*	fast_mutex);	/* in: fast mutex */

/**************************************************************

Acquires ownership of a fast mutex. */

UNIV_INTERN

void

os_fast_mutex_lock(

/*===============*/

	os_fast_mutex_t*	fast_mutex);	/* in: mutex to acquire */

/**************************************************************

Frees an mutex object. */

UNIV_INTERN

void

os_fast_mutex_free(

/*===============*/

	os_fast_mutex_t*	fast_mutex);	/* in: mutex to free */

#ifdef HAVE_GCC_ATOMIC_BUILTINS

/**************************************************************

Atomic compare-and-swap for InnoDB. Currently requires GCC atomic builtins.

Returns true if swapped, ptr is pointer to target, old_val is value to

compare to, new_val is the value to swap in. */

#define os_compare_and_swap(ptr, old_val, new_val) \

	__sync_bool_compare_and_swap(ptr, old_val, new_val)

/**************************************************************

Atomic increment for InnoDB. Currently requires GCC atomic builtins.

Returns the resulting value, ptr is pointer to target, amount is the

amount of increment. */

#define os_atomic_increment(ptr, amount) \

	__sync_add_and_fetch(ptr, amount)

#endif /* HAVE_GCC_ATOMIC_BUILTINS */

#ifndef UNIV_NONINL

#include "os0sync.ic"

#endif

#endif