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268 lines
8.2 KiB
C
268 lines
8.2 KiB
C
/******************************************************
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The interface to the operating system
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synchronization primitives.
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(c) 1995 Innobase Oy
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Created 9/6/1995 Heikki Tuuri
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*******************************************************/
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#ifndef os0sync_h
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#define os0sync_h
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#include "univ.i"
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#include "ut0lst.h"
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#ifdef __WIN__
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#define os_fast_mutex_t CRITICAL_SECTION
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typedef HANDLE os_native_event_t;
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typedef struct os_event_struct os_event_struct_t;
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typedef os_event_struct_t* os_event_t;
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struct os_event_struct {
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os_native_event_t handle;
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/* Windows event */
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UT_LIST_NODE_T(os_event_struct_t) os_event_list;
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/* list of all created events */
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};
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#else
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typedef pthread_mutex_t os_fast_mutex_t;
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typedef struct os_event_struct os_event_struct_t;
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typedef os_event_struct_t* os_event_t;
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struct os_event_struct {
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os_fast_mutex_t os_mutex; /* this mutex protects the next
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fields */
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ibool is_set; /* this is TRUE when the event is
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in the signaled state, i.e., a thread
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does not stop if it tries to wait for
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this event */
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ib_int64_t signal_count; /* this is incremented each time
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the event becomes signaled */
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pthread_cond_t cond_var; /* condition variable is used in
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waiting for the event */
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UT_LIST_NODE_T(os_event_struct_t) os_event_list;
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/* list of all created events */
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};
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#endif
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typedef struct os_mutex_struct os_mutex_str_t;
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typedef os_mutex_str_t* os_mutex_t;
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#define OS_SYNC_INFINITE_TIME ((ulint)(-1))
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#define OS_SYNC_TIME_EXCEEDED 1
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/* Mutex protecting counts and the event and OS 'slow' mutex lists */
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extern os_mutex_t os_sync_mutex;
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/* This is incremented by 1 in os_thread_create and decremented by 1 in
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os_thread_exit */
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extern ulint os_thread_count;
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extern ulint os_event_count;
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extern ulint os_mutex_count;
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extern ulint os_fast_mutex_count;
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/*************************************************************
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Initializes global event and OS 'slow' mutex lists. */
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UNIV_INTERN
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void
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os_sync_init(void);
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/*==============*/
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/*************************************************************
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Frees created events and OS 'slow' mutexes. */
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UNIV_INTERN
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void
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os_sync_free(void);
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/*==============*/
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/*************************************************************
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Creates an event semaphore, i.e., a semaphore which may just have two states:
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signaled and nonsignaled. The created event is manual reset: it must be reset
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explicitly by calling sync_os_reset_event. */
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UNIV_INTERN
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os_event_t
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os_event_create(
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/*============*/
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/* out: the event handle */
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const char* name); /* in: the name of the event, if NULL
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the event is created without a name */
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#ifdef __WIN__
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/*************************************************************
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Creates an auto-reset event semaphore, i.e., an event which is automatically
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reset when a single thread is released. Works only in Windows. */
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UNIV_INTERN
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os_event_t
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os_event_create_auto(
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/*=================*/
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/* out: the event handle */
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const char* name); /* in: the name of the event, if NULL
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the event is created without a name */
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#endif
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/**************************************************************
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Sets an event semaphore to the signaled state: lets waiting threads
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proceed. */
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UNIV_INTERN
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void
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os_event_set(
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/*=========*/
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os_event_t event); /* in: event to set */
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/**************************************************************
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Resets an event semaphore to the nonsignaled state. Waiting threads will
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stop to wait for the event.
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The return value should be passed to os_even_wait_low() if it is desired
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that this thread should not wait in case of an intervening call to
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os_event_set() between this os_event_reset() and the
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os_event_wait_low() call. See comments for os_event_wait_low(). */
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UNIV_INTERN
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ib_int64_t
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os_event_reset(
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/*===========*/
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os_event_t event); /* in: event to reset */
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/**************************************************************
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Frees an event object. */
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UNIV_INTERN
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void
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os_event_free(
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/*==========*/
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os_event_t event); /* in: event to free */
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/**************************************************************
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Waits for an event object until it is in the signaled state. If
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srv_shutdown_state == SRV_SHUTDOWN_EXIT_THREADS this also exits the
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waiting thread when the event becomes signaled (or immediately if the
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event is already in the signaled state).
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Typically, if the event has been signalled after the os_event_reset()
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we'll return immediately because event->is_set == TRUE.
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There are, however, situations (e.g.: sync_array code) where we may
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lose this information. For example:
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thread A calls os_event_reset()
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thread B calls os_event_set() [event->is_set == TRUE]
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thread C calls os_event_reset() [event->is_set == FALSE]
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thread A calls os_event_wait() [infinite wait!]
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thread C calls os_event_wait() [infinite wait!]
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Where such a scenario is possible, to avoid infinite wait, the
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value returned by os_event_reset() should be passed in as
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reset_sig_count. */
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UNIV_INTERN
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void
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os_event_wait_low(
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/*==============*/
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os_event_t event, /* in: event to wait */
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ib_int64_t reset_sig_count);/* in: zero or the value
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returned by previous call of
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os_event_reset(). */
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#define os_event_wait(event) os_event_wait_low(event, 0)
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/**************************************************************
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Waits for an event object until it is in the signaled state or
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a timeout is exceeded. In Unix the timeout is always infinite. */
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UNIV_INTERN
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ulint
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os_event_wait_time(
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/*===============*/
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/* out: 0 if success,
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OS_SYNC_TIME_EXCEEDED if timeout
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was exceeded */
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os_event_t event, /* in: event to wait */
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ulint time); /* in: timeout in microseconds, or
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OS_SYNC_INFINITE_TIME */
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#ifdef __WIN__
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/**************************************************************
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Waits for any event in an OS native event array. Returns if even a single
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one is signaled or becomes signaled. */
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UNIV_INTERN
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ulint
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os_event_wait_multiple(
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/*===================*/
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/* out: index of the event
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which was signaled */
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ulint n, /* in: number of events in the
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array */
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os_native_event_t* native_event_array);
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/* in: pointer to an array of event
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handles */
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#endif
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/*************************************************************
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Creates an operating system mutex semaphore. Because these are slow, the
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mutex semaphore of InnoDB itself (mutex_t) should be used where possible. */
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UNIV_INTERN
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os_mutex_t
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os_mutex_create(
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/*============*/
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/* out: the mutex handle */
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const char* name); /* in: the name of the mutex, if NULL
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the mutex is created without a name */
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/**************************************************************
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Acquires ownership of a mutex semaphore. */
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UNIV_INTERN
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void
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os_mutex_enter(
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/*===========*/
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os_mutex_t mutex); /* in: mutex to acquire */
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/**************************************************************
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Releases ownership of a mutex. */
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UNIV_INTERN
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void
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os_mutex_exit(
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/*==========*/
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os_mutex_t mutex); /* in: mutex to release */
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/**************************************************************
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Frees an mutex object. */
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UNIV_INTERN
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void
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os_mutex_free(
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/*==========*/
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os_mutex_t mutex); /* in: mutex to free */
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/**************************************************************
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Acquires ownership of a fast mutex. Currently in Windows this is the same
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as os_fast_mutex_lock! */
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UNIV_INLINE
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ulint
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os_fast_mutex_trylock(
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/*==================*/
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/* out: 0 if success, != 0 if
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was reserved by another
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thread */
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os_fast_mutex_t* fast_mutex); /* in: mutex to acquire */
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/**************************************************************
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Releases ownership of a fast mutex. */
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UNIV_INTERN
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void
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os_fast_mutex_unlock(
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/*=================*/
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os_fast_mutex_t* fast_mutex); /* in: mutex to release */
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/*************************************************************
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Initializes an operating system fast mutex semaphore. */
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UNIV_INTERN
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void
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os_fast_mutex_init(
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/*===============*/
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os_fast_mutex_t* fast_mutex); /* in: fast mutex */
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/**************************************************************
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Acquires ownership of a fast mutex. */
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UNIV_INTERN
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void
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os_fast_mutex_lock(
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/*===============*/
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os_fast_mutex_t* fast_mutex); /* in: mutex to acquire */
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/**************************************************************
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Frees an mutex object. */
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UNIV_INTERN
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void
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os_fast_mutex_free(
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/*===============*/
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os_fast_mutex_t* fast_mutex); /* in: mutex to free */
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#ifndef UNIV_NONINL
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#include "os0sync.ic"
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#endif
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#endif
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