condition_variable.h

Overview

The condition_variable.h file declares the condition variable APIs in C.

File to include: <ffrt/condition_variable.h>

Library: libffrt.z.so

System capability: SystemCapability.Resourceschedule.Ffrt.Core

Since: 10

Related module: FFRT

Summary

Function

Name	Description
FFRT_C_API int ffrt_cond_init(ffrt_cond_t* cond, const ffrt_condattr_t* attr)	Initializes a condition variable.
FFRT_C_API int ffrt_cond_signal(ffrt_cond_t* cond)	Unblocks at least one of the threads that are blocked on a condition variable.
FFRT_C_API int ffrt_cond_broadcast(ffrt_cond_t* cond)	Unblocks all threads currently blocked on a condition variable.
FFRT_C_API int ffrt_cond_wait(ffrt_cond_t* cond, ffrt_mutex_t* mutex)	Blocks the calling thread on a condition variable.
FFRT_C_API int ffrt_cond_timedwait(ffrt_cond_t* cond, ffrt_mutex_t* mutex, const struct timespec* time_point)	Blocks the calling thread on a condition variable for a given duration. If ffrt_cond_signal or ffrt_cond_broadcast is not called to unblock the thread when the maximum wait time is reached, the thread is automatically unblocked.
FFRT_C_API int ffrt_cond_destroy(ffrt_cond_t* cond)	Destroys a condition variable.

Function Description

ffrt_cond_init()

FFRT_C_API int ffrt_cond_init(ffrt_cond_t* cond, const ffrt_condattr_t* attr)

Description

Initializes a condition variable.

Since: 10

Parameters

Name	Description
ffrt_cond_t* cond	Pointer to the condition variable.
const ffrt_condattr_t* attr	Pointer to the condition variable attribute.

Returns

Type	Description
FFRT_C_API int	Returns ffrt_success if the condition variable is initialized; returns ffrt_error_inval otherwise.

ffrt_cond_signal()

FFRT_C_API int ffrt_cond_signal(ffrt_cond_t* cond)

Description

Unblocks at least one of the threads that are blocked on a condition variable.

Since: 10

Parameters

Name	Description
ffrt_cond_t* cond	Pointer to the condition variable.

Returns

Type	Description
FFRT_C_API int	Returns ffrt_success if at least one of the threads is unblocked; returns ffrt_error_inval otherwise.

ffrt_cond_broadcast()

FFRT_C_API int ffrt_cond_broadcast(ffrt_cond_t* cond)

Description

Unblocks all threads currently blocked on a condition variable.

Since: 10

Parameters

Name	Description
ffrt_cond_t* cond	Pointer to the condition variable.

Returns

Type	Description
FFRT_C_API int	Returns ffrt_success if all threads are unblocked successfully; returns ffrt_error_inval otherwise.

ffrt_cond_wait()

FFRT_C_API int ffrt_cond_wait(ffrt_cond_t* cond, ffrt_mutex_t* mutex)

Description

Blocks the calling thread on a condition variable.

Since: 10

Parameters

Name	Description
ffrt_cond_t* cond	Pointer to the condition variable.
ffrt_mutex_t* mutex	Pointer to the mutex.

Returns

Type	Description
FFRT_C_API int	Returns ffrt_success if the thread is unblocked after being blocked; returns ffrt_error_inval otherwise.

ffrt_cond_timedwait()

FFRT_C_API int ffrt_cond_timedwait(ffrt_cond_t* cond, ffrt_mutex_t* mutex, const struct timespec* time_point)

Description

Blocks the calling thread on a condition variable for a given duration. If ffrt_cond_signal or ffrt_cond_broadcast is not called to unblock the thread when the maximum wait time is reached, the thread is automatically unblocked.

Since: 10

Parameters

Name	Description
ffrt_cond_t* cond	Pointer to the condition variable.
ffrt_mutex_t* mutex	Pointer to the mutex.
const struct timespec* time_point	Pointer to the maximum duration that the thread is blocked.

Returns

Type	Description
FFRT_C_API int	Returns ffrt_success if the thread is unblocked after being blocked; returns ffrt_error_timedout if the wait times out; returns ffrt_error_inval if the wait fails.

ffrt_cond_destroy()

FFRT_C_API int ffrt_cond_destroy(ffrt_cond_t* cond)

Description

Destroys a condition variable.

Since: 10

Parameters

Name	Description
ffrt_cond_t* cond	Pointer to the condition variable.

Returns

Type	Description
FFRT_C_API int	Returns ffrt_success if the condition variable is destroyed successfully; returns ffrt_error_inval otherwise.