# FFRT
## Overview
Function Flow Runtime (FFRT) is a software runtime library that works with the Function Flow programming model. It is used to schedule and execute tasks of an application developed on the Function Flow programming model.
**System capability**: SystemCapability.Resourceschedule.Ffrt.Core
**Since**: 10
## Summary
### Files
| Name| Description|
| -------- | -------- |
| [condition_variable.h](condition__variable_8h.md) | Declares the condition variable interfaces in C.|
| [mutex.h](mutex_8h.md) | Declares the mutex interfaces in C.|
| [queue.h](queue_8h.md) | Declares the queue interfaces in C.|
| [sleep.h](sleep_8h.md) | Declares the sleep and yield interfaces in C.|
| [task.h](task_8h.md) | Declares the task interfaces in C.|
| [type_def.h](type__def_8h.md) | Declares the common types.|
### Structs
| Name| Description|
| -------- | -------- |
| struct [ffrt_function_header_t](ffrt__function__header__t.md) | Describes a task executor.|
| struct [ffrt_dependence_t](ffrt__dependence__t.md) | Describes a dependency.|
| struct [ffrt_deps_t](ffrt__deps__t.md) | Describes dependencies.|
| struct [ffrt_task_attr_t](ffrt__task__attr__t.md) | Describes a task attribute.|
| struct [ffrt_queue_attr_t](ffrt__queue__attr__t.md) | Describes a queue attribute.|
| struct [ffrt_condattr_t](ffrt__condattr__t.md) | Describes a condition variable attribute.|
| struct [ffrt_mutexattr_t](ffrt__mutexattr__t.md) | Describes a mutex attribute.|
| struct [ffrt_mutex_t](ffrt__mutex__t.md) | Describes a mutex.|
| struct [ffrt_cond_t](ffrt__cond__t.md) | Describes a condition variable.|
### Types
| Name| Description|
| -------- | -------- |
| typedef void \* ffrt_queue_t | Defines the handle to a queue.|
| typedef int ffrt_qos_t | Defines the QoS type.|
| typedef void(\* ffrt_function_t ) (void \*) | Defines the type of the pointer to a task execution function.|
| typedef void \* ffrt_task_handle_t | Defines the handle to a task.|
### Enums
| Name| Description|
| -------- | -------- |
| [ffrt_queue_type_t](#ffrt_queue_type_t) { ffrt_queue_serial, **ffrt_queue_max** } | Enumerates the queue types.|
| [ffrt_qos_default_t](#ffrt_qos_default_t) {
ffrt_qos_inherit = -1, ffrt_qos_background, ffrt_qos_utility, ffrt_qos_default,
ffrt_qos_user_initiated
} | Enumerates the task QoS types.|
| [ffrt_storage_size_t](#ffrt_storage_size_t) {
ffrt_task_attr_storage_size = 128, ffrt_auto_managed_function_storage_size = 64 + sizeof(ffrt_function_header_t), ffrt_mutex_storage_size = 64, ffrt_cond_storage_size = 64,
ffrt_queue_attr_storage_size = 128
} | Enumerates the storage sizes available for different types of structs.|
| [ffrt_function_kind_t](#ffrt_function_kind_t) { ffrt_function_kind_general, ffrt_function_kind_queue } | Enumerates the task types.|
| [ffrt_dependence_type_t](#ffrt_dependence_type_t) { ffrt_dependence_data, ffrt_dependence_task } | Enumerates the dependency types.|
| [ffrt_error_t](#ffrt_error_t) {
ffrt_error = -1, ffrt_success = 0, ffrt_error_nomem = ENOMEM, ffrt_error_timedout = ETIMEDOUT,
ffrt_error_busy = EBUSY, ffrt_error_inval = EINVAL
} | Enumerates the FFRT error codes.|
### Functions
| Name| Description|
| -------- | -------- |
| FFRT_C_API int [ffrt_cond_init](#ffrt_cond_init) ([ffrt_cond_t](ffrt__cond__t.md) \*cond, const [ffrt_condattr_t](ffrt__condattr__t.md) \*attr) | Initializes a condition variable.|
| FFRT_C_API int [ffrt_cond_signal](#ffrt_cond_signal) ([ffrt_cond_t](ffrt__cond__t.md) \*cond) | Unblocks at least one of the threads that are blocked on a condition variable.|
| FFRT_C_API int [ffrt_cond_broadcast](#ffrt_cond_broadcast) ([ffrt_cond_t](ffrt__cond__t.md) \*cond) | Unblocks all threads currently blocked on a condition variable.|
| FFRT_C_API int [ffrt_cond_wait](#ffrt_cond_wait) ([ffrt_cond_t](ffrt__cond__t.md) \*cond, [ffrt_mutex_t](ffrt__mutex__t.md) \*mutex) | Blocks the calling thread on a condition variable.|
| FFRT_C_API int [ffrt_cond_timedwait](#ffrt_cond_timedwait) ([ffrt_cond_t](ffrt__cond__t.md) \*cond, [ffrt_mutex_t](ffrt__mutex__t.md) \*mutex, const struct timespec \*time_point) | Blocks the calling thread on a condition variable for a given duration.|
| FFRT_C_API int [ffrt_cond_destroy](#ffrt_cond_destroy) ([ffrt_cond_t](ffrt__cond__t.md) \*cond) | Destroys a condition variable.|
| FFRT_C_API int [ffrt_mutex_init](#ffrt_mutex_init) ([ffrt_mutex_t](ffrt__mutex__t.md) \*mutex, const [ffrt_mutexattr_t](ffrt__mutexattr__t.md) \*attr) | Initializes a mutex.|
| FFRT_C_API int [ffrt_mutex_lock](#ffrt_mutex_lock) ([ffrt_mutex_t](ffrt__mutex__t.md) \*mutex) | Locks a mutex.|
| FFRT_C_API int [ffrt_mutex_unlock](#ffrt_mutex_unlock) ([ffrt_mutex_t](ffrt__mutex__t.md) \*mutex) | Unlocks a mutex.|
| FFRT_C_API int [ffrt_mutex_trylock](#ffrt_mutex_trylock) ([ffrt_mutex_t](ffrt__mutex__t.md) \*mutex) | Attempts to lock a mutex.|
| FFRT_C_API int [ffrt_mutex_destroy](#ffrt_mutex_destroy) ([ffrt_mutex_t](ffrt__mutex__t.md) \*mutex) | Destroys a mutex.|
| FFRT_C_API int [ffrt_queue_attr_init](#ffrt_queue_attr_init) ([ffrt_queue_attr_t](ffrt__queue__attr__t.md) \*attr) | Initializes a queue attribute.|
| FFRT_C_API void [ffrt_queue_attr_destroy](#ffrt_queue_attr_destroy) ([ffrt_queue_attr_t](ffrt__queue__attr__t.md) \*attr) | Destroys a queue attribute.|
| FFRT_C_API void [ffrt_queue_attr_set_qos](#ffrt_queue_attr_set_qos) ([ffrt_queue_attr_t](ffrt__queue__attr__t.md) \*attr, ffrt_qos_t qos) | Sets the queue QoS.|
| FFRT_C_API ffrt_qos_t[ffrt_queue_attr_get_qos](#ffrt_queue_attr_get_qos) (const [ffrt_queue_attr_t](ffrt__queue__attr__t.md) \*attr) | Obtains the queue QoS.|
| FFRT_C_API void [ffrt_queue_attr_set_timeout](#ffrt_queue_attr_set_timeout) ([ffrt_queue_attr_t](ffrt__queue__attr__t.md) \*attr, uint64_t timeout_us) | Sets the queue timeout.|
| FFRT_C_API uint64_t [ffrt_queue_attr_get_timeout](#ffrt_queue_attr_get_timeout) (const [ffrt_queue_attr_t](ffrt__queue__attr__t.md) \*attr) | Obtains the queue timeout.|
| FFRT_C_API void [ffrt_queue_attr_set_callback](#ffrt_queue_attr_set_callback) ([ffrt_queue_attr_t](ffrt__queue__attr__t.md) \*attr, [ffrt_function_header_t](ffrt__function__header__t.md) \*f) | Sets a callback that is invoked when a queue task times out.|
| FFRT_C_API [ffrt_function_header_t](ffrt__function__header__t.md) \* [ffrt_queue_attr_get_callback](#ffrt_queue_attr_get_callback) (const [ffrt_queue_attr_t](ffrt__queue__attr__t.md) \*attr) | Obtains the callback that is invoked when a queue task times out.|
| FFRT_C_API ffrt_queue_t[ffrt_queue_create](#ffrt_queue_create) ([ffrt_queue_type_t](#ffrt_queue_type_t) type, const char \*name, const [ffrt_queue_attr_t](ffrt__queue__attr__t.md) \*attr) | Creates a queue.|
| FFRT_C_API void [ffrt_queue_destroy](#ffrt_queue_destroy) (ffrt_queue_t queue) | Destroys a queue.|
| FFRT_C_API void [ffrt_queue_submit](#ffrt_queue_submit) (ffrt_queue_t queue, [ffrt_function_header_t](ffrt__function__header__t.md) \*f, const [ffrt_task_attr_t](ffrt__task__attr__t.md) \*attr) | Submits a task to a queue.|
| FFRT_C_API ffrt_task_handle_t[ffrt_queue_submit_h](#ffrt_queue_submit_h) (ffrt_queue_t queue, [ffrt_function_header_t](ffrt__function__header__t.md) \*f, const [ffrt_task_attr_t](ffrt__task__attr__t.md) \*attr) | Submits a task to a queue, and obtains a task handle.|
| FFRT_C_API void [ffrt_queue_wait](#ffrt_queue_wait) (ffrt_task_handle_t handle) | Waits until a task in the queue is complete.|
| FFRT_C_API int [ffrt_queue_cancel](#ffrt_queue_cancel) (ffrt_task_handle_t handle) | Cancels a task in the queue.|
| FFRT_C_API int [ffrt_usleep](#ffrt_usleep) (uint64_t usec) | Suspends the calling thread for a given duration.|
| FFRT_C_API void [ffrt_yield](#ffrt_yield) (void) | Passes control to other tasks so that they can be executed.|
| FFRT_C_API int [ffrt_task_attr_init](#ffrt_task_attr_init) ([ffrt_task_attr_t](ffrt__task__attr__t.md) \*attr) | Initializes a task attribute.|
| FFRT_C_API void [ffrt_task_attr_set_name](#ffrt_task_attr_set_name) ([ffrt_task_attr_t](ffrt__task__attr__t.md) \*attr, const char \*name) | Sets a task name.|
| FFRT_C_API const char \* [ffrt_task_attr_get_name](#ffrt_task_attr_get_name) (const [ffrt_task_attr_t](ffrt__task__attr__t.md) \*attr) | Obtains a task name.|
| FFRT_C_API void [ffrt_task_attr_destroy](#ffrt_task_attr_destroy) ([ffrt_task_attr_t](ffrt__task__attr__t.md) \*attr) | Destroys a task attribute.|
| FFRT_C_API void [ffrt_task_attr_set_qos](#ffrt_task_attr_set_qos) ([ffrt_task_attr_t](ffrt__task__attr__t.md) \*attr, ffrt_qos_t qos) | Sets the task QoS.|
| FFRT_C_API ffrt_qos_t[ffrt_task_attr_get_qos](#ffrt_task_attr_get_qos) (const [ffrt_task_attr_t](ffrt__task__attr__t.md) \*attr) | Obtains the task QoS.|
| FFRT_C_API void [ffrt_task_attr_set_delay](#ffrt_task_attr_set_delay) ([ffrt_task_attr_t](ffrt__task__attr__t.md) \*attr, uint64_t delay_us) | Sets the task delay time.|
| FFRT_C_API uint64_t [ffrt_task_attr_get_delay](#ffrt_task_attr_get_delay) (const [ffrt_task_attr_t](ffrt__task__attr__t.md) \*attr) | Obtains the task delay time.|
| FFRT_C_API int [ffrt_this_task_update_qos](#ffrt_this_task_update_qos) (ffrt_qos_t qos) | Updates the task QoS.|
| FFRT_C_API uint64_t [ffrt_this_task_get_id](#ffrt_this_task_get_id) (void) | Obtains the task ID.|
| FFRT_C_API void \* [ffrt_alloc_auto_managed_function_storage_base](#ffrt_alloc_auto_managed_function_storage_base) ([ffrt_function_kind_t](#ffrt_function_kind_t) kind) | Applies for memory for the task execution function struct.|
| FFRT_C_API void [ffrt_submit_base](#ffrt_submit_base) ([ffrt_function_header_t](ffrt__function__header__t.md) \*f, const [ffrt_deps_t](ffrt__deps__t.md) \*in_deps, const [ffrt_deps_t](ffrt__deps__t.md) \*out_deps, const [ffrt_task_attr_t](ffrt__task__attr__t.md) \*attr) | Submits a task.|
| FFRT_C_API ffrt_task_handle_t[ffrt_submit_h_base](#ffrt_submit_h_base) ([ffrt_function_header_t](ffrt__function__header__t.md) \*f, const [ffrt_deps_t](ffrt__deps__t.md) \*in_deps, const [ffrt_deps_t](ffrt__deps__t.md) \*out_deps, const [ffrt_task_attr_t](ffrt__task__attr__t.md) \*attr) | Submits a task, and obtains a task handle.|
| FFRT_C_API void [ffrt_task_handle_destroy](#ffrt_task_handle_destroy) (ffrt_task_handle_t handle) | Destroys a task handle.|
| FFRT_C_API void [ffrt_wait_deps](#ffrt_wait_deps) (const [ffrt_deps_t](ffrt__deps__t.md) \*deps) | Waits until the dependent tasks are complete.|
| FFRT_C_API void [ffrt_wait](#ffrt_wait) (void) | Waits until all submitted tasks are complete.|
### Variables
| Name| Description|
| -------- | -------- |
| ffrt_function_t[ffrt_function_header_t::exec](#exec) | Function used to execute a task.|
| ffrt_function_t[ffrt_function_header_t::destroy](#destroy) | Function used to destroy a task.|
| uint64_t [ffrt_function_header_t::reserve](#reserve) [2] | Reserved bit.|
| [ffrt_dependence_type_t](#ffrt_dependence_type_t)[ffrt_dependence_t::type](#type) | Dependency type.|
| const void \* [ffrt_dependence_t::ptr](#ptr) | Address of the dependency data.|
| uint32_t [ffrt_deps_t::len](#len) | Number of dependencies.|
| const [ffrt_dependence_t](ffrt__dependence__t.md) \* [ffrt_deps_t::items](#items) | Dependency data.|
| uint32_t [ffrt_task_attr_t::storage](#storage-46) [(ffrt_task_attr_storage_size+sizeof(uint32_t) - 1)/sizeof(uint32_t)] | Storage size of a task attribute.|
| uint32_t [ffrt_queue_attr_t::storage](#storage-36) [(ffrt_queue_attr_storage_size+sizeof(uint32_t) - 1)/sizeof(uint32_t)] | Storage size of a queue attribute.|
| long [ffrt_condattr_t::storage](#storage-56) | Storage size of a condition variable attribute.|
| long [ffrt_mutexattr_t::storage](#storage-66) | Storage size of a mutex attribute.|
| uint32_t [ffrt_mutex_t::storage](#storage-26) [(ffrt_mutex_storage_size+sizeof(uint32_t) - 1)/sizeof(uint32_t)] | Storage size of a mutex.|
| uint32_t [ffrt_cond_t::storage](#storage-16) [(ffrt_cond_storage_size+sizeof(uint32_t) - 1)/sizeof(uint32_t)] | Storage size of a condition variable.|
## Enum Description
### ffrt_dependence_type_t
```
enum ffrt_dependence_type_t
```
**Description**
Enumerates the dependency types.
| Value| Description|
| -------- | -------- |
| ffrt_dependence_data | Data dependency.|
| ffrt_dependence_task | Task dependency.|
### ffrt_error_t
```
enum ffrt_error_t
```
**Description**
Enumerates the FFRT error codes.
| Value| Description|
| -------- | -------- |
| ffrt_error | Failure.|
| ffrt_success | Success.|
| ffrt_error_nomem | Insufficient memory.|
| ffrt_error_timedout | Timeout.|
| ffrt_error_busy | Try again.|
| ffrt_error_inval | Invalid value.|
### ffrt_function_kind_t
```
enum ffrt_function_kind_t
```
**Description**
Enumerates the task types.
| Value| Description|
| -------- | -------- |
| ffrt_function_kind_general | General task.|
| ffrt_function_kind_queue | Queue task.|
### ffrt_qos_default_t
```
enum ffrt_qos_default_t
```
**Description**
Enumerates the task QoS types.
| Value| Description|
| -------- | -------- |
| ffrt_qos_inherit | Inherits the QoS of the current task.|
| ffrt_qos_background | Background task.|
| ffrt_qos_utility | Real-time tool.|
| ffrt_qos_default | Default type.|
| ffrt_qos_user_initiated | User initiated.|
### ffrt_queue_type_t
```
enum ffrt_queue_type_t
```
**Description**
Enumerates the queue types.
| Value| Description|
| -------- | -------- |
| ffrt_queue_serial | Serial queue.|
### ffrt_storage_size_t
```
enum ffrt_storage_size_t
```
**Description**
Enumerates the storage sizes available for different types of structs.
| Value| Description|
| -------- | -------- |
| ffrt_task_attr_storage_size | Storage size for the task attribute struct.|
| ffrt_auto_managed_function_storage_size | Storage size for the task execution function struct.|
| ffrt_mutex_storage_size | Storage size for the mutex struct.|
| ffrt_cond_storage_size | Storage size for the condition variable struct.|
| ffrt_queue_attr_storage_size | Storage size for the queue attribute struct.|
## Function Description
### ffrt_alloc_auto_managed_function_storage_base()
```
FFRT_C_API void* ffrt_alloc_auto_managed_function_storage_base (ffrt_function_kind_t kind)
```
**Description**
Applies for memory for the task execution function struct.
**Since**: 10
**Parameters**
| Name| Description|
| -------- | -------- |
| kind | Type of the task execution function, which can be general or queue.|
**Returns**
Returns a non-null pointer if the memory is allocated; returns a null pointer 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|
| -------- | -------- |
| cond | Pointer to the condition variable.|
**Returns**
Returns **ffrt_thrd_success** if all the threads are unblocked; returns **ffrt_thrd_error** otherwise.
### ffrt_cond_destroy()
```
FFRT_C_API int ffrt_cond_destroy (ffrt_cond_t * cond)
```
**Description**
Destroys a condition variable.
**Since**: 10
**Parameters**
| Name| Description|
| -------- | -------- |
| cond | Pointer to the condition variable.|
**Returns**
Returns **ffrt_thrd_success** if the condition variable is destroyed; returns **ffrt_thrd_error** otherwise.
### 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|
| -------- | -------- |
| cond | Pointer to the condition variable.|
| attr | Pointer to the condition variable attribute.|
**Returns**
Returns **ffrt_thrd_success** if the condition variable is initialized; returns **ffrt_thrd_error** 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|
| -------- | -------- |
| cond | Pointer to the condition variable.|
**Returns**
Returns **ffrt_thrd_success** if at least one of the threads is unblocked; returns **ffrt_thrd_error** 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.
**Since**: 10
**Parameters**
| Name| Description|
| -------- | -------- |
| cond | Pointer to the condition variable.|
| mutex | Pointer to the mutex.|
| time_point | Pointer to the maximum duration that the thread is blocked. If **ffrt_cond_signal** or **ffrt_cond_broadcast** is not called to unblock the thread when the maximum duration reaches, the thread is automatically unblocked.|
**Returns**
Returns **ffrt_thrd_success** if the thread is blocked; returns **ffrt_thrd_timedout** if the maximum duration reaches; returns **ffrt_thrd_error** if the blocking fails.
### 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|
| -------- | -------- |
| cond | Pointer to the condition variable.|
| mutex | Pointer to the mutex.|
**Returns**
Returns **ffrt_thrd_success** if the thread is blocked; returns **ffrt_thrd_error** if the blocking fails.
### ffrt_mutex_destroy()
```
FFRT_C_API int ffrt_mutex_destroy (ffrt_mutex_t * mutex)
```
**Description**
Destroys a mutex.
**Since**: 10
**Parameters**
| Name| Description|
| -------- | -------- |
| mutex | Pointer to the mutex.|
**Returns**
Returns **ffrt_thrd_success** if the mutex is destroyed; returns **ffrt_thrd_error** otherwise.
### ffrt_mutex_init()
```
FFRT_C_API int ffrt_mutex_init (ffrt_mutex_t * mutex, const ffrt_mutexattr_t * attr )
```
**Description**
Initializes a mutex.
**Since**: 10
**Parameters**
| Name| Description|
| -------- | -------- |
| mutex | Pointer to the mutex.|
| attr | Pointer to the mutex attribute.|
**Returns**
Returns **ffrt_thrd_success** if the mutex is initialized; returns **ffrt_thrd_error** otherwise.
### ffrt_mutex_lock()
```
FFRT_C_API int ffrt_mutex_lock (ffrt_mutex_t * mutex)
```
**Description**
Locks a mutex.
**Since**: 10
**Parameters**
| Name| Description|
| -------- | -------- |
| mutex | Pointer to the mutex.|
**Returns**
Returns **ffrt_thrd_success** if the mutex is locked; returns **ffrt_thrd_error** or blocks the calling thread otherwise.
### ffrt_mutex_trylock()
```
FFRT_C_API int ffrt_mutex_trylock (ffrt_mutex_t * mutex)
```
**Description**
Attempts to lock a mutex.
**Since**: 10
**Parameters**
| Name| Description|
| -------- | -------- |
| mutex | Pointer to the mutex.|
**Returns**
Returns **ffrt_thrd_success** if the mutex is locked; returns **ffrt_thrd_error** or **ffrt_thrd_busy** otherwise.
### ffrt_mutex_unlock()
```
FFRT_C_API int ffrt_mutex_unlock (ffrt_mutex_t * mutex)
```
**Description**
Unlocks a mutex.
**Since**: 10
**Parameters**
| Name| Description|
| -------- | -------- |
| mutex | Pointer to the mutex.|
**Returns**
Returns **ffrt_thrd_success** if the mutex is unlocked; returns **ffrt_thrd_error** otherwise.
### ffrt_queue_attr_destroy()
```
FFRT_C_API void ffrt_queue_attr_destroy (ffrt_queue_attr_t * attr)
```
**Description**
Destroys a queue attribute.
**Since**: 10
**Parameters**
| Name| Description|
| -------- | -------- |
| attr | Pointer to the queue attribute.|
### ffrt_queue_attr_get_callback()
```
FFRT_C_API ffrt_function_header_t* ffrt_queue_attr_get_callback (const ffrt_queue_attr_t * attr)
```
**Description**
Obtains the callback that is invoked when a queue task times out.
**Since**: 10
**Parameters**
| Name| Description|
| -------- | -------- |
| attr | Pointer to the queue attribute.|
**Returns**
Returns the callback.
### ffrt_queue_attr_get_qos()
```
FFRT_C_API ffrt_qos_t ffrt_queue_attr_get_qos (const ffrt_queue_attr_t * attr)
```
**Description**
Obtains the queue QoS.
**Since**: 10
**Parameters**
| Name| Description|
| -------- | -------- |
| attr | Pointer to the queue attribute.|
**Returns**
Returns the QoS.
### ffrt_queue_attr_get_timeout()
```
FFRT_C_API uint64_t ffrt_queue_attr_get_timeout (const ffrt_queue_attr_t * attr)
```
**Description**
Obtains the queue timeout.
**Since**: 10
**Parameters**
| Name| Description|
| -------- | -------- |
| attr | Pointer to the queue attribute.|
**Returns**
Returns the timeout.
### ffrt_queue_attr_init()
```
FFRT_C_API int ffrt_queue_attr_init (ffrt_queue_attr_t * attr)
```
**Description**
Initializes a queue attribute.
**Since**: 10
**Parameters**
| Name| Description|
| -------- | -------- |
| attr | Pointer to the queue attribute.|
**Returns**
Returns **0** if the queue attribute is initialized; returns **-1** otherwise.
### ffrt_queue_attr_set_callback()
```
FFRT_C_API void ffrt_queue_attr_set_callback (ffrt_queue_attr_t * attr, ffrt_function_header_t * f )
```
**Description**
Sets a callback that is invoked when a queue task times out.
**Since**: 10
**Parameters**
| Name| Description|
| -------- | -------- |
| attr | Pointer to the queue attribute.|
| f | Pointer to the callback function.|
### ffrt_queue_attr_set_qos()
```
FFRT_C_API void ffrt_queue_attr_set_qos (ffrt_queue_attr_t * attr, ffrt_qos_t qos )
```
**Description**
Sets the queue QoS.
**Since**: 10
**Parameters**
| Name| Description|
| -------- | -------- |
| attr | Pointer to the queue attribute.|
| qos | QoS.|
### ffrt_queue_attr_set_timeout()
```
FFRT_C_API void ffrt_queue_attr_set_timeout (ffrt_queue_attr_t * attr, uint64_t timeout_us )
```
**Description**
Sets the queue timeout.
**Since**: 10
**Parameters**
| Name| Description|
| -------- | -------- |
| attr | Pointer to the queue attribute.|
| timeout_us | Timeout.|
### ffrt_queue_cancel()
```
FFRT_C_API int ffrt_queue_cancel (ffrt_task_handle_t handle)
```
**Description**
Cancels a task in the queue.
**Since**: 10
**Parameters**
| Name| Description|
| -------- | -------- |
| handle | Task handle.|
**Returns**
Returns **0** if the task is canceled; returns **-1** otherwise.
### ffrt_queue_create()
```
FFRT_C_API ffrt_queue_t ffrt_queue_create (ffrt_queue_type_t type, const char * name, const ffrt_queue_attr_t * attr )
```
**Description**
Creates a queue.
**Since**: 10
**Parameters**
| Name| Description|
| -------- | -------- |
| type | Queue type.|
| name | Pointer to the queue name.|
| attr | Pointer to the queue attribute.|
**Returns**
Returns a non-null queue handle if the queue is created; returns a null pointer otherwise.
### ffrt_queue_destroy()
```
FFRT_C_API void ffrt_queue_destroy (ffrt_queue_t queue)
```
**Description**
Destroys a queue.
**Since**: 10
**Parameters**
| Name| Description|
| -------- | -------- |
| queue | Queue handle.|
### ffrt_queue_submit()
```
FFRT_C_API void ffrt_queue_submit (ffrt_queue_t queue, ffrt_function_header_t * f, const ffrt_task_attr_t * attr )
```
**Description**
Submits a task to a queue.
**Since**: 10
**Parameters**
| Name| Description|
| -------- | -------- |
| queue | Queue handle.|
| f | Pointer to the task execution function.|
| attr | Pointer to the task attribute.|
### ffrt_queue_submit_h()
```
FFRT_C_API ffrt_task_handle_t ffrt_queue_submit_h (ffrt_queue_t queue, ffrt_function_header_t * f, const ffrt_task_attr_t * attr )
```
**Description**
Submits a task to a queue, and obtains a task handle.
**Since**: 10
**Parameters**
| Name| Description|
| -------- | -------- |
| queue | Queue handle.|
| f | Pointer to the task execution function.|
| attr | Pointer to the task attribute.|
**Returns**
Returns a non-null task handle if the task is submitted; returns a null pointer otherwise.
### ffrt_queue_wait()
```
FFRT_C_API void ffrt_queue_wait (ffrt_task_handle_t handle)
```
**Description**
Waits until a task in the queue is complete.
**Since**: 10
**Parameters**
| Name| Description|
| -------- | -------- |
| handle | Task handle.|
### ffrt_submit_base()
```
FFRT_C_API void ffrt_submit_base (ffrt_function_header_t * f, const ffrt_deps_t * in_deps, const ffrt_deps_t * out_deps, const ffrt_task_attr_t * attr )
```
**Description**
Submits a task.
**Since**: 10
**Parameters**
| Name| Description|
| -------- | -------- |
| f | Pointer to the task execution function.|
| in_deps | Pointer to the input dependencies.|
| out_deps | Pointer to the output dependencies.|
| attr | Pointer to the task attribute.|
### ffrt_submit_h_base()
```
FFRT_C_API ffrt_task_handle_t ffrt_submit_h_base (ffrt_function_header_t * f, const ffrt_deps_t * in_deps, const ffrt_deps_t * out_deps, const ffrt_task_attr_t * attr )
```
**Description**
Submits a task, and obtains a task handle.
**Since**: 10
**Parameters**
| Name| Description|
| -------- | -------- |
| f | Pointer to the task execution function.|
| in_deps | Pointer to the input dependencies.|
| out_deps | Pointer to the output dependencies.|
| attr | Pointer to the task attribute.|
**Returns**
Returns a non-null task handle if the task is submitted; returns a null pointer otherwise.
### ffrt_task_attr_destroy()
```
FFRT_C_API void ffrt_task_attr_destroy (ffrt_task_attr_t * attr)
```
**Description**
Destroys a task attribute.
**Since**: 10
**Parameters**
| Name| Description|
| -------- | -------- |
| attr | Pointer to the task attribute.|
### ffrt_task_attr_get_delay()
```
FFRT_C_API uint64_t ffrt_task_attr_get_delay (const ffrt_task_attr_t * attr)
```
**Description**
Obtains the task delay time.
**Since**: 10
**Parameters**
| Name| Description|
| -------- | -------- |
| attr | Pointer to the task attribute.|
**Returns**
Returns the delay time.
### ffrt_task_attr_get_name()
```
FFRT_C_API const char* ffrt_task_attr_get_name (const ffrt_task_attr_t * attr)
```
**Description**
Obtains a task name.
**Since**: 10
**Parameters**
| Name| Description|
| -------- | -------- |
| attr | Pointer to the task attribute.|
**Returns**
Returns a non-null pointer to the task name if the name is obtained; returns a null pointer otherwise.
### ffrt_task_attr_get_qos()
```
FFRT_C_API ffrt_qos_t ffrt_task_attr_get_qos (const ffrt_task_attr_t * attr)
```
**Description**
Obtains the task QoS.
**Since**: 10
**Parameters**
| Name| Description|
| -------- | -------- |
| attr | Pointer to the task attribute.|
**Returns**
Returns the QoS, which is **ffrt_qos_default** by default.
### ffrt_task_attr_init()
```
FFRT_C_API int ffrt_task_attr_init (ffrt_task_attr_t * attr)
```
**Description**
Initializes a task attribute.
**Since**: 10
**Parameters**
| Name| Description|
| -------- | -------- |
| attr | Pointer to the task attribute.|
**Returns**
Returns **0** if the task attribute is initialized; returns **-1** otherwise.
### ffrt_task_attr_set_delay()
```
FFRT_C_API void ffrt_task_attr_set_delay (ffrt_task_attr_t * attr, uint64_t delay_us )
```
**Description**
Sets the task delay time.
**Since**: 10
**Parameters**
| Name| Description|
| -------- | -------- |
| attr | Pointer to the task attribute.|
| delay_us | Delay time, in microseconds.|
### ffrt_task_attr_set_name()
```
FFRT_C_API void ffrt_task_attr_set_name (ffrt_task_attr_t * attr, const char * name )
```
**Description**
Sets a task name.
**Since**: 10
**Parameters**
| Name| Description|
| -------- | -------- |
| attr | Pointer to the task attribute.|
| name | Pointer to the task name.|
### ffrt_task_attr_set_qos()
```
FFRT_C_API void ffrt_task_attr_set_qos (ffrt_task_attr_t * attr, ffrt_qos_t qos )
```
**Description**
Sets the task QoS.
**Since**: 10
**Parameters**
| Name| Description|
| -------- | -------- |
| attr | Pointer to the task attribute.|
| qos | QoS.|
### ffrt_task_handle_destroy()
```
FFRT_C_API void ffrt_task_handle_destroy (ffrt_task_handle_t handle)
```
**Description**
Destroys a task handle.
**Since**: 10
**Parameters**
| Name| Description|
| -------- | -------- |
| handle | Task handle.|
### ffrt_this_task_get_id()
```
FFRT_C_API uint64_t ffrt_this_task_get_id (void )
```
**Description**
Obtains the task ID.
**Since**: 10
**Returns**
Returns the ID.
### ffrt_this_task_update_qos()
```
FFRT_C_API int ffrt_this_task_update_qos (ffrt_qos_t qos)
```
**Description**
Updates the task QoS.
**Since**: 10
**Parameters**
| Name| Description|
| -------- | -------- |
| qos | New QoS.|
**Returns**
Returns **0** if the QoS is updated; returns **-1** otherwise.
### ffrt_usleep()
```
FFRT_C_API int ffrt_usleep (uint64_t usec)
```
**Description**
Suspends the calling thread for a given duration.
**Since**: 10
**Parameters**
| Name| Description|
| -------- | -------- |
| usec | Duration that the calling thread is suspended, in microseconds. |
**Returns**
Returns **ffrt_thrd_success** if the thread is suspended; returns **ffrt_thrd_error** otherwise.
### ffrt_wait()
```
FFRT_C_API void ffrt_wait (void )
```
**Description**
Waits until all submitted tasks are complete.
**Since**: 10
### ffrt_wait_deps()
```
FFRT_C_API void ffrt_wait_deps (const ffrt_deps_t * deps)
```
**Description**
Waits until the dependent tasks are complete.
**Since**: 10
**Parameters**
| Name| Description|
| -------- | -------- |
| deps | Pointer to the dependencies.|
### ffrt_yield()
```
FFRT_C_API void ffrt_yield (void )
```
**Description**
Passes control to other tasks so that they can be executed.
**Since**: 10
## Variable Description
### destroy
```
ffrt_function_t ffrt_function_header_t::destroy
```
**Description**
Function used to destroy a task.
### exec
```
ffrt_function_t ffrt_function_header_t::exec
```
**Description**
Function used to execute a task.
### items
```
const ffrt_dependence_t* ffrt_deps_t::items
```
**Description**
Dependency data.
### len
```
uint32_t ffrt_deps_t::len
```
**Description**
Number of dependencies.
### ptr
```
const void* ffrt_dependence_t::ptr
```
**Description**
Address of the dependency data.
### reserve
```
uint64_t ffrt_function_header_t::reserve[2]
```
**Description**
Reserved bit.
### storage [1/6]
```
uint32_t ffrt_cond_t::storage[(ffrt_cond_storage_size+sizeof(uint32_t) - 1)/sizeof(uint32_t)]
```
**Description**
Storage size of a condition variable.
### storage [2/6]
```
uint32_t ffrt_mutex_t::storage[(ffrt_mutex_storage_size+sizeof(uint32_t) - 1)/sizeof(uint32_t)]
```
**Description**
Storage size of a mutex.
### storage [3/6]
```
uint32_t ffrt_queue_attr_t::storage[(ffrt_queue_attr_storage_size+sizeof(uint32_t) - 1)/sizeof(uint32_t)]
```
**Description**
Storage size of a queue attribute.
### storage [4/6]
```
uint32_t ffrt_task_attr_t::storage[(ffrt_task_attr_storage_size+sizeof(uint32_t) - 1)/sizeof(uint32_t)]
```
**Description**
Storage size of a task attribute.
### storage [5/6]
```
long ffrt_condattr_t::storage
```
**Description**
Storage size of a condition variable attribute.
### storage [6/6]
```
long ffrt_mutexattr_t::storage
```
**Description**
Storage size of a mutex attribute.
### type
```
ffrt_dependence_type_t ffrt_dependence_t::type
```
**Description**
Dependency type.