pthread/qos.h

__API_AVAILABLE(macos(10.10), ios(8.0))
int pthread_attr_set_qos_class_np(
	pthread_attr_t *__attr,
	qos_class_t __qos_class,
	int __relative_priority
)

@function pthread_attr_set_qos_class_np @abstract Sets the QOS class and relative priority of a pthread attribute structure which may be used to specify the requested QOS class of newly created threads. @discussion The QOS class and relative priority represent an overall combination of system quality of service attributes on a thread. Subsequent calls to interfaces such as pthread_attr_setschedparam() that are incompatible or in conflict with the QOS class system will unset the QOS class requested with this interface and pthread_attr_get_qos_class_np() will return QOS_CLASS_UNSPECIFIED. @param __attr The pthread attribute structure to modify. @param __qos_class A QOS class value: - QOS_CLASS_USER_INTERACTIVE - QOS_CLASS_USER_INITIATED - QOS_CLASS_DEFAULT - QOS_CLASS_UTILITY - QOS_CLASS_BACKGROUND EINVAL will be returned if any other value is provided. @param __relative_priority A relative priority within the QOS class. This value is a negative offset from the maximum supported scheduler priority for the given class. EINVAL will be returned if the value is greater than zero or less than QOS_MIN_RELATIVE_PRIORITY. @return Zero if successful, otherwise an errno value.

__API_AVAILABLE(macos(10.10), ios(8.0))
int pthread_attr_get_qos_class_np(
	pthread_attr_t * __restrict __attr,
	qos_class_t * _Nullable __restrict __qos_class,
	int * _Nullable __restrict __relative_priority
)

@function pthread_attr_get_qos_class_np @abstract Gets the QOS class and relative priority of a pthread attribute structure. @param __attr The pthread attribute structure to inspect. @param __qos_class On output, a QOS class value: - QOS_CLASS_USER_INTERACTIVE - QOS_CLASS_USER_INITIATED - QOS_CLASS_DEFAULT - QOS_CLASS_UTILITY - QOS_CLASS_BACKGROUND - QOS_CLASS_UNSPECIFIED This value may be NULL in which case no value is returned. @param __relative_priority On output, a relative priority offset within the QOS class. This value may be NULL in which case no value is returned. @return Zero if successful, otherwise an errno value.

__API_AVAILABLE(macos(10.10), ios(8.0))
int pthread_set_qos_class_self_np(qos_class_t __qos_class, int __relative_priority)

@function pthread_set_qos_class_self_np @abstract Sets the requested QOS class and relative priority of the current thread. @discussion The QOS class and relative priority represent an overall combination of system quality of service attributes on a thread. Subsequent calls to interfaces such as pthread_setschedparam() that are incompatible or in conflict with the QOS class system will unset the QOS class requested with this interface and pthread_get_qos_class_np() will return QOS_CLASS_UNSPECIFIED thereafter. A thread so modified is permanently opted-out of the QOS class system and calls to this function to request a QOS class for such a thread will fail and return EPERM. @param __qos_class A QOS class value: - QOS_CLASS_USER_INTERACTIVE - QOS_CLASS_USER_INITIATED - QOS_CLASS_DEFAULT - QOS_CLASS_UTILITY - QOS_CLASS_BACKGROUND EINVAL will be returned if any other value is provided. @param __relative_priority A relative priority within the QOS class. This value is a negative offset from the maximum supported scheduler priority for the given class. EINVAL will be returned if the value is greater than zero or less than QOS_MIN_RELATIVE_PRIORITY. @return Zero if successful, otherwise an errno value.

__API_AVAILABLE(macos(10.10), ios(8.0))
int pthread_get_qos_class_np(
	pthread_t __pthread,
	qos_class_t * _Nullable __restrict __qos_class,
	int * _Nullable __restrict __relative_priority
)

@function pthread_get_qos_class_np @abstract Gets the requested QOS class and relative priority of a thread. @param __pthread The target thread to inspect. @param __qos_class On output, a QOS class value: - QOS_CLASS_USER_INTERACTIVE - QOS_CLASS_USER_INITIATED - QOS_CLASS_DEFAULT - QOS_CLASS_UTILITY - QOS_CLASS_BACKGROUND - QOS_CLASS_UNSPECIFIED This value may be NULL in which case no value is returned. @param __relative_priority On output, a relative priority offset within the QOS class. This value may be NULL in which case no value is returned. @return Zero if successful, otherwise an errno value.

__API_AVAILABLE(macos(10.10), ios(8.0))
pthread_override_t pthread_override_qos_class_start_np(
	pthread_t __pthread,
	qos_class_t __qos_class,
	int __relative_priority
)

@function pthread_override_qos_class_start_np @abstract Starts a QOS class override of the specified target thread. @discussion Starting a QOS class override of the specified target thread expresses that an item of pending work classified with the specified QOS class and relative priority depends on the completion of the work currently being executed by the thread (e.g. due to ordering requirements). While overrides are in effect, the specified target thread will execute at the maximum QOS class and relative priority of all overrides and of the QOS class requested by the thread itself. Starting a QOS class override does not modify the target thread's requested QOS class value and the effect of an override is not visible to the qos_class_self() and pthread_get_qos_class_np() interfaces. The returned newly allocated override object is intended to be associated with the item of pending work in question. Once the dependency has been satisfied and enabled that work to begin executing, the QOS class override must be ended by passing the associated override object to pthread_override_qos_class_end_np(). Failure to do so will result in the associated resources to be leaked and the target thread to be permanently executed at an inappropriately elevated QOS class. @param __pthread The target thread to modify. @param __qos_class A QOS class value: - QOS_CLASS_USER_INTERACTIVE - QOS_CLASS_USER_INITIATED - QOS_CLASS_DEFAULT - QOS_CLASS_UTILITY - QOS_CLASS_BACKGROUND NULL will be returned if any other value is provided. @param __relative_priority A relative priority within the QOS class. This value is a negative offset from the maximum supported scheduler priority for the given class. NULL will be returned if the value is greater than zero or less than QOS_MIN_RELATIVE_PRIORITY. @return A newly allocated override object if successful, or NULL if the override could not be started.

__API_AVAILABLE(macos(10.10), ios(8.0))
int pthread_override_qos_class_end_np(pthread_override_t __override)

@function pthread_override_qos_class_end_np @abstract Ends a QOS class override. @discussion Passing an override object returned by pthread_override_qos_class_start_np() ends the QOS class override started by that call and deallocates all associated resources as well as the override object itself. The thread starting and the thread ending a QOS class override need not be identical. If the thread ending the override is the the target thread of the override itself, it should take care to elevate its requested QOS class appropriately with pthread_set_qos_class_self_np() before ending the override. @param __override An override object returned by pthread_override_qos_class_start_np(). @return Zero if successful, otherwise an errno value.