diff options
Diffstat (limited to 'cpukit/include/rtems/score/threadq.h')
-rw-r--r-- | cpukit/include/rtems/score/threadq.h | 49 |
1 files changed, 40 insertions, 9 deletions
diff --git a/cpukit/include/rtems/score/threadq.h b/cpukit/include/rtems/score/threadq.h index 10476888d4..2fbfcd0199 100644 --- a/cpukit/include/rtems/score/threadq.h +++ b/cpukit/include/rtems/score/threadq.h @@ -406,6 +406,7 @@ typedef struct _Thread_queue_Heads { } Thread_queue_Heads; struct Thread_queue_Queue { +#if defined(RTEMS_SMP) /** * @brief Lock to protect this thread queue. * @@ -418,7 +419,6 @@ struct Thread_queue_Queue { * @see _Thread_queue_Acquire(), _Thread_queue_Acquire_critical() and * _Thread_queue_Release(). */ -#if defined(RTEMS_SMP) SMP_ticket_lock_Control Lock; #endif @@ -517,37 +517,68 @@ typedef Thread_Control *( *Thread_queue_First_operation )( ); /** - * @brief Thread queue operations. + * @brief The thread queue operations are used to manage the threads of a + * thread queue. + * + * The standard thread queue operation variants are: + * + * * ::_Thread_queue_Operations_default + * + * * ::_Thread_queue_Operations_FIFO + * + * * ::_Thread_queue_Operations_priority + * + * * ::_Thread_queue_Operations_priority_inherit * * @see _Thread_wait_Set_operations(). */ struct Thread_queue_Operations { /** - * @brief Thread queue priority actions operation. + * @brief This operation performs the thread queue priority actions. + * + * Priority actions are produced and processed during enqueue, extract, and + * surrender operations. */ Thread_queue_Priority_actions_operation priority_actions; /** - * @brief Thread queue enqueue operation. + * @brief This operation is used to enqueue the thread on the thread queue. * - * Called by object routines to enqueue the thread. + * The enqueue order is defined by the operations variant. */ Thread_queue_Enqueue_operation enqueue; /** - * @brief Thread queue extract operation. + * @brief This operation is used to extract the thread from the thread queue. * - * Called by object routines to extract a thread from a thread queue. + * The extract operation is intended for timeouts, thread restarts, and + * thread cancellation. In SMP configurations, the extract operation does + * not ensure FIFO fairness across schedulers for priority queues. The + * surrender operation should be used to dequeue a thread from the thread + * queue under normal conditions (no timeout, no thread restart, and no + * thread cancellation). */ Thread_queue_Extract_operation extract; /** - * @brief Thread queue surrender operation. + * @brief This operation is used to dequeue the thread from the thread queue + * and optionally surrender the thread queue from a previous owner to the + * thread. + * + * In addition to the optional surrender, there is a subtle difference + * between the extract and dequeue of a thread from a thread queue. In SMP + * configurations, FIFO fairness across schedulers for priority queues is + * only ensured by the dequeue done by the surrender operation and not by the + * extract operation. */ Thread_queue_Surrender_operation surrender; /** - * @brief Thread queue first operation. + * @brief This operation returns the first thread on the thread queue. + * + * This operation may be called only when the thread queue contains at least + * one thread. Use ::Thread_queue_Queue::heads to determine if a thread + * queue is empty. */ Thread_queue_First_operation first; }; |