Thread_Control *_Thread_queue_Dequeue(
Thread_queue_Control *the_thread_queue
)
{
Thread_Control *the_thread;
ISR_lock_Context lock_context;
Thread_blocking_operation_States sync_state;
the_thread = NULL;
_Thread_queue_Acquire( &lock_context );
/*
* Invoke the discipline specific dequeue method.
*/
if ( the_thread_queue->discipline == THREAD_QUEUE_DISCIPLINE_FIFO ) {
if ( !_Chain_Is_empty( &the_thread_queue->Queues.Fifo ) ) {
the_thread = (Thread_Control *)
_Chain_Get_first_unprotected( &the_thread_queue->Queues.Fifo );
}
} else { /* must be THREAD_QUEUE_DISCIPLINE_PRIORITY */
RBTree_Node *first;
first = _RBTree_Get( &the_thread_queue->Queues.Priority, RBT_LEFT );
if ( first ) {
the_thread = THREAD_RBTREE_NODE_TO_THREAD( first );
_Thread_Priority_restore_default_change_handler( the_thread );
_Thread_Lock_restore_default( the_thread );
}
}
if ( the_thread == NULL ) {
/*
* We did not find a thread to unblock in the queue. Maybe the executing
* thread is about to block on this thread queue.
*/
sync_state = the_thread_queue->sync_state;
if ( (sync_state == THREAD_BLOCKING_OPERATION_TIMEOUT) ||
(sync_state == THREAD_BLOCKING_OPERATION_NOTHING_HAPPENED) ) {
the_thread_queue->sync_state = THREAD_BLOCKING_OPERATION_SATISFIED;
the_thread = _Thread_Executing;
} else {
_Thread_queue_Release( &lock_context );
return NULL;
}
}
/*
* We found a thread to unblock.
*
* NOTE: This is invoked with interrupts still disabled.
*/
_Thread_blocking_operation_Finalize( the_thread, &lock_context );
return the_thread;
}
Thread_Control *_Thread_queue_Dequeue(
Thread_queue_Control *the_thread_queue
)
{
Thread_Control *the_thread;
ISR_Level level;
Thread_blocking_operation_States sync_state;
the_thread = NULL;
_ISR_Disable( level );
/*
* Invoke the discipline specific dequeue method.
*/
if ( the_thread_queue->discipline == THREAD_QUEUE_DISCIPLINE_FIFO ) {
if ( !_Chain_Is_empty( &the_thread_queue->Queues.Fifo ) ) {
the_thread = (Thread_Control *)
_Chain_Get_first_unprotected( &the_thread_queue->Queues.Fifo );
}
} else { /* must be THREAD_QUEUE_DISCIPLINE_PRIORITY */
RBTree_Node *first;
first = _RBTree_Get( &the_thread_queue->Queues.Priority, RBT_LEFT );
if ( first ) {
the_thread = THREAD_RBTREE_NODE_TO_THREAD( first );
}
}
/*
* We did not find a thread to unblock.
*/
if ( !the_thread ) {
sync_state = the_thread_queue->sync_state;
if ( (sync_state == THREAD_BLOCKING_OPERATION_TIMEOUT) ||
(sync_state == THREAD_BLOCKING_OPERATION_NOTHING_HAPPENED) ) {
the_thread_queue->sync_state = THREAD_BLOCKING_OPERATION_SATISFIED;
the_thread = _Thread_Executing;
}
_ISR_Enable( level );
return NULL;
}
/*
* We found a thread to unblock.
*
* NOTE: This is invoked with interrupts still disabled.
*/
_Thread_blocking_operation_Finalize( the_thread, level );
return the_thread;
}
