[PATCH 10/12] scheduler: Simplify simple scheduler

[Gedare Bloom]

On Wed, Jun 12, 2013 at 11:29 AM, Sebastian Huber
<sebastian.huber at embedded-brains.de> wrote:
> Add and use _Scheduler_simple_Insert_as_first_order(),
> _Scheduler_simple_Insert_as_last_order(),
> _Scheduler_simple_Insert_as_first() and
> _Scheduler_simple_Insert_as_last().
> ---
>  .../score/inline/rtems/score/schedulersimple.inl   |   46 ++++++++++++++++++++
>  .../score/src/schedulersimplereadyqueueenqueue.c   |   21 +--------
>  .../src/schedulersimplereadyqueueenqueuefirst.c    |   26 +----------
>  3 files changed, 50 insertions(+), 43 deletions(-)
>
> diff --git a/cpukit/score/inline/rtems/score/schedulersimple.inl b/cpukit/score/inline/rtems/score/schedulersimple.inl
> index e67fc3c..1b58c85 100644
> --- a/cpukit/score/inline/rtems/score/schedulersimple.inl
> +++ b/cpukit/score/inline/rtems/score/schedulersimple.inl
> @@ -48,6 +48,52 @@ RTEMS_INLINE_ROUTINE void _Scheduler_simple_Ready_queue_requeue(
>    _Scheduler_simple_Ready_queue_enqueue( the_thread );
>  }
>
> +RTEMS_INLINE_ROUTINE bool _Scheduler_simple_Insert_as_first_order(
> +  const Chain_Node *to_insert,
> +  const Chain_Node *next
> +)
> +{
> +  const Thread_Control *thread_to_insert = (const Thread_Control *) to_insert;
> +  const Thread_Control *thread_next = (const Thread_Control *) next;
> +
> +  return thread_to_insert->current_priority <= thread_next->current_priority;
> +}
> +
> +RTEMS_INLINE_ROUTINE bool _Scheduler_simple_Insert_as_last_order(
> +  const Chain_Node *to_insert,
> +  const Chain_Node *next
> +)
> +{
> +  const Thread_Control *thread_to_insert = (const Thread_Control *) to_insert;
> +  const Thread_Control *thread_next = (const Thread_Control *) next;
> +
> +  return thread_to_insert->current_priority < thread_next->current_priority;
> +}
> +
> +RTEMS_INLINE_ROUTINE void _Scheduler_simple_Insert_as_first(
> +  Chain_Control *chain,
> +  Thread_Control *to_insert
> +)
> +{
> +  _Chain_Insert_ordered_unprotected(
> +    chain,
> +    &to_insert->Object.Node,
> +    _Scheduler_simple_Insert_as_first_order
> +  );
> +}
> +
> +RTEMS_INLINE_ROUTINE void _Scheduler_simple_Insert_as_last(
> +  Chain_Control *chain,
> +  Thread_Control *to_insert
> +)
> +{
> +  _Chain_Insert_ordered_unprotected(
> +    chain,
> +    &to_insert->Object.Node,
> +    _Scheduler_simple_Insert_as_last_order
> +  );
> +}
For these functions _Scheduler_simple_Insert_as_first() and
_Scheduler_simple_Insert_as_last() the name means they break priority
ties by FIFO and LIFO semantics? Before I read the code, I thought it
meant break ties by inserting to the first or last position of ties,
which is the opposite. I would prefer to have
_Scheduler_simple_Insert_as_fifo()/lifo() instead for added clarity.

> +
>  /** @} */
>
>  #endif
> diff --git a/cpukit/score/src/schedulersimplereadyqueueenqueue.c b/cpukit/score/src/schedulersimplereadyqueueenqueue.c
> index ea3c2c4..8d7ef0f 100644
> --- a/cpukit/score/src/schedulersimplereadyqueueenqueue.c
> +++ b/cpukit/score/src/schedulersimplereadyqueueenqueue.c
> @@ -28,24 +28,7 @@ void _Scheduler_simple_Ready_queue_enqueue(
>    Thread_Control    *the_thread
>  )
>  {
> -  Chain_Control    *ready;
> -  Chain_Node       *the_node;
> -  Thread_Control   *current;
> +  Chain_Control *ready = (Chain_Control *) _Scheduler.information;
>
> -  ready    = (Chain_Control *)_Scheduler.information;
> -  the_node = _Chain_First( ready );
> -  current  = (Thread_Control *)ready;
> -
> -  for ( ; !_Chain_Is_tail( ready, the_node ) ; the_node = the_node->next ) {
> -    current = (Thread_Control *) the_node;
> -
> -    /* break when AT END OR PAST our priority */
> -    if ( the_thread->current_priority < current->current_priority ) {
> -      current = (Thread_Control *)current->Object.Node.previous;
> -      break;
> -    }
> -  }
> -
> -  /* enqueue */
> -  _Chain_Insert_unprotected( (Chain_Node *)current, &the_thread->Object.Node );
> +  _Scheduler_simple_Insert_as_last( ready, the_thread );
>  }
> diff --git a/cpukit/score/src/schedulersimplereadyqueueenqueuefirst.c b/cpukit/score/src/schedulersimplereadyqueueenqueuefirst.c
> index 47a4a3b..95c6fad 100644
> --- a/cpukit/score/src/schedulersimplereadyqueueenqueuefirst.c
> +++ b/cpukit/score/src/schedulersimplereadyqueueenqueuefirst.c
> @@ -27,29 +27,7 @@ void _Scheduler_simple_Ready_queue_enqueue_first(
>    Thread_Control    *the_thread
>  )
>  {
> -  Chain_Control    *ready;
> -  Chain_Node       *the_node;
> -  Thread_Control   *current;
> +  Chain_Control *ready = (Chain_Control *) _Scheduler.information;
>
> -  ready    = (Chain_Control *)_Scheduler.information;
> -  current  = (Thread_Control *)ready;
> -
> -  /*
> -   * Do NOT need to check for end of chain because there is always
> -   * at least one task on the ready chain -- the IDLE task.  It can
> -   * never block, should never attempt to obtain a semaphore or mutex,
> -   * and thus will always be there.
> -   */
> -  for ( the_node = _Chain_First(ready) ; ; the_node = the_node->next ) {
> -    current = (Thread_Control *) the_node;
> -
> -    /* break when AT HEAD OF (or PAST) our priority */
> -    if ( the_thread->current_priority <= current->current_priority ) {
> -      current = (Thread_Control *)current->Object.Node.previous;
> -      break;
> -    }
> -  }
> -
> -  /* enqueue */
> -  _Chain_Insert_unprotected( (Chain_Node *)current, &the_thread->Object.Node );
> +  _Scheduler_simple_Insert_as_first( ready, the_thread );
>  }
> --
> 1.7.7
>
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