Re: [PATCH 4/4] DEC threads: Simplify updating the thread list

[Mark Kettenis <mark.kettenis@xs4all.nl>]

> From: Pedro Alves <palves@redhat.com>
> Date: Thu,  2 Oct 2014 17:21:36 +0100
> 
> Seems to me that we can simplify DEC thread's
> target_update_thread_list implementation, avoiding the need to build
> the array of GDB threads.
> 
> I have no way to test this.

Given that Alpha True64 support is about to be removed, I don't think
anyone will care.

> gdb/
> 2014-10-02  Pedro Alves  <palves@redhat.com>
> 
> 	* dec-thread.c (dec_thread_count_gdb_threads)
> 	(dec_thread_add_gdb_thread): Delete.
> 	(dec_thread_update_thread_list): Delete.
> 	(dec_thread_find_new_threads): Rename to ...
> 	(dec_thread_update_thread_list): ... this.  Delete GDB-size
> 	threads that are no longer found in dec_thread_list.
> 	(resync_thread_list): Delete.
> 	(dec_thread_wait): Call dec_thread_update_thread_list instead of
> 	resync_thread_list.
> ---
>  gdb/dec-thread.c | 93 +++++++++++++-------------------------------------------
>  1 file changed, 21 insertions(+), 72 deletions(-)
> 
> diff --git a/gdb/dec-thread.c b/gdb/dec-thread.c
> index fc43153..d5cfad2 100644
> --- a/gdb/dec-thread.c
> +++ b/gdb/dec-thread.c
> @@ -369,40 +369,33 @@ update_dec_thread_list (void)
>    pthreadDebugThdSeqDestroy (debug_context);
>  }
>  
> -/* A callback to count the number of threads known to GDB.  */
> -
> -static int
> -dec_thread_count_gdb_threads (struct thread_info *ignored, void *context)
> -{
> -  int *count = (int *) context;
> -
> -  *count = *count + 1;
> -  return 0;
> -}
> -
> -/* A callback that saves the given thread INFO at the end of an
> -   array.  The end of the array is given in the CONTEXT and is
> -   incremented once the info has been added.  */
> -
> -static int
> -dec_thread_add_gdb_thread (struct thread_info *info, void *context)
> -{
> -  struct thread_info ***listp = (struct thread_info ***) context;
> -  
> -  **listp = info;
> -  *listp = *listp + 1;
> -  return 0;
> -}
> -
> -/* Find new threads.  */
> +/* Implement the update_thread_list target_ops method.  */
>  
>  static void
> -dec_thread_find_new_threads (struct target_ops *ops)
> +dec_thread_update_thread_list (struct target_ops *ops)
>  {
>    int i;
>    struct dec_thread_info *info;
> +  struct thread_info *tp, *tmp;
>  
>    update_dec_thread_list ();
> +
> +  /* Delete GDB-side threads no longer found in dec_thread_list.  */
> +  ALL_NON_EXITED_THREADS_SAFE (tp, tmp)
> +    {
> +      for (i = 0; VEC_iterate (dec_thread_info_s, dec_thread_list, i, info); i++)
> +	{
> +	  if (ptid_equal (info->ptid, tp->ptid))
> +	    break;
> +	}
> +      if (i == VEC_length (dec_thread_info_s, dec_thread_list))
> +	{
> +	  /* Not found.  */
> +	  delete_thread (tp->ptid);
> +	}
> +    }
> +
> +  /* And now add new threads.  */
>    for (i = 0; VEC_iterate (dec_thread_info_s, dec_thread_list, i, info); i++)
>      {
>        ptid_t ptid = ptid_build_from_info (*info);
> @@ -412,50 +405,6 @@ dec_thread_find_new_threads (struct target_ops *ops)
>      }
>  }
>  
> -/* Implement the update_thread_list target_ops method.  */
> -
> -static void
> -dec_thread_update_thread_list (struct target_ops *ops)
> -{
> -  int i;
> -  struct dec_thread_info *info;
> -
> -  /* Delete dead threads.  */
> -  prune_threads ();
> -
> -  /* Now find new threads.  */
> -  dec_thread_find_new_threads (ops);
> -}
> -
> -/* Resynchronize the list of threads known by GDB with the actual
> -   list of threads reported by libpthread_debug.  */
> -
> -static void
> -resync_thread_list (struct target_ops *ops)
> -{
> -  int i;
> -  int num_gdb_threads = 0;
> -  struct thread_info **gdb_thread_list;
> -  struct thread_info **next_thread_info;
> -
> -  /* Add new threads.  */
> -  dec_thread_find_new_threads (ops);
> -
> -  /* Remove threads that no longer exist.  To help with the search,
> -     we build an array of GDB threads, and then iterate over this
> -     array.  */
> -
> -  iterate_over_threads (dec_thread_count_gdb_threads,
> -                        (void *) &num_gdb_threads);
> -  gdb_thread_list = alloca (num_gdb_threads * sizeof (struct thread_info *));
> -  next_thread_info = gdb_thread_list;
> -  iterate_over_threads (dec_thread_add_gdb_thread, (void *) &next_thread_info);
> -
> -  for (i = 0; i < num_gdb_threads; i++)
> -    if (!dec_thread_ptid_is_alive (gdb_thread_list[i]->ptid))
> -      delete_thread (gdb_thread_list[i]->ptid);
> -}
> -
>  /* The "to_detach" method of the dec_thread_ops.  */
>  
>  static void
> @@ -502,7 +451,7 @@ dec_thread_wait (struct target_ops *ops,
>  
>    /* The ptid returned by the target beneath us is the ptid of the process.
>       We need to find which thread is currently active and return its ptid.  */
> -  resync_thread_list (ops);
> +  dec_thread_update_thread_list (ops);
>    active_ptid = get_active_ptid ();
>    if (ptid_equal (active_ptid, null_ptid))
>      return ptid;
> -- 
> 1.9.3
> 
>