[PING] Replace deprecated_target_wait_hook by observers

[PING] Replace deprecated_target_wait_hook by observers

[Patrick Monnerat]

Any more comments on the last version?

Else I would appreciate a commit.

Thanks

Re: [PING] Replace deprecated_target_wait_hook by observers

[Tom Tromey]

>>>>> "Patrick" == Patrick Monnerat via Gdb-patches <gdb-patches@sourceware.org> writes:

Patrick> Any more comments on the last version?
Patrick> Else I would appreciate a commit.

This seems to have fallen through the cracks.
Could you 'git send-email' it?  I tried 'git am', but that failed; and
it would be more convenient if it were in a format where that worked.

Tom

Re: [PING] Replace deprecated_target_wait_hook by observers

[Patrick Monnerat]

On 3/11/22 20:57, Tom Tromey wrote:
>>>>>> "Patrick" == Patrick Monnerat via Gdb-patches <gdb-patches@sourceware.org> writes:
> Patrick> Any more comments on the last version?
> Patrick> Else I would appreciate a commit.
>
> This seems to have fallen through the cracks.
> Could you 'git send-email' it?  I tried 'git am', but that failed; and
> it would be more convenient if it were in a format where that worked.

Thanks for taking care Tom.

The rebased patch follows.

Patrick

[PING] Replace deprecated_target_wait_hook by observers

[Patrick Monnerat]

Any chances to get it pushed ? Thanks in advance,

Patrick

On 8/26/21 4:40 PM, Patrick Monnerat wrote:
> Commit b60cea7 (Make target_wait options use enum flags) broke
> deprecated_target_wait_hook usage: there's a commit comment telling
> this hook has not been converted.
>
> Rather than trying to mend it, this patch replaces the hook by two
> target_wait observers:
>
> target_pre_wait (ptid_t ptid)
> target_post_wait (ptid_t event_ptid)
>
> Upon target_wait entry, target_pre_wait is notified with the ptid
> passed to target_wait. Upon exit, target_post_wait is notified with
> the event ptid returned by target_wait. Should an exception occur,
> event_ptid is null_ptid.
>
> This change benefits to Insight (out-of-tree): there's no real use of the
> late hook in gdb itself.
> ---
>   gdb/infrun.c     | 15 +++------------
>   gdb/infrun.h     |  5 ++---
>   gdb/interps.c    |  1 -
>   gdb/observable.c |  2 ++
>   gdb/observable.h |  6 ++++++
>   gdb/target.c     | 37 ++++++++++++++++++++++++++++++++++++-
>   gdb/top.c        |  7 -------
>   7 files changed, 49 insertions(+), 24 deletions(-)
>
> diff --git a/gdb/infrun.c b/gdb/infrun.c
> index 5ee650fa464..695e3b0a586 100644
> --- a/gdb/infrun.c
> +++ b/gdb/infrun.c
> @@ -366,7 +366,7 @@ show_stop_on_solib_events (struct ui_file *file, int from_tty,
>   static bool stop_print_frame;
>   
>   /* This is a cached copy of the target/ptid/waitstatus of the last
> -   event returned by target_wait()/deprecated_target_wait_hook().
> +   event returned by target_wait().
>      This information is returned by get_last_target_status().  */
>   static process_stratum_target *target_last_proc_target;
>   static ptid_t target_last_wait_ptid;
> @@ -3478,7 +3478,6 @@ static ptid_t
>   do_target_wait_1 (inferior *inf, ptid_t ptid,
>   		  target_waitstatus *status, target_wait_flags options)
>   {
> -  ptid_t event_ptid;
>     struct thread_info *tp;
>   
>     /* We know that we are looking for an event in the target of inferior
> @@ -3594,12 +3593,7 @@ do_target_wait_1 (inferior *inf, ptid_t ptid,
>     if (!target_can_async_p ())
>       options &= ~TARGET_WNOHANG;
>   
> -  if (deprecated_target_wait_hook)
> -    event_ptid = deprecated_target_wait_hook (ptid, status, options);
> -  else
> -    event_ptid = target_wait (ptid, status, options);
> -
> -  return event_ptid;
> +  return target_wait (ptid, status, options);
>   }
>   
>   /* Wrapper for target_wait that first checks whether threads have
> @@ -4558,10 +4552,7 @@ poll_one_curr_target (struct target_waitstatus *ws)
>        don't get any event.  */
>     target_dcache_invalidate ();
>   
> -  if (deprecated_target_wait_hook)
> -    event_ptid = deprecated_target_wait_hook (minus_one_ptid, ws, TARGET_WNOHANG);
> -  else
> -    event_ptid = target_wait (minus_one_ptid, ws, TARGET_WNOHANG);
> +  event_ptid = target_wait (minus_one_ptid, ws, TARGET_WNOHANG);
>   
>     if (debug_infrun)
>       print_target_wait_results (minus_one_ptid, event_ptid, ws);
> diff --git a/gdb/infrun.h b/gdb/infrun.h
> index 5a577365f94..a14e20b5f94 100644
> --- a/gdb/infrun.h
> +++ b/gdb/infrun.h
> @@ -124,9 +124,8 @@ extern process_stratum_target *user_visible_resume_target (ptid_t resume_ptid);
>   extern int normal_stop (void);
>   
>   /* Return the cached copy of the last target/ptid/waitstatus returned
> -   by target_wait()/deprecated_target_wait_hook().  The data is
> -   actually cached by handle_inferior_event(), which gets called
> -   immediately after target_wait()/deprecated_target_wait_hook().  */
> +   by target_wait().  The data is actually cached by handle_inferior_event(),
> +   which gets called immediately after target_wait().  */
>   extern void get_last_target_status (process_stratum_target **target,
>   				    ptid_t *ptid,
>   				    struct target_waitstatus *status);
> diff --git a/gdb/interps.c b/gdb/interps.c
> index ec19822b571..55bd10467c3 100644
> --- a/gdb/interps.c
> +++ b/gdb/interps.c
> @@ -356,7 +356,6 @@ clear_interpreter_hooks (void)
>     deprecated_readline_hook = 0;
>     deprecated_readline_end_hook = 0;
>     deprecated_context_hook = 0;
> -  deprecated_target_wait_hook = 0;
>     deprecated_call_command_hook = 0;
>     deprecated_error_begin_hook = 0;
>   }
> diff --git a/gdb/observable.c b/gdb/observable.c
> index 51f5edb0a1f..5724b712604 100644
> --- a/gdb/observable.c
> +++ b/gdb/observable.c
> @@ -77,6 +77,8 @@ DEFINE_OBSERVABLE (register_changed);
>   DEFINE_OBSERVABLE (user_selected_context_changed);
>   DEFINE_OBSERVABLE (source_styling_changed);
>   DEFINE_OBSERVABLE (current_source_symtab_and_line_changed);
> +DEFINE_OBSERVABLE (target_pre_wait);
> +DEFINE_OBSERVABLE (target_post_wait);
>   
>   } /* namespace observers */
>   } /* namespace gdb */
> diff --git a/gdb/observable.h b/gdb/observable.h
> index 915770ff363..652fb3df43f 100644
> --- a/gdb/observable.h
> +++ b/gdb/observable.h
> @@ -251,6 +251,12 @@ extern observable<> source_styling_changed;
>   
>   extern observable<> current_source_symtab_and_line_changed;
>   
> +/* About to enter target_wait (). */
> +extern observable <ptid_t /* ptid */> target_pre_wait;
> +
> +/* About to leave target_wait (). */
> +extern observable <ptid_t /* event_ptid */> target_post_wait;
> +
>   } /* namespace observers */
>   
>   } /* namespace gdb */
> diff --git a/gdb/target.c b/gdb/target.c
> index ae2d659583e..22e58484a18 100644
> --- a/gdb/target.c
> +++ b/gdb/target.c
> @@ -26,6 +26,7 @@
>   #include "symtab.h"
>   #include "inferior.h"
>   #include "infrun.h"
> +#include "observable.h"
>   #include "bfd.h"
>   #include "symfile.h"
>   #include "objfiles.h"
> @@ -2591,12 +2592,45 @@ target_disconnect (const char *args, int from_tty)
>     current_inferior ()->top_target ()->disconnect (args, from_tty);
>   }
>   
> +/* RAII class to handle target_wait observers.
> +   These observers allow the Insight GUI to monitor user interaction while
> +   waiting on the target. */
> +
> +class scoped_target_wait
> +{
> +public:
> +  explicit scoped_target_wait (ptid_t ptid)
> +  {
> +    m_event_ptid = null_ptid;
> +    gdb::observers::target_pre_wait.notify (ptid);
> +  }
> +
> +  ~scoped_target_wait ()
> +  {
> +    gdb::observers::target_post_wait.notify (m_event_ptid);
> +  }
> +
> +  void set (ptid_t event_ptid) noexcept
> +  {
> +    m_event_ptid = event_ptid;
> +  }
> +
> +  ptid_t get () const noexcept
> +  {
> +    return m_event_ptid;
> +  }
> +
> +private:
> +  ptid_t m_event_ptid;
> +};
> +
>   /* See target/target.h.  */
>   
>   ptid_t
>   target_wait (ptid_t ptid, struct target_waitstatus *status,
>   	     target_wait_flags options)
>   {
> +  scoped_target_wait event_ptid(ptid);
>     target_ops *target = current_inferior ()->top_target ();
>     process_stratum_target *proc_target = current_inferior ()->process_target ();
>   
> @@ -2605,7 +2639,8 @@ target_wait (ptid_t ptid, struct target_waitstatus *status,
>     if (!target->can_async_p ())
>       gdb_assert ((options & TARGET_WNOHANG) == 0);
>   
> -  return target->wait (ptid, status, options);
> +  event_ptid.set (target->wait (ptid, status, options));
> +  return event_ptid.get ();
>   }
>   
>   /* See target.h.  */
> diff --git a/gdb/top.c b/gdb/top.c
> index 0c49f4f9eb4..368166720ac 100644
> --- a/gdb/top.c
> +++ b/gdb/top.c
> @@ -249,13 +249,6 @@ void (*deprecated_readline_end_hook) (void);
>   void (*deprecated_attach_hook) (void);
>   void (*deprecated_detach_hook) (void);
>   
> -/* Called when going to wait for the target.  Usually allows the GUI
> -   to run while waiting for target events.  */
> -
> -ptid_t (*deprecated_target_wait_hook) (ptid_t ptid,
> -				       struct target_waitstatus *status,
> -				       int options);
> -
>   /* Used by UI as a wrapper around command execution.  May do various
>      things like enabling/disabling buttons, etc...  */
>