Re: async patch (no. 4)

[Nick Roberts <nickrob at snap dot net dot nz>]

 > > I'm not sure if this was the last message in the thread but I'd like to
 > > see if we can get something committed after GDB 6.7 goes out.
 > 
 > Neither of us understands what parts of the patch do; in fact, I
 > understand almost none of it.  I think it would be a very bad decision
 > for us to commit structural changes to GDB that we do not understand
 > (even if they are disabled by default), and I think we have no hope of
 > keeping the code working and improving it unless it is clearer.  These
 > are the same requirements we apply to other changes.

I don't know how you can claim to uderstand almost none of it after you
suggested to me to use SIGCHLD to interrupt the call to select instead of using
threads.  I think some of these comments are based on looking at the previous
(eponymous) patch (no. 4).

 > I'd be happy to help you merge this, if you can break it down into
 > well-understood and necessary pieces.  I can help with making the
 > native wait case asynchronous, since I know how that works.  I also
 > have a patch lying around that makes target async-remote work a bit
 > better.

This is made harder by the fact that some of the event loop is quite obscure
and I suspect has a level of abstraction that is currently unused.  Perhaps a
good starting point would be to simplify this first.

I posted a ChangeLog last time which I divided roughly into my changes and
Apple's which I post below again.  Perhaps you can help me by telling me which
parts you think are unintelligible.  I concede that some of my changes might
fit in that category and don't pretend that understand I them completely.

-- 
Nick                                           http://www.inet.net.nz/~nickrob


2006-11-21  Nick Roberts  <nickrob@snap.net.nz>

	* defs.h (async_signal_hook): Declare.
	(event_loop_p): New extern.
	(deprecated_command_loop_hook): Make argument type void*.
	
	* main.c (captured_main, print_gdb_help): Add and describe --async
	option conditional on macro ASYNC.
	(event_loop_p): New global variable.
	
	* event-loop.c (async_signal_hook): New function pointer.
	(gdb_wait_for_event): Use it.

	* linux-nat.c: Include inf-loop.h.  Include poll.h conditionally.
	(gdb_post_startup): New extern.
	(gdb_status, gdb_file_event): New variables.
	(async_mask, old_mask, async_action, old_action): New variables.
	(linux_nat_attach, linux_nat_detach): Condition on
	target_can_async_p.
	(linux_nat_resume): Add async file handler if necessary.
	(linux_nat_fetch_event): New function.
	(linux_nat_wait): Use it when asynchronous.
	(async_sigchld_handler, linux_nat_signal_hook): New functions.
	(_initialize_linux_nat): Set up signal handling and pipe for
	asynchronous behaviour.

	* infrun.c: Include event-top.h.
	(sync_execution): Set sync_execution to 1 initially.
	(proceed): Set target_executing to 0 if synchronous.
	(handle_inferior_event): Print process switching for MI(?).
	Don't call context_switch (ecs) or flush_cached_frames ().
	Use local variable was_sync_execution.

	* inf-ptrace.c: Include inf-loop.h, event-loop.h and event-top.h.
	(standard_is_async_p, standard_can_async_p)
	(initialize_sigint_signal_handler): New externs.
	(async_client_context, async_terminal_ours_p): New variables.
	(async_file_handler, inf_ptrace_async): New functions.
	(inf_ptrace_him): Use gdb_post_startup as a flag.
	(inf_ptrace_mourn_inferior): Don't call waitpid if asynchronous.
	(inf_ptrace_attach): Set gdb_post_startup.  Call wait_for_inferior
	if asynchronous.
	(async_terminal_inferior): New function.
	(inf_ptrace_target): Add methods if asynchronous.

	* exec.c (standard_async, standard_is_async_p, standard_can_async_p):
	New functions.
	(init_exec_ops): Initialise above methods if GDB is invoked
	with --async.

	* infcmd.c (jump_command): Call async_disable_stdin if necessary
	before decode_line_spec_1.
	(attach_command): Make attach work asynchronously.

	 (copied verbatim)
	* event-top.h (cli_command_loop):  Make argument type void*.

	 (copied verbatim)
	* event-top.c (cli_command_loop): Make argument void*.
	(display_gdb_prompt, async_enable_stdin)
	(async_disable_stdin, handle_sigint, async_request_quit)
	(gdb_setup_readline, _initialize_event_loop): 
	Changes for asynchronous operation.

	 (copied verbatim)
	* interps.c (interp_set): Make type struct interp *.
	Don't do_all_continuations or call clear_interpreter_hooks. 
	(current_interp_command_loop): Call command_loop with NULL argument.
	(interp_set_quiet): Don't make static.

	 (copied verbatim)
	* interps.h (interp_set, interp_set_quiet): New externs.

	 (copied verbatim)
	* inf-loop.c (inferior_event_handler, complete_execution): 
	Changes for asynchronous operation.

	 (copied verbatim)
	* cli/cli-interp.c (cli_interpreter_resume): Set sync_execution.
	(safe_execute_command): Don't make it static.
	(_initialize_cli_interp): Add cli_command_loop to interp_procs
	structure.

	 (copied verbatim)
	* wrapper.h (safe_execute_command): Declare here.

	 (copied verbatim)
	* remote.c (cleanup_sigint_signal_handler)
	(initialize_sigint_signal_handler): Don't make static.

	 (copied verbatim)
	* top.c (deprecated_command_loop_hook): Make argument type void*.

	 (copied verbatim)
	* mi/mi-interp.c (mi1_command_loop, mi2_command_loop)
	(mi3_command_loop): Make argument type void*.

	* config/i386/nm-linux.h: Add ASYNC macro definition.

	* Makefile.in (inf-ptrace.o, infrun.o, linux-nat.o)
	(cli-interp.o): Add new header dependencies.

 
 ChangeLog              |  102 +++++++++++++++++++++++++++
 Makefile.in            |    9 !!
 cli/cli-interp.c       |   11 -!
 config/i386/nm-linux.h |    3
 defs.h                 |    6 +
 event-loop.c           |   15 ++++
 event-top.c            |   93 ++++++++++++++!!!!!!!!!!!
 event-top.h            |    2
 exec.c                 |   26 ++++++-
 inf-loop.c             |   46 ++++++!!!!!!
 inf-ptrace.c           |  101 ++++++++++++++++++++++++++!
 infcmd.c               |   25 ++--!!
 infrun.c               |   34 ++++---!
 interps.c              |   40 +++!!!!!!!
 interps.h              |    3
 linux-nat.c            |  181 +++++++++++++++++++++++++++++!!!!!!!!!!!!!!!!!!!
 main.c                 |   15 ++++
 mi/mi-interp.c         |   12 !!!
 remote.c               |    8 !!
 top.c                  |    2
 wrapper.h              |    2
 21 files changed, 490 insertions(+), 25 deletions(-), 221 modifications(!)