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Enabling target-async by default will require implementing sync execution on top of an async target, much like foreground command are implemented on the CLI in async mode. In order to do that, we will need better control of when to print the MI prompt. Currently the interp->display_prompt_p hook is all we have, and MI just always returns false, meaning, make display_gdb_prompt a no-op. We'll need to be able to know to print the MI prompt in some of the conditions that display_gdb_prompt is called from the core, but not all. This is all a litte twisted currently. As we can see, display_gdb_prompt is really CLI specific, so make the console interpreters (console/tui) themselves call it. To be able to do that, and add a few different observers that the interpreters can use to distinguish when or why the the prompt is being printed: #1 - one called whenever a command is cancelled due to an error. #2 - another for when a foreground command just finished. In both cases, CLI wants to print the prompt, while MI doesn't. MI will want to print the prompt in the second case when in a special MI mode. The display_gdb_prompt call in interp_set made me pause. The comment there reads: /* Finally, put up the new prompt to show that we are indeed here. Also, display_gdb_prompt for the console does some readline magic which is needed for the console interpreter, at least... */ But, that looks very much like a no-op to me currently: - the MI interpreter always return false in the prompt hook, meaning actually display no prompt. - the interpreter used at that point is still quiet. And the console/tui interpreters return false in the prompt hook if they're quiet, meaning actually display no prompt. The only remaining possible use would then be the readline magic. But whatever that might have been, it's not reacheable today either, because display_gdb_prompt returns early, before touching readline if the interpreter returns false in the display_prompt_p hook. Tested on x86_64 Fedora 20, sync and async modes. gdb/ 2014-05-29 Pedro Alves <palves@redhat.com> * cli/cli-interp.c (cli_interpreter_display_prompt_p): Delete. (_initialize_cli_interp): Adjust. * event-loop.c: Include "observer.h". (start_event_loop): Notify 'command_error' observers instead of calling display_gdb_prompt. Remove FIXME comment. * event-top.c (display_gdb_prompt): Remove call into the interpreters. * inf-loop.c: Include "observer.h". (inferior_event_handler): Notify 'command_error' observers instead of calling display_gdb_prompt. * infrun.c (fetch_inferior_event): Notify 'sync_execution_done' observers instead of calling display_gdb_prompt. * interps.c (interp_set): Don't call display_gdb_prompt. (current_interp_display_prompt_p): Delete. * interps.h (interp_prompt_p): Delete declaration. (interp_prompt_p_ftype): Delete. (struct interp_procs) <prompt_proc_p>: Delete field. (current_interp_display_prompt_p): Delete declaration. * mi-interp.c (mi_interpreter_prompt_p): Delete. (_initialize_mi_interp): Adjust. * tui-interp.c (tui_init): Install 'sync_execution_done' and 'command_error' observers. (tui_on_sync_execution_done, tui_on_command_error): New functions. (tui_display_prompt_p): Delete. (_initialize_tui_interp): Adjust. gdb/doc/ 2014-05-29 Pedro Alves <palves@redhat.com> * observer.texi (sync_execution_done, command_error): New subjects.
288 lines
11 KiB
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288 lines
11 KiB
Text
@c -*-texinfo-*-
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@c This file is part of the GDB manual.
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@c
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@c Copyright (C) 2003-2014 Free Software Foundation, Inc.
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@c
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@c See the file gdbint.texinfo for copying conditions.
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@c
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@c Also, the @deftypefun lines from this file are processed into a
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@c header file during the GDB build process. Permission is granted
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@c to redistribute and/or modify those lines under the terms of the
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@c GNU General Public License as published by the Free Software
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@c Foundation; either version 3 of the License, or (at your option)
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@c any later version.
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@node GDB Observers
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@appendix @value{GDBN} Currently available observers
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@section Implementation rationale
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@cindex observers implementation rationale
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An @dfn{observer} is an entity which is interested in being notified
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when GDB reaches certain states, or certain events occur in GDB.
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The entity being observed is called the @dfn{subject}. To receive
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notifications, the observer attaches a callback to the subject.
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One subject can have several observers.
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@file{observer.c} implements an internal generic low-level event
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notification mechanism. This generic event notification mechanism is
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then re-used to implement the exported high-level notification
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management routines for all possible notifications.
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The current implementation of the generic observer provides support
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for contextual data. This contextual data is given to the subject
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when attaching the callback. In return, the subject will provide
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this contextual data back to the observer as a parameter of the
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callback.
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Note that the current support for the contextual data is only partial,
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as it lacks a mechanism that would deallocate this data when the
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callback is detached. This is not a problem so far, as this contextual
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data is only used internally to hold a function pointer. Later on, if
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a certain observer needs to provide support for user-level contextual
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data, then the generic notification mechanism will need to be
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enhanced to allow the observer to provide a routine to deallocate the
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data when attaching the callback.
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The observer implementation is also currently not reentrant.
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In particular, it is therefore not possible to call the attach
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or detach routines during a notification.
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@section Debugging
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Observer notifications can be traced using the command @samp{set debug
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observer 1} (@pxref{Debugging Output, , Optional messages about
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internal happenings, gdb, Debugging with @var{GDBN}}).
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@section @code{normal_stop} Notifications
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@cindex @code{normal_stop} observer
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@cindex notification about inferior execution stop
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@value{GDBN} notifies all @code{normal_stop} observers when the
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inferior execution has just stopped, the associated messages and
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annotations have been printed, and the control is about to be returned
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to the user.
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Note that the @code{normal_stop} notification is not emitted when
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the execution stops due to a breakpoint, and this breakpoint has
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a condition that is not met. If the breakpoint has any associated
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commands list, the commands are executed after the notification
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is emitted.
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The following interfaces are available to manage observers:
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@deftypefun extern struct observer *observer_attach_@var{event} (observer_@var{event}_ftype *@var{f})
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Using the function @var{f}, create an observer that is notified when
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ever @var{event} occurs, return the observer.
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@end deftypefun
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@deftypefun extern void observer_detach_@var{event} (struct observer *@var{observer});
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Remove @var{observer} from the list of observers to be notified when
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@var{event} occurs.
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@end deftypefun
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@deftypefun extern void observer_notify_@var{event} (void);
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Send a notification to all @var{event} observers.
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@end deftypefun
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The following observable events are defined:
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@deftypefun void normal_stop (struct bpstats *@var{bs}, int @var{print_frame})
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The inferior has stopped for real. The @var{bs} argument describes
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the breakpoints were are stopped at, if any. Second argument
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@var{print_frame} non-zero means display the location where the
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inferior has stopped.
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@end deftypefun
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@deftypefun void signal_received (enum gdb_signal @var{siggnal})
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The inferior was stopped by a signal.
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@end deftypefun
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@deftypefun void end_stepping_range (void)
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We are done with a step/next/si/ni command.
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@end deftypefun
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@deftypefun void signal_exited (enum gdb_signal @var{siggnal})
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The inferior was terminated by a signal.
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@end deftypefun
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@deftypefun void exited (int @var{exitstatus})
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The inferior program is finished.
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@end deftypefun
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@deftypefun void no_history (void)
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Reverse execution: target ran out of history info.
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@end deftypefun
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@deftypefun void sync_execution_done (void)
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A synchronous command finished.
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@end deftypefun
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@deftypefun void command_error (void)
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An error was caught while executing a command.
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@end deftypefun
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@deftypefun void target_changed (struct target_ops *@var{target})
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The target's register contents have changed.
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@end deftypefun
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@deftypefun void executable_changed (void)
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The executable being debugged by GDB has changed: The user decided
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to debug a different program, or the program he was debugging has
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been modified since being loaded by the debugger (by being recompiled,
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for instance).
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@end deftypefun
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@deftypefun void inferior_created (struct target_ops *@var{objfile}, int @var{from_tty})
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@value{GDBN} has just connected to an inferior. For @samp{run},
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@value{GDBN} calls this observer while the inferior is still stopped
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at the entry-point instruction. For @samp{attach} and @samp{core},
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@value{GDBN} calls this observer immediately after connecting to the
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inferior, and before any information on the inferior has been printed.
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@end deftypefun
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@deftypefun void record_changed (struct inferior *@var{inferior}, int @var{started})
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The status of process record for inferior @var{inferior} in
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@value{GDBN} has changed. The process record is started if
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@var{started} is true, and the process record is stopped if
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@var{started} is false.
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@end deftypefun
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@deftypefun void solib_loaded (struct so_list *@var{solib})
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The shared library specified by @var{solib} has been loaded. Note that
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when @value{GDBN} calls this observer, the library's symbols probably
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haven't been loaded yet.
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@end deftypefun
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@deftypefun void solib_unloaded (struct so_list *@var{solib})
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The shared library specified by @var{solib} has been unloaded.
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Note that when @value{GDBN} calls this observer, the library's
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symbols have not been unloaded yet, and thus are still available.
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@end deftypefun
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@deftypefun void new_objfile (struct objfile *@var{objfile})
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The symbol file specified by @var{objfile} has been loaded.
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Called with @var{objfile} equal to @code{NULL} to indicate
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previously loaded symbol table data has now been invalidated.
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@end deftypefun
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@deftypefun void free_objfile (struct objfile *@var{objfile})
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The object file specified by @var{objfile} is about to be freed.
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@end deftypefun
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@deftypefun void new_thread (struct thread_info *@var{t})
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The thread specified by @var{t} has been created.
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@end deftypefun
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@deftypefun void thread_exit (struct thread_info *@var{t}, int @var{silent})
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The thread specified by @var{t} has exited. The @var{silent} argument
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indicates that @value{GDBN} is removing the thread from its tables
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without wanting to notify the user about it.
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@end deftypefun
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@deftypefun void thread_stop_requested (ptid_t @var{ptid})
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An explicit stop request was issued to @var{ptid}. If @var{ptid}
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equals @var{minus_one_ptid}, the request applied to all threads. If
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@code{ptid_is_pid(ptid)} returns true, the request applied to all
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threads of the process pointed at by @var{ptid}. Otherwise, the
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request applied to the single thread pointed at by @var{ptid}.
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@end deftypefun
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@deftypefun void target_resumed (ptid_t @var{ptid})
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The target was resumed. The @var{ptid} parameter specifies which
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thread was resume, and may be RESUME_ALL if all threads are resumed.
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@end deftypefun
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@deftypefun void about_to_proceed (void)
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The target is about to be proceeded.
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@end deftypefun
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@deftypefun void breakpoint_created (struct breakpoint *@var{b})
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A new breakpoint @var{b} has been created.
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@end deftypefun
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@deftypefun void breakpoint_deleted (struct breakpoint *@var{b})
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A breakpoint has been destroyed. The argument @var{b} is the
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pointer to the destroyed breakpoint.
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@end deftypefun
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@deftypefun void breakpoint_modified (struct breakpoint *@var{b})
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A breakpoint has been modified in some way. The argument @var{b}
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is the modified breakpoint.
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@end deftypefun
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@deftypefun void traceframe_changed (int @var{tfnum}, int @var{tpnum})
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The trace frame is changed to @var{tfnum} (e.g., by using the
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@code{tfind} command). If @var{tfnum} is negative, it means
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@value{GDBN} resumes live debugging. The number of the tracepoint
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associated with this traceframe is @var{tpnum}.
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@end deftypefun
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@deftypefun void architecture_changed (struct gdbarch *@var{newarch})
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The current architecture has changed. The argument @var{newarch} is
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a pointer to the new architecture.
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@end deftypefun
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@deftypefun void thread_ptid_changed (ptid_t @var{old_ptid}, ptid_t @var{new_ptid})
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The thread's ptid has changed. The @var{old_ptid} parameter specifies
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the old value, and @var{new_ptid} specifies the new value.
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@end deftypefun
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@deftypefun void inferior_added (struct inferior *@var{inf})
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The inferior @var{inf} has been added to the list of inferiors. At
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this point, it might not be associated with any process.
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@end deftypefun
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@deftypefun void inferior_appeared (struct inferior *@var{inf})
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The inferior identified by @var{inf} has been attached to a process.
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@end deftypefun
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@deftypefun void inferior_exit (struct inferior *@var{inf})
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Either the inferior associated with @var{inf} has been detached from the
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process, or the process has exited.
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@end deftypefun
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@deftypefun void inferior_removed (struct inferior *@var{inf})
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The inferior @var{inf} has been removed from the list of inferiors.
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This method is called immediately before freeing @var{inf}.
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@end deftypefun
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@deftypefun void memory_changed (struct inferior *@var{inferior}, CORE_ADDR @var{addr}, ssize_t @var{len}, const bfd_byte *@var{data})
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Bytes from @var{data} to @var{data} + @var{len} have been written
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to the @var{inferior} at @var{addr}.
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@end deftypefun
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@deftypefun void before_prompt (const char *@var{current_prompt})
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Called before a top-level prompt is displayed. @var{current_prompt} is
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the current top-level prompt.
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@end deftypefun
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@deftypefun void gdb_datadir_changed (void)
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Variable gdb_datadir has been set. The value may not necessarily change.
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@end deftypefun
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@deftypefun void command_param_changed (const char *@var{param}, const char *@var{value})
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The parameter of some @code{set} commands in console are changed. This
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method is called after a command @code{set @var{param} @var{value}}.
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@var{param} is the parameter of @code{set} command, and @var{value}
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is the value of changed parameter.
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@end deftypefun
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@deftypefun void tsv_created (const struct trace_state_variable *@var{tsv})
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The new trace state variable @var{tsv} is created.
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@end deftypefun
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@deftypefun void tsv_deleted (const struct trace_state_variable *@var{tsv})
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The trace state variable @var{tsv} is deleted. If @var{tsv} is
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@code{NULL}, all trace state variables are deleted.
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@end deftypefun
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@deftypefun void tsv_modified (const struct trace_state_variable *@var{tsv})
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The trace state value @var{tsv} is modified.
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@end deftypefun
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@deftypefun void test_notification (int @var{somearg})
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This observer is used for internal testing. Do not use.
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See testsuite/gdb.gdb/observer.exp.
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@end deftypefun
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