mirror of
https://sourceware.org/git/binutils-gdb.git
synced 2024-12-09 04:21:49 +08:00
16d1a08426
* observer.texi: Likewise, with GPL clause for function prototypes. Remove trailing whitespace.
125 lines
5.0 KiB
Plaintext
125 lines
5.0 KiB
Plaintext
@c -*-texinfo-*-
|
|
|
|
@c This file is part of the GDB manual.
|
|
@c
|
|
@c Copyright (C) 2003, 2004, 2005, 2006
|
|
@c Free Software Foundation, Inc.
|
|
@c
|
|
@c See the file gdbint.texinfo for copying conditions.
|
|
@c
|
|
@c Also, the @deftypefun lines from this file are processed into a
|
|
@c header file during the GDB build process. Permission is granted
|
|
@c to redistribute and/or modify those lines under the terms of the
|
|
@c GNU General Public License as published by the Free Software
|
|
@c Foundation; either version 2 of the License, or (at your option)
|
|
@c any later version.
|
|
|
|
@node GDB Observers
|
|
@appendix @value{GDBN} Currently available observers
|
|
|
|
@section Implementation rationale
|
|
@cindex observers implementation rationale
|
|
|
|
An @dfn{observer} is an entity which is interested in being notified
|
|
when GDB reaches certain states, or certain events occur in GDB.
|
|
The entity being observed is called the @dfn{subject}. To receive
|
|
notifications, the observer attaches a callback to the subject.
|
|
One subject can have several observers.
|
|
|
|
@file{observer.c} implements an internal generic low-level event
|
|
notification mechanism. This generic event notification mechanism is
|
|
then re-used to implement the exported high-level notification
|
|
management routines for all possible notifications.
|
|
|
|
The current implementation of the generic observer provides support
|
|
for contextual data. This contextual data is given to the subject
|
|
when attaching the callback. In return, the subject will provide
|
|
this contextual data back to the observer as a parameter of the
|
|
callback.
|
|
|
|
Note that the current support for the contextual data is only partial,
|
|
as it lacks a mechanism that would deallocate this data when the
|
|
callback is detached. This is not a problem so far, as this contextual
|
|
data is only used internally to hold a function pointer. Later on, if
|
|
a certain observer needs to provide support for user-level contextual
|
|
data, then the generic notification mechanism will need to be
|
|
enhanced to allow the observer to provide a routine to deallocate the
|
|
data when attaching the callback.
|
|
|
|
The observer implementation is also currently not reentrant.
|
|
In particular, it is therefore not possible to call the attach
|
|
or detach routines during a notification.
|
|
|
|
@section Debugging
|
|
Observer notifications can be traced using the command @samp{set debug
|
|
observer 1} (@pxref{Debugging Output, , Optional messages about
|
|
internal happenings, gdb, Debugging with @var{GDBN}}).
|
|
|
|
@section @code{normal_stop} Notifications
|
|
@cindex @code{normal_stop} observer
|
|
@cindex notification about inferior execution stop
|
|
|
|
@value{GDBN} notifies all @code{normal_stop} observers when the
|
|
inferior execution has just stopped, the associated messages and
|
|
annotations have been printed, and the control is about to be returned
|
|
to the user.
|
|
|
|
Note that the @code{normal_stop} notification is not emitted when
|
|
the execution stops due to a breakpoint, and this breakpoint has
|
|
a condition that is not met. If the breakpoint has any associated
|
|
commands list, the commands are executed after the notification
|
|
is emitted.
|
|
|
|
The following interfaces are available to manage observers:
|
|
|
|
@deftypefun extern struct observer *observer_attach_@var{event} (observer_@var{event}_ftype *@var{f})
|
|
Using the function @var{f}, create an observer that is notified when
|
|
ever @var{event} occures, return the observer.
|
|
@end deftypefun
|
|
|
|
@deftypefun extern void observer_detach_@var{event} (struct observer *@var{observer});
|
|
Remove @var{observer} from the list of observers to be notified when
|
|
@var{event} occurs.
|
|
@end deftypefun
|
|
|
|
@deftypefun extern void observer_notify_@var{event} (void);
|
|
Send a notification to all @var{event} observers.
|
|
@end deftypefun
|
|
|
|
The following observable events are defined:
|
|
|
|
@c note: all events must take at least one parameter.
|
|
|
|
@deftypefun void normal_stop (struct bpstats *@var{bs})
|
|
The inferior has stopped for real.
|
|
@end deftypefun
|
|
|
|
@deftypefun void target_changed (struct target_ops *@var{target})
|
|
The target's register contents have changed.
|
|
@end deftypefun
|
|
|
|
@deftypefun void executable_changed (void *@var{unused_args})
|
|
The executable being debugged by GDB has changed: The user decided
|
|
to debug a different program, or the program he was debugging has
|
|
been modified since being loaded by the debugger (by being recompiled,
|
|
for instance).
|
|
@end deftypefun
|
|
|
|
@deftypefun void inferior_created (struct target_ops *@var{objfile}, int @var{from_tty})
|
|
@value{GDBN} has just connected to an inferior. For @samp{run},
|
|
@value{GDBN} calls this observer while the inferior is still stopped
|
|
at the entry-point instruction. For @samp{attach} and @samp{core},
|
|
@value{GDBN} calls this observer immediately after connecting to the
|
|
inferior, and before any information on the inferior has been printed.
|
|
@end deftypefun
|
|
|
|
@deftypefun void solib_loaded (struct so_list *@var{solib})
|
|
The shared library specified by @var{solib} has been loaded. Note that
|
|
when @value{GDBN} calls this observer, the library's symbols probably
|
|
haven't been loaded yet.
|
|
@end deftypefun
|
|
|
|
@deftypefun void solib_unloaded (struct so_list *@var{solib})
|
|
The shared library specified by @var{solib} has been unloaded.
|
|
@end deftypefun
|