mirror of
https://github.com/darlinghq/darling-gdb.git
synced 2024-11-27 05:50:43 +00:00
71 lines
2.9 KiB
Plaintext
71 lines
2.9 KiB
Plaintext
@c -*-texinfo-*-
|
|
@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 @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 interface is available to manage @code{normal_stop}
|
|
observers:
|
|
|
|
@deftypefun extern struct observer *observer_attach_normal_stop (observer_normal_stop_ftype *@var{f})
|
|
Attach the given @code{normal_stop} callback function @var{f} and
|
|
return the associated observer.
|
|
@end deftypefun
|
|
|
|
@deftypefun extern void observer_detach_normal_stop (struct observer *@var{observer});
|
|
Remove @var{observer} from the list of observers to be notified when
|
|
a @code{normal_stop} event occurs.
|
|
@end deftypefun
|
|
|
|
@deftypefun extern void observer_notify_normal_stop (void);
|
|
Send a notification to all @code{normal_stop} observers.
|
|
@end deftypefun
|
|
|
|
|