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bcd7e15f | 1 | @c -*-texinfo-*- |
16d1a084 DJ |
2 | |
3 | @c This file is part of the GDB manual. | |
4 | @c | |
0b302171 | 5 | @c Copyright (C) 2003-2006, 2008-2012 Free Software Foundation, Inc. |
16d1a084 DJ |
6 | @c |
7 | @c See the file gdbint.texinfo for copying conditions. | |
8 | @c | |
9 | @c Also, the @deftypefun lines from this file are processed into a | |
10 | @c header file during the GDB build process. Permission is granted | |
11 | @c to redistribute and/or modify those lines under the terms of the | |
12 | @c GNU General Public License as published by the Free Software | |
a1715244 | 13 | @c Foundation; either version 3 of the License, or (at your option) |
16d1a084 DJ |
14 | @c any later version. |
15 | ||
bcd7e15f JB |
16 | @node GDB Observers |
17 | @appendix @value{GDBN} Currently available observers | |
18 | ||
19 | @section Implementation rationale | |
20 | @cindex observers implementation rationale | |
21 | ||
22 | An @dfn{observer} is an entity which is interested in being notified | |
23 | when GDB reaches certain states, or certain events occur in GDB. | |
24 | The entity being observed is called the @dfn{subject}. To receive | |
25 | notifications, the observer attaches a callback to the subject. | |
26 | One subject can have several observers. | |
27 | ||
28 | @file{observer.c} implements an internal generic low-level event | |
6be67e67 | 29 | notification mechanism. This generic event notification mechanism is |
bcd7e15f JB |
30 | then re-used to implement the exported high-level notification |
31 | management routines for all possible notifications. | |
32 | ||
33 | The current implementation of the generic observer provides support | |
34 | for contextual data. This contextual data is given to the subject | |
35 | when attaching the callback. In return, the subject will provide | |
36 | this contextual data back to the observer as a parameter of the | |
37 | callback. | |
38 | ||
39 | Note that the current support for the contextual data is only partial, | |
40 | as it lacks a mechanism that would deallocate this data when the | |
41 | callback is detached. This is not a problem so far, as this contextual | |
42 | data is only used internally to hold a function pointer. Later on, if | |
43 | a certain observer needs to provide support for user-level contextual | |
6be67e67 | 44 | data, then the generic notification mechanism will need to be |
bcd7e15f JB |
45 | enhanced to allow the observer to provide a routine to deallocate the |
46 | data when attaching the callback. | |
47 | ||
48 | The observer implementation is also currently not reentrant. | |
49 | In particular, it is therefore not possible to call the attach | |
50 | or detach routines during a notification. | |
51 | ||
2b4855ab AC |
52 | @section Debugging |
53 | Observer notifications can be traced using the command @samp{set debug | |
54 | observer 1} (@pxref{Debugging Output, , Optional messages about | |
55 | internal happenings, gdb, Debugging with @var{GDBN}}). | |
56 | ||
bcd7e15f JB |
57 | @section @code{normal_stop} Notifications |
58 | @cindex @code{normal_stop} observer | |
59 | @cindex notification about inferior execution stop | |
60 | ||
6be67e67 JB |
61 | @value{GDBN} notifies all @code{normal_stop} observers when the |
62 | inferior execution has just stopped, the associated messages and | |
63 | annotations have been printed, and the control is about to be returned | |
16d1a084 | 64 | to the user. |
6be67e67 JB |
65 | |
66 | Note that the @code{normal_stop} notification is not emitted when | |
67 | the execution stops due to a breakpoint, and this breakpoint has | |
68 | a condition that is not met. If the breakpoint has any associated | |
69 | commands list, the commands are executed after the notification | |
70 | is emitted. | |
bcd7e15f | 71 | |
7a464420 | 72 | The following interfaces are available to manage observers: |
bcd7e15f | 73 | |
7a464420 AC |
74 | @deftypefun extern struct observer *observer_attach_@var{event} (observer_@var{event}_ftype *@var{f}) |
75 | Using the function @var{f}, create an observer that is notified when | |
d3e8051b | 76 | ever @var{event} occurs, return the observer. |
bcd7e15f JB |
77 | @end deftypefun |
78 | ||
7a464420 | 79 | @deftypefun extern void observer_detach_@var{event} (struct observer *@var{observer}); |
bcd7e15f | 80 | Remove @var{observer} from the list of observers to be notified when |
7a464420 | 81 | @var{event} occurs. |
bcd7e15f JB |
82 | @end deftypefun |
83 | ||
7a464420 AC |
84 | @deftypefun extern void observer_notify_@var{event} (void); |
85 | Send a notification to all @var{event} observers. | |
bcd7e15f JB |
86 | @end deftypefun |
87 | ||
7a464420 | 88 | The following observable events are defined: |
bcd7e15f | 89 | |
1d33d6ba VP |
90 | @deftypefun void normal_stop (struct bpstats *@var{bs}, int @var{print_frame}) |
91 | The inferior has stopped for real. The @var{bs} argument describes | |
92 | the breakpoints were are stopped at, if any. Second argument | |
93 | @var{print_frame} non-zero means display the location where the | |
94 | inferior has stopped. | |
7a464420 | 95 | @end deftypefun |
79346bcb OF |
96 | |
97 | @deftypefun void target_changed (struct target_ops *@var{target}) | |
67ab9a76 | 98 | The target's register contents have changed. |
79346bcb | 99 | @end deftypefun |
59caf092 | 100 | |
781b42b0 | 101 | @deftypefun void executable_changed (void) |
ea53e89f JB |
102 | The executable being debugged by GDB has changed: The user decided |
103 | to debug a different program, or the program he was debugging has | |
104 | been modified since being loaded by the debugger (by being recompiled, | |
105 | for instance). | |
106 | @end deftypefun | |
107 | ||
59caf092 AC |
108 | @deftypefun void inferior_created (struct target_ops *@var{objfile}, int @var{from_tty}) |
109 | @value{GDBN} has just connected to an inferior. For @samp{run}, | |
110 | @value{GDBN} calls this observer while the inferior is still stopped | |
111 | at the entry-point instruction. For @samp{attach} and @samp{core}, | |
112 | @value{GDBN} calls this observer immediately after connecting to the | |
113 | inferior, and before any information on the inferior has been printed. | |
114 | @end deftypefun | |
f3bb6704 | 115 | |
fbd1b305 MK |
116 | @deftypefun void solib_loaded (struct so_list *@var{solib}) |
117 | The shared library specified by @var{solib} has been loaded. Note that | |
118 | when @value{GDBN} calls this observer, the library's symbols probably | |
119 | haven't been loaded yet. | |
f3bb6704 JJ |
120 | @end deftypefun |
121 | ||
fbd1b305 MK |
122 | @deftypefun void solib_unloaded (struct so_list *@var{solib}) |
123 | The shared library specified by @var{solib} has been unloaded. | |
30a4a70c JB |
124 | Note that when @value{GDBN} calls this observer, the library's |
125 | symbols have not been unloaded yet, and thus are still available. | |
fbd1b305 | 126 | @end deftypefun |
06d3b283 UW |
127 | |
128 | @deftypefun void new_objfile (struct objfile *@var{objfile}) | |
129 | The symbol file specified by @var{objfile} has been loaded. | |
130 | Called with @var{objfile} equal to @code{NULL} to indicate | |
131 | previously loaded symbol table data has now been invalidated. | |
132 | @end deftypefun | |
133 | ||
683f2885 VP |
134 | @deftypefun void new_thread (struct thread_info *@var{t}) |
135 | The thread specified by @var{t} has been created. | |
136 | @end deftypefun | |
137 | ||
a07daef3 PA |
138 | @deftypefun void thread_exit (struct thread_info *@var{t}, int @var{silent}) |
139 | The thread specified by @var{t} has exited. The @var{silent} argument | |
140 | indicates that @value{GDBN} is removing the thread from its tables | |
141 | without wanting to notify the user about it. | |
063bfe2e VP |
142 | @end deftypefun |
143 | ||
252fbfc8 PA |
144 | @deftypefun void thread_stop_requested (ptid_t @var{ptid}) |
145 | An explicit stop request was issued to @var{ptid}. If @var{ptid} | |
146 | equals @var{minus_one_ptid}, the request applied to all threads. If | |
147 | @code{ptid_is_pid(ptid)} returns true, the request applied to all | |
148 | threads of the process pointed at by @var{ptid}. Otherwise, the | |
149 | request applied to the single thread pointed at by @var{ptid}. | |
150 | @end deftypefun | |
151 | ||
e1ac3328 VP |
152 | @deftypefun void target_resumed (ptid_t @var{ptid}) |
153 | The target was resumed. The @var{ptid} parameter specifies which | |
154 | thread was resume, and may be RESUME_ALL if all threads are resumed. | |
155 | @end deftypefun | |
383f836e | 156 | |
f3b1572e PA |
157 | @deftypefun void about_to_proceed (void) |
158 | The target is about to be proceeded. | |
159 | @end deftypefun | |
160 | ||
8d3788bd VP |
161 | @deftypefun void breakpoint_created (struct breakpoint *@var{b}) |
162 | A new breakpoint @var{b} has been created. | |
383f836e TT |
163 | @end deftypefun |
164 | ||
8d3788bd VP |
165 | @deftypefun void breakpoint_deleted (struct breakpoint *@var{b}) |
166 | A breakpoint has been destroyed. The argument @var{b} is the | |
167 | pointer to the destroyed breakpoint. | |
383f836e TT |
168 | @end deftypefun |
169 | ||
8d3788bd VP |
170 | @deftypefun void breakpoint_modified (struct breakpoint *@var{b}) |
171 | A breakpoint has been modified in some way. The argument @var{b} | |
172 | is the modified breakpoint. | |
383f836e TT |
173 | @end deftypefun |
174 | ||
175 | @deftypefun void tracepoint_created (int @var{tpnum}) | |
176 | A new tracepoint has been created. The argument @var{tpnum} is the | |
177 | number of the newly-created tracepoint. | |
178 | @end deftypefun | |
179 | ||
180 | @deftypefun void tracepoint_deleted (int @var{tpnum}) | |
181 | A tracepoint has been destroyed. The argument @var{tpnum} is the | |
182 | number of the newly-destroyed tracepoint. | |
183 | @end deftypefun | |
184 | ||
185 | @deftypefun void tracepoint_modified (int @var{tpnum}) | |
186 | A tracepoint has been modified in some way. The argument @var{tpnum} | |
187 | is the number of the modified tracepoint. | |
188 | @end deftypefun | |
189 | ||
190 | @deftypefun void architecture_changed (struct gdbarch *@var{newarch}) | |
191 | The current architecture has changed. The argument @var{newarch} is | |
192 | a pointer to the new architecture. | |
193 | @end deftypefun | |
194 | ||
5231c1fd PA |
195 | @deftypefun void thread_ptid_changed (ptid_t @var{old_ptid}, ptid_t @var{new_ptid}) |
196 | The thread's ptid has changed. The @var{old_ptid} parameter specifies | |
197 | the old value, and @var{new_ptid} specifies the new value. | |
198 | @end deftypefun | |
4a92f99b | 199 | |
a79b8f6e VP |
200 | @deftypefun void inferior_added (struct inferior *@var{inf}) |
201 | The inferior @var{inf} has been added to the list of inferiors. At | |
202 | this point, it might not be associated with any process. | |
4a92f99b VP |
203 | @end deftypefun |
204 | ||
a79b8f6e VP |
205 | @deftypefun void inferior_appeared (struct inferior *@var{inf}) |
206 | The inferior identified by @var{inf} has been attached to a process. | |
207 | @end deftypefun | |
208 | ||
209 | @deftypefun void inferior_exit (struct inferior *@var{inf}) | |
210 | Either the inferior associated with @var{inf} has been detached from the | |
211 | process, or the process has exited. | |
212 | @end deftypefun | |
213 | ||
214 | @deftypefun void inferior_removed (struct inferior *@var{inf}) | |
215 | The inferior @var{inf} has been removed from the list of inferiors. | |
216 | This method is called immediately before freeing @var{inf}. | |
8cebebb9 PP |
217 | @end deftypefun |
218 | ||
219 | @deftypefun void memory_changed (CORE_ADDR @var{addr}, int @var{len}, const bfd_byte *@var{data}) | |
220 | Bytes from @var{data} to @var{data} + @var{len} have been written | |
221 | to the current inferior at @var{addr}. | |
4a92f99b VP |
222 | @end deftypefun |
223 | ||
d17b6f81 PM |
224 | @deftypefun void before_prompt (const char *@var{current_prompt}) |
225 | Called before a top-level prompt is displayed. @var{current_prompt} is | |
226 | the current top-level prompt. | |
227 | @end deftypefun | |
228 | ||
6dea1fbd JK |
229 | @deftypefun void gdb_datadir_changed (void) |
230 | Variable gdb_datadir has been set. The value may not necessarily change. | |
231 | @end deftypefun | |
232 | ||
5b9afe8a YQ |
233 | @deftypefun void command_param_changed (const char *@var{param}, const char *@var{value}) |
234 | The parameter of some @code{set} commands in console are changed. This | |
235 | method is called after a command @code{set @var{param} @var{value}}. | |
236 | @var{param} is the parameter of @code{set} command, and @var{value} | |
237 | is the value of changed parameter. | |
238 | ||
239 | @end deftypefun | |
240 | ||
a79b8f6e | 241 | @deftypefun void test_notification (int @var{somearg}) |
3ea85240 VP |
242 | This observer is used for internal testing. Do not use. |
243 | See testsuite/gdb.gdb/observer.exp. | |
a79b8f6e | 244 | @end deftypefun |
3ea85240 | 245 |