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/tmp/gdb-8.1/gdb/event-loop.h
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1 /* Definitions used by the GDB event loop.
2 Copyright (C) 1999-2018 Free Software Foundation, Inc.
3 Written by Elena Zannoni <ezannoni@cygnus.com> of Cygnus Solutions.
4
5 This file is part of GDB.
6
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3 of the License, or
10 (at your option) any later version.
11
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
16
17 You should have received a copy of the GNU General Public License
18 along with this program. If not, see <http://www.gnu.org/licenses/>. */
19
20 /* An event loop listens for events from multiple event sources. When
21 an event arrives, it is queued and processed by calling the
22 appropriate event handler. The event loop then continues to listen
23 for more events. An event loop completes when there are no event
24 sources to listen on. External event sources can be plugged into
25 the loop.
26
27 There are 4 main components:
28 - a list of file descriptors to be monitored, GDB_NOTIFIER.
29 - a list of asynchronous event sources to be monitored,
30 ASYNC_EVENT_HANDLER_LIST.
31 - a list of events that have occurred, EVENT_QUEUE.
32 - a list of signal handling functions, SIGHANDLER_LIST.
33
34 GDB_NOTIFIER keeps track of the file descriptor based event
35 sources. ASYNC_EVENT_HANDLER_LIST keeps track of asynchronous
36 event sources that are signalled by some component of gdb, usually
37 a target_ops instance. Event sources for gdb are currently the UI
38 and the target. Gdb communicates with the command line user
39 interface via the readline library and usually communicates with
40 remote targets via a serial port. Serial ports are represented in
41 GDB as file descriptors and select/poll calls. For native targets
42 instead, the communication varies across operating system debug
43 APIs, but usually consists of calls to ptrace and waits (via
44 signals) or calls to poll/select (via file descriptors). In the
45 current gdb, the code handling events related to the target resides
46 in wait_for_inferior for synchronous targets; or, for asynchronous
47 capable targets, by having the target register either a target
48 controlled file descriptor and/or an asynchronous event source in
49 the event loop, with the fetch_inferior_event function as the event
50 callback. In both the synchronous and asynchronous cases, usually
51 the target event is collected through the target_wait interface.
52 The target is free to install other event sources in the event loop
53 if it so requires.
54
55 EVENT_QUEUE keeps track of the events that have happened during the
56 last iteration of the event loop, and need to be processed. An
57 event is represented by a procedure to be invoked in order to
58 process the event. The queue is scanned head to tail. If the
59 event of interest is a change of state in a file descriptor, then a
60 call to poll or select will be made to detect it.
61
62 If the events generate signals, they are also queued by special
63 functions that are invoked through traditional signal handlers.
64 The actions to be taken is response to such events will be executed
65 when the SIGHANDLER_LIST is scanned, the next time through the
66 infinite loop.
67
68 Corollary tasks are the creation and deletion of event sources. */
69
70 typedef void *gdb_client_data;
71 struct async_signal_handler;
72 struct async_event_handler;
73 typedef void (handler_func) (int, gdb_client_data);
74 typedef void (sig_handler_func) (gdb_client_data);
75 typedef void (async_event_handler_func) (gdb_client_data);
76 typedef void (timer_handler_func) (gdb_client_data);
77
78 /* Exported functions from event-loop.c */
79
80 extern void start_event_loop (void);
81 extern int gdb_do_one_event (void);
82 extern void delete_file_handler (int fd);
83 extern void add_file_handler (int fd, handler_func *proc,
84 gdb_client_data client_data);
85 extern struct async_signal_handler *
86 create_async_signal_handler (sig_handler_func *proc,
87 gdb_client_data client_data);
88 extern void delete_async_signal_handler (struct async_signal_handler **);
89 extern int create_timer (int milliseconds,
90 timer_handler_func *proc,
91 gdb_client_data client_data);
92 extern void delete_timer (int id);
93
94 /* Call the handler from HANDLER the next time through the event
95 loop. */
96 extern void mark_async_signal_handler (struct async_signal_handler *handler);
97
98 /* Returns true if HANDLER is marked ready. */
99
100 extern int
101 async_signal_handler_is_marked (struct async_signal_handler *handler);
102
103 /* Mark HANDLER as NOT ready. */
104
105 extern void clear_async_signal_handler (struct async_signal_handler *handler);
106
107 /* Create and register an asynchronous event source in the event loop,
108 and set PROC as its callback. CLIENT_DATA is passed as argument to
109 PROC upon its invocation. Returns a pointer to an opaque structure
110 used to mark as ready and to later delete this event source from
111 the event loop. */
112 extern struct async_event_handler *
113 create_async_event_handler (async_event_handler_func *proc,
114 gdb_client_data client_data);
115
116 /* Remove the event source pointed by HANDLER_PTR created by
117 CREATE_ASYNC_EVENT_HANDLER from the event loop, and release it. */
118 extern void
119 delete_async_event_handler (struct async_event_handler **handler_ptr);
120
121 /* Call the handler from HANDLER the next time through the event
122 loop. */
123 extern void mark_async_event_handler (struct async_event_handler *handler);
124
125 /* Mark the handler (ASYNC_HANDLER_PTR) as NOT ready. */
126
127 extern void clear_async_event_handler (struct async_event_handler *handler);
128
129 extern void initialize_async_signal_handlers (void);
handler_func
void() handler_func(int, gdb_client_data)
Definition: event-loop.h:73
clear_async_signal_handler
void clear_async_signal_handler(struct async_signal_handler *handler)
Definition: event-loop.c:930
create_async_signal_handler
struct async_signal_handler * create_async_signal_handler(sig_handler_func *proc, gdb_client_data client_data)
Definition: event-loop.c:898
delete_timer
void delete_timer(int id)
Definition: event-loop.c:1156
initialize_async_signal_handlers
void initialize_async_signal_handlers(void)
Definition: event-loop.c:281
mark_async_event_handler
void mark_async_event_handler(struct async_event_handler *handler)
Definition: event-loop.c:1036
gdb_do_one_event
int gdb_do_one_event(void)
Definition: event-loop.c:295
async_signal_handler_is_marked
int async_signal_handler_is_marked(struct async_signal_handler *handler)
Definition: event-loop.c:938
async_event_handler
Definition: event-loop.c:123
create_async_event_handler
struct async_event_handler * create_async_event_handler(async_event_handler_func *proc, gdb_client_data client_data)
Definition: event-loop.c:1013
proc
Definition: gnu-nat.h:42
sig_handler_func
void() sig_handler_func(gdb_client_data)
Definition: event-loop.h:74
timer_handler_func
void() timer_handler_func(gdb_client_data)
Definition: event-loop.h:76
mark_async_signal_handler
void mark_async_signal_handler(struct async_signal_handler *handler)
Definition: event-loop.c:921
create_timer
int create_timer(int milliseconds, timer_handler_func *proc, gdb_client_data client_data)
Definition: event-loop.c:1106
gdb_client_data
void * gdb_client_data
Definition: event-loop.h:70
delete_async_signal_handler
void delete_async_signal_handler(struct async_signal_handler **)
Definition: event-loop.c:984
async_signal_handler
Definition: event-loop.c:106
delete_async_event_handler
void delete_async_event_handler(struct async_event_handler **handler_ptr)
Definition: event-loop.c:1075
clear_async_event_handler
void clear_async_event_handler(struct async_event_handler *handler)
Definition: event-loop.c:1044
add_file_handler
void add_file_handler(int fd, handler_func *proc, gdb_client_data client_data)
Definition: event-loop.c:413
async_event_handler_func
void() async_event_handler_func(gdb_client_data)
Definition: event-loop.h:75
start_event_loop
void start_event_loop(void)
Definition: event-loop.c:359
async_event_handler::client_data
gdb_client_data client_data
Definition: event-loop.c:136
async_signal_handler::client_data
gdb_client_data client_data
Definition: event-loop.c:113
delete_file_handler
void delete_file_handler(int fd)
Definition: event-loop.c:564