1 /*
2 Unix SMB/CIFS implementation.
3 main select loop and event handling
4 Copyright (C) Andrew Tridgell 2003
5
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2 of the License, or
9 (at your option) any later version.
10
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
15
16 You should have received a copy of the GNU General Public License
17 along with this program; if not, write to the Free Software
18 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
19 */
20
21 /*
22 PLEASE READ THIS BEFORE MODIFYING!
23
24 This module is a general abstraction for the main select loop and
25 event handling. Do not ever put any localised hacks in here, instead
26 register one of the possible event types and implement that event
27 somewhere else.
28
29 There are 2 types of event handling that are handled in this module:
30
31 1) a file descriptor becoming readable or writeable. This is mostly
32 used for network sockets, but can be used for any type of file
33 descriptor. You may only register one handler for each file
34 descriptor/io combination or you will get unpredictable results
35 (this means that you can have a handler for read events, and a
36 separate handler for write events, but not two handlers that are
37 both handling read events)
38
39 2) a timed event. You can register an event that happens at a
40 specific time. You can register as many of these as you
41 like. They are single shot - add a new timed event in the event
42 handler to get another event.
43
44 To setup a set of events you first need to create a event_context
45 structure using the function event_context_init(); This returns a
46 'struct event_context' that you use in all subsequent calls.
47
48 After that you can add/remove events that you are interested in
49 using event_add_*() and talloc_free()
50
51 Finally, you call event_loop_wait_once() to block waiting for one of the
52 events to occor or event_loop_wait() which will loop
53 forever.
54
55 */
56
57 #include "includes.h"
58 #include "lib/events/events.h"
59 #include "lib/events/events_internal.h"
60
61 /*
62 create a event_context structure for a specific implemementation.
63 This must be the first events call, and all subsequent calls pass
64 this event_context as the first element. Event handlers also
65 receive this as their first argument.
66
67 This function is for allowing third-party-applications to hook in gluecode
68 to their own event loop code, so that they can make async usage of our client libs
69
70 NOTE: use event_context_init() inside of samba!
71 */
event_context_init_ops(TALLOC_CTX * mem_ctx,const struct event_ops * ops,void * private_data)72 struct event_context *event_context_init_ops(TALLOC_CTX *mem_ctx, const struct event_ops *ops, void *private_data)
73 {
74 struct event_context *ev;
75 int ret;
76
77 ev = talloc_zero(mem_ctx, struct event_context);
78 if (!ev) return NULL;
79
80 ev->ops = ops;
81
82 ret = ev->ops->context_init(ev, private_data);
83 if (ret != 0) {
84 talloc_free(ev);
85 return NULL;
86 }
87
88 return ev;
89 }
90
91 /*
92 create a event_context structure. This must be the first events
93 call, and all subsequent calls pass this event_context as the first
94 element. Event handlers also receive this as their first argument.
95 */
event_context_init(TALLOC_CTX * mem_ctx)96 struct event_context *event_context_init(TALLOC_CTX *mem_ctx)
97 {
98 const struct event_ops *ops = event_standard_get_ops();
99 return event_context_init_ops(mem_ctx, ops, NULL);
100 }
101
102 /*
103 add a fd based event
104 return NULL on failure (memory allocation error)
105 */
event_add_fd(struct event_context * ev,TALLOC_CTX * mem_ctx,int fd,uint16_t flags,event_fd_handler_t handler,void * private_data)106 struct fd_event *event_add_fd(struct event_context *ev, TALLOC_CTX *mem_ctx,
107 int fd, uint16_t flags, event_fd_handler_t handler,
108 void *private_data)
109 {
110 return ev->ops->add_fd(ev, mem_ctx, fd, flags, handler, private_data);
111 }
112
113 /*
114 return the fd event flags
115 */
event_get_fd_flags(struct fd_event * fde)116 uint16_t event_get_fd_flags(struct fd_event *fde)
117 {
118 if (!fde) return 0;
119 return fde->event_ctx->ops->get_fd_flags(fde);
120 }
121
122 /*
123 set the fd event flags
124 */
event_set_fd_flags(struct fd_event * fde,uint16_t flags)125 void event_set_fd_flags(struct fd_event *fde, uint16_t flags)
126 {
127 if (!fde) return;
128 fde->event_ctx->ops->set_fd_flags(fde, flags);
129 }
130
131 /*
132 add a timed event
133 return NULL on failure
134 */
event_add_timed(struct event_context * ev,TALLOC_CTX * mem_ctx,struct timeval next_event,event_timed_handler_t handler,void * private_data)135 struct timed_event *event_add_timed(struct event_context *ev, TALLOC_CTX *mem_ctx,
136 struct timeval next_event,
137 event_timed_handler_t handler,
138 void *private_data)
139 {
140 return ev->ops->add_timed(ev, mem_ctx, next_event, handler, private_data);
141 }
142
143 /*
144 do a single event loop using the events defined in ev
145 */
event_loop_once(struct event_context * ev)146 _PUBLIC_ int event_loop_once(struct event_context *ev)
147 {
148 return ev->ops->loop_once(ev);
149 }
150
151 /*
152 return on failure or (with 0) if all fd events are removed
153 */
event_loop_wait(struct event_context * ev)154 int event_loop_wait(struct event_context *ev)
155 {
156 return ev->ops->loop_wait(ev);
157 }
158
159 /*
160 find an event context that is a parent of the given memory context,
161 or create a new event context as a child of the given context if
162 none is found
163
164 This should be used in preference to event_context_init() in places
165 where you would prefer to use the existing event context if possible
166 (which is most situations)
167 */
event_context_find(TALLOC_CTX * mem_ctx)168 struct event_context *event_context_find(TALLOC_CTX *mem_ctx)
169 {
170 struct event_context *ev = talloc_find_parent_bytype(mem_ctx, struct event_context);
171 if (ev == NULL) {
172 ev = event_context_init(mem_ctx);
173 }
174 return ev;
175 }
176