Add poll/epoll compat layer for session daemon
[lttng-tools.git] / ltt-sessiond / compat / poll.h
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5eb91c98
DG
1/*
2 * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
3 *
4 * This program is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License as published by the Free
6 * Software Foundation; only version 2 of the License.
7 *
8 * This program is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
11 * more details.
12 *
13 * You should have received a copy of the GNU General Public License along with
14 * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
15 * Place - Suite 330, Boston, MA 02111-1307, USA.
16 */
17
18#ifndef _LTT_POLL_H
19#define _LTT_POLL_H
20
21#include <string.h>
22#include <unistd.h>
23
24#include <lttng-share.h>
25
26/*
27 * Value taken from the hard limit allowed by the kernel when using setrlimit
28 * with RLIMIT_NOFILE on an Intel i7 CPU and Linux 3.0.3.
29 */
30#define LTTNG_POLL_DEFAULT_SIZE 65535
31
32/*
33 * Maximum number of fd we can monitor.
34 *
35 * For epoll(7), /proc/sys/fs/epoll/max_user_watches (since Linux 2.6.28) will
36 * be used for the maximum size of the poll set. If this interface is not
37 * available, according to the manpage, the max_user_watches value is 1/25 (4%)
38 * of the available low memory divided by the registration cost in bytes which
39 * is 90 bytes on a 32-bit kernel and 160 bytes on a 64-bit kernel.
40 *
41 * For poll(2), the max fds must not exceed RLIMIT_NOFILE given by
42 * getrlimit(2).
43 */
44extern unsigned int poll_max_size;
45
46/*
47 * Used by lttng_poll_clean to free the events structure in a lttng_poll_event.
48 */
49static inline void __lttng_poll_free(void *events)
50{
51 free(events);
52}
53
54/*
55 * epoll(7) implementation.
56 */
57#ifdef HAVE_EPOLL
58#include <sys/epoll.h>
59
60/* See man epoll(7) for this define path */
61#define LTTNG_EPOLL_PROC_PATH "/proc/sys/fs/epoll/max_user_watches"
62
63enum {
64 /* Polling variables compatibility for epoll */
65 LPOLLIN = EPOLLIN,
66 LPOLLPRI = EPOLLPRI,
67 LPOLLOUT = EPOLLOUT,
68 LPOLLRDNORM = EPOLLRDNORM,
69 LPOLLRDBAND = EPOLLRDBAND,
70 LPOLLWRNORM = EPOLLWRNORM,
71 LPOLLWRBAND = EPOLLWRBAND,
72 LPOLLMSG = EPOLLMSG,
73 LPOLLERR = EPOLLERR,
74 LPOLLHUP = EPOLLHUP,
75 LPOLLNVAL = EPOLLHUP,
76 LPOLLRDHUP = EPOLLRDHUP,
77 /* Close on exec feature of epoll */
78 LTTNG_CLOEXEC = EPOLL_CLOEXEC,
79};
80
81struct compat_epoll_event {
82 int epfd;
83 uint32_t nb_fd; /* Current number of fd in events */
84 uint32_t events_size; /* Size of events array */
85 struct epoll_event *events;
86};
87#define lttng_poll_event compat_epoll_event
88
89/*
90 * For the following calls, consider 'e' to be a lttng_poll_event pointer and i
91 * being the index of the events array.
92 */
93#define LTTNG_POLL_GETFD(e, i) LTTNG_REF(e)->events[i].data.fd
94#define LTTNG_POLL_GETEV(e, i) LTTNG_REF(e)->events[i].events
95#define LTTNG_POLL_GETNB(e) LTTNG_REF(e)->nb_fd
96#define LTTNG_POLL_GETSZ(e) LTTNG_REF(e)->events_size
97
98/*
99 * Create the epoll set. No memory allocation is done here.
100 */
101extern int compat_epoll_create(struct lttng_poll_event *events,
102 int size, int flags);
103#define lttng_poll_create(events, size, flags) \
104 compat_epoll_create(events, size, flags);
105
106/*
107 * Wait on epoll set with the number of fd registered to the lttng_poll_event
108 * data structure (events).
109 */
110extern int compat_epoll_wait(struct lttng_poll_event *events, int timeout);
111#define lttng_poll_wait(events, timeout) \
112 compat_epoll_wait(events, timeout);
113
114/*
115 * Add a fd to the epoll set and resize the epoll_event structure if needed.
116 */
117extern int compat_epoll_add(struct lttng_poll_event *events,
118 int fd, uint32_t req_events);
119#define lttng_poll_add(events, fd, req_events) \
120 compat_epoll_add(events, fd, req_events);
121
122/*
123 * Remove a fd from the epoll set.
124 */
125extern int compat_epoll_del(struct lttng_poll_event *events, int fd);
126#define lttng_poll_del(events, fd) \
127 compat_epoll_del(events, fd);
128
129/*
130 * Set up the poll set limits variable poll_max_size
131 */
132extern void compat_epoll_set_max_size(void);
133#define lttng_poll_set_max_size(void) \
134 compat_epoll_set_max_size(void);
135
136/*
137 * This function memset with zero the structure since it can be reused at each
138 * round of a main loop. Being in a loop and using a non static number of fds,
139 * this function must be called to insure coherent events with associted fds.
140 */
141static inline void lttng_poll_reset(struct lttng_poll_event *events)
142{
143 if (events && events->events) {
144 memset(events->events, 0,
145 events->nb_fd * sizeof(struct epoll_event));
146 }
147}
148
149/*
150 * Clean the events structure of a lttng_poll_event. It's the caller
151 * responsability to free the lttng_poll_event memory.
152 */
153static inline void lttng_poll_clean(struct lttng_poll_event *events)
154{
155 if (events) {
156 close(events->epfd);
157 __lttng_poll_free((void *) events->events);
158 }
159}
160
161#else /* HAVE_EPOLL */
162/*
163 * Fallback on poll(2) API
164 */
165
166/* Needed for some poll event values */
167#ifndef __USE_XOPEN
168#define __USE_XOPEN
169#endif
170
171/* Needed for some poll event values */
172#ifndef __USE_GNU
173#define __USE_GNU
174#endif
175
176#include <poll.h>
177#include <stdint.h>
178
179enum {
180 /* Polling variables compatibility for poll */
181 LPOLLIN = POLLIN,
182 LPOLLPRI = POLLPRI,
183 LPOLLOUT = POLLOUT,
184 LPOLLRDNORM = POLLRDNORM,
185 LPOLLRDBAND = POLLRDBAND,
186 LPOLLWRNORM = POLLWRNORM,
187 LPOLLWRBAND = POLLWRBAND,
188 LPOLLMSG = POLLMSG,
189 LPOLLERR = POLLERR,
190 LPOLLHUP = POLLHUP | POLLNVAL,
191 LPOLLRDHUP = POLLRDHUP,
192 /* Close on exec feature does not exist for poll(2) */
193 LTTNG_CLOEXEC = 0xdead,
194};
195
196struct compat_poll_event {
197 uint32_t nb_fd; /* Current number of fd in events */
198 uint32_t events_size; /* Size of events array */
199 struct pollfd *events;
200};
201#define lttng_poll_event compat_poll_event
202
203/*
204 * For the following calls, consider 'e' to be a lttng_poll_event pointer and i
205 * being the index of the events array.
206 */
207#define LTTNG_POLL_GETFD(e, i) LTTNG_REF(e)->events[i].fd
208#define LTTNG_POLL_GETEV(e, i) LTTNG_REF(e)->events[i].revents
209#define LTTNG_POLL_GETNB(e) LTTNG_REF(e)->nb_fd
210#define LTTNG_POLL_GETSZ(e) LTTNG_REF(e)->events_size
211
212/*
213 * Create a pollfd structure of size 'size'.
214 */
215extern int compat_poll_create(struct lttng_poll_event *events, int size);
216#define lttng_poll_create(events, size, flags) \
217 compat_poll_create(events, size);
218
219/*
220 * Wait on poll(2) event with nb_fd registered to the lttng_poll_event data
221 * structure.
222 */
223extern int compat_poll_wait(struct lttng_poll_event *events, int timeout);
224#define lttng_poll_wait(events, timeout) \
225 compat_poll_wait(events, timeout);
226
227/*
228 * Add the fd to the pollfd structure. Resize if needed.
229 */
230extern int compat_poll_add(struct lttng_poll_event *events,
231 int fd, uint32_t req_events);
232#define lttng_poll_add(events, fd, req_events) \
233 compat_poll_add(events, fd, req_events);
234
235/*
236 * Remove the fd from the pollfd. Memory allocation is done to recreate a new
237 * pollfd, data is copied from the old pollfd to the new and, finally, the old
238 * one is freed().
239 */
240extern int compat_poll_del(struct lttng_poll_event *events, int fd);
241#define lttng_poll_del(events, fd) \
242 compat_poll_del(events, fd);
243
244/*
245 * Set up the poll set limits variable poll_max_size
246 */
247extern void compat_poll_set_max_size(void);
248#define lttng_poll_set_max_size(void) \
249 compat_poll_set_max_size(void);
250
251/*
252 * No need to reset a pollfd structure for poll(2)
253 */
254static inline void lttng_poll_reset(struct lttng_poll_event *events)
255{}
256
257/*
258 * Clean the events structure of a lttng_poll_event. It's the caller
259 * responsability to free the lttng_poll_event memory.
260 */
261static inline void lttng_poll_clean(struct lttng_poll_event *events)
262{
263 if (events) {
264 __lttng_poll_free((void *) events->events);
265 }
266}
267
268#endif /* HAVE_EPOLL */
269
270#endif /* _LTT_POLL_H */
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