Merge branch 'master' of git://git.lttng.org/lttng-tools

[lttng-tools.git] / lttng-sessiond / compat / poll.h

/*
 * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; only version 2 of the License.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
 * Place - Suite 330, Boston, MA  02111-1307, USA.
 */

#ifndef _LTT_POLL_H
#define _LTT_POLL_H

#include <string.h>
#include <unistd.h>

#include <lttng-share.h>

/*
 * Value taken from the hard limit allowed by the kernel when using setrlimit
 * with RLIMIT_NOFILE on an Intel i7 CPU and Linux 3.0.3.
 */
#define LTTNG_POLL_DEFAULT_SIZE 65535

/*
 * Maximum number of fd we can monitor.
 *
 * For epoll(7), /proc/sys/fs/epoll/max_user_watches (since Linux 2.6.28) will
 * be used for the maximum size of the poll set. If this interface is not
 * available, according to the manpage, the max_user_watches value is 1/25 (4%)
 * of the available low memory divided by the registration cost in bytes which
 * is 90 bytes on a 32-bit kernel and 160 bytes on a 64-bit kernel.
 *
 * For poll(2), the max fds must not exceed RLIMIT_NOFILE given by
 * getrlimit(2).
 */
extern unsigned int poll_max_size;

/*
 * Used by lttng_poll_clean to free the events structure in a lttng_poll_event.
 */
static inline void __lttng_poll_free(void *events)
{
	free(events);
}

/*
 * epoll(7) implementation.
 */
#ifdef HAVE_EPOLL
#include <sys/epoll.h>

/* See man epoll(7) for this define path */
#define LTTNG_EPOLL_PROC_PATH "/proc/sys/fs/epoll/max_user_watches"

enum {
	/* Polling variables compatibility for epoll */
	LPOLLIN = EPOLLIN,
	LPOLLPRI = EPOLLPRI,
	LPOLLOUT = EPOLLOUT,
	LPOLLRDNORM = EPOLLRDNORM,
	LPOLLRDBAND = EPOLLRDBAND,
	LPOLLWRNORM = EPOLLWRNORM,
	LPOLLWRBAND = EPOLLWRBAND,
	LPOLLMSG = EPOLLMSG,
	LPOLLERR = EPOLLERR,
	LPOLLHUP = EPOLLHUP,
	LPOLLNVAL = EPOLLHUP,
	LPOLLRDHUP = EPOLLRDHUP,
	/* Close on exec feature of epoll */
	LTTNG_CLOEXEC = EPOLL_CLOEXEC,
};

struct compat_epoll_event {
	int epfd;
	uint32_t nb_fd;       /* Current number of fd in events */
	uint32_t events_size; /* Size of events array */
	struct epoll_event *events;
};
#define lttng_poll_event compat_epoll_event

/*
 * For the following calls, consider 'e' to be a lttng_poll_event pointer and i
 * being the index of the events array.
 */
#define LTTNG_POLL_GETFD(e, i) LTTNG_REF(e)->events[i].data.fd
#define LTTNG_POLL_GETEV(e, i) LTTNG_REF(e)->events[i].events
#define LTTNG_POLL_GETNB(e) LTTNG_REF(e)->nb_fd
#define LTTNG_POLL_GETSZ(e) LTTNG_REF(e)->events_size

/*
 * Create the epoll set. No memory allocation is done here.
 */
extern int compat_epoll_create(struct lttng_poll_event *events,
		int size, int flags);
#define lttng_poll_create(events, size, flags) \
	compat_epoll_create(events, size, flags);

/*
 * Wait on epoll set with the number of fd registered to the lttng_poll_event
 * data structure (events).
 */
extern int compat_epoll_wait(struct lttng_poll_event *events, int timeout);
#define lttng_poll_wait(events, timeout) \
	compat_epoll_wait(events, timeout);

/*
 * Add a fd to the epoll set and resize the epoll_event structure if needed.
 */
extern int compat_epoll_add(struct lttng_poll_event *events,
		int fd, uint32_t req_events);
#define lttng_poll_add(events, fd, req_events) \
	compat_epoll_add(events, fd, req_events);

/*
 * Remove a fd from the epoll set.
 */
extern int compat_epoll_del(struct lttng_poll_event *events, int fd);
#define lttng_poll_del(events, fd) \
	compat_epoll_del(events, fd);

/*
 * Set up the poll set limits variable poll_max_size
 */
extern void compat_epoll_set_max_size(void);
#define lttng_poll_set_max_size(void) \
	compat_epoll_set_max_size(void);

/*
 * This function memset with zero the structure since it can be reused at each
 * round of a main loop. Being in a loop and using a non static number of fds,
 * this function must be called to insure coherent events with associted fds.
 */
static inline void lttng_poll_reset(struct lttng_poll_event *events)
{
	if (events && events->events) {
		memset(events->events, 0,
				events->nb_fd * sizeof(struct epoll_event));
	}
}

/*
 * Clean the events structure of a lttng_poll_event. It's the caller
 * responsability to free the lttng_poll_event memory.
 */
static inline void lttng_poll_clean(struct lttng_poll_event *events)
{
	if (events) {
		close(events->epfd);
		__lttng_poll_free((void *) events->events);
	}
}

#else	/* HAVE_EPOLL */
/*
 * Fallback on poll(2) API
 */

/* Needed for some poll event values */
#ifndef __USE_XOPEN
#define __USE_XOPEN
#endif

/* Needed for some poll event values */
#ifndef __USE_GNU
#define __USE_GNU
#endif

#include <poll.h>
#include <stdint.h>

enum {
	/* Polling variables compatibility for poll */
	LPOLLIN = POLLIN,
	LPOLLPRI = POLLPRI,
	LPOLLOUT = POLLOUT,
	LPOLLRDNORM = POLLRDNORM,
	LPOLLRDBAND = POLLRDBAND,
	LPOLLWRNORM = POLLWRNORM,
	LPOLLWRBAND = POLLWRBAND,
	LPOLLMSG = POLLMSG,
	LPOLLERR = POLLERR,
	LPOLLHUP = POLLHUP | POLLNVAL,
	LPOLLRDHUP = POLLRDHUP,
	/* Close on exec feature does not exist for poll(2) */
	LTTNG_CLOEXEC = 0xdead,
};

struct compat_poll_event {
	uint32_t nb_fd;       /* Current number of fd in events */
	uint32_t events_size; /* Size of events array */
	struct pollfd *events;
};
#define lttng_poll_event compat_poll_event

/*
 * For the following calls, consider 'e' to be a lttng_poll_event pointer and i
 * being the index of the events array.
 */
#define LTTNG_POLL_GETFD(e, i) LTTNG_REF(e)->events[i].fd
#define LTTNG_POLL_GETEV(e, i) LTTNG_REF(e)->events[i].revents
#define LTTNG_POLL_GETNB(e) LTTNG_REF(e)->nb_fd
#define LTTNG_POLL_GETSZ(e) LTTNG_REF(e)->events_size

/*
 * Create a pollfd structure of size 'size'.
 */
extern int compat_poll_create(struct lttng_poll_event *events, int size);
#define lttng_poll_create(events, size, flags) \
	compat_poll_create(events, size);

/*
 * Wait on poll(2) event with nb_fd registered to the lttng_poll_event data
 * structure.
 */
extern int compat_poll_wait(struct lttng_poll_event *events, int timeout);
#define lttng_poll_wait(events, timeout) \
	compat_poll_wait(events, timeout);

/*
 * Add the fd to the pollfd structure. Resize if needed.
 */
extern int compat_poll_add(struct lttng_poll_event *events,
		int fd, uint32_t req_events);
#define lttng_poll_add(events, fd, req_events) \
	compat_poll_add(events, fd, req_events);

/*
 * Remove the fd from the pollfd. Memory allocation is done to recreate a new
 * pollfd, data is copied from the old pollfd to the new and, finally, the old
 * one is freed().
 */
extern int compat_poll_del(struct lttng_poll_event *events, int fd);
#define lttng_poll_del(events, fd) \
	compat_poll_del(events, fd);

/*
 * Set up the poll set limits variable poll_max_size
 */
extern void compat_poll_set_max_size(void);
#define lttng_poll_set_max_size(void) \
	compat_poll_set_max_size(void);

/*
 * No need to reset a pollfd structure for poll(2)
 */
static inline void lttng_poll_reset(struct lttng_poll_event *events)
{}

/*
 * Clean the events structure of a lttng_poll_event. It's the caller
 * responsability to free the lttng_poll_event memory.
 */
static inline void lttng_poll_clean(struct lttng_poll_event *events)
{
	if (events) {
		__lttng_poll_free((void *) events->events);
	}
}

#endif /* HAVE_EPOLL */

#endif /* _LTT_POLL_H */