src/bin/lttng-sessiond/fd-limit.c

   1 /*
   2  * Copyright (C) 2012 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License, version 2 only,
   6  * as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along
  14  * with this program; if not, write to the Free Software Foundation, Inc.,
  15  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  16  */
  17
  18 #define _GNU_SOURCE
  19 #include <urcu/uatomic.h>
  20 #include <sys/time.h>
  21 #include <sys/resource.h>
  22 #include <errno.h>
  23 #include <stdio.h>
  24 #include "fd-limit.h"
  25
  26 /* total count of fd. */
  27 static long fd_count;
  28
  29 /*
  30  * threshold in % of number of fd allowed.
  31  */
  32 static long fd_threshold[LTTNG_FD_NR_TYPES] = {
  33         [LTTNG_FD_APPS] = 75,
  34 };
  35
  36 static rlim_t max_nr_fd;
  37
  38 int lttng_fd_get(enum lttng_fd_type type, unsigned int nr)
  39 {
  40         long newval;
  41
  42         if (type >= LTTNG_FD_NR_TYPES) {
  43                 return -EINVAL;
  44         }
  45
  46         newval = uatomic_add_return(&fd_count, (long) nr);
  47         if ((long) (newval * 100)
  48                         - (long) (max_nr_fd * fd_threshold[type]) > 0) {
  49                 uatomic_sub(&fd_count, (long) nr);
  50                 return -EPERM;
  51         }
  52         return 0;
  53 }
  54
  55 void lttng_fd_put(enum lttng_fd_type type, unsigned int nr)
  56 {
  57         uatomic_sub(&fd_count, (long) nr);
  58 }
  59
  60 void lttng_fd_init(void)
  61 {
  62         struct rlimit rlim;
  63         int ret;
  64
  65         ret = getrlimit(RLIMIT_NOFILE, &rlim);
  66         if (ret < 0) {
  67                 perror("getrlimit");
  68         }
  69         max_nr_fd = rlim.rlim_cur;
  70 }