lttng-sessiond/session.h

   1 /*
   2  * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License
   6  * as published by the Free Software Foundation; only version 2
   7  * of the License.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  17  */
  18
  19 #ifndef _LTT_SESSION_H
  20 #define _LTT_SESSION_H
  21
  22 #include <pthread.h>
  23 #include <unistd.h>
  24 #include <urcu/list.h>
  25
  26 #include "trace-kernel.h"
  27 #include "trace-ust.h"
  28
  29 /*
  30  * Tracing session list
  31  *
  32  * Statically declared in session.c and can be accessed by using
  33  * session_get_list() function that returns the pointer to the list.
  34  */
  35 struct ltt_session_list {
  36         /*
  37          * This lock protects any read/write access to the list and count (which is
  38          * basically the list size). All public functions in session.c acquire this
  39          * lock and release it before returning. If none of those functions are
  40          * used, the lock MUST be acquired in order to iterate or/and do any
  41          * actions on that list.
  42          */
  43         pthread_mutex_t lock;
  44
  45         /*
  46          * Number of element in the list. The session list lock MUST be acquired if
  47          * this counter is used when iterating over the session list.
  48          */
  49         unsigned int count;
  50
  51         /* Linked list head */
  52         struct cds_list_head head;
  53 };
  54
  55 /*
  56  * This data structure contains information needed to identify a tracing
  57  * session for both LTTng and UST.
  58  */
  59 struct ltt_session {
  60         char name[NAME_MAX];
  61         char path[PATH_MAX];
  62         struct ltt_kernel_session *kernel_session;
  63         struct ltt_ust_session *ust_session;
  64         /*
  65          * Protect any read/write on this session data structure. This lock must be
  66          * acquired *before* using any public functions declared below. Use
  67          * session_lock() and session_unlock() for that.
  68          */
  69         pthread_mutex_t lock;
  70         struct cds_list_head list;
  71         int enabled;    /* enabled/started flag */
  72         int id;         /* session unique identifier */
  73         /* UID/GID of the user owning the session */
  74         uid_t uid;
  75         gid_t gid;
  76 };
  77
  78 /* Prototypes */
  79 int session_create(char *name, char *path, uid_t uid, gid_t gid);
  80 int session_destroy(struct ltt_session *session);
  81
  82 void session_lock(struct ltt_session *session);
  83 void session_lock_list(void);
  84 void session_unlock(struct ltt_session *session);
  85 void session_unlock_list(void);
  86
  87 struct ltt_session *session_find_by_name(char *name);
  88 struct ltt_session_list *session_get_list(void);
  89
  90 #endif /* _LTT_SESSION_H */