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 <urcu/list.h>
  24
  25 #include "trace-kernel.h"
  26 #include "trace-ust.h"
  27
  28 /*
  29  * Tracing session list
  30  *
  31  * Statically declared in session.c and can be accessed by using
  32  * session_get_list() function that returns the pointer to the list.
  33  */
  34 struct ltt_session_list {
  35         /*
  36          * This lock protects any read/write access to the list and count (which is
  37          * basically the list size). All public functions in session.c acquire this
  38          * lock and release it before returning. If none of those functions are
  39          * used, the lock MUST be acquired in order to iterate or/and do any
  40          * actions on that list.
  41          */
  42         pthread_mutex_t lock;
  43
  44         /*
  45          * Number of element in the list. The session list lock MUST be acquired if
  46          * this counter is used when iterating over the session list.
  47          */
  48         unsigned int count;
  49
  50         /* Linked list head */
  51         struct cds_list_head head;
  52 };
  53
  54 /*
  55  * This data structure contains information needed to identify a tracing
  56  * session for both LTTng and UST.
  57  */
  58 struct ltt_session {
  59         char name[NAME_MAX];
  60         char path[PATH_MAX];
  61         struct ltt_kernel_session *kernel_session;
  62         struct ltt_ust_session *ust_session;
  63         /*
  64          * Protect any read/write on this session data structure. This lock must be
  65          * acquired *before* using any public functions declared below. Use
  66          * session_lock() and session_unlock() for that.
  67          */
  68         pthread_mutex_t lock;
  69         struct cds_list_head list;
  70         int enabled;    /* enabled/started flag */
  71         int id;         /* session unique identifier */
  72 };
  73
  74 /* Prototypes */
  75 int session_create(char *name, char *path);
  76 int session_destroy(struct ltt_session *session);
  77
  78 void session_lock(struct ltt_session *session);
  79 void session_lock_list(void);
  80 void session_unlock(struct ltt_session *session);
  81 void session_unlock_list(void);
  82
  83 struct ltt_session *session_find_by_name(char *name);
  84 struct ltt_session_list *session_get_list(void);
  85
  86 #endif /* _LTT_SESSION_H */