src/bin/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 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 #ifndef _LTT_SESSION_H
  19 #define _LTT_SESSION_H
  20
  21 #include <urcu/list.h>
  22
  23 #include <common/hashtable/hashtable.h>
  24
  25 #include "snapshot.h"
  26 #include "trace-kernel.h"
  27
  28 struct ltt_ust_session;
  29
  30 /*
  31  * Tracing session list
  32  *
  33  * Statically declared in session.c and can be accessed by using
  34  * session_get_list() function that returns the pointer to the list.
  35  */
  36 struct ltt_session_list {
  37         /*
  38          * This lock protects any read/write access to the list and
  39          * next_uuid. All public functions in session.c acquire this
  40          * lock and release it before returning. If none of those
  41          * functions are used, the lock MUST be acquired in order to
  42          * iterate or/and do any actions on that list.
  43          */
  44         pthread_mutex_t lock;
  45
  46         /*
  47          * Session unique ID generator. The session list lock MUST be
  48          * upon update and read of this counter.
  49          */
  50         uint64_t next_uuid;
  51
  52         /* Linked list head */
  53         struct cds_list_head head;
  54 };
  55
  56 /*
  57  * This data structure contains information needed to identify a tracing
  58  * session for both LTTng and UST.
  59  */
  60 struct ltt_session {
  61         char name[NAME_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         uint64_t id;            /* session unique identifier */
  73         /* UID/GID of the user owning the session */
  74         uid_t uid;
  75         gid_t gid;
  76         /*
  77          * Network session handle. A value of 0 means that there is no remote
  78          * session established.
  79          */
  80         uint64_t net_handle;
  81         /*
  82          * This consumer is only set when the create_session_uri call is made.
  83          * This contains the temporary information for a consumer output. Upon
  84          * creation of the UST or kernel session, this consumer, if available, is
  85          * copied into those sessions.
  86          */
  87         struct consumer_output *consumer;
  88
  89         /* Did a start command occured before the kern/ust session creation? */
  90         unsigned int started;
  91
  92         /* Snapshot representation in a session. */
  93         struct snapshot snapshot;
  94         /* Indicate if the session has to output the traces or not. */
  95         unsigned int output_traces;
  96         /*
  97          * This session is in snapshot mode. This means that every channel enabled
  98          * will be set in overwrite mode and mmap. It is considered exclusively for
  99          * snapshot purposes.
 100          */
 101         unsigned int snapshot_mode;
 102 };
 103
 104 /* Prototypes */
 105 int session_create(char *name, uid_t uid, gid_t gid);
 106 int session_destroy(struct ltt_session *session);
 107
 108 void session_lock(struct ltt_session *session);
 109 void session_lock_list(void);
 110 void session_unlock(struct ltt_session *session);
 111 void session_unlock_list(void);
 112
 113 struct ltt_session *session_find_by_name(char *name);
 114 struct ltt_session_list *session_get_list(void);
 115
 116 int session_access_ok(struct ltt_session *session, uid_t uid, gid_t gid);
 117
 118 #endif /* _LTT_SESSION_H */