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 <limits.h>
  22 #include <urcu/list.h>
  23
  24 #include <common/hashtable/hashtable.h>
  25
  26 #include "snapshot.h"
  27 #include "trace-kernel.h"
  28
  29 struct ltt_ust_session;
  30
  31 /*
  32  * Tracing session list
  33  *
  34  * Statically declared in session.c and can be accessed by using
  35  * session_get_list() function that returns the pointer to the list.
  36  */
  37 struct ltt_session_list {
  38         /*
  39          * This lock protects any read/write access to the list and
  40          * next_uuid. All public functions in session.c acquire this
  41          * lock and release it before returning. If none of those
  42          * functions are used, the lock MUST be acquired in order to
  43          * iterate or/and do any actions on that list.
  44          */
  45         pthread_mutex_t lock;
  46
  47         /*
  48          * Session unique ID generator. The session list lock MUST be
  49          * upon update and read of this counter.
  50          */
  51         uint64_t next_uuid;
  52
  53         /* Linked list head */
  54         struct cds_list_head head;
  55 };
  56
  57 /*
  58  * This data structure contains information needed to identify a tracing
  59  * session for both LTTng and UST.
  60  */
  61 struct ltt_session {
  62         char name[NAME_MAX];
  63         char hostname[HOST_NAME_MAX]; /* Local hostname. */
  64         struct ltt_kernel_session *kernel_session;
  65         struct ltt_ust_session *ust_session;
  66         /*
  67          * Protect any read/write on this session data structure. This lock must be
  68          * acquired *before* using any public functions declared below. Use
  69          * session_lock() and session_unlock() for that.
  70          */
  71         pthread_mutex_t lock;
  72         struct cds_list_head list;
  73         uint64_t id;            /* session unique identifier */
  74         /* UID/GID of the user owning the session */
  75         uid_t uid;
  76         gid_t gid;
  77         /*
  78          * Network session handle. A value of 0 means that there is no remote
  79          * session established.
  80          */
  81         uint64_t net_handle;
  82         /*
  83          * This consumer is only set when the create_session_uri call is made.
  84          * This contains the temporary information for a consumer output. Upon
  85          * creation of the UST or kernel session, this consumer, if available, is
  86          * copied into those sessions.
  87          */
  88         struct consumer_output *consumer;
  89
  90         /* Did at least ONE start command has been triggered?. */
  91         unsigned int has_been_started:1;
  92         /*
  93          * Is the session active? Start trace command sets this to 1 and the stop
  94          * command reset it to 0.
  95          */
  96         unsigned int active:1;
  97
  98         /* Snapshot representation in a session. */
  99         struct snapshot snapshot;
 100         /* Indicate if the session has to output the traces or not. */
 101         unsigned int output_traces;
 102         /*
 103          * This session is in snapshot mode. This means that every channel enabled
 104          * will be set in overwrite mode and mmap. It is considered exclusively for
 105          * snapshot purposes.
 106          */
 107         unsigned int snapshot_mode;
 108         /*
 109          * Timer set when the session is created for live reading.
 110          */
 111         unsigned int live_timer;
 112 };
 113
 114 /* Prototypes */
 115 int session_create(char *name, uid_t uid, gid_t gid);
 116 int session_destroy(struct ltt_session *session);
 117
 118 void session_lock(struct ltt_session *session);
 119 void session_lock_list(void);
 120 void session_unlock(struct ltt_session *session);
 121 void session_unlock_list(void);
 122
 123 struct ltt_session *session_find_by_name(const char *name);
 124 struct ltt_session_list *session_get_list(void);
 125
 126 int session_access_ok(struct ltt_session *session, uid_t uid, gid_t gid);
 127
 128 #endif /* _LTT_SESSION_H */