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 struct ltt_session_chunk {
  58         /*
  59          * When the rotation is in progress, the temporary path name is
  60          * stored here. When the rotation is complete, the final path name
  61          * is here and can be queried with the rotate_pending call.
  62          */
  63         char current_rotate_path[PATH_MAX];
  64         /*
  65          * The path where the consumer is currently writing after the first
  66          * session rotation.
  67          */
  68         char active_tracing_path[PATH_MAX];
  69 };
  70
  71 /*
  72  * This data structure contains information needed to identify a tracing
  73  * session for both LTTng and UST.
  74  */
  75 struct ltt_session {
  76         char name[NAME_MAX];
  77         char hostname[HOST_NAME_MAX]; /* Local hostname. */
  78         struct ltt_kernel_session *kernel_session;
  79         struct ltt_ust_session *ust_session;
  80         /*
  81          * Protect any read/write on this session data structure. This lock must be
  82          * acquired *before* using any public functions declared below. Use
  83          * session_lock() and session_unlock() for that.
  84          */
  85         pthread_mutex_t lock;
  86         struct cds_list_head list;
  87         uint64_t id;            /* session unique identifier */
  88         /* UID/GID of the user owning the session */
  89         uid_t uid;
  90         gid_t gid;
  91         /*
  92          * Network session handle. A value of 0 means that there is no remote
  93          * session established.
  94          */
  95         uint64_t net_handle;
  96         /*
  97          * This consumer is only set when the create_session_uri call is made.
  98          * This contains the temporary information for a consumer output. Upon
  99          * creation of the UST or kernel session, this consumer, if available, is
 100          * copied into those sessions.
 101          */
 102         struct consumer_output *consumer;
 103
 104         /* Did at least ONE start command has been triggered?. */
 105         unsigned int has_been_started:1;
 106         /*
 107          * Is the session active? Start trace command sets this to 1 and the stop
 108          * command reset it to 0.
 109          */
 110         unsigned int active:1;
 111
 112         /* Snapshot representation in a session. */
 113         struct snapshot snapshot;
 114         /* Indicate if the session has to output the traces or not. */
 115         unsigned int output_traces;
 116         /*
 117          * This session is in snapshot mode. This means that every channel enabled
 118          * will be set in overwrite mode and mmap. It is considered exclusively for
 119          * snapshot purposes.
 120          */
 121         unsigned int snapshot_mode;
 122         /*
 123          * Timer set when the session is created for live reading.
 124          */
 125         unsigned int live_timer;
 126         /*
 127          * Path where to keep the shared memory files.
 128          */
 129         char shm_path[PATH_MAX];
 130         /*
 131          * Node in ltt_sessions_ht_by_id.
 132          */
 133         struct lttng_ht_node_u64 node;
 134         /*
 135          * Number of session rotation for this session.
 136          */
 137         uint64_t rotate_count;
 138         unsigned int rotate_pending:1;
 139         /*
 140          * Number of channels waiting for a rotate.
 141          * When this number reaches 0, we can handle the rename of the chunk
 142          * folder and inform the client that the rotate is finished.
 143          *
 144          * TODO: replace rotate_pending checks by that.
 145          */
 146         unsigned int nr_chan_rotate_pending;
 147         struct ltt_session_chunk rotation_chunk;
 148         /*
 149          * The timestamp of the beginning of the previous chunk. For the
 150          * first chunk, this is the "lttng start" timestamp. For the
 151          * subsequent ones, this copies the current_chunk_start_ts value when
 152          * a new rotation starts. This value is used to set the name of a
 153          * complete chunk directory, ex: "last_chunk_start_ts-now()".
 154          */
 155         time_t last_chunk_start_ts;
 156         /*
 157          * This is the timestamp when a new chunk starts. When a new rotation
 158          * starts, we copy this value to last_chunk_start_ts and override it
 159          * with the current timestamp.
 160          */
 161         time_t current_chunk_start_ts;
 162         time_t session_last_stop_ts;
 163         time_t last_begin_rotation_ts;
 164 };
 165
 166 /* Prototypes */
 167 int session_create(char *name, uid_t uid, gid_t gid);
 168 int session_destroy(struct ltt_session *session);
 169
 170 void session_lock(struct ltt_session *session);
 171 void session_lock_list(void);
 172 void session_unlock(struct ltt_session *session);
 173 void session_unlock_list(void);
 174
 175 struct ltt_session *session_find_by_name(const char *name);
 176 struct ltt_session *session_find_by_id(uint64_t id);
 177 struct ltt_session_list *session_get_list(void);
 178
 179 int session_access_ok(struct ltt_session *session, uid_t uid, gid_t gid);
 180
 181 #endif /* _LTT_SESSION_H */