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 <stdbool.h>
  23 #include <urcu/list.h>
  24
  25 #include <common/hashtable/hashtable.h>
  26 #include <lttng/rotation.h>
  27
  28 #include "snapshot.h"
  29 #include "trace-kernel.h"
  30
  31 struct ltt_ust_session;
  32
  33 /*
  34  * Tracing session list
  35  *
  36  * Statically declared in session.c and can be accessed by using
  37  * session_get_list() function that returns the pointer to the list.
  38  */
  39 struct ltt_session_list {
  40         /*
  41          * This lock protects any read/write access to the list and
  42          * next_uuid. All public functions in session.c acquire this
  43          * lock and release it before returning. If none of those
  44          * functions are used, the lock MUST be acquired in order to
  45          * iterate or/and do any actions on that list.
  46          */
  47         pthread_mutex_t lock;
  48
  49         /*
  50          * Session unique ID generator. The session list lock MUST be
  51          * upon update and read of this counter.
  52          */
  53         uint64_t next_uuid;
  54
  55         /* Linked list head */
  56         struct cds_list_head head;
  57 };
  58
  59 /*
  60  * This data structure contains information needed to identify a tracing
  61  * session for both LTTng and UST.
  62  */
  63 struct ltt_session {
  64         char name[NAME_MAX];
  65         char hostname[HOST_NAME_MAX]; /* Local hostname. */
  66         struct ltt_kernel_session *kernel_session;
  67         struct ltt_ust_session *ust_session;
  68         /*
  69          * Protect any read/write on this session data structure. This lock must be
  70          * acquired *before* using any public functions declared below. Use
  71          * session_lock() and session_unlock() for that.
  72          */
  73         pthread_mutex_t lock;
  74         struct cds_list_head list;
  75         uint64_t id;            /* session unique identifier */
  76         /* UID/GID of the user owning the session */
  77         uid_t uid;
  78         gid_t gid;
  79         /*
  80          * Network session handle. A value of 0 means that there is no remote
  81          * session established.
  82          */
  83         uint64_t net_handle;
  84         /*
  85          * This consumer is only set when the create_session_uri call is made.
  86          * This contains the temporary information for a consumer output. Upon
  87          * creation of the UST or kernel session, this consumer, if available, is
  88          * copied into those sessions.
  89          */
  90         struct consumer_output *consumer;
  91
  92         /* Did at least ONE start command has been triggered?. */
  93         unsigned int has_been_started:1;
  94         /*
  95          * Is the session active? Start trace command sets this to 1 and the stop
  96          * command reset it to 0.
  97          */
  98         unsigned int active:1;
  99
 100         /* Snapshot representation in a session. */
 101         struct snapshot snapshot;
 102         /* Indicate if the session has to output the traces or not. */
 103         unsigned int output_traces;
 104         /*
 105          * This session is in snapshot mode. This means that every channel enabled
 106          * will be set in overwrite mode and mmap. It is considered exclusively for
 107          * snapshot purposes.
 108          */
 109         unsigned int snapshot_mode;
 110         /*
 111          * Timer set when the session is created for live reading.
 112          */
 113         unsigned int live_timer;
 114         /*
 115          * Path where to keep the shared memory files.
 116          */
 117         char shm_path[PATH_MAX];
 118         /*
 119          * Node in ltt_sessions_ht_by_id.
 120          */
 121         struct lttng_ht_node_u64 node;
 122         /* Number of session rotation for this session. */
 123         uint64_t rotate_count;
 124         /*
 125          * Rotation is pending between the time it starts until the consumer has
 126          * finished extracting the data. If the session uses a relay, data related
 127          * to a rotation can still be in flight after that, see
 128          * rotate_pending_relay.
 129          */
 130         bool rotate_pending;
 131         /*
 132          * True until the relay has finished the rotation of all the streams.
 133          */
 134         bool rotate_pending_relay;
 135         /* Current state of a rotation. */
 136         enum lttng_rotation_state rotation_state;
 137         /*
 138          * Number of channels waiting for a rotation.
 139          * When this number reaches 0, we can handle the rename of the chunk
 140          * folder and inform the client that the rotate is finished.
 141          */
 142         unsigned int nr_chan_rotate_pending;
 143         struct {
 144                 /*
 145                  * When the rotation is in progress, the temporary path name is
 146                  * stored here. When the rotation is complete, the final path name
 147                  * is here and can be queried with the rotate_pending call.
 148                  */
 149                 char current_rotate_path[LTTNG_PATH_MAX];
 150                 /*
 151                  * The path where the consumer is currently writing after the first
 152                  * session rotation.
 153                  */
 154                 char active_tracing_path[LTTNG_PATH_MAX];
 155         } rotation_chunk;
 156         /*
 157          * The timestamp of the beginning of the previous chunk. For the
 158          * first chunk, this is the "lttng start" timestamp. For the
 159          * subsequent ones, this copies the current_chunk_start_ts value when
 160          * a new rotation starts. This value is used to set the name of a
 161          * complete chunk directory, ex: "last_chunk_start_ts-now()".
 162          */
 163         time_t last_chunk_start_ts;
 164         /*
 165          * This is the timestamp when a new chunk starts. When a new rotation
 166          * starts, we copy this value to last_chunk_start_ts and replace it
 167          * with the current timestamp.
 168          */
 169         time_t current_chunk_start_ts;
 170         /*
 171          * Timer to check periodically if a relay has completed the last
 172          * rotation.
 173          */
 174         bool rotate_relay_pending_timer_enabled;
 175         timer_t rotate_relay_pending_timer;
 176         /* Timer to periodically rotate a session. */
 177         bool rotate_timer_enabled;
 178         timer_t rotate_timer;
 179         uint64_t rotate_timer_period;
 180         /* Value for size-based rotation, 0 if disabled. */
 181         uint64_t rotate_size;
 182         /*
 183          * Keep a state if this session was rotated after the last stop command.
 184          * We only allow one rotation after a stop. At destroy, we also need to
 185          * know if a rotation occured since the last stop to rename the current
 186          * chunk.
 187          */
 188         bool rotated_after_last_stop;
 189 };
 190
 191 /* Prototypes */
 192 int session_create(char *name, uid_t uid, gid_t gid);
 193 int session_destroy(struct ltt_session *session);
 194
 195 void session_lock(struct ltt_session *session);
 196 void session_lock_list(void);
 197 void session_unlock(struct ltt_session *session);
 198 void session_unlock_list(void);
 199
 200 struct ltt_session *session_find_by_name(const char *name);
 201 struct ltt_session *session_find_by_id(uint64_t id);
 202 struct ltt_session_list *session_get_list(void);
 203
 204 int session_access_ok(struct ltt_session *session, uid_t uid, gid_t gid);
 205
 206 #endif /* _LTT_SESSION_H */