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 #include <lttng/location.h>
  28
  29 #include "snapshot.h"
  30 #include "trace-kernel.h"
  31 #include "consumer.h"
  32
  33 struct ltt_ust_session;
  34
  35 /*
  36  * Tracing session list
  37  *
  38  * Statically declared in session.c and can be accessed by using
  39  * session_get_list() function that returns the pointer to the list.
  40  */
  41 struct ltt_session_list {
  42         /*
  43          * This lock protects any read/write access to the list and
  44          * next_uuid. All public functions in session.c acquire this
  45          * lock and release it before returning. If none of those
  46          * functions are used, the lock MUST be acquired in order to
  47          * iterate or/and do any actions on that list.
  48          */
  49         pthread_mutex_t lock;
  50
  51         /*
  52          * Session unique ID generator. The session list lock MUST be
  53          * upon update and read of this counter.
  54          */
  55         uint64_t next_uuid;
  56
  57         /* Linked list head */
  58         struct cds_list_head head;
  59 };
  60
  61 /*
  62  * This data structure contains information needed to identify a tracing
  63  * session for both LTTng and UST.
  64  */
  65 struct ltt_session {
  66         char name[NAME_MAX];
  67         char hostname[HOST_NAME_MAX]; /* Local hostname. */
  68         struct ltt_kernel_session *kernel_session;
  69         struct ltt_ust_session *ust_session;
  70         /*
  71          * Protect any read/write on this session data structure. This lock must be
  72          * acquired *before* using any public functions declared below. Use
  73          * session_lock() and session_unlock() for that.
  74          */
  75         pthread_mutex_t lock;
  76         struct cds_list_head list;
  77         uint64_t id;            /* session unique identifier */
  78         /* UID/GID of the user owning the session */
  79         uid_t uid;
  80         gid_t gid;
  81         /*
  82          * Network session handle. A value of 0 means that there is no remote
  83          * session established.
  84          */
  85         uint64_t net_handle;
  86         /*
  87          * This consumer is only set when the create_session_uri call is made.
  88          * This contains the temporary information for a consumer output. Upon
  89          * creation of the UST or kernel session, this consumer, if available, is
  90          * copied into those sessions.
  91          */
  92         struct consumer_output *consumer;
  93
  94         /* Did at least ONE start command has been triggered?. */
  95         unsigned int has_been_started:1;
  96         /*
  97          * Is the session active? Start trace command sets this to 1 and the stop
  98          * command reset it to 0.
  99          */
 100         unsigned int active:1;
 101
 102         /* Snapshot representation in a session. */
 103         struct snapshot snapshot;
 104         /* Indicate if the session has to output the traces or not. */
 105         unsigned int output_traces;
 106         /*
 107          * This session is in snapshot mode. This means that every channel enabled
 108          * will be set in overwrite mode and mmap. It is considered exclusively for
 109          * snapshot purposes.
 110          */
 111         unsigned int snapshot_mode;
 112         /*
 113          * Timer set when the session is created for live reading.
 114          */
 115         unsigned int live_timer;
 116         /*
 117          * Path where to keep the shared memory files.
 118          */
 119         char shm_path[PATH_MAX];
 120         /*
 121          * Node in ltt_sessions_ht_by_id.
 122          */
 123         struct lttng_ht_node_u64 node;
 124         /*
 125          * The current archive id corresponds to the number of session rotations
 126          * that have occured for this session. The archive id
 127          * is used to tag the "generation" of a stream. This tag allows the
 128          * consumer and relay daemons to track when a given stream was created
 129          * during the lifetime of a session.
 130          *
 131          * For instance, if a stream is created after a session rotation was
 132          * launched, the consumer and relay daemons must not check its position
 133          * to determine if that specific session rotation was completed. It is
 134          * implicitly "completed" since the stream appeared _after_ the session
 135          * rotation was initiated.
 136          */
 137         uint64_t current_archive_id;
 138         /*
 139          * Rotation is considered pending between the time it is launched up
 140          * until the moment when the data has been writen at the destination
 141          * and the trace archive has been renamed.
 142          *
 143          * When tracing locally, only 'rotation_pending_local' is used since
 144          * no remote checks are needed. However, when tracing to a relay daemon,
 145          * a second check is needed to ensure that the data has been
 146          * commited at the remote destination.
 147          */
 148         bool rotation_pending_local;
 149         bool rotation_pending_relay;
 150         /* Current state of a rotation. */
 151         enum lttng_rotation_state rotation_state;
 152         struct {
 153                 /*
 154                  * When the rotation is in progress, the temporary path name is
 155                  * stored here. When the rotation is complete, the final path name
 156                  * is here and can be queried with the rotate_pending call.
 157                  */
 158                 char current_rotate_path[LTTNG_PATH_MAX];
 159                 /*
 160                  * The path where the consumer is currently writing after the first
 161                  * session rotation.
 162                  */
 163                 char active_tracing_path[LTTNG_PATH_MAX];
 164         } rotation_chunk;
 165         /*
 166          * The timestamp of the beginning of the previous chunk. For the
 167          * first chunk, this is the "lttng start" timestamp. For the
 168          * subsequent ones, this copies the current_chunk_start_ts value when
 169          * a new rotation starts. This value is used to set the name of a
 170          * complete chunk directory, ex: "last_chunk_start_ts-now()".
 171          */
 172         time_t last_chunk_start_ts;
 173         /*
 174          * This is the timestamp when a new chunk starts. When a new rotation
 175          * starts, we copy this value to last_chunk_start_ts and replace it
 176          * with the current timestamp.
 177          */
 178         time_t current_chunk_start_ts;
 179         /*
 180          * Timer to check periodically if a relay and/or consumer has completed
 181          * the last rotation.
 182          */
 183         bool rotation_pending_check_timer_enabled;
 184         timer_t rotation_pending_check_timer;
 185         /* Timer to periodically rotate a session. */
 186         bool rotation_schedule_timer_enabled;
 187         timer_t rotation_schedule_timer;
 188         /* Value for periodic rotations, 0 if disabled. */
 189         uint64_t rotate_timer_period;
 190         /* Value for size-based rotations, 0 if disabled. */
 191         uint64_t rotate_size;
 192         /*
 193          * Keep a state if this session was rotated after the last stop command.
 194          * We only allow one rotation after a stop. At destroy, we also need to
 195          * know if a rotation occured since the last stop to rename the current
 196          * chunk.
 197          */
 198         bool rotated_after_last_stop;
 199         /*
 200          * Condition and trigger for size-based rotations.
 201          */
 202         struct lttng_condition *rotate_condition;
 203         struct lttng_trigger *rotate_trigger;
 204 };
 205
 206 /* Prototypes */
 207 int session_create(char *name, uid_t uid, gid_t gid);
 208 int session_destroy(struct ltt_session *session);
 209
 210 void session_lock(struct ltt_session *session);
 211 void session_lock_list(void);
 212 int session_trylock_list(void);
 213 void session_unlock(struct ltt_session *session);
 214 void session_unlock_list(void);
 215
 216 enum consumer_dst_type session_get_consumer_destination_type(
 217                 const struct ltt_session *session);
 218 const char *session_get_net_consumer_hostname(
 219                 const struct ltt_session *session);
 220 void session_get_net_consumer_ports(
 221                 const struct ltt_session *session,
 222                 uint16_t *control_port, uint16_t *data_port);
 223 struct lttng_trace_archive_location *session_get_trace_archive_location(
 224                 struct ltt_session *session);
 225
 226 struct ltt_session *session_find_by_name(const char *name);
 227 struct ltt_session *session_find_by_id(uint64_t id);
 228 struct ltt_session_list *session_get_list(void);
 229
 230 int session_access_ok(struct ltt_session *session, uid_t uid, gid_t gid);
 231
 232 #endif /* _LTT_SESSION_H */