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          * This condition variable is signaled on every removal from
  52          * the session list.
  53          */
  54         pthread_cond_t removal_cond;
  55
  56         /*
  57          * Session unique ID generator. The session list lock MUST be
  58          * upon update and read of this counter.
  59          */
  60         uint64_t next_uuid;
  61
  62         /* Linked list head */
  63         struct cds_list_head head;
  64 };
  65
  66 /*
  67  * This data structure contains information needed to identify a tracing
  68  * session for both LTTng and UST.
  69  */
  70 struct ltt_session {
  71         char name[NAME_MAX];
  72         char hostname[HOST_NAME_MAX]; /* Local hostname. */
  73         struct ltt_kernel_session *kernel_session;
  74         struct ltt_ust_session *ust_session;
  75         struct urcu_ref ref;
  76         /*
  77          * Protect any read/write on this session data structure. This lock must be
  78          * acquired *before* using any public functions declared below. Use
  79          * session_lock() and session_unlock() for that.
  80          */
  81         pthread_mutex_t lock;
  82         struct cds_list_head list;
  83         uint64_t id;            /* session unique identifier */
  84         /* Indicates if a destroy command has been applied to this session. */
  85         bool destroyed;
  86         /* UID/GID of the user owning the session */
  87         uid_t uid;
  88         gid_t gid;
  89         /*
  90          * Network session handle. A value of 0 means that there is no remote
  91          * session established.
  92          */
  93         uint64_t net_handle;
  94         /*
  95          * This consumer is only set when the create_session_uri call is made.
  96          * This contains the temporary information for a consumer output. Upon
  97          * creation of the UST or kernel session, this consumer, if available, is
  98          * copied into those sessions.
  99          */
 100         struct consumer_output *consumer;
 101
 102         /* Did at least ONE start command has been triggered?. */
 103         unsigned int has_been_started:1;
 104         /*
 105          * Is the session active? Start trace command sets this to 1 and the stop
 106          * command reset it to 0.
 107          */
 108         unsigned int active:1;
 109
 110         /* Snapshot representation in a session. */
 111         struct snapshot snapshot;
 112         /* Indicate if the session has to output the traces or not. */
 113         unsigned int output_traces;
 114         /*
 115          * This session is in snapshot mode. This means that every channel enabled
 116          * will be set in overwrite mode and mmap. It is considered exclusively for
 117          * snapshot purposes.
 118          */
 119         unsigned int snapshot_mode;
 120         /*
 121          * Timer set when the session is created for live reading.
 122          */
 123         unsigned int live_timer;
 124         /*
 125          * Path where to keep the shared memory files.
 126          */
 127         char shm_path[PATH_MAX];
 128         /*
 129          * Node in ltt_sessions_ht_by_id.
 130          */
 131         struct lttng_ht_node_u64 node;
 132         /*
 133          * The current archive id corresponds to the number of session rotations
 134          * that have occurred for this session. The archive id
 135          * is used to tag the "generation" of a stream. This tag allows the
 136          * consumer and relay daemons to track when a given stream was created
 137          * during the lifetime of a session.
 138          *
 139          * For instance, if a stream is created after a session rotation was
 140          * launched, the consumer and relay daemons must not check its position
 141          * to determine if that specific session rotation was completed. It is
 142          * implicitly "completed" since the stream appeared _after_ the session
 143          * rotation was initiated.
 144          */
 145         uint64_t current_archive_id;
 146         /*
 147          * Rotation is considered pending between the time it is launched up
 148          * until the moment when the data has been writen at the destination
 149          * and the trace archive has been renamed.
 150          *
 151          * When tracing locally, only 'rotation_pending_local' is used since
 152          * no remote checks are needed. However, when tracing to a relay daemon,
 153          * a second check is needed to ensure that the data has been
 154          * commited at the remote destination.
 155          */
 156         bool rotation_pending_local;
 157         bool rotation_pending_relay;
 158         /* Current state of a rotation. */
 159         enum lttng_rotation_state rotation_state;
 160         struct {
 161                 /*
 162                  * When the rotation is in progress, the temporary path name is
 163                  * stored here. When the rotation is complete, the final path name
 164                  * is here and can be queried with the rotate_pending call.
 165                  */
 166                 char current_rotate_path[LTTNG_PATH_MAX];
 167                 /*
 168                  * The path where the consumer is currently writing after the first
 169                  * session rotation.
 170                  */
 171                 char active_tracing_path[LTTNG_PATH_MAX];
 172         } rotation_chunk;
 173         /*
 174          * The timestamp of the beginning of the previous chunk. For the
 175          * first chunk, this is the "lttng start" timestamp. For the
 176          * subsequent ones, this copies the current_chunk_start_ts value when
 177          * a new rotation starts. This value is used to set the name of a
 178          * complete chunk directory, ex: "last_chunk_start_ts-now()".
 179          */
 180         time_t last_chunk_start_ts;
 181         /*
 182          * This is the timestamp when a new chunk starts. When a new rotation
 183          * starts, we copy this value to last_chunk_start_ts and replace it
 184          * with the current timestamp.
 185          */
 186         time_t current_chunk_start_ts;
 187         /*
 188          * Timer to check periodically if a relay and/or consumer has completed
 189          * the last rotation.
 190          */
 191         bool rotation_pending_check_timer_enabled;
 192         timer_t rotation_pending_check_timer;
 193         /* Timer to periodically rotate a session. */
 194         bool rotation_schedule_timer_enabled;
 195         timer_t rotation_schedule_timer;
 196         /* Value for periodic rotations, 0 if disabled. */
 197         uint64_t rotate_timer_period;
 198         /* Value for size-based rotations, 0 if disabled. */
 199         uint64_t rotate_size;
 200         /*
 201          * Keep a state if this session was rotated after the last stop command.
 202          * We only allow one rotation after a stop. At destroy, we also need to
 203          * know if a rotation occurred since the last stop to rename the current
 204          * chunk.
 205          */
 206         bool rotated_after_last_stop;
 207         /*
 208          * Condition and trigger for size-based rotations.
 209          */
 210         struct lttng_condition *rotate_condition;
 211         struct lttng_trigger *rotate_trigger;
 212 };
 213
 214 /* Prototypes */
 215 int session_create(char *name, uid_t uid, gid_t gid);
 216
 217 void session_lock(struct ltt_session *session);
 218 void session_lock_list(void);
 219 int session_trylock_list(void);
 220 void session_unlock(struct ltt_session *session);
 221 void session_unlock_list(void);
 222
 223 void session_destroy(struct ltt_session *session);
 224
 225 bool session_get(struct ltt_session *session);
 226 void session_put(struct ltt_session *session);
 227
 228 enum consumer_dst_type session_get_consumer_destination_type(
 229                 const struct ltt_session *session);
 230 const char *session_get_net_consumer_hostname(
 231                 const struct ltt_session *session);
 232 void session_get_net_consumer_ports(
 233                 const struct ltt_session *session,
 234                 uint16_t *control_port, uint16_t *data_port);
 235 struct lttng_trace_archive_location *session_get_trace_archive_location(
 236                 struct ltt_session *session);
 237
 238 struct ltt_session *session_find_by_name(const char *name);
 239 struct ltt_session *session_find_by_id(uint64_t id);
 240
 241 struct ltt_session_list *session_get_list(void);
 242 void session_list_wait_empty(void);
 243
 244 int session_access_ok(struct ltt_session *session, uid_t uid, gid_t gid);
 245
 246 int session_reset_rotation_state(struct ltt_session *session,
 247                 enum lttng_rotation_state result);
 248
 249 #endif /* _LTT_SESSION_H */