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 the session has been added to the session list and ht.*/
  85         bool published;
  86         /* Indicates if a destroy command has been applied to this session. */
  87         bool destroyed;
  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          * The current archive id corresponds to the number of session rotations
 136          * that have occurred for this session. The archive id
 137          * is used to tag the "generation" of a stream. This tag allows the
 138          * consumer and relay daemons to track when a given stream was created
 139          * during the lifetime of a session.
 140          *
 141          * For instance, if a stream is created after a session rotation was
 142          * launched, the consumer and relay daemons must not check its position
 143          * to determine if that specific session rotation was completed. It is
 144          * implicitly "completed" since the stream appeared _after_ the session
 145          * rotation was initiated.
 146          */
 147         uint64_t current_archive_id;
 148         /*
 149          * Rotation is considered pending between the time it is launched up
 150          * until the moment when the data has been writen at the destination
 151          * and the trace archive has been renamed.
 152          *
 153          * When tracing locally, only 'rotation_pending_local' is used since
 154          * no remote checks are needed. However, when tracing to a relay daemon,
 155          * a second check is needed to ensure that the data has been
 156          * commited at the remote destination.
 157          */
 158         bool rotation_pending_local;
 159         bool rotation_pending_relay;
 160         /* Current state of a rotation. */
 161         enum lttng_rotation_state rotation_state;
 162         struct {
 163                 /*
 164                  * When the rotation is in progress, the temporary path name is
 165                  * stored here. When the rotation is complete, the final path name
 166                  * is here and can be queried with the rotate_pending call.
 167                  */
 168                 char current_rotate_path[LTTNG_PATH_MAX];
 169                 /*
 170                  * The path where the consumer is currently writing after the first
 171                  * session rotation.
 172                  */
 173                 char active_tracing_path[LTTNG_PATH_MAX];
 174         } rotation_chunk;
 175         /*
 176          * The timestamp of the beginning of the previous chunk. For the
 177          * first chunk, this is the "lttng start" timestamp. For the
 178          * subsequent ones, this copies the current_chunk_start_ts value when
 179          * a new rotation starts. This value is used to set the name of a
 180          * complete chunk directory, ex: "last_chunk_start_ts-now()".
 181          */
 182         time_t last_chunk_start_ts;
 183         /*
 184          * This is the timestamp when a new chunk starts. When a new rotation
 185          * starts, we copy this value to last_chunk_start_ts and replace it
 186          * with the current timestamp.
 187          */
 188         time_t current_chunk_start_ts;
 189         /*
 190          * Timer to check periodically if a relay and/or consumer has completed
 191          * the last rotation.
 192          */
 193         bool rotation_pending_check_timer_enabled;
 194         timer_t rotation_pending_check_timer;
 195         /* Timer to periodically rotate a session. */
 196         bool rotation_schedule_timer_enabled;
 197         timer_t rotation_schedule_timer;
 198         /* Value for periodic rotations, 0 if disabled. */
 199         uint64_t rotate_timer_period;
 200         /* Value for size-based rotations, 0 if disabled. */
 201         uint64_t rotate_size;
 202         /*
 203          * Keep a state if this session was rotated after the last stop command.
 204          * We only allow one rotation after a stop. At destroy, we also need to
 205          * know if a rotation occurred since the last stop to rename the current
 206          * chunk.
 207          */
 208         bool rotated_after_last_stop;
 209         /*
 210          * Condition and trigger for size-based rotations.
 211          */
 212         struct lttng_condition *rotate_condition;
 213         struct lttng_trigger *rotate_trigger;
 214 };
 215
 216 /* Prototypes */
 217 int session_create(char *name, uid_t uid, gid_t gid);
 218
 219 void session_lock(struct ltt_session *session);
 220 void session_lock_list(void);
 221 int session_trylock_list(void);
 222 void session_unlock(struct ltt_session *session);
 223 void session_unlock_list(void);
 224
 225 void session_destroy(struct ltt_session *session);
 226
 227 bool session_get(struct ltt_session *session);
 228 void session_put(struct ltt_session *session);
 229
 230 enum consumer_dst_type session_get_consumer_destination_type(
 231                 const struct ltt_session *session);
 232 const char *session_get_net_consumer_hostname(
 233                 const struct ltt_session *session);
 234 void session_get_net_consumer_ports(
 235                 const struct ltt_session *session,
 236                 uint16_t *control_port, uint16_t *data_port);
 237 struct lttng_trace_archive_location *session_get_trace_archive_location(
 238                 struct ltt_session *session);
 239
 240 struct ltt_session *session_find_by_name(const char *name);
 241 struct ltt_session *session_find_by_id(uint64_t id);
 242
 243 struct ltt_session_list *session_get_list(void);
 244 void session_list_wait_empty(void);
 245
 246 int session_access_ok(struct ltt_session *session, uid_t uid, gid_t gid);
 247
 248 int session_reset_rotation_state(struct ltt_session *session,
 249                 enum lttng_rotation_state result);
 250
 251 #endif /* _LTT_SESSION_H */