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         bool has_auto_generated_name;
  73         char hostname[HOST_NAME_MAX]; /* Local hostname. */
  74         time_t creation_time;
  75         struct ltt_kernel_session *kernel_session;
  76         struct ltt_ust_session *ust_session;
  77         struct urcu_ref ref;
  78         /*
  79          * Protect any read/write on this session data structure. This lock must be
  80          * acquired *before* using any public functions declared below. Use
  81          * session_lock() and session_unlock() for that.
  82          */
  83         pthread_mutex_t lock;
  84         struct cds_list_head list;
  85         uint64_t id;            /* session unique identifier */
  86         /* Indicates if the session has been added to the session list and ht.*/
  87         bool published;
  88         /* Indicates if a destroy command has been applied to this session. */
  89         bool destroyed;
  90         /* UID/GID of the user owning the session */
  91         uid_t uid;
  92         gid_t gid;
  93         /*
  94          * Network session handle. A value of 0 means that there is no remote
  95          * session established.
  96          */
  97         uint64_t net_handle;
  98         /*
  99          * This consumer is only set when the create_session_uri call is made.
 100          * This contains the temporary information for a consumer output. Upon
 101          * creation of the UST or kernel session, this consumer, if available, is
 102          * copied into those sessions.
 103          */
 104         struct consumer_output *consumer;
 105         /*
 106          * Indicates whether or not the user has specified an output directory
 107          * or if it was configured using the default configuration.
 108          */
 109         bool has_user_specified_directory;
 110         /* Did at least ONE start command has been triggered?. */
 111         unsigned int has_been_started:1;
 112         /*
 113          * Is the session active? Start trace command sets this to 1 and the stop
 114          * command reset it to 0.
 115          */
 116         unsigned int active:1;
 117
 118         /* Snapshot representation in a session. */
 119         struct snapshot snapshot;
 120         /* Indicate if the session has to output the traces or not. */
 121         unsigned int output_traces;
 122         /*
 123          * This session is in snapshot mode. This means that channels enabled
 124          * will be set in overwrite mode by default and must be in mmap
 125          * output mode. Note that snapshots can be taken on a session that
 126          * is not in "snapshot_mode". This parameter only affects channel
 127          * creation defaults.
 128          */
 129         unsigned int snapshot_mode;
 130         /*
 131          * A session that has channels that don't use 'mmap' output can't be
 132          * used to capture snapshots. This is set to true whenever a
 133          * 'splice' kernel channel is enabled.
 134          */
 135         bool has_non_mmap_channel;
 136         /*
 137          * Timer set when the session is created for live reading.
 138          */
 139         unsigned int live_timer;
 140         /*
 141          * Path where to keep the shared memory files.
 142          */
 143         char shm_path[PATH_MAX];
 144         /*
 145          * Node in ltt_sessions_ht_by_id.
 146          */
 147         struct lttng_ht_node_u64 node;
 148         /*
 149          * The current archive id corresponds to the number of session rotations
 150          * that have occurred for this session. The archive id
 151          * is used to tag the "generation" of a stream. This tag allows the
 152          * consumer and relay daemons to track when a given stream was created
 153          * during the lifetime of a session.
 154          *
 155          * For instance, if a stream is created after a session rotation was
 156          * launched, the consumer and relay daemons must not check its position
 157          * to determine if that specific session rotation was completed. It is
 158          * implicitly "completed" since the stream appeared _after_ the session
 159          * rotation was initiated.
 160          */
 161         uint64_t current_archive_id;
 162         /*
 163          * Rotation is considered pending between the time it is launched up
 164          * until the moment when the data has been writen at the destination
 165          * and the trace archive has been renamed.
 166          *
 167          * When tracing locally, only 'rotation_pending_local' is used since
 168          * no remote checks are needed. However, when tracing to a relay daemon,
 169          * a second check is needed to ensure that the data has been
 170          * commited at the remote destination.
 171          */
 172         bool rotation_pending_local;
 173         bool rotation_pending_relay;
 174         /* Current state of a rotation. */
 175         enum lttng_rotation_state rotation_state;
 176         struct {
 177                 /*
 178                  * When the rotation is in progress, the temporary path name is
 179                  * stored here. When the rotation is complete, the final path name
 180                  * is here and can be queried with the rotate_pending call.
 181                  */
 182                 char current_rotate_path[LTTNG_PATH_MAX];
 183                 /*
 184                  * The path where the consumer is currently writing after the first
 185                  * session rotation.
 186                  */
 187                 char active_tracing_path[LTTNG_PATH_MAX];
 188         } rotation_chunk;
 189         /*
 190          * The timestamp of the beginning of the previous chunk. For the
 191          * first chunk, this is the "lttng start" timestamp. For the
 192          * subsequent ones, this copies the current_chunk_start_ts value when
 193          * a new rotation starts. This value is used to set the name of a
 194          * complete chunk directory, ex: "last_chunk_start_ts-now()".
 195          */
 196         time_t last_chunk_start_ts;
 197         /*
 198          * This is the timestamp when a new chunk starts. When a new rotation
 199          * starts, we copy this value to last_chunk_start_ts and replace it
 200          * with the current timestamp.
 201          */
 202         time_t current_chunk_start_ts;
 203         /*
 204          * Timer to check periodically if a relay and/or consumer has completed
 205          * the last rotation.
 206          */
 207         bool rotation_pending_check_timer_enabled;
 208         timer_t rotation_pending_check_timer;
 209         /* Timer to periodically rotate a session. */
 210         bool rotation_schedule_timer_enabled;
 211         timer_t rotation_schedule_timer;
 212         /* Value for periodic rotations, 0 if disabled. */
 213         uint64_t rotate_timer_period;
 214         /* Value for size-based rotations, 0 if disabled. */
 215         uint64_t rotate_size;
 216         /*
 217          * Keep a state if this session was rotated after the last stop command.
 218          * We only allow one rotation after a stop. At destroy, we also need to
 219          * know if a rotation occurred since the last stop to rename the current
 220          * chunk.
 221          */
 222         bool rotated_after_last_stop;
 223         /*
 224          * Condition and trigger for size-based rotations.
 225          */
 226         struct lttng_condition *rotate_condition;
 227         struct lttng_trigger *rotate_trigger;
 228 };
 229
 230 /* Prototypes */
 231 enum lttng_error_code session_create(const char *name, uid_t uid, gid_t gid,
 232                 struct ltt_session **out_session);
 233 void session_lock(struct ltt_session *session);
 234 void session_lock_list(void);
 235 int session_trylock_list(void);
 236 void session_unlock(struct ltt_session *session);
 237 void session_unlock_list(void);
 238
 239 void session_destroy(struct ltt_session *session);
 240
 241 bool session_get(struct ltt_session *session);
 242 void session_put(struct ltt_session *session);
 243
 244 enum consumer_dst_type session_get_consumer_destination_type(
 245                 const struct ltt_session *session);
 246 const char *session_get_net_consumer_hostname(
 247                 const struct ltt_session *session);
 248 void session_get_net_consumer_ports(
 249                 const struct ltt_session *session,
 250                 uint16_t *control_port, uint16_t *data_port);
 251 struct lttng_trace_archive_location *session_get_trace_archive_location(
 252                 struct ltt_session *session);
 253
 254 struct ltt_session *session_find_by_name(const char *name);
 255 struct ltt_session *session_find_by_id(uint64_t id);
 256
 257 struct ltt_session_list *session_get_list(void);
 258 void session_list_wait_empty(void);
 259
 260 int session_access_ok(struct ltt_session *session, uid_t uid, gid_t gid);
 261
 262 int session_reset_rotation_state(struct ltt_session *session,
 263                 enum lttng_rotation_state result);
 264
 265 #endif /* _LTT_SESSION_H */