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 #include <lttng/lttng-error.h>
  29
  30 #include "snapshot.h"
  31 #include "trace-kernel.h"
  32 #include "consumer.h"
  33
  34 struct ltt_ust_session;
  35
  36 /*
  37  * Tracing session list
  38  *
  39  * Statically declared in session.c and can be accessed by using
  40  * session_get_list() function that returns the pointer to the list.
  41  */
  42 struct ltt_session_list {
  43         /*
  44          * This lock protects any read/write access to the list and
  45          * next_uuid. All public functions in session.c acquire this
  46          * lock and release it before returning. If none of those
  47          * functions are used, the lock MUST be acquired in order to
  48          * iterate or/and do any actions on that list.
  49          */
  50         pthread_mutex_t lock;
  51         /*
  52          * This condition variable is signaled on every removal from
  53          * the session list.
  54          */
  55         pthread_cond_t removal_cond;
  56
  57         /*
  58          * Session unique ID generator. The session list lock MUST be
  59          * upon update and read of this counter.
  60          */
  61         uint64_t next_uuid;
  62
  63         /* Linked list head */
  64         struct cds_list_head head;
  65 };
  66
  67 /*
  68  * This data structure contains information needed to identify a tracing
  69  * session for both LTTng and UST.
  70  */
  71 struct ltt_session {
  72         char name[NAME_MAX];
  73         bool has_auto_generated_name;
  74         char hostname[HOST_NAME_MAX]; /* Local hostname. */
  75         time_t creation_time;
  76         struct ltt_kernel_session *kernel_session;
  77         struct ltt_ust_session *ust_session;
  78         struct urcu_ref ref;
  79         /*
  80          * Protect any read/write on this session data structure. This lock must be
  81          * acquired *before* using any public functions declared below. Use
  82          * session_lock() and session_unlock() for that.
  83          */
  84         pthread_mutex_t lock;
  85         struct cds_list_head list;
  86         uint64_t id;            /* session unique identifier */
  87         /* Indicates if the session has been added to the session list and ht.*/
  88         bool published;
  89         /* Indicates if a destroy command has been applied to this session. */
  90         bool destroyed;
  91         /* UID/GID of the user owning the session */
  92         uid_t uid;
  93         gid_t gid;
  94         /*
  95          * Network session handle. A value of 0 means that there is no remote
  96          * session established.
  97          */
  98         uint64_t net_handle;
  99         /*
 100          * This consumer is only set when the create_session_uri call is made.
 101          * This contains the temporary information for a consumer output. Upon
 102          * creation of the UST or kernel session, this consumer, if available, is
 103          * copied into those sessions.
 104          */
 105         struct consumer_output *consumer;
 106         /*
 107          * Indicates whether or not the user has specified an output directory
 108          * or if it was configured using the default configuration.
 109          */
 110         bool has_user_specified_directory;
 111         /* Did at least ONE start command has been triggered?. */
 112         unsigned int has_been_started:1;
 113         /*
 114          * Is the session active? Start trace command sets this to 1 and the stop
 115          * command reset it to 0.
 116          */
 117         unsigned int active:1;
 118
 119         /* Snapshot representation in a session. */
 120         struct snapshot snapshot;
 121         /* Indicate if the session has to output the traces or not. */
 122         unsigned int output_traces;
 123         /*
 124          * This session is in snapshot mode. This means that channels enabled
 125          * will be set in overwrite mode by default and must be in mmap
 126          * output mode. Note that snapshots can be taken on a session that
 127          * is not in "snapshot_mode". This parameter only affects channel
 128          * creation defaults.
 129          */
 130         unsigned int snapshot_mode;
 131         /*
 132          * A session that has channels that don't use 'mmap' output can't be
 133          * used to capture snapshots. This is set to true whenever a
 134          * 'splice' kernel channel is enabled.
 135          */
 136         bool has_non_mmap_channel;
 137         /*
 138          * Timer set when the session is created for live reading.
 139          */
 140         unsigned int live_timer;
 141         /*
 142          * Path where to keep the shared memory files.
 143          */
 144         char shm_path[PATH_MAX];
 145         /*
 146          * Node in ltt_sessions_ht_by_id.
 147          */
 148         struct lttng_ht_node_u64 node;
 149         /*
 150          * The current archive id corresponds to the number of session rotations
 151          * that have occurred for this session. The archive id
 152          * is used to tag the "generation" of a stream. This tag allows the
 153          * consumer and relay daemons to track when a given stream was created
 154          * during the lifetime of a session.
 155          *
 156          * For instance, if a stream is created after a session rotation was
 157          * launched, the consumer and relay daemons must not check its position
 158          * to determine if that specific session rotation was completed. It is
 159          * implicitly "completed" since the stream appeared _after_ the session
 160          * rotation was initiated.
 161          */
 162         uint64_t current_archive_id;
 163         /*
 164          * Rotation is considered pending between the time it is launched up
 165          * until the moment when the data has been writen at the destination
 166          * and the trace archive has been renamed.
 167          *
 168          * When tracing locally, only 'rotation_pending_local' is used since
 169          * no remote checks are needed. However, when tracing to a relay daemon,
 170          * a second check is needed to ensure that the data has been
 171          * commited at the remote destination.
 172          */
 173         bool rotation_pending_local;
 174         bool rotation_pending_relay;
 175         /* Current state of a rotation. */
 176         enum lttng_rotation_state rotation_state;
 177         struct {
 178                 /*
 179                  * When the rotation is in progress, the temporary path name is
 180                  * stored here. When the rotation is complete, the final path name
 181                  * is here and can be queried with the rotate_pending call.
 182                  */
 183                 char current_rotate_path[LTTNG_PATH_MAX];
 184                 /*
 185                  * The path where the consumer is currently writing after the first
 186                  * session rotation.
 187                  */
 188                 char active_tracing_path[LTTNG_PATH_MAX];
 189         } rotation_chunk;
 190         /*
 191          * The timestamp of the beginning of the previous chunk. For the
 192          * first chunk, this is the "lttng start" timestamp. For the
 193          * subsequent ones, this copies the current_chunk_start_ts value when
 194          * a new rotation starts. This value is used to set the name of a
 195          * complete chunk directory, ex: "last_chunk_start_ts-now()".
 196          */
 197         time_t last_chunk_start_ts;
 198         /*
 199          * This is the timestamp when a new chunk starts. When a new rotation
 200          * starts, we copy this value to last_chunk_start_ts and replace it
 201          * with the current timestamp.
 202          */
 203         time_t current_chunk_start_ts;
 204         /*
 205          * Timer to check periodically if a relay and/or consumer has completed
 206          * the last rotation.
 207          */
 208         bool rotation_pending_check_timer_enabled;
 209         timer_t rotation_pending_check_timer;
 210         /* Timer to periodically rotate a session. */
 211         bool rotation_schedule_timer_enabled;
 212         timer_t rotation_schedule_timer;
 213         /* Value for periodic rotations, 0 if disabled. */
 214         uint64_t rotate_timer_period;
 215         /* Value for size-based rotations, 0 if disabled. */
 216         uint64_t rotate_size;
 217         /*
 218          * Keep a state if this session was rotated after the last stop command.
 219          * We only allow one rotation after a stop. At destroy, we also need to
 220          * know if a rotation occurred since the last stop to rename the current
 221          * chunk.
 222          */
 223         bool rotated_after_last_stop;
 224         /*
 225          * Condition and trigger for size-based rotations.
 226          */
 227         struct lttng_condition *rotate_condition;
 228         struct lttng_trigger *rotate_trigger;
 229         LTTNG_OPTIONAL(uint64_t) last_trace_chunk_id;
 230         struct lttng_trace_chunk *current_trace_chunk;
 231 };
 232
 233 /* Prototypes */
 234 enum lttng_error_code session_create(const char *name, uid_t uid, gid_t gid,
 235                 struct ltt_session **out_session);
 236 void session_lock(struct ltt_session *session);
 237 void session_lock_list(void);
 238 int session_trylock_list(void);
 239 void session_unlock(struct ltt_session *session);
 240 void session_unlock_list(void);
 241
 242 void session_destroy(struct ltt_session *session);
 243
 244 bool session_get(struct ltt_session *session);
 245 void session_put(struct ltt_session *session);
 246
 247 enum consumer_dst_type session_get_consumer_destination_type(
 248                 const struct ltt_session *session);
 249 const char *session_get_net_consumer_hostname(
 250                 const struct ltt_session *session);
 251 void session_get_net_consumer_ports(
 252                 const struct ltt_session *session,
 253                 uint16_t *control_port, uint16_t *data_port);
 254 struct lttng_trace_archive_location *session_get_trace_archive_location(
 255                 struct ltt_session *session);
 256
 257 struct ltt_session *session_find_by_name(const char *name);
 258 struct ltt_session *session_find_by_id(uint64_t id);
 259
 260 struct ltt_session_list *session_get_list(void);
 261 void session_list_wait_empty(void);
 262
 263 int session_access_ok(struct ltt_session *session, uid_t uid, gid_t gid);
 264
 265 int session_reset_rotation_state(struct ltt_session *session,
 266                 enum lttng_rotation_state result);
 267
 268 enum lttng_error_code session_switch_trace_chunk(struct ltt_session *session,
 269                 const char *session_base_path_override,
 270                 const char *chunk_name_override);
 271 int session_set_trace_chunk(struct ltt_session *session,
 272                 struct lttng_trace_chunk *current_trace_chunk);
 273
 274 #endif /* _LTT_SESSION_H */