src/bin/lttng-sessiond/session.hpp

   1 /*
   2  * Copyright (C) 2011 EfficiOS Inc.
   3  *
   4  * SPDX-License-Identifier: GPL-2.0-only
   5  *
   6  */
   7
   8 #ifndef _LTT_SESSION_H
   9 #define _LTT_SESSION_H
  10
  11 #include <limits.h>
  12 #include <stdbool.h>
  13 #include <urcu/list.h>
  14
  15 #include <common/hashtable/hashtable.hpp>
  16 #include <common/dynamic-array.hpp>
  17 #include <common/make-unique-wrapper.hpp>
  18 #include <common/pthread-lock.hpp>
  19 #include <lttng/rotation.h>
  20 #include <lttng/location.h>
  21 #include <lttng/lttng-error.h>
  22
  23 #include "snapshot.hpp"
  24 #include "trace-kernel.hpp"
  25 #include "consumer.hpp"
  26
  27 #define ASSERT_SESSION_LIST_LOCKED() LTTNG_ASSERT(session_trylock_list())
  28
  29 struct ltt_ust_session;
  30
  31 typedef void (*ltt_session_destroy_notifier)(const struct ltt_session *session,
  32                 void *user_data);
  33 typedef void (*ltt_session_clear_notifier)(const struct ltt_session *session,
  34                 void *user_data);
  35
  36 namespace lttng {
  37 namespace sessiond {
  38 namespace details {
  39 void locked_session_release(ltt_session *session);
  40 } /* namespace details */
  41 } /* namespace sessiond */
  42 } /* namespace lttng */
  43
  44 /*
  45  * Tracing session list
  46  *
  47  * Statically declared in session.c and can be accessed by using
  48  * session_get_list() function that returns the pointer to the list.
  49  */
  50 struct ltt_session_list {
  51         /*
  52          * This lock protects any read/write access to the list and
  53          * next_uuid. All public functions in session.c acquire this
  54          * lock and release it before returning. If none of those
  55          * functions are used, the lock MUST be acquired in order to
  56          * iterate or/and do any actions on that list.
  57          */
  58         pthread_mutex_t lock;
  59         /*
  60          * This condition variable is signaled on every removal from
  61          * the session list.
  62          */
  63         pthread_cond_t removal_cond;
  64
  65         /*
  66          * Session unique ID generator. The session list lock MUST be
  67          * upon update and read of this counter.
  68          */
  69         uint64_t next_uuid;
  70
  71         /* Linked list head */
  72         struct cds_list_head head;
  73 };
  74
  75 /*
  76  * This data structure contains information needed to identify a tracing
  77  * session for both LTTng and UST.
  78  */
  79 struct ltt_session {
  80         using id_t = uint64_t;
  81         using locked_ptr = std::unique_ptr<ltt_session,
  82                         lttng::details::create_unique_class<ltt_session,
  83                                         lttng::sessiond::details::locked_session_release>::deleter>;
  84         using sptr = std::shared_ptr<ltt_session>;
  85
  86         char name[NAME_MAX];
  87         bool has_auto_generated_name;
  88         bool name_contains_creation_time;
  89         char hostname[LTTNG_HOST_NAME_MAX]; /* Local hostname. */
  90         /* Path of the last closed chunk. */
  91         char last_chunk_path[LTTNG_PATH_MAX];
  92         time_t creation_time;
  93         struct ltt_kernel_session *kernel_session;
  94         struct ltt_ust_session *ust_session;
  95         struct urcu_ref ref;
  96         /*
  97          * Protect any read/write on this session data structure. This lock must be
  98          * acquired *before* using any public functions declared below. Use
  99          * session_lock() and session_unlock() for that.
 100          */
 101         pthread_mutex_t lock;
 102         struct cds_list_head list;
 103         /* session unique identifier */
 104         id_t id;
 105         /* Indicates if the session has been added to the session list and ht.*/
 106         bool published;
 107         /* Indicates if a destroy command has been applied to this session. */
 108         bool destroyed;
 109         /* UID/GID of the user owning the session */
 110         uid_t uid;
 111         gid_t gid;
 112         /*
 113          * Network session handle. A value of 0 means that there is no remote
 114          * session established.
 115          */
 116         uint64_t net_handle;
 117         /*
 118          * This consumer is only set when the create_session_uri call is made.
 119          * This contains the temporary information for a consumer output. Upon
 120          * creation of the UST or kernel session, this consumer, if available, is
 121          * copied into those sessions.
 122          */
 123         struct consumer_output *consumer;
 124         /*
 125          * Indicates whether or not the user has specified an output directory
 126          * or if it was configured using the default configuration.
 127          */
 128         bool has_user_specified_directory;
 129         /* Did at least ONE start command has been triggered?. */
 130         unsigned int has_been_started:1;
 131         /*
 132          * Is the session active? Start trace command sets this to 1 and the stop
 133          * command reset it to 0.
 134          */
 135         unsigned int active:1;
 136
 137         /* Snapshot representation in a session. */
 138         struct snapshot snapshot;
 139         /* Indicate if the session has to output the traces or not. */
 140         unsigned int output_traces;
 141         /*
 142          * This session is in snapshot mode. This means that channels enabled
 143          * will be set in overwrite mode by default and must be in mmap
 144          * output mode. Note that snapshots can be taken on a session that
 145          * is not in "snapshot_mode". This parameter only affects channel
 146          * creation defaults.
 147          */
 148         unsigned int snapshot_mode;
 149         /*
 150          * A session that has channels that don't use 'mmap' output can't be
 151          * used to capture snapshots. This is set to true whenever a
 152          * 'splice' kernel channel is enabled.
 153          */
 154         bool has_non_mmap_channel;
 155         /*
 156          * Timer set when the session is created for live reading.
 157          */
 158         unsigned int live_timer;
 159         /*
 160          * Path where to keep the shared memory files.
 161          */
 162         char shm_path[PATH_MAX];
 163         /*
 164          * Node in ltt_sessions_ht_by_id.
 165          */
 166         struct lttng_ht_node_u64 node;
 167         /*
 168          * Node in ltt_sessions_ht_by_name.
 169          */
 170         struct lttng_ht_node_str node_by_name;
 171         /*
 172          * Timer to check periodically if a relay and/or consumer has completed
 173          * the last rotation.
 174          */
 175         bool rotation_pending_check_timer_enabled;
 176         timer_t rotation_pending_check_timer;
 177         /* Timer to periodically rotate a session. */
 178         bool rotation_schedule_timer_enabled;
 179         timer_t rotation_schedule_timer;
 180         /* Value for periodic rotations, 0 if disabled. */
 181         uint64_t rotate_timer_period;
 182         /* Value for size-based rotations, 0 if disabled. */
 183         uint64_t rotate_size;
 184         /*
 185          * Keep a state if this session was rotated after the last stop command.
 186          * We only allow one rotation after a stop. At destroy, we also need to
 187          * know if a rotation occurred since the last stop to rename the current
 188          * chunk. After a stop followed by rotate, all subsequent clear
 189          * (without prior start) will succeed, but will be effect-less.
 190          */
 191         bool rotated_after_last_stop;
 192         /*
 193          * Track whether the session was cleared after last stop. All subsequent
 194          * clear (without prior start) will succeed, but will be effect-less. A
 195          * subsequent rotate (without prior start) will return an error.
 196          */
 197         bool cleared_after_last_stop;
 198         /*
 199          * True if the session has had an explicit non-quiet rotation.
 200          */
 201         bool rotated;
 202         /*
 203          * Trigger for size-based rotations.
 204          */
 205         struct lttng_trigger *rotate_trigger;
 206         LTTNG_OPTIONAL(uint64_t) most_recent_chunk_id;
 207         struct lttng_trace_chunk *current_trace_chunk;
 208         struct lttng_trace_chunk *chunk_being_archived;
 209         /* Current state of a rotation. */
 210         enum lttng_rotation_state rotation_state;
 211         bool quiet_rotation;
 212         char *last_archived_chunk_name;
 213         LTTNG_OPTIONAL(uint64_t) last_archived_chunk_id;
 214         struct lttng_dynamic_array destroy_notifiers;
 215         struct lttng_dynamic_array clear_notifiers;
 216         /* Session base path override. Set non-null. */
 217         char *base_path;
 218 };
 219
 220 enum lttng_error_code session_create(const char *name, uid_t uid, gid_t gid,
 221                 struct ltt_session **out_session);
 222 void session_lock(struct ltt_session *session);
 223 void session_unlock(struct ltt_session *session);
 224
 225 /*
 226  * The session list lock covers more ground than its name implies. While
 227  * it does protect against concurent mutations of the session list, it is
 228  * also used as a multi-session lock when synchronizing newly-registered
 229  * 'user space tracer' and 'agent' applications.
 230  *
 231  * In other words, it prevents tracer configurations from changing while they
 232  * are being transmitted to the various applications.
 233  */
 234 void session_lock_list(void);
 235 int session_trylock_list(void);
 236 void session_unlock_list(void);
 237
 238 void session_destroy(struct ltt_session *session);
 239 int session_add_destroy_notifier(struct ltt_session *session,
 240                 ltt_session_destroy_notifier notifier, void *user_data);
 241
 242 int session_add_clear_notifier(struct ltt_session *session,
 243                 ltt_session_clear_notifier notifier, void *user_data);
 244 void session_notify_clear(struct ltt_session *session);
 245
 246 bool session_get(struct ltt_session *session);
 247 void session_put(struct ltt_session *session);
 248
 249 enum consumer_dst_type session_get_consumer_destination_type(
 250                 const struct ltt_session *session);
 251 const char *session_get_net_consumer_hostname(
 252                 const struct ltt_session *session);
 253 void session_get_net_consumer_ports(
 254                 const struct ltt_session *session,
 255                 uint16_t *control_port, uint16_t *data_port);
 256 struct lttng_trace_archive_location *session_get_trace_archive_location(
 257                 const struct ltt_session *session);
 258
 259 struct ltt_session *session_find_by_name(const char *name);
 260 struct ltt_session *session_find_by_id(ltt_session::id_t id);
 261
 262 struct ltt_session_list *session_get_list(void);
 263 void session_list_wait_empty(void);
 264
 265 bool session_access_ok(struct ltt_session *session, uid_t uid);
 266
 267 int session_reset_rotation_state(struct ltt_session *session,
 268                 enum lttng_rotation_state result);
 269
 270 /* Create a new trace chunk object from the session's configuration. */
 271 struct lttng_trace_chunk *session_create_new_trace_chunk(
 272                 const struct ltt_session *session,
 273                 const struct consumer_output *consumer_output_override,
 274                 const char *session_base_path_override,
 275                 const char *chunk_name_override);
 276
 277 /*
 278  * Set `new_trace_chunk` as the session's current trace chunk. A reference
 279  * to `new_trace_chunk` is acquired by the session. The chunk is created
 280  * on remote peers (consumer and relay daemons).
 281  *
 282  * A reference to the session's current trace chunk is returned through
 283  * `current_session_trace_chunk` on success.
 284  */
 285 int session_set_trace_chunk(struct ltt_session *session,
 286                 struct lttng_trace_chunk *new_trace_chunk,
 287                 struct lttng_trace_chunk **current_session_trace_chunk);
 288
 289 /*
 290  * Close a chunk on the remote peers of a session. Has no effect on the
 291  * ltt_session itself.
 292  */
 293 int session_close_trace_chunk(struct ltt_session *session,
 294                 struct lttng_trace_chunk *trace_chunk,
 295                 enum lttng_trace_chunk_command_type close_command,
 296                 char *path);
 297
 298 /* Open a packet in all channels of a given session. */
 299 enum lttng_error_code session_open_packets(struct ltt_session *session);
 300
 301 bool session_output_supports_trace_chunks(const struct ltt_session *session);
 302
 303 /*
 304  * Sample the id of a session looked up via its name.
 305  * Here the term "sampling" hint the caller that this return the id at a given
 306  * point in time with no guarantee that the session for which the id was
 307  * sampled still exist at that point.
 308  *
 309  * Return 0 when the session is not found,
 310  * Return 1 when the session is found and set `id`.
 311  */
 312 bool sample_session_id_by_name(const char *name, uint64_t *id);
 313
 314 namespace lttng {
 315 namespace sessiond {
 316
 317 /*
 318  * Session list lock must be acquired by the caller.
 319  * The caller must not keep the ownership of the returned locked session
 320  * for longer than strictly necessary. If your intention is to acquire
 321  * a reference to an ltt_session, see `find_session_by_id()`.
 322  */
 323 ltt_session::locked_ptr find_locked_session_by_id(ltt_session::id_t id);
 324
 325 /*
 326  * Session list lock must be acquired by the caller.
 327  * The caller must not keep the ownership of the returned locked session
 328  * for longer than strictly necessary. If your intention is to acquire
 329  * a reference to an ltt_session, see `find_session_by_id()`.
 330  */
 331 ltt_session::sptr find_session_by_id(ltt_session::id_t id);
 332
 333 } /* namespace sessiond */
 334 } /* namespace lttng */
 335
 336 #endif /* _LTT_SESSION_H */