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         ltt_session()
  87         {
  88                 has_been_started = 0;
  89                 active = 0;
  90         };
  91         ~ltt_session() = default;
  92
  93         char name[NAME_MAX]{0};
  94         bool has_auto_generated_name{false};
  95         bool name_contains_creation_time{false};
  96         char hostname[LTTNG_HOST_NAME_MAX]{0}; /* Local hostname. */
  97         /* Path of the last closed chunk. */
  98         char last_chunk_path[LTTNG_PATH_MAX]{0};
  99         time_t creation_time{};
 100         struct ltt_kernel_session *kernel_session{};
 101         struct ltt_ust_session *ust_session{};
 102         struct urcu_ref ref {};
 103         /*
 104          * Protect any read/write on this session data structure. This lock must be
 105          * acquired *before* using any public functions declared below. Use
 106          * session_lock() and session_unlock() for that.
 107          */
 108         pthread_mutex_t lock{};
 109         struct cds_list_head list {};
 110         id_t id{}; /* session unique identifier */
 111         /* Indicates if the session has been added to the session list and ht.*/
 112         bool published{false};
 113         /* Indicates if a destroy command has been applied to this session. */
 114         bool destroyed{false};
 115         /* UID/GID of the user owning the session */
 116         uid_t uid{};
 117         gid_t gid{};
 118         /*
 119          * Network session handle. A value of 0 means that there is no remote
 120          * session established.
 121          */
 122         uint64_t net_handle{};
 123         /*
 124          * This consumer is only set when the create_session_uri call is made.
 125          * This contains the temporary information for a consumer output. Upon
 126          * creation of the UST or kernel session, this consumer, if available, is
 127          * copied into those sessions.
 128          */
 129         struct consumer_output *consumer{};
 130         /*
 131          * Indicates whether or not the user has specified an output directory
 132          * or if it was configured using the default configuration.
 133          */
 134         bool has_user_specified_directory{false};
 135         /* Did at least ONE start command has been triggered?. */
 136         bool has_been_started{false};
 137         /*
 138          * Is the session active? Start trace command sets this to true and the stop
 139          * command reset it to false.
 140          */
 141         bool active{false};
 142
 143         /* Snapshot representation in a session. */
 144         struct snapshot snapshot {};
 145         /* Indicate if the session has to output the traces or not. */
 146         unsigned int output_traces{};
 147         /*
 148          * This session is in snapshot mode. This means that channels enabled
 149          * will be set in overwrite mode by default and must be in mmap
 150          * output mode. Note that snapshots can be taken on a session that
 151          * is not in "snapshot_mode". This parameter only affects channel
 152          * creation defaults.
 153          */
 154         unsigned int snapshot_mode{};
 155         /*
 156          * A session that has channels that don't use 'mmap' output can't be
 157          * used to capture snapshots. This is set to true whenever a
 158          * 'splice' kernel channel is enabled.
 159          */
 160         bool has_non_mmap_channel{false};
 161         /*
 162          * Timer set when the session is created for live reading.
 163          */
 164         unsigned int live_timer{0};
 165         /*
 166          * Path where to keep the shared memory files.
 167          */
 168         char shm_path[PATH_MAX]{};
 169         /*
 170          * Node in ltt_sessions_ht_by_id.
 171          */
 172         struct lttng_ht_node_u64 node {};
 173         /*
 174          * Node in ltt_sessions_ht_by_name.
 175          */
 176         struct lttng_ht_node_str node_by_name {};
 177         /*
 178          * Timer to check periodically if a relay and/or consumer has completed
 179          * the last rotation.
 180          */
 181         bool rotation_pending_check_timer_enabled{false};
 182         timer_t rotation_pending_check_timer{};
 183         /* Timer to periodically rotate a session. */
 184         bool rotation_schedule_timer_enabled{false};
 185         timer_t rotation_schedule_timer{};
 186         /* Value for periodic rotations, 0 if disabled. */
 187         uint64_t rotate_timer_period{};
 188         /* Value for size-based rotations, 0 if disabled. */
 189         uint64_t rotate_size{};
 190         /*
 191          * Keep a state if this session was rotated after the last stop command.
 192          * We only allow one rotation after a stop. At destroy, we also need to
 193          * know if a rotation occurred since the last stop to rename the current
 194          * chunk. After a stop followed by rotate, all subsequent clear
 195          * (without prior start) will succeed, but will be effect-less.
 196          */
 197         bool rotated_after_last_stop{false};
 198         /*
 199          * Track whether the session was cleared after last stop. All subsequent
 200          * clear (without prior start) will succeed, but will be effect-less. A
 201          * subsequent rotate (without prior start) will return an error.
 202          */
 203         bool cleared_after_last_stop{false};
 204         /*
 205          * True if the session has had an explicit non-quiet rotation.
 206          */
 207         bool rotated{false};
 208         /*
 209          * Trigger for size-based rotations.
 210          */
 211         struct lttng_trigger *rotate_trigger{};
 212         LTTNG_OPTIONAL(uint64_t) most_recent_chunk_id{};
 213         struct lttng_trace_chunk *current_trace_chunk{};
 214         struct lttng_trace_chunk *chunk_being_archived{};
 215         /* Current state of a rotation. */
 216         enum lttng_rotation_state rotation_state { LTTNG_ROTATION_STATE_NO_ROTATION };
 217         bool quiet_rotation{false};
 218         char *last_archived_chunk_name{};
 219         LTTNG_OPTIONAL(uint64_t) last_archived_chunk_id{};
 220         struct lttng_dynamic_array destroy_notifiers {};
 221         struct lttng_dynamic_array clear_notifiers {};
 222         /* Session base path override. Set non-null. */
 223         char *base_path{};
 224 };
 225
 226 enum lttng_error_code session_create(const char *name, uid_t uid, gid_t gid,
 227                 struct ltt_session **out_session);
 228 void session_lock(struct ltt_session *session);
 229 void session_unlock(struct ltt_session *session);
 230
 231 /*
 232  * The session list lock covers more ground than its name implies. While
 233  * it does protect against concurent mutations of the session list, it is
 234  * also used as a multi-session lock when synchronizing newly-registered
 235  * 'user space tracer' and 'agent' applications.
 236  *
 237  * In other words, it prevents tracer configurations from changing while they
 238  * are being transmitted to the various applications.
 239  */
 240 void session_lock_list(void);
 241 int session_trylock_list(void);
 242 void session_unlock_list(void);
 243
 244 void session_destroy(struct ltt_session *session);
 245 int session_add_destroy_notifier(struct ltt_session *session,
 246                 ltt_session_destroy_notifier notifier, void *user_data);
 247
 248 int session_add_clear_notifier(struct ltt_session *session,
 249                 ltt_session_clear_notifier notifier, void *user_data);
 250 void session_notify_clear(struct ltt_session *session);
 251
 252 bool session_get(struct ltt_session *session);
 253 void session_put(struct ltt_session *session);
 254
 255 enum consumer_dst_type session_get_consumer_destination_type(
 256                 const struct ltt_session *session);
 257 const char *session_get_net_consumer_hostname(
 258                 const struct ltt_session *session);
 259 void session_get_net_consumer_ports(
 260                 const struct ltt_session *session,
 261                 uint16_t *control_port, uint16_t *data_port);
 262 struct lttng_trace_archive_location *session_get_trace_archive_location(
 263                 const struct ltt_session *session);
 264
 265 struct ltt_session *session_find_by_name(const char *name);
 266 struct ltt_session *session_find_by_id(ltt_session::id_t id);
 267
 268 struct ltt_session_list *session_get_list(void);
 269 void session_list_wait_empty(void);
 270
 271 bool session_access_ok(struct ltt_session *session, uid_t uid);
 272
 273 int session_reset_rotation_state(struct ltt_session *session,
 274                 enum lttng_rotation_state result);
 275
 276 /* Create a new trace chunk object from the session's configuration. */
 277 struct lttng_trace_chunk *session_create_new_trace_chunk(
 278                 const struct ltt_session *session,
 279                 const struct consumer_output *consumer_output_override,
 280                 const char *session_base_path_override,
 281                 const char *chunk_name_override);
 282
 283 /*
 284  * Set `new_trace_chunk` as the session's current trace chunk. A reference
 285  * to `new_trace_chunk` is acquired by the session. The chunk is created
 286  * on remote peers (consumer and relay daemons).
 287  *
 288  * A reference to the session's current trace chunk is returned through
 289  * `current_session_trace_chunk` on success.
 290  */
 291 int session_set_trace_chunk(struct ltt_session *session,
 292                 struct lttng_trace_chunk *new_trace_chunk,
 293                 struct lttng_trace_chunk **current_session_trace_chunk);
 294
 295 /*
 296  * Close a chunk on the remote peers of a session. Has no effect on the
 297  * ltt_session itself.
 298  */
 299 int session_close_trace_chunk(struct ltt_session *session,
 300                 struct lttng_trace_chunk *trace_chunk,
 301                 enum lttng_trace_chunk_command_type close_command,
 302                 char *path);
 303
 304 /* Open a packet in all channels of a given session. */
 305 enum lttng_error_code session_open_packets(struct ltt_session *session);
 306
 307 bool session_output_supports_trace_chunks(const struct ltt_session *session);
 308
 309 /*
 310  * Sample the id of a session looked up via its name.
 311  * Here the term "sampling" hint the caller that this return the id at a given
 312  * point in time with no guarantee that the session for which the id was
 313  * sampled still exist at that point.
 314  *
 315  * Return 0 when the session is not found,
 316  * Return 1 when the session is found and set `id`.
 317  */
 318 bool sample_session_id_by_name(const char *name, uint64_t *id);
 319
 320 namespace lttng {
 321 namespace sessiond {
 322
 323 /*
 324  * Session list lock must be acquired by the caller.
 325  * The caller must not keep the ownership of the returned locked session
 326  * for longer than strictly necessary. If your intention is to acquire
 327  * a reference to an ltt_session, see `find_session_by_id()`.
 328  */
 329 ltt_session::locked_ptr find_locked_session_by_id(ltt_session::id_t id);
 330
 331 /*
 332  * Session list lock must be acquired by the caller.
 333  * The caller must not keep the ownership of the returned locked session
 334  * for longer than strictly necessary. If your intention is to acquire
 335  * a reference to an ltt_session, see `find_session_by_id()`.
 336  */
 337 ltt_session::sptr find_session_by_id(ltt_session::id_t id);
 338
 339 } /* namespace sessiond */
 340 } /* namespace lttng */
 341
 342 #endif /* _LTT_SESSION_H */