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