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 "consumer.hpp"
  12 #include "snapshot.hpp"
  13 #include "trace-kernel.hpp"
  14
  15 #include <common/dynamic-array.hpp>
  16 #include <common/hashtable/hashtable.hpp>
  17 #include <common/make-unique-wrapper.hpp>
  18 #include <common/pthread-lock.hpp>
  19
  20 #include <lttng/location.h>
  21 #include <lttng/lttng-error.h>
  22 #include <lttng/rotation.h>
  23
  24 #include <condition_variable>
  25 #include <limits.h>
  26 #include <mutex>
  27 #include <stdbool.h>
  28 #include <urcu/list.h>
  29
  30 #define ASSERT_SESSION_LIST_LOCKED() LTTNG_ASSERT(session_trylock_list())
  31
  32 struct ltt_ust_session;
  33
  34 using ltt_session_destroy_notifier = void (*)(const struct ltt_session *, void *);
  35 using ltt_session_clear_notifier = void (*)(const struct ltt_session *, void *);
  36
  37 namespace lttng {
  38 namespace sessiond {
  39 namespace details {
  40 void locked_session_release(ltt_session *session);
  41 } /* namespace details */
  42 } /* namespace sessiond */
  43 } /* namespace lttng */
  44
  45 /*
  46  * Tracing session list
  47  *
  48  * Statically declared in session.c and can be accessed by using
  49  * session_get_list() function that returns the pointer to the list.
  50  */
  51 struct ltt_session_list {
  52         /*
  53          * This lock protects any read/write access to the list and
  54          * next_uuid. All public functions in session.c acquire this
  55          * lock and release it before returning. If none of those
  56          * functions are used, the lock MUST be acquired in order to
  57          * iterate or/and do any actions on that list.
  58          */
  59         std::mutex lock;
  60         /*
  61          * This condition variable is signaled on every removal from
  62          * the session list.
  63          */
  64         std::condition_variable removal_cond;
  65
  66         /*
  67          * Session unique ID generator. The session list lock MUST be
  68          * upon update and read of this counter.
  69          */
  70         uint64_t next_uuid = 0;
  71
  72         /* Linked list head */
  73         struct cds_list_head head = CDS_LIST_HEAD_INIT(head);
  74 };
  75
  76 /*
  77  * This data structure contains information needed to identify a tracing
  78  * session for both LTTng and UST.
  79  */
  80 struct ltt_session {
  81         using id_t = uint64_t;
  82         using locked_ref =
  83                 std::unique_ptr<ltt_session,
  84                                 lttng::memory::create_deleter_class<
  85                                         ltt_session,
  86                                         lttng::sessiond::details::locked_session_release>::deleter>;
  87         using sptr = std::shared_ptr<ltt_session>;
  88
  89         char name[NAME_MAX];
  90         bool has_auto_generated_name;
  91         bool name_contains_creation_time;
  92         char hostname[LTTNG_HOST_NAME_MAX]; /* Local hostname. */
  93         /* Path of the last closed chunk. */
  94         char last_chunk_path[LTTNG_PATH_MAX];
  95         time_t creation_time;
  96         struct ltt_kernel_session *kernel_session;
  97         struct ltt_ust_session *ust_session;
  98         struct urcu_ref ref;
  99         /*
 100          * Protect any read/write on this session data structure. This lock must be
 101          * acquired *before* using any public functions declared below. Use
 102          * session_lock() and session_unlock() for that.
 103          */
 104         pthread_mutex_t lock;
 105         struct cds_list_head list;
 106         /* session unique identifier */
 107         id_t id;
 108         /* Indicates if the session has been added to the session list and ht.*/
 109         bool published;
 110         /* Indicates if a destroy command has been applied to this session. */
 111         bool destroyed;
 112         /* UID/GID of the user owning the session */
 113         uid_t uid;
 114         gid_t gid;
 115         /*
 116          * Network session handle. A value of 0 means that there is no remote
 117          * session established.
 118          */
 119         uint64_t net_handle;
 120         /*
 121          * This consumer is only set when the create_session_uri call is made.
 122          * This contains the temporary information for a consumer output. Upon
 123          * creation of the UST or kernel session, this consumer, if available, is
 124          * copied into those sessions.
 125          */
 126         struct consumer_output *consumer;
 127         /*
 128          * Indicates whether or not the user has specified an output directory
 129          * or if it was configured using the default configuration.
 130          */
 131         bool has_user_specified_directory;
 132         /* Did at least ONE start command has been triggered?. */
 133         bool has_been_started;
 134         /* Is the session active? */
 135         bool active;
 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
 221 session_create(const char *name, uid_t uid, gid_t gid, 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() noexcept;
 235 int session_trylock_list() noexcept;
 236 void session_unlock_list() noexcept;
 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,
 241                                  void *user_data);
 242
 243 int session_add_clear_notifier(struct ltt_session *session,
 244                                ltt_session_clear_notifier notifier,
 245                                void *user_data);
 246 void session_notify_clear(ltt_session& session);
 247
 248 bool session_get(struct ltt_session *session);
 249 void session_put(struct ltt_session *session);
 250
 251 enum consumer_dst_type session_get_consumer_destination_type(const struct ltt_session *session);
 252 const char *session_get_net_consumer_hostname(const struct ltt_session *session);
 253 void session_get_net_consumer_ports(const struct ltt_session *session,
 254                                     uint16_t *control_port,
 255                                     uint16_t *data_port);
 256 struct lttng_trace_archive_location *
 257 session_get_trace_archive_location(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();
 263 void session_list_wait_empty();
 264
 265 bool session_access_ok(struct ltt_session *session, uid_t uid);
 266
 267 int session_reset_rotation_state(ltt_session& session, enum lttng_rotation_state result);
 268
 269 /* Create a new trace chunk object from the session's configuration. */
 270 struct lttng_trace_chunk *
 271 session_create_new_trace_chunk(const struct ltt_session *session,
 272                                const struct consumer_output *consumer_output_override,
 273                                const char *session_base_path_override,
 274                                const char *chunk_name_override);
 275
 276 /*
 277  * Set `new_trace_chunk` as the session's current trace chunk. A reference
 278  * to `new_trace_chunk` is acquired by the session. The chunk is created
 279  * on remote peers (consumer and relay daemons).
 280  *
 281  * A reference to the session's current trace chunk is returned through
 282  * `current_session_trace_chunk` on success.
 283  */
 284 int session_set_trace_chunk(struct ltt_session *session,
 285                             struct lttng_trace_chunk *new_trace_chunk,
 286                             struct lttng_trace_chunk **current_session_trace_chunk);
 287
 288 /*
 289  * Close a chunk on the remote peers of a session. Has no effect on the
 290  * ltt_session itself.
 291  */
 292 int session_close_trace_chunk(struct ltt_session *session,
 293                               struct lttng_trace_chunk *trace_chunk,
 294                               enum lttng_trace_chunk_command_type close_command,
 295                               char *path);
 296
 297 /* Open a packet in all channels of a given session. */
 298 enum lttng_error_code session_open_packets(struct ltt_session *session);
 299
 300 bool session_output_supports_trace_chunks(const struct ltt_session *session);
 301
 302 /*
 303  * Sample the id of a session looked up via its name.
 304  * Here the term "sampling" hint the caller that this return the id at a given
 305  * point in time with no guarantee that the session for which the id was
 306  * sampled still exist at that point.
 307  *
 308  * Return 0 when the session is not found,
 309  * Return 1 when the session is found and set `id`.
 310  */
 311 bool sample_session_id_by_name(const char *name, uint64_t *id);
 312
 313 namespace lttng {
 314 namespace sessiond {
 315
 316 /*
 317  * Session list lock must be acquired by the caller.
 318  * The caller must not keep the ownership of the returned locked session
 319  * for longer than strictly necessary. If your intention is to acquire
 320  * a reference to an ltt_session, see `find_session_by_id()`.
 321  */
 322 ltt_session::locked_ref find_locked_session_by_id(ltt_session::id_t id);
 323
 324 ltt_session::sptr find_session_by_id(ltt_session::id_t id);
 325
 326 } /* namespace sessiond */
 327 } /* namespace lttng */
 328
 329 #endif /* _LTT_SESSION_H */