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         unsigned int has_been_started:1;
 129         /*
 130          * Is the session active? Start trace command sets this to 1 and the stop
 131          * command reset it to 0.
 132          */
 133         unsigned int active:1;
 134
 135         /* Snapshot representation in a session. */
 136         struct snapshot snapshot;
 137         /* Indicate if the session has to output the traces or not. */
 138         unsigned int output_traces;
 139         /*
 140          * This session is in snapshot mode. This means that channels enabled
 141          * will be set in overwrite mode by default and must be in mmap
 142          * output mode. Note that snapshots can be taken on a session that
 143          * is not in "snapshot_mode". This parameter only affects channel
 144          * creation defaults.
 145          */
 146         unsigned int snapshot_mode;
 147         /*
 148          * A session that has channels that don't use 'mmap' output can't be
 149          * used to capture snapshots. This is set to true whenever a
 150          * 'splice' kernel channel is enabled.
 151          */
 152         bool has_non_mmap_channel;
 153         /*
 154          * Timer set when the session is created for live reading.
 155          */
 156         unsigned int live_timer;
 157         /*
 158          * Path where to keep the shared memory files.
 159          */
 160         char shm_path[PATH_MAX];
 161         /*
 162          * Node in ltt_sessions_ht_by_id.
 163          */
 164         struct lttng_ht_node_u64 node;
 165         /*
 166          * Node in ltt_sessions_ht_by_name.
 167          */
 168         struct lttng_ht_node_str node_by_name;
 169         /*
 170          * Timer to check periodically if a relay and/or consumer has completed
 171          * the last rotation.
 172          */
 173         bool rotation_pending_check_timer_enabled;
 174         timer_t rotation_pending_check_timer;
 175         /* Timer to periodically rotate a session. */
 176         bool rotation_schedule_timer_enabled;
 177         timer_t rotation_schedule_timer;
 178         /* Value for periodic rotations, 0 if disabled. */
 179         uint64_t rotate_timer_period;
 180         /* Value for size-based rotations, 0 if disabled. */
 181         uint64_t rotate_size;
 182         /*
 183          * Keep a state if this session was rotated after the last stop command.
 184          * We only allow one rotation after a stop. At destroy, we also need to
 185          * know if a rotation occurred since the last stop to rename the current
 186          * chunk. After a stop followed by rotate, all subsequent clear
 187          * (without prior start) will succeed, but will be effect-less.
 188          */
 189         bool rotated_after_last_stop;
 190         /*
 191          * Track whether the session was cleared after last stop. All subsequent
 192          * clear (without prior start) will succeed, but will be effect-less. A
 193          * subsequent rotate (without prior start) will return an error.
 194          */
 195         bool cleared_after_last_stop;
 196         /*
 197          * True if the session has had an explicit non-quiet rotation.
 198          */
 199         bool rotated;
 200         /*
 201          * Trigger for size-based rotations.
 202          */
 203         struct lttng_trigger *rotate_trigger;
 204         LTTNG_OPTIONAL(uint64_t) most_recent_chunk_id;
 205         struct lttng_trace_chunk *current_trace_chunk;
 206         struct lttng_trace_chunk *chunk_being_archived;
 207         /* Current state of a rotation. */
 208         enum lttng_rotation_state rotation_state;
 209         bool quiet_rotation;
 210         char *last_archived_chunk_name;
 211         LTTNG_OPTIONAL(uint64_t) last_archived_chunk_id;
 212         struct lttng_dynamic_array destroy_notifiers;
 213         struct lttng_dynamic_array clear_notifiers;
 214         /* Session base path override. Set non-null. */
 215         char *base_path;
 216 };
 217
 218 enum lttng_error_code session_create(const char *name, uid_t uid, gid_t gid,
 219                 struct ltt_session **out_session);
 220 void session_lock(struct ltt_session *session);
 221 void session_unlock(struct ltt_session *session);
 222
 223 /*
 224  * The session list lock covers more ground than its name implies. While
 225  * it does protect against concurent mutations of the session list, it is
 226  * also used as a multi-session lock when synchronizing newly-registered
 227  * 'user space tracer' and 'agent' applications.
 228  *
 229  * In other words, it prevents tracer configurations from changing while they
 230  * are being transmitted to the various applications.
 231  */
 232 void session_lock_list();
 233 int session_trylock_list();
 234 void session_unlock_list();
 235
 236 void session_destroy(struct ltt_session *session);
 237 int session_add_destroy_notifier(struct ltt_session *session,
 238                 ltt_session_destroy_notifier notifier, void *user_data);
 239
 240 int session_add_clear_notifier(struct ltt_session *session,
 241                 ltt_session_clear_notifier notifier, void *user_data);
 242 void session_notify_clear(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                 const struct ltt_session *session);
 256
 257 struct ltt_session *session_find_by_name(const char *name);
 258 struct ltt_session *session_find_by_id(ltt_session::id_t id);
 259
 260 struct ltt_session_list *session_get_list();
 261 void session_list_wait_empty();
 262
 263 bool session_access_ok(struct ltt_session *session, uid_t uid);
 264
 265 int session_reset_rotation_state(struct ltt_session *session,
 266                 enum lttng_rotation_state result);
 267
 268 /* Create a new trace chunk object from the session's configuration. */
 269 struct lttng_trace_chunk *session_create_new_trace_chunk(
 270                 const struct ltt_session *session,
 271                 const struct consumer_output *consumer_output_override,
 272                 const char *session_base_path_override,
 273                 const char *chunk_name_override);
 274
 275 /*
 276  * Set `new_trace_chunk` as the session's current trace chunk. A reference
 277  * to `new_trace_chunk` is acquired by the session. The chunk is created
 278  * on remote peers (consumer and relay daemons).
 279  *
 280  * A reference to the session's current trace chunk is returned through
 281  * `current_session_trace_chunk` on success.
 282  */
 283 int session_set_trace_chunk(struct ltt_session *session,
 284                 struct lttng_trace_chunk *new_trace_chunk,
 285                 struct lttng_trace_chunk **current_session_trace_chunk);
 286
 287 /*
 288  * Close a chunk on the remote peers of a session. Has no effect on the
 289  * ltt_session itself.
 290  */
 291 int session_close_trace_chunk(struct ltt_session *session,
 292                 struct lttng_trace_chunk *trace_chunk,
 293                 enum lttng_trace_chunk_command_type close_command,
 294                 char *path);
 295
 296 /* Open a packet in all channels of a given session. */
 297 enum lttng_error_code session_open_packets(struct ltt_session *session);
 298
 299 bool session_output_supports_trace_chunks(const struct ltt_session *session);
 300
 301 /*
 302  * Sample the id of a session looked up via its name.
 303  * Here the term "sampling" hint the caller that this return the id at a given
 304  * point in time with no guarantee that the session for which the id was
 305  * sampled still exist at that point.
 306  *
 307  * Return 0 when the session is not found,
 308  * Return 1 when the session is found and set `id`.
 309  */
 310 bool sample_session_id_by_name(const char *name, uint64_t *id);
 311
 312 namespace lttng {
 313 namespace sessiond {
 314
 315 /*
 316  * Session list lock must be acquired by the caller.
 317  * The caller must not keep the ownership of the returned locked session
 318  * for longer than strictly necessary. If your intention is to acquire
 319  * a reference to an ltt_session, see `find_session_by_id()`.
 320  */
 321 ltt_session::locked_ptr find_locked_session_by_id(ltt_session::id_t id);
 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::sptr find_session_by_id(ltt_session::id_t id);
 330
 331 } /* namespace sessiond */
 332 } /* namespace lttng */
 333
 334 #endif /* _LTT_SESSION_H */