src/bin/lttng-sessiond/session.h

   1 /*
   2  * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License, version 2 only,
   6  * as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along
  14  * with this program; if not, write to the Free Software Foundation, Inc.,
  15  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  16  */
  17
  18 #ifndef _LTT_SESSION_H
  19 #define _LTT_SESSION_H
  20
  21 #include <limits.h>
  22 #include <stdbool.h>
  23 #include <urcu/list.h>
  24
  25 #include <common/hashtable/hashtable.h>
  26 #include <lttng/rotation.h>
  27
  28 #include "snapshot.h"
  29 #include "trace-kernel.h"
  30 #include "consumer.h"
  31
  32 struct ltt_ust_session;
  33
  34 /*
  35  * Tracing session list
  36  *
  37  * Statically declared in session.c and can be accessed by using
  38  * session_get_list() function that returns the pointer to the list.
  39  */
  40 struct ltt_session_list {
  41         /*
  42          * This lock protects any read/write access to the list and
  43          * next_uuid. All public functions in session.c acquire this
  44          * lock and release it before returning. If none of those
  45          * functions are used, the lock MUST be acquired in order to
  46          * iterate or/and do any actions on that list.
  47          */
  48         pthread_mutex_t lock;
  49
  50         /*
  51          * Session unique ID generator. The session list lock MUST be
  52          * upon update and read of this counter.
  53          */
  54         uint64_t next_uuid;
  55
  56         /* Linked list head */
  57         struct cds_list_head head;
  58 };
  59
  60 /*
  61  * This data structure contains information needed to identify a tracing
  62  * session for both LTTng and UST.
  63  */
  64 struct ltt_session {
  65         char name[NAME_MAX];
  66         char hostname[HOST_NAME_MAX]; /* Local hostname. */
  67         struct ltt_kernel_session *kernel_session;
  68         struct ltt_ust_session *ust_session;
  69         /*
  70          * Protect any read/write on this session data structure. This lock must be
  71          * acquired *before* using any public functions declared below. Use
  72          * session_lock() and session_unlock() for that.
  73          */
  74         pthread_mutex_t lock;
  75         struct cds_list_head list;
  76         uint64_t id;            /* session unique identifier */
  77         /* UID/GID of the user owning the session */
  78         uid_t uid;
  79         gid_t gid;
  80         /*
  81          * Network session handle. A value of 0 means that there is no remote
  82          * session established.
  83          */
  84         uint64_t net_handle;
  85         /*
  86          * This consumer is only set when the create_session_uri call is made.
  87          * This contains the temporary information for a consumer output. Upon
  88          * creation of the UST or kernel session, this consumer, if available, is
  89          * copied into those sessions.
  90          */
  91         struct consumer_output *consumer;
  92
  93         /* Did at least ONE start command has been triggered?. */
  94         unsigned int has_been_started:1;
  95         /*
  96          * Is the session active? Start trace command sets this to 1 and the stop
  97          * command reset it to 0.
  98          */
  99         unsigned int active:1;
 100
 101         /* Snapshot representation in a session. */
 102         struct snapshot snapshot;
 103         /* Indicate if the session has to output the traces or not. */
 104         unsigned int output_traces;
 105         /*
 106          * This session is in snapshot mode. This means that every channel enabled
 107          * will be set in overwrite mode and mmap. It is considered exclusively for
 108          * snapshot purposes.
 109          */
 110         unsigned int snapshot_mode;
 111         /*
 112          * Timer set when the session is created for live reading.
 113          */
 114         unsigned int live_timer;
 115         /*
 116          * Path where to keep the shared memory files.
 117          */
 118         char shm_path[PATH_MAX];
 119         /*
 120          * Node in ltt_sessions_ht_by_id.
 121          */
 122         struct lttng_ht_node_u64 node;
 123         /*
 124          * The current archive id corresponds to the number of session rotations
 125          * that have occured for this session. The archive id
 126          * is used to tag the "generation" of a stream. This tag allows the
 127          * consumer and relay daemons to track when a given stream was created
 128          * during the lifetime of a session.
 129          *
 130          * For instance, if a stream is created after a session rotation was
 131          * launched, the consumer and relay daemons must not check its position
 132          * to determine if that specific session rotation was completed. It is
 133          * implicitly "completed" since the stream appeared _after_ the session
 134          * rotation was initiated.
 135          */
 136         uint64_t current_archive_id;
 137         /*
 138          * Rotation is pending between the time it starts until the consumer has
 139          * finished extracting the data. If the session uses a relay, data related
 140          * to a rotation can still be in flight after that, see
 141          * rotate_pending_relay.
 142          */
 143         bool rotate_pending;
 144         /*
 145          * True until the relay has finished the rotation of all the streams.
 146          */
 147         bool rotate_pending_relay;
 148         /* Current state of a rotation. */
 149         enum lttng_rotation_state rotation_state;
 150         /*
 151          * Number of channels waiting for a rotation.
 152          * When this number reaches 0, we can handle the rename of the chunk
 153          * folder and inform the client that the rotate is finished.
 154          */
 155         unsigned int nr_chan_rotate_pending;
 156         struct {
 157                 /*
 158                  * When the rotation is in progress, the temporary path name is
 159                  * stored here. When the rotation is complete, the final path name
 160                  * is here and can be queried with the rotate_pending call.
 161                  */
 162                 char current_rotate_path[LTTNG_PATH_MAX];
 163                 /*
 164                  * The path where the consumer is currently writing after the first
 165                  * session rotation.
 166                  */
 167                 char active_tracing_path[LTTNG_PATH_MAX];
 168         } rotation_chunk;
 169         /*
 170          * The timestamp of the beginning of the previous chunk. For the
 171          * first chunk, this is the "lttng start" timestamp. For the
 172          * subsequent ones, this copies the current_chunk_start_ts value when
 173          * a new rotation starts. This value is used to set the name of a
 174          * complete chunk directory, ex: "last_chunk_start_ts-now()".
 175          */
 176         time_t last_chunk_start_ts;
 177         /*
 178          * This is the timestamp when a new chunk starts. When a new rotation
 179          * starts, we copy this value to last_chunk_start_ts and replace it
 180          * with the current timestamp.
 181          */
 182         time_t current_chunk_start_ts;
 183         /*
 184          * Timer to check periodically if a relay has completed the last
 185          * rotation.
 186          */
 187         bool rotate_relay_pending_timer_enabled;
 188         timer_t rotate_relay_pending_timer;
 189         /* Timer to periodically rotate a session. */
 190         bool rotate_timer_enabled;
 191         timer_t rotate_timer;
 192         /* Value for periodic rotations, 0 if disabled. */
 193         uint64_t rotate_timer_period;
 194         /* Value for size-based rotations, 0 if disabled. */
 195         uint64_t rotate_size;
 196         /*
 197          * Keep a state if this session was rotated after the last stop command.
 198          * We only allow one rotation after a stop. At destroy, we also need to
 199          * know if a rotation occured since the last stop to rename the current
 200          * chunk.
 201          */
 202         bool rotated_after_last_stop;
 203         /*
 204          * Condition and trigger for size-based rotations.
 205          */
 206         struct lttng_condition *rotate_condition;
 207         struct lttng_trigger *rotate_trigger;
 208 };
 209
 210 /* Prototypes */
 211 int session_create(char *name, uid_t uid, gid_t gid);
 212 int session_destroy(struct ltt_session *session);
 213
 214 void session_lock(struct ltt_session *session);
 215 void session_lock_list(void);
 216 int session_trylock_list(void);
 217 void session_unlock(struct ltt_session *session);
 218 void session_unlock_list(void);
 219
 220 enum consumer_dst_type session_get_consumer_destination_type(
 221                 const struct ltt_session *session);
 222 const char *session_get_net_consumer_hostname(
 223                 const struct ltt_session *session);
 224 void session_get_net_consumer_ports(
 225                 const struct ltt_session *session,
 226                 uint16_t *control_port, uint16_t *data_port);
 227
 228 struct ltt_session *session_find_by_name(const char *name);
 229 struct ltt_session *session_find_by_id(uint64_t id);
 230 struct ltt_session_list *session_get_list(void);
 231
 232 int session_access_ok(struct ltt_session *session, uid_t uid, gid_t gid);
 233
 234 #endif /* _LTT_SESSION_H */