Docs: clarify the meaning of the snapshot_mode flag in ltt_session
[lttng-tools.git] / 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 #include <lttng/location.h>
28
29 #include "snapshot.h"
30 #include "trace-kernel.h"
31 #include "consumer.h"
32
33 struct ltt_ust_session;
34
35 /*
36 * Tracing session list
37 *
38 * Statically declared in session.c and can be accessed by using
39 * session_get_list() function that returns the pointer to the list.
40 */
41 struct ltt_session_list {
42 /*
43 * This lock protects any read/write access to the list and
44 * next_uuid. All public functions in session.c acquire this
45 * lock and release it before returning. If none of those
46 * functions are used, the lock MUST be acquired in order to
47 * iterate or/and do any actions on that list.
48 */
49 pthread_mutex_t lock;
50 /*
51 * This condition variable is signaled on every removal from
52 * the session list.
53 */
54 pthread_cond_t removal_cond;
55
56 /*
57 * Session unique ID generator. The session list lock MUST be
58 * upon update and read of this counter.
59 */
60 uint64_t next_uuid;
61
62 /* Linked list head */
63 struct cds_list_head head;
64 };
65
66 /*
67 * This data structure contains information needed to identify a tracing
68 * session for both LTTng and UST.
69 */
70 struct ltt_session {
71 char name[NAME_MAX];
72 char hostname[HOST_NAME_MAX]; /* Local hostname. */
73 struct ltt_kernel_session *kernel_session;
74 struct ltt_ust_session *ust_session;
75 struct urcu_ref ref;
76 /*
77 * Protect any read/write on this session data structure. This lock must be
78 * acquired *before* using any public functions declared below. Use
79 * session_lock() and session_unlock() for that.
80 */
81 pthread_mutex_t lock;
82 struct cds_list_head list;
83 uint64_t id; /* session unique identifier */
84 /* Indicates if the session has been added to the session list and ht.*/
85 bool published;
86 /* Indicates if a destroy command has been applied to this session. */
87 bool destroyed;
88 /* UID/GID of the user owning the session */
89 uid_t uid;
90 gid_t gid;
91 /*
92 * Network session handle. A value of 0 means that there is no remote
93 * session established.
94 */
95 uint64_t net_handle;
96 /*
97 * This consumer is only set when the create_session_uri call is made.
98 * This contains the temporary information for a consumer output. Upon
99 * creation of the UST or kernel session, this consumer, if available, is
100 * copied into those sessions.
101 */
102 struct consumer_output *consumer;
103
104 /* Did at least ONE start command has been triggered?. */
105 unsigned int has_been_started:1;
106 /*
107 * Is the session active? Start trace command sets this to 1 and the stop
108 * command reset it to 0.
109 */
110 unsigned int active:1;
111
112 /* Snapshot representation in a session. */
113 struct snapshot snapshot;
114 /* Indicate if the session has to output the traces or not. */
115 unsigned int output_traces;
116 /*
117 * This session is in snapshot mode. This means that channels enabled
118 * will be set in overwrite mode by default and must be in mmap
119 * output mode. Note that snapshots can be taken on a session that
120 * is not in "snapshot_mode". This parameter only affects channel
121 * creation defaults.
122 */
123 unsigned int snapshot_mode;
124 /*
125 * Timer set when the session is created for live reading.
126 */
127 unsigned int live_timer;
128 /*
129 * Path where to keep the shared memory files.
130 */
131 char shm_path[PATH_MAX];
132 /*
133 * Node in ltt_sessions_ht_by_id.
134 */
135 struct lttng_ht_node_u64 node;
136 /*
137 * The current archive id corresponds to the number of session rotations
138 * that have occurred for this session. The archive id
139 * is used to tag the "generation" of a stream. This tag allows the
140 * consumer and relay daemons to track when a given stream was created
141 * during the lifetime of a session.
142 *
143 * For instance, if a stream is created after a session rotation was
144 * launched, the consumer and relay daemons must not check its position
145 * to determine if that specific session rotation was completed. It is
146 * implicitly "completed" since the stream appeared _after_ the session
147 * rotation was initiated.
148 */
149 uint64_t current_archive_id;
150 /*
151 * Rotation is considered pending between the time it is launched up
152 * until the moment when the data has been writen at the destination
153 * and the trace archive has been renamed.
154 *
155 * When tracing locally, only 'rotation_pending_local' is used since
156 * no remote checks are needed. However, when tracing to a relay daemon,
157 * a second check is needed to ensure that the data has been
158 * commited at the remote destination.
159 */
160 bool rotation_pending_local;
161 bool rotation_pending_relay;
162 /* Current state of a rotation. */
163 enum lttng_rotation_state rotation_state;
164 struct {
165 /*
166 * When the rotation is in progress, the temporary path name is
167 * stored here. When the rotation is complete, the final path name
168 * is here and can be queried with the rotate_pending call.
169 */
170 char current_rotate_path[LTTNG_PATH_MAX];
171 /*
172 * The path where the consumer is currently writing after the first
173 * session rotation.
174 */
175 char active_tracing_path[LTTNG_PATH_MAX];
176 } rotation_chunk;
177 /*
178 * The timestamp of the beginning of the previous chunk. For the
179 * first chunk, this is the "lttng start" timestamp. For the
180 * subsequent ones, this copies the current_chunk_start_ts value when
181 * a new rotation starts. This value is used to set the name of a
182 * complete chunk directory, ex: "last_chunk_start_ts-now()".
183 */
184 time_t last_chunk_start_ts;
185 /*
186 * This is the timestamp when a new chunk starts. When a new rotation
187 * starts, we copy this value to last_chunk_start_ts and replace it
188 * with the current timestamp.
189 */
190 time_t current_chunk_start_ts;
191 /*
192 * Timer to check periodically if a relay and/or consumer has completed
193 * the last rotation.
194 */
195 bool rotation_pending_check_timer_enabled;
196 timer_t rotation_pending_check_timer;
197 /* Timer to periodically rotate a session. */
198 bool rotation_schedule_timer_enabled;
199 timer_t rotation_schedule_timer;
200 /* Value for periodic rotations, 0 if disabled. */
201 uint64_t rotate_timer_period;
202 /* Value for size-based rotations, 0 if disabled. */
203 uint64_t rotate_size;
204 /*
205 * Keep a state if this session was rotated after the last stop command.
206 * We only allow one rotation after a stop. At destroy, we also need to
207 * know if a rotation occurred since the last stop to rename the current
208 * chunk.
209 */
210 bool rotated_after_last_stop;
211 /*
212 * Condition and trigger for size-based rotations.
213 */
214 struct lttng_condition *rotate_condition;
215 struct lttng_trigger *rotate_trigger;
216 };
217
218 /* Prototypes */
219 int session_create(char *name, uid_t uid, gid_t gid);
220
221 void session_lock(struct ltt_session *session);
222 void session_lock_list(void);
223 int session_trylock_list(void);
224 void session_unlock(struct ltt_session *session);
225 void session_unlock_list(void);
226
227 void session_destroy(struct ltt_session *session);
228
229 bool session_get(struct ltt_session *session);
230 void session_put(struct ltt_session *session);
231
232 enum consumer_dst_type session_get_consumer_destination_type(
233 const struct ltt_session *session);
234 const char *session_get_net_consumer_hostname(
235 const struct ltt_session *session);
236 void session_get_net_consumer_ports(
237 const struct ltt_session *session,
238 uint16_t *control_port, uint16_t *data_port);
239 struct lttng_trace_archive_location *session_get_trace_archive_location(
240 struct ltt_session *session);
241
242 struct ltt_session *session_find_by_name(const char *name);
243 struct ltt_session *session_find_by_id(uint64_t id);
244
245 struct ltt_session_list *session_get_list(void);
246 void session_list_wait_empty(void);
247
248 int session_access_ok(struct ltt_session *session, uid_t uid, gid_t gid);
249
250 int session_reset_rotation_state(struct ltt_session *session,
251 enum lttng_rotation_state result);
252
253 #endif /* _LTT_SESSION_H */
This page took 0.050085 seconds and 4 git commands to generate.