6a059798d925afbd681f07a898f866e7dc8374f2
[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 /*
52 * Session unique ID generator. The session list lock MUST be
53 * upon update and read of this counter.
54 */
55 uint64_t next_uuid;
56
57 /* Linked list head */
58 struct cds_list_head head;
59 };
60
61 /*
62 * This data structure contains information needed to identify a tracing
63 * session for both LTTng and UST.
64 */
65 struct ltt_session {
66 char name[NAME_MAX];
67 char hostname[HOST_NAME_MAX]; /* Local hostname. */
68 struct ltt_kernel_session *kernel_session;
69 struct ltt_ust_session *ust_session;
70 struct urcu_ref ref;
71 /*
72 * Protect any read/write on this session data structure. This lock must be
73 * acquired *before* using any public functions declared below. Use
74 * session_lock() and session_unlock() for that.
75 */
76 pthread_mutex_t lock;
77 struct cds_list_head list;
78 uint64_t id; /* session unique identifier */
79 /* Indicates if a destroy command has been applied to this session. */
80 bool destroyed;
81 /* UID/GID of the user owning the session */
82 uid_t uid;
83 gid_t gid;
84 /*
85 * Network session handle. A value of 0 means that there is no remote
86 * session established.
87 */
88 uint64_t net_handle;
89 /*
90 * This consumer is only set when the create_session_uri call is made.
91 * This contains the temporary information for a consumer output. Upon
92 * creation of the UST or kernel session, this consumer, if available, is
93 * copied into those sessions.
94 */
95 struct consumer_output *consumer;
96
97 /* Did at least ONE start command has been triggered?. */
98 unsigned int has_been_started:1;
99 /*
100 * Is the session active? Start trace command sets this to 1 and the stop
101 * command reset it to 0.
102 */
103 unsigned int active:1;
104
105 /* Snapshot representation in a session. */
106 struct snapshot snapshot;
107 /* Indicate if the session has to output the traces or not. */
108 unsigned int output_traces;
109 /*
110 * This session is in snapshot mode. This means that every channel enabled
111 * will be set in overwrite mode and mmap. It is considered exclusively for
112 * snapshot purposes.
113 */
114 unsigned int snapshot_mode;
115 /*
116 * Timer set when the session is created for live reading.
117 */
118 unsigned int live_timer;
119 /*
120 * Path where to keep the shared memory files.
121 */
122 char shm_path[PATH_MAX];
123 /*
124 * Node in ltt_sessions_ht_by_id.
125 */
126 struct lttng_ht_node_u64 node;
127 /*
128 * The current archive id corresponds to the number of session rotations
129 * that have occurred for this session. The archive id
130 * is used to tag the "generation" of a stream. This tag allows the
131 * consumer and relay daemons to track when a given stream was created
132 * during the lifetime of a session.
133 *
134 * For instance, if a stream is created after a session rotation was
135 * launched, the consumer and relay daemons must not check its position
136 * to determine if that specific session rotation was completed. It is
137 * implicitly "completed" since the stream appeared _after_ the session
138 * rotation was initiated.
139 */
140 uint64_t current_archive_id;
141 /*
142 * Rotation is considered pending between the time it is launched up
143 * until the moment when the data has been writen at the destination
144 * and the trace archive has been renamed.
145 *
146 * When tracing locally, only 'rotation_pending_local' is used since
147 * no remote checks are needed. However, when tracing to a relay daemon,
148 * a second check is needed to ensure that the data has been
149 * commited at the remote destination.
150 */
151 bool rotation_pending_local;
152 bool rotation_pending_relay;
153 /* Current state of a rotation. */
154 enum lttng_rotation_state rotation_state;
155 struct {
156 /*
157 * When the rotation is in progress, the temporary path name is
158 * stored here. When the rotation is complete, the final path name
159 * is here and can be queried with the rotate_pending call.
160 */
161 char current_rotate_path[LTTNG_PATH_MAX];
162 /*
163 * The path where the consumer is currently writing after the first
164 * session rotation.
165 */
166 char active_tracing_path[LTTNG_PATH_MAX];
167 } rotation_chunk;
168 /*
169 * The timestamp of the beginning of the previous chunk. For the
170 * first chunk, this is the "lttng start" timestamp. For the
171 * subsequent ones, this copies the current_chunk_start_ts value when
172 * a new rotation starts. This value is used to set the name of a
173 * complete chunk directory, ex: "last_chunk_start_ts-now()".
174 */
175 time_t last_chunk_start_ts;
176 /*
177 * This is the timestamp when a new chunk starts. When a new rotation
178 * starts, we copy this value to last_chunk_start_ts and replace it
179 * with the current timestamp.
180 */
181 time_t current_chunk_start_ts;
182 /*
183 * Timer to check periodically if a relay and/or consumer has completed
184 * the last rotation.
185 */
186 bool rotation_pending_check_timer_enabled;
187 timer_t rotation_pending_check_timer;
188 /* Timer to periodically rotate a session. */
189 bool rotation_schedule_timer_enabled;
190 timer_t rotation_schedule_timer;
191 /* Value for periodic rotations, 0 if disabled. */
192 uint64_t rotate_timer_period;
193 /* Value for size-based rotations, 0 if disabled. */
194 uint64_t rotate_size;
195 /*
196 * Keep a state if this session was rotated after the last stop command.
197 * We only allow one rotation after a stop. At destroy, we also need to
198 * know if a rotation occurred since the last stop to rename the current
199 * chunk.
200 */
201 bool rotated_after_last_stop;
202 /*
203 * Condition and trigger for size-based rotations.
204 */
205 struct lttng_condition *rotate_condition;
206 struct lttng_trigger *rotate_trigger;
207 };
208
209 /* Prototypes */
210 int session_create(char *name, uid_t uid, gid_t gid);
211
212 void session_lock(struct ltt_session *session);
213 void session_lock_list(void);
214 int session_trylock_list(void);
215 void session_unlock(struct ltt_session *session);
216 void session_unlock_list(void);
217
218 void session_destroy(struct ltt_session *session);
219
220 bool session_get(struct ltt_session *session);
221 void session_put(struct ltt_session *session);
222
223 enum consumer_dst_type session_get_consumer_destination_type(
224 const struct ltt_session *session);
225 const char *session_get_net_consumer_hostname(
226 const struct ltt_session *session);
227 void session_get_net_consumer_ports(
228 const struct ltt_session *session,
229 uint16_t *control_port, uint16_t *data_port);
230 struct lttng_trace_archive_location *session_get_trace_archive_location(
231 struct ltt_session *session);
232
233 struct ltt_session *session_find_by_name(const char *name);
234 struct ltt_session *session_find_by_id(uint64_t id);
235 struct ltt_session_list *session_get_list(void);
236
237 int session_access_ok(struct ltt_session *session, uid_t uid, gid_t gid);
238
239 int session_reset_rotation_state(struct ltt_session *session,
240 enum lttng_rotation_state result);
241
242 #endif /* _LTT_SESSION_H */
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