ab9b1a9a4355edf8aa98ecb29d7350802d96fb26
[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
28 #include "snapshot.h"
29 #include "trace-kernel.h"
30
31 struct ltt_ust_session;
32
33 /*
34 * Tracing session list
35 *
36 * Statically declared in session.c and can be accessed by using
37 * session_get_list() function that returns the pointer to the list.
38 */
39 struct ltt_session_list {
40 /*
41 * This lock protects any read/write access to the list and
42 * next_uuid. All public functions in session.c acquire this
43 * lock and release it before returning. If none of those
44 * functions are used, the lock MUST be acquired in order to
45 * iterate or/and do any actions on that list.
46 */
47 pthread_mutex_t lock;
48
49 /*
50 * Session unique ID generator. The session list lock MUST be
51 * upon update and read of this counter.
52 */
53 uint64_t next_uuid;
54
55 /* Linked list head */
56 struct cds_list_head head;
57 };
58
59 /*
60 * This data structure contains information needed to identify a tracing
61 * session for both LTTng and UST.
62 */
63 struct ltt_session {
64 char name[NAME_MAX];
65 char hostname[HOST_NAME_MAX]; /* Local hostname. */
66 struct ltt_kernel_session *kernel_session;
67 struct ltt_ust_session *ust_session;
68 /*
69 * Protect any read/write on this session data structure. This lock must be
70 * acquired *before* using any public functions declared below. Use
71 * session_lock() and session_unlock() for that.
72 */
73 pthread_mutex_t lock;
74 struct cds_list_head list;
75 uint64_t id; /* session unique identifier */
76 /* UID/GID of the user owning the session */
77 uid_t uid;
78 gid_t gid;
79 /*
80 * Network session handle. A value of 0 means that there is no remote
81 * session established.
82 */
83 uint64_t net_handle;
84 /*
85 * This consumer is only set when the create_session_uri call is made.
86 * This contains the temporary information for a consumer output. Upon
87 * creation of the UST or kernel session, this consumer, if available, is
88 * copied into those sessions.
89 */
90 struct consumer_output *consumer;
91
92 /* Did at least ONE start command has been triggered?. */
93 unsigned int has_been_started:1;
94 /*
95 * Is the session active? Start trace command sets this to 1 and the stop
96 * command reset it to 0.
97 */
98 unsigned int active:1;
99
100 /* Snapshot representation in a session. */
101 struct snapshot snapshot;
102 /* Indicate if the session has to output the traces or not. */
103 unsigned int output_traces;
104 /*
105 * This session is in snapshot mode. This means that every channel enabled
106 * will be set in overwrite mode and mmap. It is considered exclusively for
107 * snapshot purposes.
108 */
109 unsigned int snapshot_mode;
110 /*
111 * Timer set when the session is created for live reading.
112 */
113 unsigned int live_timer;
114 /*
115 * Path where to keep the shared memory files.
116 */
117 char shm_path[PATH_MAX];
118 /*
119 * Node in ltt_sessions_ht_by_id.
120 */
121 struct lttng_ht_node_u64 node;
122 /* Number of session rotation for this session. */
123 uint64_t rotate_count;
124 /*
125 * Rotation is pending between the time it starts until the consumer has
126 * finished extracting the data. If the session uses a relay, data related
127 * to a rotation can still be in flight after that, see
128 * rotate_pending_relay.
129 */
130 bool rotate_pending;
131 /*
132 * True until the relay has finished the rotation of all the streams.
133 */
134 bool rotate_pending_relay;
135 /* Current state of a rotation. */
136 enum lttng_rotation_state rotation_state;
137 /*
138 * Number of channels waiting for a rotation.
139 * When this number reaches 0, we can handle the rename of the chunk
140 * folder and inform the client that the rotate is finished.
141 */
142 unsigned int nr_chan_rotate_pending;
143 struct {
144 /*
145 * When the rotation is in progress, the temporary path name is
146 * stored here. When the rotation is complete, the final path name
147 * is here and can be queried with the rotate_pending call.
148 */
149 char current_rotate_path[LTTNG_PATH_MAX];
150 /*
151 * The path where the consumer is currently writing after the first
152 * session rotation.
153 */
154 char active_tracing_path[LTTNG_PATH_MAX];
155 } rotation_chunk;
156 /*
157 * The timestamp of the beginning of the previous chunk. For the
158 * first chunk, this is the "lttng start" timestamp. For the
159 * subsequent ones, this copies the current_chunk_start_ts value when
160 * a new rotation starts. This value is used to set the name of a
161 * complete chunk directory, ex: "last_chunk_start_ts-now()".
162 */
163 time_t last_chunk_start_ts;
164 /*
165 * This is the timestamp when a new chunk starts. When a new rotation
166 * starts, we copy this value to last_chunk_start_ts and replace it
167 * with the current timestamp.
168 */
169 time_t current_chunk_start_ts;
170 /*
171 * Timer to check periodically if a relay has completed the last
172 * rotation.
173 */
174 bool rotate_relay_pending_timer_enabled;
175 timer_t rotate_relay_pending_timer;
176 /* Timer to periodically rotate a session. */
177 bool rotate_timer_enabled;
178 timer_t rotate_timer;
179 uint64_t rotate_timer_period;
180 /* Value for size-based rotation, 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 occured since the last stop to rename the current
186 * chunk.
187 */
188 bool rotated_after_last_stop;
189 /*
190 * Condition and trigger for size-based rotations.
191 */
192 struct lttng_condition *rotate_condition;
193 struct lttng_trigger *rotate_trigger;
194 };
195
196 /* Prototypes */
197 int session_create(char *name, uid_t uid, gid_t gid);
198 int session_destroy(struct ltt_session *session);
199
200 void session_lock(struct ltt_session *session);
201 void session_lock_list(void);
202 void session_unlock(struct ltt_session *session);
203 void session_unlock_list(void);
204
205 struct ltt_session *session_find_by_name(const char *name);
206 struct ltt_session *session_find_by_id(uint64_t id);
207 struct ltt_session_list *session_get_list(void);
208
209 int session_access_ok(struct ltt_session *session, uid_t uid, gid_t gid);
210
211 #endif /* _LTT_SESSION_H */
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