Fix: force the client to create a viewer session before attaching
[lttng-tools.git] / src / bin / lttng-relayd / session.h
1 /*
2 * Copyright (C) 2013 - Julien Desfossez <jdesfossez@efficios.com>
3 * David Goulet <dgoulet@efficios.com>
4 *
5 * This program is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License, version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This program is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
12 * more details.
13 *
14 * You should have received a copy of the GNU General Public License along with
15 * this program; if not, write to the Free Software Foundation, Inc., 51
16 * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
17 */
18
19 #ifndef _SESSION_H
20 #define _SESSION_H
21
22 #include <limits.h>
23 #include <inttypes.h>
24 #include <pthread.h>
25 #include <urcu/list.h>
26
27 #include <common/hashtable/hashtable.h>
28
29 /*
30 * Represents a session for the relay point of view
31 */
32 struct relay_session {
33 /*
34 * This session id is used to identify a set of stream to a tracing session
35 * but also make sure we have a unique session id associated with a session
36 * daemon which can provide multiple data source.
37 */
38 uint64_t id;
39 char session_name[NAME_MAX];
40 char hostname[HOST_NAME_MAX];
41 uint32_t live_timer;
42 struct lttng_ht_node_u64 session_n;
43 struct rcu_head rcu_node;
44 uint32_t stream_count;
45 /* Tell if this session is for a snapshot or not. */
46 unsigned int snapshot:1;
47 /* Tell if the session has been closed on the streaming side. */
48 unsigned int close_flag:1;
49
50 /* Number of viewer using it. Set to 0, it should be destroyed. */
51 int viewer_refcount;
52
53 /* Contains ctf_trace object of that session indexed by path name. */
54 struct lttng_ht *ctf_traces_ht;
55
56 /*
57 * Indicate version protocol for this session. This is especially useful
58 * for the data thread that has no idea which version it operates on since
59 * linking control/data sockets is non trivial.
60 */
61 uint64_t minor;
62 uint64_t major;
63 /*
64 * Flag checked and exchanged with uatomic_cmpxchg to tell the
65 * viewer-side if new streams got added since the last check.
66 */
67 unsigned long new_streams;
68
69 /*
70 * Used to synchronize the process where we flag every streams readiness
71 * for the viewer when the streams_sent message is received and the viewer
72 * process of sending those streams.
73 */
74 pthread_mutex_t viewer_ready_lock;
75
76 /*
77 * Member of the session list in struct relay_viewer_session.
78 */
79 struct cds_list_head viewer_session_list;
80 };
81
82 struct relay_viewer_session {
83 struct cds_list_head sessions_head;
84 };
85
86 static inline void session_viewer_attach(struct relay_session *session)
87 {
88 uatomic_inc(&session->viewer_refcount);
89 }
90
91 static inline void session_viewer_detach(struct relay_session *session)
92 {
93 uatomic_add(&session->viewer_refcount, -1);
94 }
95
96 struct relay_session *session_find_by_id(struct lttng_ht *ht, uint64_t id);
97 struct relay_session *session_create(void);
98 int session_delete(struct lttng_ht *ht, struct relay_session *session);
99
100 /*
101 * Direct destroy without reading the refcount.
102 */
103 void session_destroy(struct relay_session *session);
104
105 /*
106 * Destroy the session if the refcount is down to 0.
107 */
108 void session_try_destroy(struct lttng_ht *ht, struct relay_session *session);
109
110 /*
111 * Decrement the viewer refcount and destroy it if down to 0.
112 */
113 void session_viewer_try_destroy(struct lttng_ht *ht,
114 struct relay_session *session);
115
116 #endif /* _SESSION_H */
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