Fix: notification thread: RCU-safe reclaim of hash table nodes
[lttng-tools.git] / src / bin / lttng-sessiond / notification-thread-internal.h
1 /*
2 * Copyright (C) 2017 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
3 *
4 * This program is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License, version 2 only, as
6 * published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
11 * more details.
12 *
13 * You should have received a copy of the GNU General Public License along with
14 * this program; if not, write to the Free Software Foundation, Inc., 51
15 * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
16 */
17
18 #ifndef NOTIFICATION_THREAD_INTERNAL_H
19 #define NOTIFICATION_THREAD_INTERNAL_H
20
21 #include <lttng/ref-internal.h>
22 #include <urcu/rculfhash.h>
23 #include <unistd.h>
24
25 struct channel_key {
26 uint64_t key;
27 enum lttng_domain_type domain;
28 };
29
30 struct session_info {
31 struct lttng_ref ref;
32 char *name;
33 uid_t uid;
34 gid_t gid;
35 /*
36 * Hashtable containing back-refs (weak) to all channels in this session.
37 * The hashtable's key is a hash of (struct channel_key) and
38 * the value is of type (struct channel_info *).
39 */
40 struct cds_lfht *channel_infos_ht;
41 struct lttng_session_trigger_list *trigger_list;
42 /* Node in the notification thread state's sessions_ht. */
43 struct cds_lfht_node sessions_ht_node;
44 /*
45 * Weak reference to the thread state's sessions_ht. Used for removal on
46 * destruction.
47 */
48 struct cds_lfht *sessions_ht;
49 uint64_t consumed_data_size;
50 struct {
51 /* Whether a rotation is ongoing for this session. */
52 bool ongoing;
53 /* Identifier of the currently ongoing rotation. */
54 uint64_t id;
55 } rotation;
56 /* call_rcu delayed reclaim. */
57 struct rcu_head rcu_node;
58 };
59
60 struct channel_info {
61 struct channel_key key;
62 char *name;
63 uint64_t capacity;
64 /*
65 * A channel info holds a reference (lttng_ref) on session_info.
66 * session_info, in return, holds a weak reference to the channel.
67 */
68 struct session_info *session_info;
69 /* Node in the notification thread state's channels_ht. */
70 struct cds_lfht_node channels_ht_node;
71 /* Node in the session_info's channels_ht. */
72 struct cds_lfht_node session_info_channels_ht_node;
73 /* call_rcu delayed reclaim. */
74 struct rcu_head rcu_node;
75 };
76
77 #endif /* NOTIFICATION_THREAD_INTERNAL_H */
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