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 */