src/bin/lttng-relayd/viewer-session.c

   1 /*
   2  * Copyright (C) 2013 - Julien Desfossez <jdesfossez@efficios.com>
   3  *                      David Goulet <dgoulet@efficios.com>
   4  *               2015 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License, version 2 only, as
   8  * published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
  13  * more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along with
  16  * this program; if not, write to the Free Software Foundation, Inc., 51
  17  * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  18  */
  19
  20 #define _LGPL_SOURCE
  21 #include <common/common.h>
  22 #include <urcu/rculist.h>
  23
  24 #include "lttng-relayd.h"
  25 #include "ctf-trace.h"
  26 #include "session.h"
  27 #include "viewer-session.h"
  28 #include "viewer-stream.h"
  29 #include "stream.h"
  30
  31 struct relay_viewer_session *viewer_session_create(void)
  32 {
  33         struct relay_viewer_session *vsession;
  34
  35         vsession = zmalloc(sizeof(*vsession));
  36         if (!vsession) {
  37                 goto end;
  38         }
  39         CDS_INIT_LIST_HEAD(&vsession->session_list);
  40 end:
  41         return vsession;
  42 }
  43
  44 /* The existence of session must be guaranteed by the caller. */
  45 int viewer_session_attach(struct relay_viewer_session *vsession,
  46                 struct relay_session *session)
  47 {
  48         int ret = 0;
  49
  50         ASSERT_LOCKED(session->lock);
  51
  52         /* Will not fail, as per the ownership guarantee. */
  53         if (!session_get(session)) {
  54                 ret = -1;
  55                 goto end;
  56         }
  57         if (session->viewer_attached) {
  58                 ret = -1;
  59         } else {
  60                 session->viewer_attached = true;
  61         }
  62
  63         if (!ret) {
  64                 pthread_mutex_lock(&vsession->session_list_lock);
  65                 /* Ownership is transfered to the list. */
  66                 cds_list_add_rcu(&session->viewer_session_node,
  67                                 &vsession->session_list);
  68                 pthread_mutex_unlock(&vsession->session_list_lock);
  69         } else {
  70                 /* Put our local ref. */
  71                 session_put(session);
  72         }
  73 end:
  74         return ret;
  75 }
  76
  77 /* The existence of session must be guaranteed by the caller. */
  78 static int viewer_session_detach(struct relay_viewer_session *vsession,
  79                 struct relay_session *session)
  80 {
  81         int ret = 0;
  82
  83         pthread_mutex_lock(&session->lock);
  84         if (!session->viewer_attached) {
  85                 ret = -1;
  86         } else {
  87                 session->viewer_attached = false;
  88         }
  89
  90         if (!ret) {
  91                 pthread_mutex_lock(&vsession->session_list_lock);
  92                 cds_list_del_rcu(&session->viewer_session_node);
  93                 pthread_mutex_unlock(&vsession->session_list_lock);
  94                 /* Release reference held by the list. */
  95                 session_put(session);
  96         }
  97         /* Safe since we know the session exists. */
  98         pthread_mutex_unlock(&session->lock);
  99         return ret;
 100 }
 101
 102 void viewer_session_destroy(struct relay_viewer_session *vsession)
 103 {
 104         free(vsession);
 105 }
 106
 107 /*
 108  * Release ownership of all the streams of one session and detach the viewer.
 109  */
 110 void viewer_session_close_one_session(struct relay_viewer_session *vsession,
 111                 struct relay_session *session)
 112 {
 113         struct lttng_ht_iter iter;
 114         struct relay_viewer_stream *vstream;
 115
 116         /*
 117          * TODO: improvement: create more efficient list of
 118          * vstream per session.
 119          */
 120         cds_lfht_for_each_entry(viewer_streams_ht->ht, &iter.iter,
 121                         vstream, stream_n.node) {
 122                 if (!viewer_stream_get(vstream)) {
 123                         continue;
 124                 }
 125                 if (vstream->stream->trace->session != session) {
 126                         viewer_stream_put(vstream);
 127                         continue;
 128                 }
 129                 /* Put local reference. */
 130                 viewer_stream_put(vstream);
 131                 /*
 132                  * We have reached one of the viewer stream's lifetime
 133                  * end condition. This "put" will cause the proper
 134                  * teardown of the viewer stream.
 135                  */
 136                 viewer_stream_put(vstream);
 137         }
 138
 139         viewer_session_detach(vsession, session);
 140 }
 141
 142 void viewer_session_close(struct relay_viewer_session *vsession)
 143 {
 144         struct relay_session *session;
 145
 146         rcu_read_lock();
 147         cds_list_for_each_entry_rcu(session,
 148                         &vsession->session_list, viewer_session_node) {
 149                 viewer_session_close_one_session(vsession, session);
 150         }
 151         rcu_read_unlock();
 152 }
 153
 154 /*
 155  * Check if a connection is attached to a session.
 156  * Return 1 if attached, 0 if not attached, a negative value on error.
 157  */
 158 int viewer_session_is_attached(struct relay_viewer_session *vsession,
 159                 struct relay_session *session)
 160 {
 161         struct relay_session *iter;
 162         int found = 0;
 163
 164         pthread_mutex_lock(&session->lock);
 165         if (!vsession) {
 166                 goto end;
 167         }
 168         if (!session->viewer_attached) {
 169                 goto end;
 170         }
 171         rcu_read_lock();
 172         cds_list_for_each_entry_rcu(iter,
 173                         &vsession->session_list,
 174                         viewer_session_node) {
 175                 if (session == iter) {
 176                         found = 1;
 177                         goto end_rcu_unlock;
 178                 }
 179         }
 180 end_rcu_unlock:
 181         rcu_read_unlock();
 182 end:
 183         pthread_mutex_unlock(&session->lock);
 184         return found;
 185 }