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         /* Will not fail, as per the ownership guarantee. */
  51         if (!session_get(session)) {
  52                 ret = -1;
  53                 goto end;
  54         }
  55         pthread_mutex_lock(&session->lock);
  56         if (session->viewer_attached) {
  57                 ret = -1;
  58         } else {
  59                 session->viewer_attached = true;
  60         }
  61
  62         if (!ret) {
  63                 pthread_mutex_lock(&vsession->session_list_lock);
  64                 /* Ownership is transfered to the list. */
  65                 cds_list_add_rcu(&session->viewer_session_node,
  66                                 &vsession->session_list);
  67                 pthread_mutex_unlock(&vsession->session_list_lock);
  68         } else {
  69                 /* Put our local ref. */
  70                 session_put(session);
  71         }
  72         /* Safe since we know the session exists. */
  73         pthread_mutex_unlock(&session->lock);
  74 end:
  75         return ret;
  76 }
  77
  78 /* The existence of session must be guaranteed by the caller. */
  79 static int viewer_session_detach(struct relay_viewer_session *vsession,
  80                 struct relay_session *session)
  81 {
  82         int ret = 0;
  83
  84         pthread_mutex_lock(&session->lock);
  85         if (!session->viewer_attached) {
  86                 ret = -1;
  87         } else {
  88                 session->viewer_attached = false;
  89         }
  90
  91         if (!ret) {
  92                 pthread_mutex_lock(&vsession->session_list_lock);
  93                 cds_list_del_rcu(&session->viewer_session_node);
  94                 pthread_mutex_unlock(&vsession->session_list_lock);
  95                 /* Release reference held by the list. */
  96                 session_put(session);
  97         }
  98         /* Safe since we know the session exists. */
  99         pthread_mutex_unlock(&session->lock);
 100         return ret;
 101 }
 102
 103 void viewer_session_destroy(struct relay_viewer_session *vsession)
 104 {
 105         free(vsession);
 106 }
 107
 108 /*
 109  * Release ownership of all the streams of one session and detach the viewer.
 110  */
 111 void viewer_session_close_one_session(struct relay_viewer_session *vsession,
 112                 struct relay_session *session)
 113 {
 114         struct lttng_ht_iter iter;
 115         struct relay_viewer_stream *vstream;
 116
 117         /*
 118          * TODO: improvement: create more efficient list of
 119          * vstream per session.
 120          */
 121         cds_lfht_for_each_entry(viewer_streams_ht->ht, &iter.iter,
 122                         vstream, stream_n.node) {
 123                 if (!viewer_stream_get(vstream)) {
 124                         continue;
 125                 }
 126                 if (vstream->stream->trace->session != session) {
 127                         viewer_stream_put(vstream);
 128                         continue;
 129                 }
 130                 /* Put local reference. */
 131                 viewer_stream_put(vstream);
 132                 /*
 133                  * We have reached one of the viewer stream's lifetime
 134                  * end condition. This "put" will cause the proper
 135                  * teardown of the viewer stream.
 136                  */
 137                 viewer_stream_put(vstream);
 138         }
 139
 140         viewer_session_detach(vsession, session);
 141 }
 142
 143 void viewer_session_close(struct relay_viewer_session *vsession)
 144 {
 145         struct relay_session *session;
 146
 147         rcu_read_lock();
 148         cds_list_for_each_entry_rcu(session,
 149                         &vsession->session_list, viewer_session_node) {
 150                 viewer_session_close_one_session(vsession, session);
 151         }
 152         rcu_read_unlock();
 153 }
 154
 155 /*
 156  * Check if a connection is attached to a session.
 157  * Return 1 if attached, 0 if not attached, a negative value on error.
 158  */
 159 int viewer_session_is_attached(struct relay_viewer_session *vsession,
 160                 struct relay_session *session)
 161 {
 162         struct relay_session *iter;
 163         int found = 0;
 164
 165         pthread_mutex_lock(&session->lock);
 166         if (!vsession) {
 167                 goto end;
 168         }
 169         if (!session->viewer_attached) {
 170                 goto end;
 171         }
 172         rcu_read_lock();
 173         cds_list_for_each_entry_rcu(iter,
 174                         &vsession->session_list,
 175                         viewer_session_node) {
 176                 if (session == iter) {
 177                         found = 1;
 178                         goto end_rcu_unlock;
 179                 }
 180         }
 181 end_rcu_unlock:
 182         rcu_read_unlock();
 183 end:
 184         pthread_mutex_unlock(&session->lock);
 185         return found;
 186 }