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 static int viewer_session_set_trace_chunk_copy(struct relay_viewer_session *vsession,
  45                 struct lttng_trace_chunk *relay_session_trace_chunk)
  46 {
  47         int ret = 0;
  48         struct lttng_trace_chunk *viewer_chunk;
  49
  50         assert(relay_session_trace_chunk);
  51         assert(!vsession->current_trace_chunk);
  52
  53         DBG("Copying relay session's current trace chunk to the viewer session");
  54         viewer_chunk = lttng_trace_chunk_copy(relay_session_trace_chunk);
  55         if (!viewer_chunk) {
  56                 ERR("Failed to create a viewer trace chunk from the relay session's current chunk");
  57                 ret = -1;
  58                 goto end;
  59         }
  60
  61         vsession->current_trace_chunk = viewer_chunk;
  62 end:
  63         return ret;
  64 }
  65
  66 /* The existence of session must be guaranteed by the caller. */
  67 enum lttng_viewer_attach_return_code viewer_session_attach(
  68                 struct relay_viewer_session *vsession,
  69                 struct relay_session *session)
  70 {
  71         enum lttng_viewer_attach_return_code viewer_attach_status =
  72                         LTTNG_VIEWER_ATTACH_OK;
  73
  74         ASSERT_LOCKED(session->lock);
  75
  76         /* Will not fail, as per the ownership guarantee. */
  77         if (!session_get(session)) {
  78                 viewer_attach_status = LTTNG_VIEWER_ATTACH_UNK;
  79                 goto end;
  80         }
  81         if (session->viewer_attached) {
  82                 viewer_attach_status = LTTNG_VIEWER_ATTACH_ALREADY;
  83         } else {
  84                 int ret;
  85
  86                 assert(session->current_trace_chunk);
  87                 assert(!vsession->current_trace_chunk);
  88                 session->viewer_attached = true;
  89
  90                 ret = viewer_session_set_trace_chunk_copy(vsession,
  91                                 session->current_trace_chunk);
  92                 if (ret) {
  93                         /*
  94                          * The live protocol does not define a generic error
  95                          * value for the "attach" command. The "unknown"
  96                          * status is used so that the viewer may handle this
  97                          * failure as if the session didn't exist anymore.
  98                          */
  99                         DBG("Failed to create a viewer trace chunk from the current trace chunk of session \"%s\", returning LTTNG_VIEWER_ATTACH_UNK",
 100                                         session->session_name);
 101                         viewer_attach_status = LTTNG_VIEWER_ATTACH_UNK;
 102                 }
 103         }
 104
 105         if (viewer_attach_status == LTTNG_VIEWER_ATTACH_OK) {
 106                 pthread_mutex_lock(&vsession->session_list_lock);
 107                 /* Ownership is transfered to the list. */
 108                 cds_list_add_rcu(&session->viewer_session_node,
 109                                 &vsession->session_list);
 110                 pthread_mutex_unlock(&vsession->session_list_lock);
 111         } else {
 112                 /* Put our local ref. */
 113                 session_put(session);
 114         }
 115 end:
 116         return viewer_attach_status;
 117 }
 118
 119 /* The existence of session must be guaranteed by the caller. */
 120 static int viewer_session_detach(struct relay_viewer_session *vsession,
 121                 struct relay_session *session)
 122 {
 123         int ret = 0;
 124
 125         pthread_mutex_lock(&session->lock);
 126         if (!session->viewer_attached) {
 127                 ret = -1;
 128         } else {
 129                 session->viewer_attached = false;
 130         }
 131
 132         if (!ret) {
 133                 pthread_mutex_lock(&vsession->session_list_lock);
 134                 cds_list_del_rcu(&session->viewer_session_node);
 135                 pthread_mutex_unlock(&vsession->session_list_lock);
 136                 /* Release reference held by the list. */
 137                 session_put(session);
 138         }
 139         /* Safe since we know the session exists. */
 140         pthread_mutex_unlock(&session->lock);
 141         return ret;
 142 }
 143
 144 void viewer_session_destroy(struct relay_viewer_session *vsession)
 145 {
 146         lttng_trace_chunk_put(vsession->current_trace_chunk);
 147         free(vsession);
 148 }
 149
 150 /*
 151  * Release ownership of all the streams of one session and detach the viewer.
 152  */
 153 void viewer_session_close_one_session(struct relay_viewer_session *vsession,
 154                 struct relay_session *session)
 155 {
 156         struct lttng_ht_iter iter;
 157         struct relay_viewer_stream *vstream;
 158
 159         /*
 160          * TODO: improvement: create more efficient list of
 161          * vstream per session.
 162          */
 163         cds_lfht_for_each_entry(viewer_streams_ht->ht, &iter.iter,
 164                         vstream, stream_n.node) {
 165                 if (!viewer_stream_get(vstream)) {
 166                         continue;
 167                 }
 168                 if (vstream->stream->trace->session != session) {
 169                         viewer_stream_put(vstream);
 170                         continue;
 171                 }
 172                 /* Put local reference. */
 173                 viewer_stream_put(vstream);
 174                 /*
 175                  * We have reached one of the viewer stream's lifetime
 176                  * end condition. This "put" will cause the proper
 177                  * teardown of the viewer stream.
 178                  */
 179                 viewer_stream_put(vstream);
 180         }
 181
 182         viewer_session_detach(vsession, session);
 183 }
 184
 185 void viewer_session_close(struct relay_viewer_session *vsession)
 186 {
 187         struct relay_session *session;
 188
 189         rcu_read_lock();
 190         cds_list_for_each_entry_rcu(session,
 191                         &vsession->session_list, viewer_session_node) {
 192                 viewer_session_close_one_session(vsession, session);
 193         }
 194         rcu_read_unlock();
 195 }
 196
 197 /*
 198  * Check if a connection is attached to a session.
 199  * Return 1 if attached, 0 if not attached, a negative value on error.
 200  */
 201 int viewer_session_is_attached(struct relay_viewer_session *vsession,
 202                 struct relay_session *session)
 203 {
 204         struct relay_session *iter;
 205         int found = 0;
 206
 207         pthread_mutex_lock(&session->lock);
 208         if (!vsession) {
 209                 goto end;
 210         }
 211         if (!session->viewer_attached) {
 212                 goto end;
 213         }
 214         rcu_read_lock();
 215         cds_list_for_each_entry_rcu(iter,
 216                         &vsession->session_list,
 217                         viewer_session_node) {
 218                 if (session == iter) {
 219                         found = 1;
 220                         goto end_rcu_unlock;
 221                 }
 222         }
 223 end_rcu_unlock:
 224         rcu_read_unlock();
 225 end:
 226         pthread_mutex_unlock(&session->lock);
 227         return found;
 228 }