src/bin/lttng-relayd/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 "stream.h"
  28
  29 /* Global session id used in the session creation. */
  30 static uint64_t last_relay_session_id;
  31 static pthread_mutex_t last_relay_session_id_lock = PTHREAD_MUTEX_INITIALIZER;
  32
  33 /*
  34  * Create a new session by assigning a new session ID.
  35  *
  36  * Return allocated session or else NULL.
  37  */
  38 struct relay_session *session_create(const char *session_name,
  39                 const char *hostname, uint32_t live_timer,
  40                 bool snapshot, uint32_t major, uint32_t minor)
  41 {
  42         struct relay_session *session;
  43
  44         session = zmalloc(sizeof(*session));
  45         if (!session) {
  46                 PERROR("relay session zmalloc");
  47                 goto error;
  48         }
  49
  50         session->ctf_traces_ht = lttng_ht_new(0, LTTNG_HT_TYPE_STRING);
  51         if (!session->ctf_traces_ht) {
  52                 free(session);
  53                 session = NULL;
  54                 goto error;
  55         }
  56
  57         pthread_mutex_lock(&last_relay_session_id_lock);
  58         session->id = ++last_relay_session_id;
  59         pthread_mutex_unlock(&last_relay_session_id_lock);
  60
  61         session->major = major;
  62         session->minor = minor;
  63         lttng_ht_node_init_u64(&session->session_n, session->id);
  64         urcu_ref_init(&session->ref);
  65         CDS_INIT_LIST_HEAD(&session->recv_list);
  66         pthread_mutex_init(&session->lock, NULL);
  67         pthread_mutex_init(&session->reflock, NULL);
  68         pthread_mutex_init(&session->recv_list_lock, NULL);
  69
  70         strncpy(session->session_name, session_name,
  71                         sizeof(session->session_name));
  72         strncpy(session->hostname, hostname,
  73                         sizeof(session->hostname));
  74         session->live_timer = live_timer;
  75         session->snapshot = snapshot;
  76
  77         lttng_ht_add_unique_u64(sessions_ht, &session->session_n);
  78
  79 error:
  80         return session;
  81 }
  82
  83 /* Should be called with RCU read-side lock held. */
  84 bool session_get(struct relay_session *session)
  85 {
  86         bool has_ref = false;
  87
  88         pthread_mutex_lock(&session->reflock);
  89         if (session->ref.refcount != 0) {
  90                 has_ref = true;
  91                 urcu_ref_get(&session->ref);
  92         }
  93         pthread_mutex_unlock(&session->reflock);
  94
  95         return has_ref;
  96 }
  97
  98 /*
  99  * Lookup a session within the session hash table using the session id
 100  * as key. A session reference is taken when a session is returned.
 101  * session_put() must be called on that session.
 102  *
 103  * Return session or NULL if not found.
 104  */
 105 struct relay_session *session_get_by_id(uint64_t id)
 106 {
 107         struct relay_session *session = NULL;
 108         struct lttng_ht_node_u64 *node;
 109         struct lttng_ht_iter iter;
 110
 111         rcu_read_lock();
 112         lttng_ht_lookup(sessions_ht, &id, &iter);
 113         node = lttng_ht_iter_get_node_u64(&iter);
 114         if (!node) {
 115                 DBG("Session find by ID %" PRIu64 " id NOT found", id);
 116                 goto end;
 117         }
 118         session = caa_container_of(node, struct relay_session, session_n);
 119         DBG("Session find by ID %" PRIu64 " id found", id);
 120         if (!session_get(session)) {
 121                 session = NULL;
 122         }
 123 end:
 124         rcu_read_unlock();
 125         return session;
 126 }
 127
 128 static void rcu_destroy_session(struct rcu_head *rcu_head)
 129 {
 130         struct relay_session *session =
 131                         caa_container_of(rcu_head, struct relay_session,
 132                                 rcu_node);
 133         /*
 134          * Since each trace has a reference on the session, it means
 135          * that if we are at the point where we teardown the session, no
 136          * trace belonging to that session exist at this point.
 137          * Calling lttng_ht_destroy in call_rcu worker thread so we
 138          * don't hold the RCU read-side lock while calling it.
 139          */
 140         lttng_ht_destroy(session->ctf_traces_ht);
 141         free(session);
 142 }
 143
 144 /*
 145  * Delete session from the given hash table.
 146  *
 147  * Return lttng ht del error code being 0 on success and 1 on failure.
 148  */
 149 static int session_delete(struct relay_session *session)
 150 {
 151         struct lttng_ht_iter iter;
 152
 153         iter.iter.node = &session->session_n.node;
 154         return lttng_ht_del(sessions_ht, &iter);
 155 }
 156
 157
 158 static void destroy_session(struct relay_session *session)
 159 {
 160         int ret;
 161
 162         ret = session_delete(session);
 163         assert(!ret);
 164         call_rcu(&session->rcu_node, rcu_destroy_session);
 165 }
 166
 167 void session_release(struct urcu_ref *ref)
 168 {
 169         struct relay_session *session =
 170                         caa_container_of(ref, struct relay_session, ref);
 171
 172         destroy_session(session);
 173 }
 174
 175 void session_put(struct relay_session *session)
 176 {
 177         rcu_read_lock();
 178         pthread_mutex_lock(&session->reflock);
 179         urcu_ref_put(&session->ref, session_release);
 180         pthread_mutex_unlock(&session->reflock);
 181         rcu_read_unlock();
 182 }
 183
 184 int session_close(struct relay_session *session)
 185 {
 186         int ret = 0;
 187         struct ctf_trace *trace;
 188         struct lttng_ht_iter iter;
 189         struct relay_stream *stream;
 190
 191         pthread_mutex_lock(&session->lock);
 192         DBG("closing session %" PRIu64 ": is conn already closed %d",
 193                         session->id, session->connection_closed);
 194         if (session->connection_closed) {
 195                 ret = -1;
 196                 goto unlock;
 197         }
 198         session->connection_closed = true;
 199 unlock:
 200         pthread_mutex_unlock(&session->lock);
 201         if (ret) {
 202                 return ret;
 203         }
 204
 205         rcu_read_lock();
 206         cds_lfht_for_each_entry(session->ctf_traces_ht->ht,
 207                         &iter.iter, trace, node.node) {
 208                 ret = ctf_trace_close(trace);
 209                 if (ret) {
 210                         goto rcu_unlock;
 211                 }
 212         }
 213         cds_list_for_each_entry_rcu(stream, &session->recv_list,
 214                         recv_node) {
 215                 /* Close streams which have not been published yet. */
 216                 try_stream_close(stream);
 217         }
 218 rcu_unlock:
 219         rcu_read_unlock();
 220         if (ret) {
 221                 return ret;
 222         }
 223         /* Put self-reference from create. */
 224         session_put(session);
 225         return ret;
 226 }
 227
 228 void print_sessions(void)
 229 {
 230         struct lttng_ht_iter iter;
 231         struct relay_session *session;
 232
 233         rcu_read_lock();
 234         cds_lfht_for_each_entry(sessions_ht->ht, &iter.iter, session,
 235                         session_n.node) {
 236                 if (!session_get(session)) {
 237                         continue;
 238                 }
 239                 DBG("session %p refcount %ld session %" PRIu64,
 240                         session,
 241                         session->ref.refcount,
 242                         session->id);
 243                 session_put(session);
 244         }
 245         rcu_read_unlock();
 246 }