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 _GNU_SOURCE
  21 #define _LGPL_SOURCE
  22 #include <common/common.h>
  23 #include <urcu/rculist.h>
  24
  25 #include "lttng-relayd.h"
  26 #include "ctf-trace.h"
  27 #include "session.h"
  28 #include "stream.h"
  29
  30 /* Global session id used in the session creation. */
  31 static uint64_t last_relay_session_id;
  32 static pthread_mutex_t last_relay_session_id_lock = PTHREAD_MUTEX_INITIALIZER;
  33
  34 /*
  35  * Create a new session by assigning a new session ID.
  36  *
  37  * Return allocated session or else NULL.
  38  */
  39 struct relay_session *session_create(const char *session_name,
  40                 const char *hostname, uint32_t live_timer,
  41                 bool snapshot, uint32_t major, uint32_t minor)
  42 {
  43         struct relay_session *session;
  44
  45         session = zmalloc(sizeof(*session));
  46         if (!session) {
  47                 PERROR("relay session zmalloc");
  48                 goto error;
  49         }
  50
  51         session->ctf_traces_ht = lttng_ht_new(0, LTTNG_HT_TYPE_STRING);
  52         if (!session->ctf_traces_ht) {
  53                 free(session);
  54                 session = NULL;
  55                 goto error;
  56         }
  57
  58         pthread_mutex_lock(&last_relay_session_id_lock);
  59         session->id = ++last_relay_session_id;
  60         pthread_mutex_unlock(&last_relay_session_id_lock);
  61
  62         session->major = major;
  63         session->minor = minor;
  64         lttng_ht_node_init_u64(&session->session_n, session->id);
  65         urcu_ref_init(&session->ref);
  66         CDS_INIT_LIST_HEAD(&session->recv_list);
  67         pthread_mutex_init(&session->lock, NULL);
  68         pthread_mutex_init(&session->reflock, NULL);
  69         pthread_mutex_init(&session->recv_list_lock, NULL);
  70
  71         strncpy(session->session_name, session_name,
  72                         sizeof(session->session_name));
  73         strncpy(session->hostname, hostname,
  74                         sizeof(session->hostname));
  75         session->live_timer = live_timer;
  76         session->snapshot = snapshot;
  77
  78         lttng_ht_add_unique_u64(sessions_ht, &session->session_n);
  79
  80 error:
  81         return session;
  82 }
  83
  84 /* Should be called with RCU read-side lock held. */
  85 bool session_get(struct relay_session *session)
  86 {
  87         bool has_ref = false;
  88
  89         pthread_mutex_lock(&session->reflock);
  90         if (session->ref.refcount != 0) {
  91                 has_ref = true;
  92                 urcu_ref_get(&session->ref);
  93         }
  94         pthread_mutex_unlock(&session->reflock);
  95
  96         return has_ref;
  97 }
  98
  99 /*
 100  * Lookup a session within the session hash table using the session id
 101  * as key. A session reference is taken when a session is returned.
 102  * session_put() must be called on that session.
 103  *
 104  * Return session or NULL if not found.
 105  */
 106 struct relay_session *session_get_by_id(uint64_t id)
 107 {
 108         struct relay_session *session = NULL;
 109         struct lttng_ht_node_u64 *node;
 110         struct lttng_ht_iter iter;
 111
 112         rcu_read_lock();
 113         lttng_ht_lookup(sessions_ht, &id, &iter);
 114         node = lttng_ht_iter_get_node_u64(&iter);
 115         if (!node) {
 116                 DBG("Session find by ID %" PRIu64 " id NOT found", id);
 117                 goto end;
 118         }
 119         session = caa_container_of(node, struct relay_session, session_n);
 120         DBG("Session find by ID %" PRIu64 " id found", id);
 121         if (!session_get(session)) {
 122                 session = NULL;
 123         }
 124 end:
 125         rcu_read_unlock();
 126         return session;
 127 }
 128
 129 static void rcu_destroy_session(struct rcu_head *rcu_head)
 130 {
 131         struct relay_session *session =
 132                         caa_container_of(rcu_head, struct relay_session,
 133                                 rcu_node);
 134         /*
 135          * Since each trace has a reference on the session, it means
 136          * that if we are at the point where we teardown the session, no
 137          * trace belonging to that session exist at this point.
 138          * Calling lttng_ht_destroy in call_rcu worker thread so we
 139          * don't hold the RCU read-side lock while calling it.
 140          */
 141         lttng_ht_destroy(session->ctf_traces_ht);
 142         free(session);
 143 }
 144
 145 /*
 146  * Delete session from the given hash table.
 147  *
 148  * Return lttng ht del error code being 0 on success and 1 on failure.
 149  */
 150 static int session_delete(struct relay_session *session)
 151 {
 152         struct lttng_ht_iter iter;
 153
 154         iter.iter.node = &session->session_n.node;
 155         return lttng_ht_del(sessions_ht, &iter);
 156 }
 157
 158
 159 static void destroy_session(struct relay_session *session)
 160 {
 161         int ret;
 162
 163         ret = session_delete(session);
 164         assert(!ret);
 165         call_rcu(&session->rcu_node, rcu_destroy_session);
 166 }
 167
 168 void session_release(struct urcu_ref *ref)
 169 {
 170         struct relay_session *session =
 171                         caa_container_of(ref, struct relay_session, ref);
 172
 173         destroy_session(session);
 174 }
 175
 176 void session_put(struct relay_session *session)
 177 {
 178         rcu_read_lock();
 179         pthread_mutex_lock(&session->reflock);
 180         urcu_ref_put(&session->ref, session_release);
 181         pthread_mutex_unlock(&session->reflock);
 182         rcu_read_unlock();
 183 }
 184
 185 int session_close(struct relay_session *session)
 186 {
 187         int ret = 0;
 188         struct ctf_trace *trace;
 189         struct lttng_ht_iter iter;
 190         struct relay_stream *stream;
 191
 192         pthread_mutex_lock(&session->lock);
 193         DBG("closing session %" PRIu64 ": is conn already closed %d",
 194                         session->id, session->connection_closed);
 195         if (session->connection_closed) {
 196                 ret = -1;
 197                 goto unlock;
 198         }
 199         session->connection_closed = true;
 200 unlock:
 201         pthread_mutex_unlock(&session->lock);
 202         if (ret) {
 203                 return ret;
 204         }
 205
 206         rcu_read_lock();
 207         cds_lfht_for_each_entry(session->ctf_traces_ht->ht,
 208                         &iter.iter, trace, node.node) {
 209                 ret = ctf_trace_close(trace);
 210                 if (ret) {
 211                         goto rcu_unlock;
 212                 }
 213         }
 214         cds_list_for_each_entry_rcu(stream, &session->recv_list,
 215                         recv_node) {
 216                 /* Close streams which have not been published yet. */
 217                 try_stream_close(stream);
 218         }
 219 rcu_unlock:
 220         rcu_read_unlock();
 221         if (ret) {
 222                 return ret;
 223         }
 224         /* Put self-reference from create. */
 225         session_put(session);
 226         return ret;
 227 }
 228
 229 void print_sessions(void)
 230 {
 231         struct lttng_ht_iter iter;
 232         struct relay_session *session;
 233
 234         rcu_read_lock();
 235         cds_lfht_for_each_entry(sessions_ht->ht, &iter.iter, session,
 236                         session_n.node) {
 237                 if (!session_get(session)) {
 238                         continue;
 239                 }
 240                 DBG("session %p refcount %ld session %" PRIu64,
 241                         session,
 242                         session->ref.refcount,
 243                         session->id);
 244                 session_put(session);
 245         }
 246         rcu_read_unlock();
 247 }