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 #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         if (lttng_strncpy(session->session_name, session_name,
  50                         sizeof(session->session_name))) {
  51                 goto error;
  52         }
  53         if (lttng_strncpy(session->hostname, hostname,
  54                         sizeof(session->hostname))) {
  55                 goto error;
  56         }
  57         session->ctf_traces_ht = lttng_ht_new(0, LTTNG_HT_TYPE_STRING);
  58         if (!session->ctf_traces_ht) {
  59                 goto error;
  60         }
  61
  62         pthread_mutex_lock(&last_relay_session_id_lock);
  63         session->id = ++last_relay_session_id;
  64         pthread_mutex_unlock(&last_relay_session_id_lock);
  65
  66         session->major = major;
  67         session->minor = minor;
  68         lttng_ht_node_init_u64(&session->session_n, session->id);
  69         urcu_ref_init(&session->ref);
  70         CDS_INIT_LIST_HEAD(&session->recv_list);
  71         pthread_mutex_init(&session->lock, NULL);
  72         pthread_mutex_init(&session->reflock, NULL);
  73         pthread_mutex_init(&session->recv_list_lock, NULL);
  74
  75         session->live_timer = live_timer;
  76         session->snapshot = snapshot;
  77
  78         lttng_ht_add_unique_u64(sessions_ht, &session->session_n);
  79         return session;
  80
  81 error:
  82         free(session);
  83         return NULL;
  84 }
  85
  86 /* Should be called with RCU read-side lock held. */
  87 bool session_get(struct relay_session *session)
  88 {
  89         bool has_ref = false;
  90
  91         pthread_mutex_lock(&session->reflock);
  92         if (session->ref.refcount != 0) {
  93                 has_ref = true;
  94                 urcu_ref_get(&session->ref);
  95         }
  96         pthread_mutex_unlock(&session->reflock);
  97
  98         return has_ref;
  99 }
 100
 101 /*
 102  * Lookup a session within the session hash table using the session id
 103  * as key. A session reference is taken when a session is returned.
 104  * session_put() must be called on that session.
 105  *
 106  * Return session or NULL if not found.
 107  */
 108 struct relay_session *session_get_by_id(uint64_t id)
 109 {
 110         struct relay_session *session = NULL;
 111         struct lttng_ht_node_u64 *node;
 112         struct lttng_ht_iter iter;
 113
 114         rcu_read_lock();
 115         lttng_ht_lookup(sessions_ht, &id, &iter);
 116         node = lttng_ht_iter_get_node_u64(&iter);
 117         if (!node) {
 118                 DBG("Session find by ID %" PRIu64 " id NOT found", id);
 119                 goto end;
 120         }
 121         session = caa_container_of(node, struct relay_session, session_n);
 122         DBG("Session find by ID %" PRIu64 " id found", id);
 123         if (!session_get(session)) {
 124                 session = NULL;
 125         }
 126 end:
 127         rcu_read_unlock();
 128         return session;
 129 }
 130
 131 static void rcu_destroy_session(struct rcu_head *rcu_head)
 132 {
 133         struct relay_session *session =
 134                         caa_container_of(rcu_head, struct relay_session,
 135                                 rcu_node);
 136
 137         free(session);
 138 }
 139
 140 /*
 141  * Delete session from the given hash table.
 142  *
 143  * Return lttng ht del error code being 0 on success and 1 on failure.
 144  */
 145 static int session_delete(struct relay_session *session)
 146 {
 147         struct lttng_ht_iter iter;
 148
 149         iter.iter.node = &session->session_n.node;
 150         return lttng_ht_del(sessions_ht, &iter);
 151 }
 152
 153
 154 static void destroy_session(struct relay_session *session)
 155 {
 156         int ret;
 157
 158         ret = session_delete(session);
 159         assert(!ret);
 160         /*
 161          * Since each trace has a reference on the session, it means
 162          * that if we are at the point where we teardown the session, no
 163          * trace belonging to that session exist at this point.
 164          */
 165         lttng_ht_destroy(session->ctf_traces_ht);
 166         call_rcu(&session->rcu_node, rcu_destroy_session);
 167 }
 168
 169 void session_release(struct urcu_ref *ref)
 170 {
 171         struct relay_session *session =
 172                         caa_container_of(ref, struct relay_session, ref);
 173
 174         destroy_session(session);
 175 }
 176
 177 void session_put(struct relay_session *session)
 178 {
 179         rcu_read_lock();
 180         pthread_mutex_lock(&session->reflock);
 181         urcu_ref_put(&session->ref, session_release);
 182         pthread_mutex_unlock(&session->reflock);
 183         rcu_read_unlock();
 184 }
 185
 186 int session_close(struct relay_session *session)
 187 {
 188         int ret = 0;
 189         struct ctf_trace *trace;
 190         struct lttng_ht_iter iter;
 191         struct relay_stream *stream;
 192
 193         pthread_mutex_lock(&session->lock);
 194         DBG("closing session %" PRIu64 ": is conn already closed %d",
 195                         session->id, session->connection_closed);
 196         if (session->connection_closed) {
 197                 ret = -1;
 198                 goto unlock;
 199         }
 200         session->connection_closed = true;
 201 unlock:
 202         pthread_mutex_unlock(&session->lock);
 203         if (ret) {
 204                 return ret;
 205         }
 206
 207         rcu_read_lock();
 208         cds_lfht_for_each_entry(session->ctf_traces_ht->ht,
 209                         &iter.iter, trace, node.node) {
 210                 ret = ctf_trace_close(trace);
 211                 if (ret) {
 212                         goto rcu_unlock;
 213                 }
 214         }
 215         cds_list_for_each_entry_rcu(stream, &session->recv_list,
 216                         recv_node) {
 217                 /* Close streams which have not been published yet. */
 218                 try_stream_close(stream);
 219         }
 220 rcu_unlock:
 221         rcu_read_unlock();
 222         if (ret) {
 223                 return ret;
 224         }
 225         /* Put self-reference from create. */
 226         session_put(session);
 227         return ret;
 228 }
 229
 230 void print_sessions(void)
 231 {
 232         struct lttng_ht_iter iter;
 233         struct relay_session *session;
 234
 235         rcu_read_lock();
 236         cds_lfht_for_each_entry(sessions_ht->ht, &iter.iter, session,
 237                         session_n.node) {
 238                 if (!session_get(session)) {
 239                         continue;
 240                 }
 241                 DBG("session %p refcount %ld session %" PRIu64,
 242                         session,
 243                         session->ref.refcount,
 244                         session->id);
 245                 session_put(session);
 246         }
 247         rcu_read_unlock();
 248 }