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         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          * Since each trace has a reference on the session, it means
 138          * that if we are at the point where we teardown the session, no
 139          * trace belonging to that session exist at this point.
 140          * Calling lttng_ht_destroy in call_rcu worker thread so we
 141          * don't hold the RCU read-side lock while calling it.
 142          */
 143         lttng_ht_destroy(session->ctf_traces_ht);
 144         free(session);
 145 }
 146
 147 /*
 148  * Delete session from the given hash table.
 149  *
 150  * Return lttng ht del error code being 0 on success and 1 on failure.
 151  */
 152 static int session_delete(struct relay_session *session)
 153 {
 154         struct lttng_ht_iter iter;
 155
 156         iter.iter.node = &session->session_n.node;
 157         return lttng_ht_del(sessions_ht, &iter);
 158 }
 159
 160
 161 static void destroy_session(struct relay_session *session)
 162 {
 163         int ret;
 164
 165         ret = session_delete(session);
 166         assert(!ret);
 167         call_rcu(&session->rcu_node, rcu_destroy_session);
 168 }
 169
 170 void session_release(struct urcu_ref *ref)
 171 {
 172         struct relay_session *session =
 173                         caa_container_of(ref, struct relay_session, ref);
 174
 175         destroy_session(session);
 176 }
 177
 178 void session_put(struct relay_session *session)
 179 {
 180         rcu_read_lock();
 181         pthread_mutex_lock(&session->reflock);
 182         urcu_ref_put(&session->ref, session_release);
 183         pthread_mutex_unlock(&session->reflock);
 184         rcu_read_unlock();
 185 }
 186
 187 int session_close(struct relay_session *session)
 188 {
 189         int ret = 0;
 190         struct ctf_trace *trace;
 191         struct lttng_ht_iter iter;
 192         struct relay_stream *stream;
 193
 194         pthread_mutex_lock(&session->lock);
 195         DBG("closing session %" PRIu64 ": is conn already closed %d",
 196                         session->id, session->connection_closed);
 197         if (session->connection_closed) {
 198                 ret = -1;
 199                 goto unlock;
 200         }
 201         session->connection_closed = true;
 202 unlock:
 203         pthread_mutex_unlock(&session->lock);
 204         if (ret) {
 205                 return ret;
 206         }
 207
 208         rcu_read_lock();
 209         cds_lfht_for_each_entry(session->ctf_traces_ht->ht,
 210                         &iter.iter, trace, node.node) {
 211                 ret = ctf_trace_close(trace);
 212                 if (ret) {
 213                         goto rcu_unlock;
 214                 }
 215         }
 216         cds_list_for_each_entry_rcu(stream, &session->recv_list,
 217                         recv_node) {
 218                 /* Close streams which have not been published yet. */
 219                 try_stream_close(stream);
 220         }
 221 rcu_unlock:
 222         rcu_read_unlock();
 223         if (ret) {
 224                 return ret;
 225         }
 226         /* Put self-reference from create. */
 227         session_put(session);
 228         return ret;
 229 }
 230
 231 int session_abort(struct relay_session *session)
 232 {
 233         int ret = 0;
 234
 235         if (!session) {
 236                 return 0;
 237         }
 238
 239         pthread_mutex_lock(&session->lock);
 240         DBG("aborting session %" PRIu64, session->id);
 241         if (session->aborted) {
 242                 ERR("session %" PRIu64 " is already aborted", session->id);
 243                 ret = -1;
 244                 goto unlock;
 245         }
 246         session->aborted = true;
 247 unlock:
 248         pthread_mutex_unlock(&session->lock);
 249         return ret;
 250 }
 251
 252 void print_sessions(void)
 253 {
 254         struct lttng_ht_iter iter;
 255         struct relay_session *session;
 256
 257         if (!sessions_ht) {
 258                 return;
 259         }
 260
 261         rcu_read_lock();
 262         cds_lfht_for_each_entry(sessions_ht->ht, &iter.iter, session,
 263                         session_n.node) {
 264                 if (!session_get(session)) {
 265                         continue;
 266                 }
 267                 DBG("session %p refcount %ld session %" PRIu64,
 268                         session,
 269                         session->ref.refcount,
 270                         session->id);
 271                 session_put(session);
 272         }
 273         rcu_read_unlock();
 274 }