Fix: only create UST metadata on start trace

Fixes #739

Acked-by: Julien Desfossez <julien.desfossez@efficios.com>
Signed-off-by: David Goulet <dgoulet@efficios.com>

diff --git a/src/bin/lttng-sessiond/channel.c b/src/bin/lttng-sessiond/channel.c
index 817100ff449128e2f71705623d6ac4a39d95e0f4..fc343f5910a8babab0737a90955284209438061f 100644 (file)
--- a/src/bin/lttng-sessiond/channel.c
+++ b/src/bin/lttng-sessiond/channel.c
@@ -366,7 +366,10 @@ int channel_ust_create(struct ltt_ust_session *usess,
 
        /* Adding the channel to the channel hash table. */
        rcu_read_lock();
-       lttng_ht_add_unique_str(usess->domain_global.channels, &uchan->node);
+       if (strncmp(uchan->name, DEFAULT_METADATA_NAME,
+                               sizeof(uchan->name))) {
+               lttng_ht_add_unique_str(usess->domain_global.channels, &uchan->node);
+       }
        rcu_read_unlock();
 
        DBG2("Channel %s created successfully", uchan->name);

diff --git a/src/bin/lttng-sessiond/ust-app.c b/src/bin/lttng-sessiond/ust-app.c
index c32bf2b6847e147bcfcfe31041c7cfb300ef2edf..5aad28bbc6d57b458935578f002c658db82ecede 100644 (file)
--- a/src/bin/lttng-sessiond/ust-app.c
+++ b/src/bin/lttng-sessiond/ust-app.c
@@ -827,6 +827,15 @@ struct ust_app_session *alloc_ust_app_session(struct ust_app *app)
        ua_sess->channels = lttng_ht_new(0, LTTNG_HT_TYPE_STRING);
        pthread_mutex_init(&ua_sess->lock, NULL);
 
+       /* Set default metadata channel attribute. */
+       ua_sess->metadata_attr.overwrite = DEFAULT_CHANNEL_OVERWRITE;
+       ua_sess->metadata_attr.subbuf_size = default_get_metadata_subbuf_size();
+       ua_sess->metadata_attr.num_subbuf = DEFAULT_METADATA_SUBBUF_NUM;
+       ua_sess->metadata_attr.switch_timer_interval = DEFAULT_METADATA_SWITCH_TIMER;
+       ua_sess->metadata_attr.read_timer_interval = DEFAULT_METADATA_READ_TIMER;
+       ua_sess->metadata_attr.output = LTTNG_UST_MMAP;
+       ua_sess->metadata_attr.type = LTTNG_UST_CHAN_METADATA;
+
        return ua_sess;
 
 error_free:
@@ -2714,8 +2723,7 @@ error:
  * Called with UST app session lock held and RCU read side lock.
  */
 static int create_ust_app_metadata(struct ust_app_session *ua_sess,
-               struct ust_app *app, struct consumer_output *consumer,
-               struct ustctl_consumer_channel_attr *attr)
+               struct ust_app *app, struct consumer_output *consumer)
 {
        int ret = 0;
        struct ust_app_channel *metadata;
@@ -2743,20 +2751,7 @@ static int create_ust_app_metadata(struct ust_app_session *ua_sess,
                goto error;
        }
 
-       if (!attr) {
-               /* Set default attributes for metadata. */
-               metadata->attr.overwrite = DEFAULT_CHANNEL_OVERWRITE;
-               metadata->attr.subbuf_size = default_get_metadata_subbuf_size();
-               metadata->attr.num_subbuf = DEFAULT_METADATA_SUBBUF_NUM;
-               metadata->attr.switch_timer_interval = DEFAULT_METADATA_SWITCH_TIMER;
-               metadata->attr.read_timer_interval = DEFAULT_METADATA_READ_TIMER;
-               metadata->attr.output = LTTNG_UST_MMAP;
-               metadata->attr.type = LTTNG_UST_CHAN_METADATA;
-       } else {
-               memcpy(&metadata->attr, attr, sizeof(metadata->attr));
-               metadata->attr.output = LTTNG_UST_MMAP;
-               metadata->attr.type = LTTNG_UST_CHAN_METADATA;
-       }
+       memcpy(&metadata->attr, &ua_sess->metadata_attr, sizeof(metadata->attr));
 
        /* Need one fd for the channel. */
        ret = lttng_fd_get(LTTNG_FD_APPS, 1);
@@ -3582,10 +3577,8 @@ int ust_app_create_channel_glb(struct ltt_ust_session *usess,
                pthread_mutex_lock(&ua_sess->lock);
                if (!strncmp(uchan->name, DEFAULT_METADATA_NAME,
                                        sizeof(uchan->name))) {
-                       struct ustctl_consumer_channel_attr attr;
-                       copy_channel_attr_to_ustctl(&attr, &uchan->attr);
-                       ret = create_ust_app_metadata(ua_sess, app, usess->consumer,
-                                       &attr);
+                       copy_channel_attr_to_ustctl(&ua_sess->metadata_attr, &uchan->attr);
+                       ret = 0;
                } else {
                        /* Create channel onto application. We don't need the chan ref. */
                        ret = create_ust_app_channel(ua_sess, uchan, app,
@@ -3790,7 +3783,7 @@ int ust_app_start_trace(struct ltt_ust_session *usess, struct ust_app *app)
         * Create the metadata for the application. This returns gracefully if a
         * metadata was already set for the session.
         */
-       ret = create_ust_app_metadata(ua_sess, app, usess->consumer, NULL);
+       ret = create_ust_app_metadata(ua_sess, app, usess->consumer);
        if (ret < 0) {
                goto error_unlock;
        }
@@ -4217,31 +4210,14 @@ void ust_app_global_update(struct ltt_ust_session *usess, int sock)
         */
        cds_lfht_for_each_entry(ua_sess->channels->ht, &iter.iter, ua_chan,
                        node.node) {
-               /*
-                * For a metadata channel, handle it differently.
-                */
-               if (!strncmp(ua_chan->name, DEFAULT_METADATA_NAME,
-                                       sizeof(ua_chan->name))) {
-                       ret = create_ust_app_metadata(ua_sess, app, usess->consumer,
-                                       &ua_chan->attr);
-                       if (ret < 0) {
-                               goto error_unlock;
-                       }
-                       /* Remove it from the hash table and continue!. */
-                       ret = lttng_ht_del(ua_sess->channels, &iter);
-                       assert(!ret);
-                       delete_ust_app_channel(-1, ua_chan, app);
-                       continue;
-               } else {
-                       ret = do_create_channel(app, usess, ua_sess, ua_chan);
-                       if (ret < 0) {
-                               /*
-                                * Stop everything. On error, the application failed, no more
-                                * file descriptor are available or ENOMEM so stopping here is
-                                * the only thing we can do for now.
-                                */
-                               goto error_unlock;
-                       }
+               ret = do_create_channel(app, usess, ua_sess, ua_chan);
+               if (ret < 0) {
+                       /*
+                        * Stop everything. On error, the application failed, no more
+                        * file descriptor are available or ENOMEM so stopping here is
+                        * the only thing we can do for now.
+                        */
+                       goto error_unlock;
                }
 
                /*

diff --git a/src/bin/lttng-sessiond/ust-app.h b/src/bin/lttng-sessiond/ust-app.h
index fe040ae503db83436c8d93a1f23ecf6fc97e3b3c..2fd3b56d936f764e46c31c3ba0e19ba53480dbb2 100644 (file)
--- a/src/bin/lttng-sessiond/ust-app.h
+++ b/src/bin/lttng-sessiond/ust-app.h
@@ -212,6 +212,9 @@ struct ust_app_session {
        /* If the channel's streams have to be outputed or not. */
        unsigned int output_traces;
        unsigned int live_timer_interval;       /* usec */
+
+       /* Metadata channel attributes. */
+       struct ustctl_consumer_channel_attr metadata_attr;
 };
 
 /*