+/*
+ * Iterate over all stream element of the hashtable and free them. This is race
+ * free since the hashtable received MUST be in a race free synchronization
+ * state. It's the caller responsability to make sure of that.
+ */
+static void destroy_stream_ht(struct lttng_ht *ht)
+{
+ int ret;
+ struct lttng_ht_iter iter;
+ struct lttng_consumer_stream *stream;
+
+ if (ht == NULL) {
+ return;
+ }
+
+ rcu_read_lock();
+ cds_lfht_for_each_entry(ht->ht, &iter.iter, stream, node.node) {
+ ret = lttng_ht_del(ht, &iter);
+ assert(!ret);
+
+ free(stream);
+ }
+ rcu_read_unlock();
+
+ lttng_ht_destroy(ht);
+}
+
+/*
+ * Clean up a metadata stream and free its memory.
+ */
+static void consumer_del_metadata_stream(struct lttng_consumer_stream *stream)
+{
+ int ret;
+ struct consumer_relayd_sock_pair *relayd;
+
+ assert(stream);
+ /*
+ * This call should NEVER receive regular stream. It must always be
+ * metadata stream and this is crucial for data structure synchronization.
+ */
+ assert(stream->metadata_flag);
+
+ pthread_mutex_lock(&consumer_data.lock);
+ switch (consumer_data.type) {
+ case LTTNG_CONSUMER_KERNEL:
+ if (stream->mmap_base != NULL) {
+ ret = munmap(stream->mmap_base, stream->mmap_len);
+ if (ret != 0) {
+ PERROR("munmap metadata stream");
+ }
+ }
+ break;
+ case LTTNG_CONSUMER32_UST:
+ case LTTNG_CONSUMER64_UST:
+ lttng_ustconsumer_del_stream(stream);
+ break;
+ default:
+ ERR("Unknown consumer_data type");
+ assert(0);
+ }
+ pthread_mutex_unlock(&consumer_data.lock);
+
+ if (stream->out_fd >= 0) {
+ ret = close(stream->out_fd);
+ if (ret) {
+ PERROR("close");
+ }
+ }
+
+ if (stream->wait_fd >= 0 && !stream->wait_fd_is_copy) {
+ ret = close(stream->wait_fd);
+ if (ret) {
+ PERROR("close");
+ }
+ }
+
+ if (stream->shm_fd >= 0 && stream->wait_fd != stream->shm_fd) {
+ ret = close(stream->shm_fd);
+ if (ret) {
+ PERROR("close");
+ }
+ }
+
+ /* Check and cleanup relayd */
+ rcu_read_lock();
+ relayd = consumer_find_relayd(stream->net_seq_idx);
+ if (relayd != NULL) {
+ uatomic_dec(&relayd->refcount);
+ assert(uatomic_read(&relayd->refcount) >= 0);
+
+ /* Closing streams requires to lock the control socket. */
+ pthread_mutex_lock(&relayd->ctrl_sock_mutex);
+ ret = relayd_send_close_stream(&relayd->control_sock,
+ stream->relayd_stream_id, stream->next_net_seq_num - 1);
+ pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
+ if (ret < 0) {
+ DBG("Unable to close stream on the relayd. Continuing");
+ /*
+ * Continue here. There is nothing we can do for the relayd.
+ * Chances are that the relayd has closed the socket so we just
+ * continue cleaning up.
+ */
+ }
+
+ /* Both conditions are met, we destroy the relayd. */
+ if (uatomic_read(&relayd->refcount) == 0 &&
+ uatomic_read(&relayd->destroy_flag)) {
+ destroy_relayd(relayd);
+ }
+ }
+ rcu_read_unlock();
+
+ /* Atomically decrement channel refcount since other threads can use it. */
+ uatomic_dec(&stream->chan->refcount);
+ if (!uatomic_read(&stream->chan->refcount)
+ && !uatomic_read(&stream->chan->nb_init_streams)) {
+ /* Go for channel deletion! */
+ consumer_del_channel(stream->chan);
+ }
+
+ free(stream);
+}
+
+/*
+ * Action done with the metadata stream when adding it to the consumer internal
+ * data structures to handle it.
+ */
+static void consumer_add_metadata_stream(struct lttng_consumer_stream *stream)
+{
+ struct consumer_relayd_sock_pair *relayd;
+
+ /* Find relayd and, if one is found, increment refcount. */
+ rcu_read_lock();
+ relayd = consumer_find_relayd(stream->net_seq_idx);
+ if (relayd != NULL) {
+ uatomic_inc(&relayd->refcount);
+ }
+ rcu_read_unlock();
+}
+
+/*
+ * Thread polls on metadata file descriptor and write them on disk or on the
+ * network.
+ */
+void *lttng_consumer_thread_poll_metadata(void *data)
+{
+ int ret, i, pollfd;
+ uint32_t revents, nb_fd;
+ struct lttng_consumer_stream *stream;
+ struct lttng_ht_iter iter;
+ struct lttng_ht_node_ulong *node;
+ struct lttng_ht *metadata_ht = NULL;
+ struct lttng_poll_event events;
+ struct lttng_consumer_local_data *ctx = data;
+ ssize_t len;
+
+ rcu_register_thread();
+
+ DBG("Thread metadata poll started");
+
+ metadata_ht = lttng_ht_new(0, LTTNG_HT_TYPE_ULONG);
+ if (metadata_ht == NULL) {
+ goto end;
+ }
+
+ /* Size is set to 1 for the consumer_metadata pipe */
+ ret = lttng_poll_create(&events, 2, LTTNG_CLOEXEC);
+ if (ret < 0) {
+ ERR("Poll set creation failed");
+ goto end;
+ }
+
+ ret = lttng_poll_add(&events, ctx->consumer_metadata_pipe[0], LPOLLIN);
+ if (ret < 0) {
+ goto end;
+ }
+
+ /* Main loop */
+ DBG("Metadata main loop started");
+
+ while (1) {
+ lttng_poll_reset(&events);
+
+ nb_fd = LTTNG_POLL_GETNB(&events);
+
+ /* Only the metadata pipe is set */
+ if (nb_fd == 0 && consumer_quit == 1) {
+ goto end;
+ }
+
+restart:
+ DBG("Metadata poll wait with %d fd(s)", nb_fd);
+ ret = lttng_poll_wait(&events, -1);
+ DBG("Metadata event catched in thread");
+ if (ret < 0) {
+ if (errno == EINTR) {
+ goto restart;
+ }
+ goto error;
+ }
+
+ for (i = 0; i < nb_fd; i++) {
+ revents = LTTNG_POLL_GETEV(&events, i);
+ pollfd = LTTNG_POLL_GETFD(&events, i);
+
+ /* Check the metadata pipe for incoming metadata. */
+ if (pollfd == ctx->consumer_metadata_pipe[0]) {
+ if (revents & (LPOLLERR | LPOLLHUP )) {
+ DBG("Metadata thread pipe hung up");
+ /*
+ * Remove the pipe from the poll set and continue the loop
+ * since their might be data to consume.
+ */
+ lttng_poll_del(&events, ctx->consumer_metadata_pipe[0]);
+ close(ctx->consumer_metadata_pipe[0]);
+ continue;
+ } else if (revents & LPOLLIN) {
+ stream = zmalloc(sizeof(struct lttng_consumer_stream));
+ if (stream == NULL) {
+ PERROR("zmalloc metadata consumer stream");
+ goto error;
+ }
+
+ do {
+ /* Get the stream and add it to the local hash table */
+ ret = read(pollfd, stream,
+ sizeof(struct lttng_consumer_stream));
+ } while (ret < 0 && errno == EINTR);
+ if (ret < 0 || ret < sizeof(struct lttng_consumer_stream)) {
+ PERROR("read metadata stream");
+ free(stream);
+ /*
+ * Let's continue here and hope we can still work
+ * without stopping the consumer. XXX: Should we?
+ */
+ continue;
+ }
+
+ DBG("Adding metadata stream %d to poll set",
+ stream->wait_fd);
+
+ rcu_read_lock();
+ /* The node should be init at this point */
+ lttng_ht_add_unique_ulong(metadata_ht,
+ &stream->waitfd_node);
+ rcu_read_unlock();
+
+ /* Add metadata stream to the global poll events list */
+ lttng_poll_add(&events, stream->wait_fd,
+ LPOLLIN | LPOLLPRI);
+
+ consumer_add_metadata_stream(stream);
+ }
+
+ /* Metadata pipe handled. Continue handling the others */
+ continue;
+ }
+
+ /* From here, the event is a metadata wait fd */
+
+ rcu_read_lock();
+ lttng_ht_lookup(metadata_ht, (void *)((unsigned long) pollfd),
+ &iter);
+ node = lttng_ht_iter_get_node_ulong(&iter);
+ if (node == NULL) {
+ /* FD not found, continue loop */
+ rcu_read_unlock();
+ continue;
+ }
+
+ stream = caa_container_of(node, struct lttng_consumer_stream,
+ waitfd_node);
+
+ /* Get the data out of the metadata file descriptor */
+ if (revents & (LPOLLIN | LPOLLPRI)) {
+ DBG("Metadata available on fd %d", pollfd);
+ assert(stream->wait_fd == pollfd);
+
+ len = ctx->on_buffer_ready(stream, ctx);
+ /* It's ok to have an unavailable sub-buffer */
+ if (len < 0 && len != -EAGAIN) {
+ rcu_read_unlock();
+ goto end;
+ } else if (len > 0) {
+ stream->data_read = 1;
+ }
+ }
+
+ /*
+ * Remove the stream from the hash table since there is no data
+ * left on the fd because we previously did a read on the buffer.
+ */
+ if (revents & (LPOLLERR | LPOLLHUP)) {
+ DBG("Metadata fd %d is hup|err|nval.", pollfd);
+ if (!stream->hangup_flush_done
+ && (consumer_data.type == LTTNG_CONSUMER32_UST
+ || consumer_data.type == LTTNG_CONSUMER64_UST)) {
+ DBG("Attempting to flush and consume the UST buffers");
+ lttng_ustconsumer_on_stream_hangup(stream);
+
+ /* We just flushed the stream now read it. */
+ len = ctx->on_buffer_ready(stream, ctx);
+ /* It's ok to have an unavailable sub-buffer */
+ if (len < 0 && len != -EAGAIN) {
+ rcu_read_unlock();
+ goto end;
+ }
+ }
+
+ /* Removing it from hash table, poll set and free memory */
+ lttng_ht_del(metadata_ht, &iter);
+
+ lttng_poll_del(&events, stream->wait_fd);
+ consumer_del_metadata_stream(stream);
+ }
+ rcu_read_unlock();
+ }
+ }
+
+error:
+end:
+ DBG("Metadata poll thread exiting");
+ lttng_poll_clean(&events);
+
+ if (metadata_ht) {
+ destroy_stream_ht(metadata_ht);
+ }
+
+ rcu_unregister_thread();
+ return NULL;
+}
+