+ ustctl_flush_buffer(stream->ustream, 1);
+
+ ret = lttng_ustconsumer_take_snapshot(stream);
+ if (ret < 0) {
+ ERR("Taking UST snapshot");
+ goto error_unlock;
+ }
+
+ ret = lttng_ustconsumer_get_produced_snapshot(stream, &produced_pos);
+ if (ret < 0) {
+ ERR("Produced UST snapshot position");
+ goto error_unlock;
+ }
+
+ ret = lttng_ustconsumer_get_consumed_snapshot(stream, &consumed_pos);
+ if (ret < 0) {
+ ERR("Consumerd UST snapshot position");
+ goto error_unlock;
+ }
+
+ /*
+ * The original value is sent back if max stream size is larger than
+ * the possible size of the snapshot. Also, we asume that the session
+ * daemon should never send a maximum stream size that is lower than
+ * subbuffer size.
+ */
+ consumed_pos = consumer_get_consumed_maxsize(consumed_pos,
+ produced_pos, max_stream_size);
+
+ while (consumed_pos < produced_pos) {
+ ssize_t read_len;
+ unsigned long len, padded_len;
+
+ health_code_update();
+
+ DBG("UST consumer taking snapshot at pos %lu", consumed_pos);
+
+ ret = ustctl_get_subbuf(stream->ustream, &consumed_pos);
+ if (ret < 0) {
+ if (ret != -EAGAIN) {
+ PERROR("ustctl_get_subbuf snapshot");
+ goto error_close_stream;
+ }
+ DBG("UST consumer get subbuf failed. Skipping it.");
+ consumed_pos += stream->max_sb_size;
+ continue;
+ }
+
+ ret = ustctl_get_subbuf_size(stream->ustream, &len);
+ if (ret < 0) {
+ ERR("Snapshot ustctl_get_subbuf_size");
+ goto error_put_subbuf;
+ }
+
+ ret = ustctl_get_padded_subbuf_size(stream->ustream, &padded_len);
+ if (ret < 0) {
+ ERR("Snapshot ustctl_get_padded_subbuf_size");
+ goto error_put_subbuf;
+ }
+
+ read_len = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, len,
+ padded_len - len, NULL);
+ if (use_relayd) {
+ if (read_len != len) {
+ ret = -EPERM;
+ goto error_put_subbuf;
+ }
+ } else {
+ if (read_len != padded_len) {
+ ret = -EPERM;
+ goto error_put_subbuf;
+ }
+ }
+
+ ret = ustctl_put_subbuf(stream->ustream);
+ if (ret < 0) {
+ ERR("Snapshot ustctl_put_subbuf");
+ goto error_close_stream;
+ }
+ consumed_pos += stream->max_sb_size;
+ }
+
+ /* Simply close the stream so we can use it on the next snapshot. */
+ consumer_stream_close(stream);
+ pthread_mutex_unlock(&stream->lock);
+ }
+
+ rcu_read_unlock();
+ return 0;
+
+error_put_subbuf:
+ if (ustctl_put_subbuf(stream->ustream) < 0) {
+ ERR("Snapshot ustctl_put_subbuf");
+ }
+error_close_stream:
+ consumer_stream_close(stream);
+error_unlock:
+ pthread_mutex_unlock(&stream->lock);
+error:
+ rcu_read_unlock();
+ return ret;
+}
+
+/*
+ * Receive the metadata updates from the sessiond.
+ */
+int lttng_ustconsumer_recv_metadata(int sock, uint64_t key, uint64_t offset,
+ uint64_t len, struct lttng_consumer_channel *channel,
+ int timer, int wait)
+{
+ int ret, ret_code = LTTCOMM_CONSUMERD_SUCCESS;
+ char *metadata_str;
+
+ DBG("UST consumer push metadata key %" PRIu64 " of len %" PRIu64, key, len);
+
+ metadata_str = zmalloc(len * sizeof(char));
+ if (!metadata_str) {
+ PERROR("zmalloc metadata string");
+ ret_code = LTTCOMM_CONSUMERD_ENOMEM;
+ goto end;
+ }
+
+ health_code_update();
+
+ /* Receive metadata string. */
+ ret = lttcomm_recv_unix_sock(sock, metadata_str, len);
+ if (ret < 0) {
+ /* Session daemon is dead so return gracefully. */
+ ret_code = ret;
+ goto end_free;
+ }
+
+ health_code_update();
+
+ pthread_mutex_lock(&channel->metadata_cache->lock);
+ ret = consumer_metadata_cache_write(channel, offset, len, metadata_str);
+ if (ret < 0) {
+ /* Unable to handle metadata. Notify session daemon. */
+ ret_code = LTTCOMM_CONSUMERD_ERROR_METADATA;
+ /*
+ * Skip metadata flush on write error since the offset and len might
+ * not have been updated which could create an infinite loop below when
+ * waiting for the metadata cache to be flushed.
+ */
+ pthread_mutex_unlock(&channel->metadata_cache->lock);
+ goto end_free;
+ }
+ pthread_mutex_unlock(&channel->metadata_cache->lock);
+
+ if (!wait) {
+ goto end_free;
+ }
+ while (consumer_metadata_cache_flushed(channel, offset + len, timer)) {
+ DBG("Waiting for metadata to be flushed");
+
+ health_code_update();
+
+ usleep(DEFAULT_METADATA_AVAILABILITY_WAIT_TIME);
+ }
+
+end_free:
+ free(metadata_str);
+end:
+ return ret_code;
+}
+
+/*
+ * Receive command from session daemon and process it.
+ *
+ * Return 1 on success else a negative value or 0.
+ */
+int lttng_ustconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
+ int sock, struct pollfd *consumer_sockpoll)
+{
+ ssize_t ret;
+ enum lttcomm_return_code ret_code = LTTCOMM_CONSUMERD_SUCCESS;
+ struct lttcomm_consumer_msg msg;
+ struct lttng_consumer_channel *channel = NULL;
+
+ health_code_update();
+
+ ret = lttcomm_recv_unix_sock(sock, &msg, sizeof(msg));
+ if (ret != sizeof(msg)) {
+ DBG("Consumer received unexpected message size %zd (expects %zu)",
+ ret, sizeof(msg));
+ /*
+ * The ret value might 0 meaning an orderly shutdown but this is ok
+ * since the caller handles this.
+ */
+ if (ret > 0) {
+ lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_CMD);
+ ret = -1;
+ }
+ return ret;
+ }
+
+ health_code_update();
+
+ /* deprecated */
+ assert(msg.cmd_type != LTTNG_CONSUMER_STOP);
+
+ health_code_update();
+
+ /* relayd needs RCU read-side lock */
+ rcu_read_lock();
+
+ switch (msg.cmd_type) {
+ case LTTNG_CONSUMER_ADD_RELAYD_SOCKET:
+ {
+ /* Session daemon status message are handled in the following call. */
+ ret = consumer_add_relayd_socket(msg.u.relayd_sock.net_index,
+ msg.u.relayd_sock.type, ctx, sock, consumer_sockpoll,
+ &msg.u.relayd_sock.sock, msg.u.relayd_sock.session_id,
+ msg.u.relayd_sock.relayd_session_id);
+ goto end_nosignal;
+ }
+ case LTTNG_CONSUMER_DESTROY_RELAYD:
+ {
+ uint64_t index = msg.u.destroy_relayd.net_seq_idx;
+ struct consumer_relayd_sock_pair *relayd;
+
+ DBG("UST consumer destroying relayd %" PRIu64, index);
+
+ /* Get relayd reference if exists. */
+ relayd = consumer_find_relayd(index);
+ if (relayd == NULL) {
+ DBG("Unable to find relayd %" PRIu64, index);
+ ret_code = LTTCOMM_CONSUMERD_RELAYD_FAIL;
+ }
+
+ /*