src.ctf.lttng-live: make `lttng_live_get_one_metadata_packet()` return status

[babeltrace.git] / src / plugins / ctf / lttng-live / metadata.c

diff --git a/src/plugins/ctf/lttng-live/metadata.c b/src/plugins/ctf/lttng-live/metadata.c
index f77d62f8baf74d1ce049b1e35cb201b10563f03a..df75b15f5e9410d10fb1f9c28d1985adad683526 100644 (file)
--- a/src/plugins/ctf/lttng-live/metadata.c
+++ b/src/plugins/ctf/lttng-live/metadata.c
@@ -120,15 +120,16 @@ enum lttng_live_iterator_status lttng_live_metadata_update(
 {
        struct lttng_live_session *session = trace->session;
        struct lttng_live_metadata *metadata = trace->metadata;
-       ssize_t ret = 0;
        size_t size, len_read = 0;
        char *metadata_buf = NULL;
+       bool keep_receiving;
        FILE *fp = NULL;
        enum ctf_metadata_decoder_status decoder_status;
        enum lttng_live_iterator_status status =
                LTTNG_LIVE_ITERATOR_STATUS_OK;
        bt_logging_level log_level = trace->log_level;
        bt_self_component *self_comp = trace->self_comp;
+       enum lttng_live_get_one_metadata_status metadata_status;
 
        /* No metadata stream yet. */
        if (!metadata) {
@@ -156,42 +157,49 @@ enum lttng_live_iterator_status lttng_live_metadata_update(
                goto error;
        }
 
+       keep_receiving = true;
        /* Grab all available metadata. */
-       do {
+       while (keep_receiving) {
+               size_t reply_len = 0;
                /*
-                * get_one_metadata_packet returns the number of bytes
-                * received, 0 when we have received everything, a
-                * negative value on error.
+                * lttng_live_get_one_metadata_packet() asks the Relay Daemon
+                * for new metadata. If new metadata is received, the function
+                * writes it to the provided file handle and updates the
+                * reply_len output parameter. We call this function in loop
+                * until it returns _END meaning that no new metadata is
+                * available.
+                * We may receive a _CLOSED status if the metadata stream we
+                * are requesting is no longer available on the relay.
+                * If we receive an _ERROR status, it means there was a
+                * networking, allocating, or some other unrecoverable error.
                 */
-               ret = lttng_live_get_one_metadata_packet(trace, fp);
-               if (ret > 0) {
-                       len_read += ret;
+               metadata_status = lttng_live_get_one_metadata_packet(trace, fp,
+                       &reply_len);
+
+               switch (metadata_status) {
+               case LTTNG_LIVE_GET_ONE_METADATA_STATUS_OK:
+                       len_read += reply_len;
+                       break;
+               case LTTNG_LIVE_GET_ONE_METADATA_STATUS_END:
+                       keep_receiving = false;
+                       break;
+               case LTTNG_LIVE_GET_ONE_METADATA_STATUS_CLOSED:
+                       keep_receiving = false;
+                       break;
+               case LTTNG_LIVE_GET_ONE_METADATA_STATUS_ERROR:
+                       goto error;
+               default:
+                       abort();
                }
-       } while (ret > 0);
+       }
 
        /*
-        * Consider metadata closed as soon as we get an error reading
-        * it (e.g. cannot be found).
+        * A closed metadata stream means the trace is no longer active. Return
+        * _END so that the caller can remove the trace from its list.
         */
-       if (ret < 0) {
-               if (!metadata->closed) {
-                       metadata->closed = true;
-                       /*
-                        * Release our reference on the trace as soon as
-                        * we know the metadata stream is not available
-                        * anymore. This won't necessarily teardown the
-                        * metadata objects immediately, but only when
-                        * the data streams are done.
-                        */
-                       metadata->trace = NULL;
-               }
-               if (errno == EINTR) {
-                       if (lttng_live_graph_is_canceled(
-                                       session->lttng_live_msg_iter)) {
-                               status = LTTNG_LIVE_ITERATOR_STATUS_AGAIN;
-                               goto end;
-                       }
-               }
+       if (metadata_status == LTTNG_LIVE_GET_ONE_METADATA_STATUS_CLOSED) {
+               status = LTTNG_LIVE_ITERATOR_STATUS_END;
+               goto end;
        }
 
        if (bt_close_memstream(&metadata_buf, &size, fp)) {
@@ -260,8 +268,15 @@ enum lttng_live_iterator_status lttng_live_metadata_update(
        }
 
        goto end;
+
 error:
-       status = LTTNG_LIVE_ITERATOR_STATUS_ERROR;
+       if (errno == EINTR) {
+               if (lttng_live_graph_is_canceled(session->lttng_live_msg_iter)) {
+                       status = LTTNG_LIVE_ITERATOR_STATUS_AGAIN;
+               }
+       } else {
+               status = LTTNG_LIVE_ITERATOR_STATUS_ERROR;
+       }
 end:
        if (fp) {
                int closeret;