With a DECTRIS detector the broker starts the writers - and so learned the collection's start
message - only when the detector's own start message arrived, after /start had returned. A reader
started right after /start found no collection (404) and had to wait for, and race with, the
detector.
- /start registers the collection in LiveCollection (Expect) as it is accepted, so GET /live/events
is accepted from then on. The image pusher fills in the start message when it starts the writers
(Begin) - at once on the FPGA path, when the detector's start message arrives on the DECTRIS path.
- The event stream's first event is now `start`, carrying that start message (CBOR, base64) with
run number, file prefix, image count and images per file; it replaces `collection`. Until it is
known the stream only keeps alive. file and end follow as before.
- However the measurement thread ends, it ends a collection the pusher did not end (EndIfOpen), so a
cancel or a failure before the detector streamed reaches the reader as `end` with an error. The
wait is event-driven: it ends with the start message or with the measurement.
- GET /live/start.cbor is removed: the stream carries the start message, one route less.
- rugnux takes the start message from the stream (BrokerFeed::WaitForStart), so it can be started
right after /start; files reported before it attached the reader are replayed to it.
Tests: LiveCollection_ExpectedAtStart; BrokerFeed_StartFromEventStream (an event stream whose start
message comes late, then a file and the end).
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SVmAWnzCmRKAXVUCdc4iNi
rugnux <path>/<prefix>_master.h5 http://<broker>:<port>/ - when the master file is not on disk yet -
processes the broker's current collection as it is written:
- the start message comes from GET /live/start.cbor; the given path has to end in the collection's
master file name, and the data files are read next to it;
- JFJochStartMessageReader builds the dataset from the start message (detector, geometry,
goniometer, mask) and reads the images straight from the data files; a read of an image whose file
the broker has not reported waits for it;
- BrokerFeed reads GET /live/events in a thread of its own and hands the reader each closed file. On
end, the run finishes with the images the collection delivered (a read past them returns no image).
A broken stream, another collection, or a refused follower makes every waiting read throw
LiveCollectionLost, which ends the run like a fatal resource error;
- the token is taken from JUNGFRAUJOCH_HTTP_TOKEN (the variable the viewer uses) and sent only in
the Authorization header; without it, and with no master file on disk, rugnux stops at once;
- rotation data and --mode mx only; plain http only (TLS is not linked into rugnux).
With the master file on disk, the URL is ignored and the run is offline as before. The streamed run
does not read the master file and is not compared with it: its result can differ from an offline run
of the same files in the last bits of the metadata.
Tests ([Live]): LiveCollection, the server-sent-event parser, the FileWriter callback, the TCP
pusher's closed-file reports with two real writers, and JFJochStartMessageReader against the
master the writer produced.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SVmAWnzCmRKAXVUCdc4iNi
leonarski_fandClaude Opus 5.5