Function process_scan_payload 

pub(crate) fn process_scan_payload(
    payload: &[u8],
    channel: u8,
    asset: u32,
    parquet_root: &Path,
    active_calibration: &CalibrationSpec,
    rotate_secs: u64,
    logger: &mut Option<ParquetLogger>,
    file_index: &mut usize,
    last_sequence: &mut Option<u64>,
) -> CloseOutcome

Decodes one FlatBuffer scan payload and writes its samples to Parquet.

The payload contains the first sample timestamp plus a fixed interval, so this function reconstructs each sample timestamp and rotates files at aligned source-time windows and UTC date changes. The returned outcome tells the caller which buffered JetStream messages are now safe to ack.

Before each sample, the open file is closed and a new one opened (with the next free part index) when there is no open file, when the sample’s UTC date differs from the file’s, or when ParquetLogger::should_rotate_before says so. A single payload can therefore close a file part way through. The check is made once per run of samples rather than once per sample: ParquetLogger::write_run buffers, in one go, as many of the following samples as the open file accepts. The files and row groups are the same as with a check per sample.

Sequence gaps and resets are logged but do not stop the write. A payload that is not a valid FlatBuffer Scan is logged and writes nothing. If a sample timestamp overflows, the rest of that payload is dropped. If closing a file or writing a row group fails, the failure is counted in the outcome and the rest of the payload is skipped, since the message will be redelivered.

Arguments

• payload - FlatBuffer Scan bytes from one JetStream message.
• channel - LabJack channel the payload belongs to.
• asset - Asset number for output paths.
• parquet_root - Root output directory.
• active_calibration - Calibration stored in any file opened here.
• rotate_secs - Rotation window length in seconds.
• logger - Open file of the channel, if any; replaced when the file rotates.
• file_index - Part index of the open file; updated when a new file is opened.
• last_sequence - Sequence number of the previous scan, for gap detection; updated to this scan’s sequence.

Returns

How many files were closed and how many closes failed while writing this payload.

Panics

Panics if a new file cannot be created (see ParquetLogger::new and next_file_index).