Struct CsvRowWriter 

pub(crate) struct CsvRowWriter {
    pub(crate) timestamps: Rfc3339Formatter,
    pub(crate) values: ValueTextCache,
    pub(crate) channel_field: Vec<u8>,
}

Writes export CSV rows into a chunk buffer.

A row is <timestamp>,chNN,<raw_value>,<calibrated_value>,<calibration_id>, plus ,<filtered_value> in a filtered export, then \n: byte for byte what writeln! with {} for every field gives (floats in Rust’s default Display format, the filtered value empty when it is not finite). It formats the timestamp with Rfc3339Formatter and the values through ValueTextCache, and builds ,chNN, once per channel, so a row normally costs no allocation and at most one float formatting (the filtered value).

Fields

timestamps: Rfc3339Formatter

Timestamp formatter, shared by every row of the export.

values: ValueTextCache

Recent raw,calibrated texts.

channel_field: Vec<u8>

,chNN, of the channel being written.

Implementations

impl CsvRowWriter

pub(crate) fn new() -> Self

Creates a writer; call Self::set_channel before the first row.

pub(crate) fn set_channel(&mut self, channel: u8)

Sets the channel written in the following rows.

pub(crate) fn write_row( &mut self, out: &mut Vec<u8>, timestamp_unix_ns: i64, raw_value: f64, spec: &CalibrationSpec, calibration_id: &str, filtered: FilteredColumn, )

Appends one row to out.

Arguments

• out - Chunk buffer.
• timestamp_unix_ns - Sample time.
• raw_value - Value stored in the Parquet file.
• spec - Calibration of the row’s file.
• calibration_id - Calibration id written in the fifth column.
• filtered - The filtered_value column, if any.