Struct V3Writer 

pub struct V3Writer { /* private fields */ }

V3 columnar metrics writer.

Accumulates metrics in columnar format with dictionary deduplication. Call V3Writer::write for each metric, then V3Writer::finalize to finalize and get the encoded data.

Implementations

impl V3Writer

pub fn new() -> Self

Creates a new V3 writer.

pub fn metric_count(&self) -> usize

Returns the number of metrics written so far.

pub fn estimated_uncompressed_len(&self) -> usize

Returns an estimate, in bytes, of the uncompressed size of the payload this writer would currently finalize to.

This exists so callers can decide when to stop adding metrics to a batch, rather than encoding an oversized batch and discovering afterwards that it has to be split and re-encoded. It is deliberately cheap: it inspects only the lengths of the accumulated columns, so it is O(1) and safe to call after every metric.

The figure is an estimate, not the exact finalized size. Dictionary string buffers are counted exactly, since they dominate for the high-cardinality workloads this guards against, while packed integer columns are counted at a fixed per-entry allowance because their true varint widths are only known once delta encoding runs during V3Writer::finalize. The allowance errs on the high side, so batches are cut slightly early rather than slightly late; callers MUST still check the finalized payload against their real size limits.

pub fn write( &mut self, metric_type: V3MetricType, name: &str, ) -> V3MetricBuilder<'_>

Begins writing a new metric.

Returns a V3MetricBuilder that must be used to set the metric’s properties and add points, then closed with V3MetricBuilder::close.

pub fn finalize(self) -> Result<V3EncodedMetrics, V3EncodeError>

Finalizes the writer and serializes the data to the given output buffer.

This performs delta encoding on all index arrays.

Trait Implementations

impl Debug for V3Writer

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for V3Writer

fn default() -> V3Writer

Returns the “default value” for a type.