Struct HistogramEngine 

pub struct HistogramEngine { /* private fields */ }

Engine for computing histograms from journal files.

The engine maintains caches and resources for efficiently computing histograms across multiple queries. It can be reused for multiple histogram computations.

Implementations

impl HistogramEngine

pub fn new() -> Self

Creates a new HistogramEngine with a default capacity of 1000 bucket responses.

pub fn with_capacity(capacity: usize) -> Self

Creates a new HistogramEngine with the specified cache capacity.

The capacity determines how many bucket responses will be cached before old entries are evicted using an LRU policy.

pub fn compute_from_indexes( &self, indexed_files: &[(FileIndexKey, FileIndex)], time_range: &QueryTimeRange, facets: &[String], filter_expr: &Filter, ) -> Result<Histogram>

Compute a histogram from pre-indexed files.

This method allows you to compute histograms from file indexes that have already been loaded, avoiding redundant cache lookups and file discoveries.

Arguments

• indexed_files - Pre-computed file indexes
• time_range - Query time range with aligned boundaries and bucket duration
• facets - Fields to index
• filter_expr - Filter expression to apply