urna-runtime 0.5.1

mmap runtime of the urna vector database: simd exact search, hnsw, bm25, graph and hybrid search with mandatory exact rerank
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59

//! Multimodal space open logic (0x15 space_table + the 0x20-0x2F vector
//! bands), carved out of `mmap_file.rs` so that file stays under the
//! 300-line crate guard. Opens only behind the additive
//! `supports_multimodal` capability, mirroring how the blob pair opens
//! behind `blobs_present`. The bands are fixed-stride slabs read straight
//! off the mmap by the per-space exact search.

use urna_format::layout::{SECTION_SPACE_EMBEDDINGS_BASE, SECTION_SPACE_TABLE};
use urna_format::reader::UrnaView;
use urna_format::sections::{SpaceEntry, decode_space_table};

use crate::error::RuntimeError;
use urna_format::reader::validate_slab_values;

/// one opened space: its directory entry plus the byte range of its band
/// slab inside the mmap (resolved once at open time).
#[derive(Clone, Debug)]
pub(crate) struct OpenSpace {
    pub entry: SpaceEntry,
    pub offset: usize,
    pub size: usize,
}

/// Open the space_table and resolve each listed space's band range.
/// `None` when the capability or the section is absent. the band's
/// presence and exact size were already validated by the reader
/// (`validate_space_bands`), so a missing band here is a typed error,
/// never a silent skip.
pub(crate) fn open_space_sections(view: &UrnaView) -> Result<Option<Vec<OpenSpace>>, RuntimeError> {
    let multimodal = view
        .manifest
        .capabilities_ext
        .as_ref()
        .and_then(|e| e.supports_multimodal)
        .unwrap_or(false);
    if !multimodal || view.entry(SECTION_SPACE_TABLE).is_err() {
        return Ok(None);
    }
    let entries = decode_space_table(&view.decoded_section(SECTION_SPACE_TABLE)?)?;
    let mut spaces = Vec::with_capacity(entries.len());
    for entry in entries {
        let band_id = SECTION_SPACE_EMBEDDINGS_BASE + entry.space_index as u32;
        let band = view.entry(band_id)?;
        // same NaN/Inf gate the canonical embeddings pass at open: a band
        // lane the kernels would score must be finite.
        validate_slab_values(
            band.encoding,
            view.get_section_data(band_id)?,
            entry.n_vectors as usize,
            entry.dim as usize,
        )?;
        spaces.push(OpenSpace {
            entry,
            offset: band.offset as usize,
            size: band.size as usize,
        });
    }
    Ok(Some(spaces))
}