Function split_into_chunks

nodedb-array/src/sync/snapshot.rs:153–200

Split a [`TileSnapshot`] into a header plus a sequence of fixed-size chunks. `max_chunk_bytes` must be at least 64. Returns [`ArrayError::InvalidOp`] if it is smaller. `total_chunks = ceil(blob.len() / max_chunk_bytes).max(1)` — there is always at least one chunk, even for an empty blob.

(
    s: &TileSnapshot,
    max_chunk_bytes: usize,
)

/// `total_chunks = ceil(blob.len() / max_chunk_bytes).max(1)` — there is
/// always at least one chunk, even for an empty blob.
pub fn split_into_chunks(
    s: &TileSnapshot,
    max_chunk_bytes: usize,
) -> ArrayResult<(SnapshotHeader, Vec<SnapshotChunk>)> {
    if max_chunk_bytes < 64 {
        return Err(ArrayError::InvalidOp {
            detail: "max_chunk_bytes too small".into(),
        });
    }

    let blob = &s.tile_blob;
    let total_chunks = if blob.is_empty() {
        1
    } else {
        blob.len().div_ceil(max_chunk_bytes).max(1) as u32
    };

    let header = SnapshotHeader {
        array: s.array.clone(),
        coord_range: s.coord_range.clone(),
        total_chunks,
        snapshot_hlc: s.snapshot_hlc,
        schema_hlc: s.schema_hlc,
    };

    let chunks: Vec<SnapshotChunk> = if blob.is_empty() {
        vec![SnapshotChunk {
            array: s.array.clone(),
            chunk_index: 0,
            total_chunks: 1,
            payload: Vec::new(),
            snapshot_hlc: s.snapshot_hlc,
        }]
    } else {
        blob.chunks(max_chunk_bytes)
            .enumerate()
            .map(|(i, slice)| SnapshotChunk {
                array: s.array.clone(),
                chunk_index: i as u32,
                total_chunks,
                payload: slice.to_vec(),
                snapshot_hlc: s.snapshot_hlc,
            })
            .collect()
    };

    Ok((header, chunks))
}

/// Reassemble a [`TileSnapshot`] from a header and a slice of chunks.
///