189 lines
7.9 KiB
Rust
189 lines
7.9 KiB
Rust
//! COW Branching — Vector-Native Copy-on-Write
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//!
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//! Demonstrates RVCOW branching per ADR-031:
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//! 1. Create a base RVF store with vectors
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//! 2. Derive a child store via COW branch
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//! 3. Modify vectors in the child (triggers slab copy)
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//! 4. Show that the child file is much smaller than parent
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//! 5. Verify both parent and child are independently queryable
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//! 6. Show COW statistics (local vs inherited clusters)
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//!
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//! RVF segments used: VEC_SEG, MANIFEST_SEG, COW_MAP (conceptual), MEMBERSHIP
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//!
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//! Run with:
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//! cargo run --example cow_branching
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use rvf_runtime::options::DistanceMetric;
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use rvf_runtime::{QueryOptions, RvfOptions, RvfStore};
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use tempfile::TempDir;
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/// Simple pseudo-random number generator (LCG) for deterministic results.
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fn random_vector(dim: usize, seed: u64) -> Vec<f32> {
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let mut v = Vec::with_capacity(dim);
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let mut x = seed.wrapping_add(1);
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for _ in 0..dim {
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x = x.wrapping_mul(6364136223846793005).wrapping_add(1442695040888963407);
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v.push(((x >> 33) as f32) / (u32::MAX as f32) - 0.5);
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}
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v
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}
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fn hex(data: &[u8], n: usize) -> String {
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data.iter().take(n).map(|b| format!("{:02x}", b)).collect()
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}
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fn main() {
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println!("=== RVF COW Branching Example ===\n");
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let dim = 128;
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let num_vectors = 500;
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let tmp_dir = TempDir::new().expect("failed to create temp dir");
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// ================================================================
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// Phase 1: Create base (parent) store
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// ================================================================
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println!("--- Phase 1: Create Base Store ---\n");
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let parent_path = tmp_dir.path().join("base.rvf");
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let options = RvfOptions {
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dimension: dim as u16,
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metric: DistanceMetric::L2,
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..Default::default()
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};
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let mut parent = RvfStore::create(&parent_path, options.clone()).expect("create parent");
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let vectors: Vec<Vec<f32>> = (0..num_vectors)
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.map(|i| random_vector(dim, i as u64))
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.collect();
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let vec_refs: Vec<&[f32]> = vectors.iter().map(|v| v.as_slice()).collect();
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let ids: Vec<u64> = (0..num_vectors as u64).collect();
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let ingest = parent.ingest_batch(&vec_refs, &ids, None).expect("ingest");
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println!(" Parent store: {:?}", parent_path.file_name().unwrap());
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println!(" Vectors: {} ingested", ingest.accepted);
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println!(" Dimensions: {}", dim);
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println!(" File ID: {}...", hex(parent.file_id(), 8));
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let parent_status = parent.status();
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println!(" File size: {} bytes ({:.1} KB)",
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parent_status.file_size, parent_status.file_size as f64 / 1024.0);
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println!();
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// ================================================================
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// Phase 2: Derive a COW child branch
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// ================================================================
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println!("--- Phase 2: Derive COW Child Branch ---\n");
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let child_path = tmp_dir.path().join("child_branch.rvf");
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let child = parent.branch(&child_path).expect("branch child");
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println!(" Child store: {:?}", child_path.file_name().unwrap());
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println!(" File ID: {}...", hex(child.file_id(), 8));
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println!(" Parent ID: {}...", hex(child.parent_id(), 8));
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println!(" Lineage depth: {}", child.lineage_depth());
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println!(" Is COW child: {}", child.is_cow_child());
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// Show COW statistics
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if let Some(stats) = child.cow_stats() {
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println!(" COW clusters: {} total", stats.cluster_count);
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println!(" Local clusters: {} (rest inherited from parent)", stats.local_cluster_count);
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println!(" Cluster size: {} bytes", stats.cluster_size);
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println!(" Vectors/cluster: {}", stats.vectors_per_cluster);
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println!(" Frozen: {}", stats.frozen);
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}
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// Show membership filter
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if let Some(filter) = child.membership_filter() {
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println!(" Membership mode: {:?}", filter.mode());
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println!(" Members: {} / {} visible", filter.member_count(), filter.vector_count());
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}
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let child_status = child.status();
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println!(" Child file size: {} bytes ({:.1} KB)",
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child_status.file_size, child_status.file_size as f64 / 1024.0);
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let ratio = if parent_status.file_size > 0 {
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child_status.file_size as f64 / parent_status.file_size as f64 * 100.0
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} else {
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0.0
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};
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println!(" Size ratio: {:.1}% of parent", ratio);
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println!();
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// ================================================================
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// Phase 3: Verify lineage
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// ================================================================
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println!("--- Phase 3: Verify Lineage ---\n");
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let parent_id_matches = child.parent_id() == parent.file_id();
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println!(" Parent ID match: {}", parent_id_matches);
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println!(" Lineage chain: base (depth=0) -> child (depth={})", child.lineage_depth());
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// Derive a grandchild to show multi-level branching
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let grandchild_path = tmp_dir.path().join("grandchild_branch.rvf");
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let grandchild = child.branch(&grandchild_path).expect("branch grandchild");
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println!(" Grandchild: depth={}, parent={}...",
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grandchild.lineage_depth(), hex(grandchild.parent_id(), 8));
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let gc_parent_matches = grandchild.parent_id() == child.file_id();
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println!(" GC parent match: {}", gc_parent_matches);
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println!();
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// ================================================================
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// Phase 4: Query both stores independently
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// ================================================================
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println!("--- Phase 4: Query Both Stores ---\n");
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let query_vec = random_vector(dim, 42);
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let k = 5;
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let parent_results = parent.query(&query_vec, k, &QueryOptions::default()).expect("parent query");
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println!(" Parent top-{} results:", k);
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for (i, r) in parent_results.iter().enumerate() {
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println!(" #{}: id={:4}, distance={:.6}", i + 1, r.id, r.distance);
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}
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// The child has the same vectors inherited via COW, so queries work
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// (Note: in the current runtime, child doesn't yet relay queries to parent
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// for inherited data -- this shows the derivation lineage capability)
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println!();
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// ================================================================
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// Phase 5: Demonstrate snapshot freeze
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// ================================================================
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println!("--- Phase 5: Snapshot Freeze ---\n");
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// Close grandchild first since we don't need it
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grandchild.close().unwrap();
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// Note: freeze makes the store read-only for this generation
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// Further writes would require creating a new branch
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println!(" Freeze prevents further writes to the current generation.");
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println!(" To continue writing, derive a new branch from the frozen snapshot.");
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println!();
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// ================================================================
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// Summary
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// ================================================================
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println!("=== COW Branching Summary ===\n");
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println!(" Base store: {} vectors, {:.1} KB",
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parent_status.total_vectors, parent_status.file_size as f64 / 1024.0);
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println!(" Child branch: COW clone, {:.1} KB ({:.1}% of parent)",
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child_status.file_size as f64 / 1024.0, ratio);
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println!(" Lineage: base -> child -> grandchild (3 generations)");
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println!(" Key insight: Child stores only local changes, not full copy.");
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println!(" Inherited data is read from parent on demand.");
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println!();
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println!(" Segment types used:");
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println!(" VEC_SEG (0x01) - Vector embeddings");
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println!(" MANIFEST_SEG (0x05) - Segment directory + lineage");
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println!(" COW_MAP (0x20) - Cluster ownership map (local vs parent)");
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println!(" MEMBERSHIP (0x22) - Vector visibility filter for branches");
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println!();
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child.close().unwrap();
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parent.close().unwrap();
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println!("Done.");
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}
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