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support ACORN-1 #673

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0a733a1
acorn-1
cpegeric Oct 29, 2025
27e8554
update
cpegeric Oct 29, 2025
9b317d9
update
cpegeric Oct 29, 2025
92d5e78
fmt
cpegeric Oct 29, 2025
4226ecb
prefetch
cpegeric Oct 29, 2025
5afdae1
update
vderic Oct 29, 2025
1eaff90
fmt
cpegeric Oct 29, 2025
55c7961
Fix: remove 2-hop-neighbour visit
cpegeric Oct 29, 2025
12cde8b
Revert "Fix: remove 2-hop-neighbour visit"
cpegeric Oct 29, 2025
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109 changes: 89 additions & 20 deletions include/usearch/index.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -4213,30 +4213,99 @@ class index_gt {
next.pop();
context.iteration_cycles++;

neighbors_ref_t candidate_neighbors = neighbors_base_(node_at_(candidate.slot));
if (is_dummy<predicate_at>()) {

// Optional prefetching
if (!is_dummy<prefetch_at>()) {
candidates_range_t missing_candidates{*this, candidate_neighbors, visits};
prefetch(missing_candidates.begin(), missing_candidates.end());
}
neighbors_ref_t candidate_neighbors = neighbors_base_(node_at_(candidate.slot));

// Assume the worst-case when reserving memory
if (!visits.reserve(visits.size() + candidate_neighbors.size()))
return false;
// Optional prefetching
if (!is_dummy<prefetch_at>()) {
candidates_range_t missing_candidates{*this, candidate_neighbors, visits};
prefetch(missing_candidates.begin(), missing_candidates.end());
}

for (compressed_slot_t successor_slot : candidate_neighbors) {
if (visits.set(successor_slot))
continue;
// Assume the worst-case when reserving memory
if (!visits.reserve(visits.size() + candidate_neighbors.size()))
return false;

distance_t successor_dist = context.measure(query, citerator_at(successor_slot), metric);
if (top.size() < top_limit || successor_dist < radius) {
// This can substantially grow our priority queue:
next.insert({-successor_dist, successor_slot});
if (is_dummy<predicate_at>() ||
predicate(member_cref_t{node_at_(successor_slot).ckey(), successor_slot})) {
top.insert({successor_dist, successor_slot}, top_limit);
radius = top.top().distance;
for (compressed_slot_t successor_slot : candidate_neighbors) {
if (visits.set(successor_slot))
continue;

distance_t successor_dist = context.measure(query, citerator_at(successor_slot), metric);
if (top.size() < top_limit || successor_dist < radius) {
// This can substantially grow our priority queue:
next.insert({-successor_dist, successor_slot});
if (is_dummy<predicate_at>() ||
predicate(member_cref_t{node_at_(successor_slot).ckey(), successor_slot})) {
top.insert({successor_dist, successor_slot}, top_limit);
radius = top.top().distance;
}
}
}

} else {
// ACORN-1

// explore 1-hop neighbors
neighbors_ref_t candidate_neighbors = neighbors_base_(node_at_(candidate.slot));

// Optional prefetching
if (!is_dummy<prefetch_at>()) {
candidates_range_t missing_candidates{*this, candidate_neighbors, visits};
prefetch(missing_candidates.begin(), missing_candidates.end());
}

// Assume the worst-case when reserving memory
if (!visits.reserve(visits.size() + candidate_neighbors.size()))
return false;

for (compressed_slot_t successor_slot : candidate_neighbors) {
if (visits.set(successor_slot))
continue;

if (predicate(member_cref_t{node_at_(successor_slot).ckey(), successor_slot})) {
distance_t successor_dist = context.measure(query, citerator_at(successor_slot), metric);
if (top.size() < top_limit || successor_dist < radius) {
// This can substantially grow our priority queue:
next.insert({-successor_dist, successor_slot});

top.insert({successor_dist, successor_slot}, top_limit);
radius = top.top().distance;
}
}
}


// explore 2-hop neighbors
for (compressed_slot_t successor_slot : candidate_neighbors) {
neighbors_ref_t hop2_candidate_neighbors = neighbors_base_(node_at_(successor_slot));

// Optional prefetching
if (!is_dummy<prefetch_at>()) {
candidates_range_t missing_candidates{*this, hop2_candidate_neighbors, visits};
prefetch(missing_candidates.begin(), missing_candidates.end());
}

// Assume the worst-case when reserving memory
if (!visits.reserve(visits.size() + hop2_candidate_neighbors.size()))
return false;

for (compressed_slot_t hop2_successor_slot : hop2_candidate_neighbors) {

if (visits.set(hop2_successor_slot))
continue;

if (predicate(member_cref_t{node_at_(hop2_successor_slot).ckey(), hop2_successor_slot})) {
distance_t hop2_successor_dist =
context.measure(query, citerator_at(hop2_successor_slot), metric);
if (top.size() < top_limit || hop2_successor_dist < radius) {
// This can substantially grow our priority queue:
next.insert({-hop2_successor_dist, hop2_successor_slot});

top.insert({hop2_successor_dist, hop2_successor_slot}, top_limit);
radius = top.top().distance;
}
}
}
}
}
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