diff options
Diffstat (limited to 'eval/src/tests/ann/xp-hnswlike-nns.cpp')
| -rw-r--r-- | eval/src/tests/ann/xp-hnswlike-nns.cpp | 612 |
1 files changed, 273 insertions, 339 deletions
diff --git a/eval/src/tests/ann/xp-hnswlike-nns.cpp b/eval/src/tests/ann/xp-hnswlike-nns.cpp index 5cdbdd8efa3..b7cae9f731c 100644 --- a/eval/src/tests/ann/xp-hnswlike-nns.cpp +++ b/eval/src/tests/ann/xp-hnswlike-nns.cpp @@ -1,11 +1,6 @@ // Copyright 2020 Oath Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root. -#include <algorithm> -#include <assert.h> -#include <queue> -#include <cinttypes> -#include "std-random.h" -#include "nns.h" +#include "hnsw-like.h" /* Todo: @@ -32,356 +27,223 @@ static size_t distcalls_heuristic; static size_t distcalls_shrink; static size_t distcalls_refill; static size_t refill_needed_calls; - -struct LinkList : std::vector<uint32_t> -{ - bool has_link_to(uint32_t id) const { - auto iter = std::find(begin(), end(), id); - return (iter != end()); - } - void remove_link(uint32_t id) { - uint32_t last = back(); - for (iterator iter = begin(); iter != end(); ++iter) { - if (*iter == id) { - *iter = last; - pop_back(); - return; - } - } - fprintf(stderr, "BAD missing link to remove: %u\n", id); - abort(); - } -}; - -struct Node { - std::vector<LinkList> _links; - Node(uint32_t , uint32_t numLevels, uint32_t M) - : _links(numLevels) - { - for (uint32_t i = 0; i < _links.size(); ++i) { - _links[i].reserve((i == 0) ? (2 * M + 1) : (M+1)); - } - } -}; - -struct VisitedSet +static size_t shrink_needed_calls; +static size_t disconnected_weak_links; +static size_t disconnected_for_symmetry; +static size_t select_n_full; +static size_t select_n_partial; + + + +HnswLikeNns::HnswLikeNns(uint32_t numDims, const DocVectorAccess<float> &dva) + : NNS(numDims, dva), + _nodes(), + _entryId(0), + _entryLevel(-1), + _M(16), + _efConstruction(200), + _levelMultiplier(1.0 / log(1.0 * _M)), + _rndGen(), + _ops_counter(0) { - using Mark = unsigned short; - Mark *ptr; - Mark curval; - size_t sz; - VisitedSet(const VisitedSet &) = delete; - VisitedSet& operator=(const VisitedSet &) = delete; - explicit VisitedSet(size_t size) { - ptr = (Mark *)malloc(size * sizeof(Mark)); - curval = -1; - sz = size; - } - void clear() { - ++curval; - if (curval == 0) { - memset(ptr, 0, sz * sizeof(Mark)); - ++curval; - } - } - ~VisitedSet() { free(ptr); } - void mark(size_t id) { ptr[id] = curval; } - bool isMarked(size_t id) const { return ptr[id] == curval; } -}; - -struct VisitedSetPool -{ - std::unique_ptr<VisitedSet> lastUsed; - VisitedSetPool() { - lastUsed = std::make_unique<VisitedSet>(250); - } - ~VisitedSetPool() {} - VisitedSet &get(size_t size) { - if (size > lastUsed->sz) { - lastUsed = std::make_unique<VisitedSet>(size*2); - } - lastUsed->clear(); - return *lastUsed; - } -}; - -struct HnswHit { - double dist; - uint32_t docid; - HnswHit(uint32_t di, SqDist sq) : dist(sq.distance), docid(di) {} -}; - -struct GreaterDist { - bool operator() (const HnswHit &lhs, const HnswHit& rhs) const { - return (rhs.dist < lhs.dist); - } -}; -struct LesserDist { - bool operator() (const HnswHit &lhs, const HnswHit& rhs) const { - return (lhs.dist < rhs.dist); - } -}; - -using NearestList = std::vector<HnswHit>; - -struct NearestPriQ : std::priority_queue<HnswHit, NearestList, GreaterDist> -{ -}; - -struct FurthestPriQ : std::priority_queue<HnswHit, NearestList, LesserDist> -{ - NearestList steal() { - NearestList result; - c.swap(result); - return result; - } - const NearestList& peek() const { return c; } -}; - -class HnswLikeNns : public NNS<float> -{ -private: - std::vector<Node> _nodes; - uint32_t _entryId; - int _entryLevel; - uint32_t _M; - uint32_t _efConstruction; - double _levelMultiplier; - RndGen _rndGen; - VisitedSetPool _visitedSetPool; - size_t _ops_counter; - - double distance(Vector v, uint32_t id) const; - - double distance(uint32_t a, uint32_t b) const { - Vector v = _dva.get(a); - return distance(v, b); - } - - int randomLevel() { - double unif = _rndGen.nextUniform(); - double r = -log(1.0-unif) * _levelMultiplier; - return (int) r; - } - - uint32_t count_reachable() const; - void dumpStats() const; - -public: - HnswLikeNns(uint32_t numDims, const DocVectorAccess<float> &dva) - : NNS(numDims, dva), - _nodes(), - _entryId(0), - _entryLevel(-1), - _M(16), - _efConstruction(200), - _levelMultiplier(1.0 / log(1.0 * _M)), - _rndGen(), - _ops_counter(0) - { - } - - ~HnswLikeNns() { dumpStats(); } - - LinkList& getLinkList(uint32_t docid, uint32_t level) { - // assert(docid < _nodes.size()); - // assert(level < _nodes[docid]._links.size()); - return _nodes[docid]._links[level]; - } - - const LinkList& getLinkList(uint32_t docid, uint32_t level) const { - return _nodes[docid]._links[level]; - } +} - // simple greedy search - HnswHit search_layer_simple(Vector vector, HnswHit curPoint, uint32_t searchLevel) { - bool keepGoing = true; - while (keepGoing) { - keepGoing = false; - const LinkList& neighbors = getLinkList(curPoint.docid, searchLevel); - for (uint32_t n_id : neighbors) { - double dist = distance(vector, n_id); - ++distcalls_simple; - if (dist < curPoint.dist) { - curPoint = HnswHit(n_id, SqDist(dist)); - keepGoing = true; - } +// simple greedy search +HnswHit +HnswLikeNns::search_layer_simple(Vector vector, HnswHit curPoint, uint32_t searchLevel) { + bool keepGoing = true; + while (keepGoing) { + keepGoing = false; + const LinkList& neighbors = getLinkList(curPoint.docid, searchLevel); + for (uint32_t n_id : neighbors) { + double dist = distance(vector, n_id); + ++distcalls_simple; + if (dist < curPoint.dist) { + curPoint = HnswHit(n_id, SqDist(dist)); + keepGoing = true; } } - return curPoint; } + return curPoint; +} - void search_layer(Vector vector, FurthestPriQ &w, - uint32_t ef, uint32_t searchLevel); - - bool haveCloserDistance(HnswHit e, const LinkList &r) const { - for (uint32_t prevId : r) { - double dist = distance(e.docid, prevId); - ++distcalls_heuristic; - if (dist < e.dist) return true; - } - return false; +bool +HnswLikeNns::haveCloserDistance(HnswHit e, const LinkList &r) const { + for (uint32_t prevId : r) { + double dist = distance(e.docid, prevId); + ++distcalls_heuristic; + if (dist < e.dist) return true; } + return false; +} - LinkList select_neighbors(const NearestList &neighbors, uint32_t curMax) const; - - LinkList remove_weakest(const NearestList &neighbors, uint32_t curMax, LinkList &removed) const; - - void addDoc(uint32_t docid) override { - Vector vector = _dva.get(docid); - for (uint32_t id = _nodes.size(); id <= docid; ++id) { - _nodes.emplace_back(id, 0, _M); - } - int level = randomLevel(); - assert(_nodes[docid]._links.size() == 0); - _nodes[docid] = Node(docid, level+1, _M); - if (_entryLevel < 0) { - _entryId = docid; - _entryLevel = level; - track_ops(); - return; - } - int searchLevel = _entryLevel; - double entryDist = distance(vector, _entryId); - ++distcalls_other; - HnswHit entryPoint(_entryId, SqDist(entryDist)); - while (searchLevel > level) { - entryPoint = search_layer_simple(vector, entryPoint, searchLevel); - --searchLevel; - } - searchLevel = std::min(level, _entryLevel); - FurthestPriQ w; - w.push(entryPoint); - while (searchLevel >= 0) { - search_layer(vector, w, _efConstruction, searchLevel); - LinkList neighbors = select_neighbors(w.peek(), _M); - connect_new_node(docid, neighbors, searchLevel); - each_shrink_ifneeded(neighbors, searchLevel); - --searchLevel; - } - if (level > _entryLevel) { - _entryLevel = level; - _entryId = docid; - } +void +HnswLikeNns::addDoc(uint32_t docid) { + Vector vector = _dva.get(docid); + for (uint32_t id = _nodes.size(); id <= docid; ++id) { + _nodes.emplace_back(id, 0, _M); + } + int level = randomLevel(); + assert(_nodes[docid]._links.size() == 0); + _nodes[docid] = Node(docid, level+1, _M); + if (_entryLevel < 0) { + _entryId = docid; + _entryLevel = level; track_ops(); - } - - void track_ops() { - _ops_counter++; - if ((_ops_counter % 10000) == 0) { - double div = _ops_counter; - fprintf(stderr, "add / remove ops: %zu\n", _ops_counter); - fprintf(stderr, "distance calls for layer: %zu is %.3f per op\n", distcalls_search_layer, distcalls_search_layer/ div); - fprintf(stderr, "distance calls for heuristic: %zu is %.3f per op\n", distcalls_heuristic, distcalls_heuristic / div); - fprintf(stderr, "distance calls for simple: %zu is %.3f per op\n", distcalls_simple, distcalls_simple / div); - fprintf(stderr, "distance calls for shrink: %zu is %.3f per op\n", distcalls_shrink, distcalls_shrink / div); - fprintf(stderr, "distance calls for refill: %zu is %.3f per op\n", distcalls_refill, distcalls_refill / div); - fprintf(stderr, "distance calls for other: %zu is %.3f per op\n", distcalls_other, distcalls_other / div); - fprintf(stderr, "refill needed calls: %zu is %.3f per op\n", refill_needed_calls, refill_needed_calls / div); - } - } + return; + } + int searchLevel = _entryLevel; + double entryDist = distance(vector, _entryId); + ++distcalls_other; + HnswHit entryPoint(_entryId, SqDist(entryDist)); + while (searchLevel > level) { + entryPoint = search_layer_simple(vector, entryPoint, searchLevel); + --searchLevel; + } + searchLevel = std::min(level, _entryLevel); + FurthestPriQ w; + w.push(entryPoint); + while (searchLevel >= 0) { + search_layer(vector, w, _efConstruction, searchLevel); + LinkList neighbors = select_neighbors(w.peek(), _M); + connect_new_node(docid, neighbors, searchLevel); + each_shrink_ifneeded(neighbors, searchLevel); + --searchLevel; + } + if (level > _entryLevel) { + _entryLevel = level; + _entryId = docid; + } + track_ops(); +} - void remove_link_from(uint32_t from_id, uint32_t remove_id, uint32_t level) { - LinkList &links = getLinkList(from_id, level); - links.remove_link(remove_id); - } +void +HnswLikeNns::track_ops() { + _ops_counter++; + if ((_ops_counter % 10000) == 0) { + double div = _ops_counter; + fprintf(stderr, "add / remove ops: %zu\n", _ops_counter); + fprintf(stderr, "distance calls for layer: %zu is %.3f per op\n", distcalls_search_layer, distcalls_search_layer/ div); + fprintf(stderr, "distance calls for heuristic: %zu is %.3f per op\n", distcalls_heuristic, distcalls_heuristic / div); + fprintf(stderr, "distance calls for simple: %zu is %.3f per op\n", distcalls_simple, distcalls_simple / div); + fprintf(stderr, "distance calls for shrink: %zu is %.3f per op\n", distcalls_shrink, distcalls_shrink / div); + fprintf(stderr, "distance calls for refill: %zu is %.3f per op\n", distcalls_refill, distcalls_refill / div); + fprintf(stderr, "distance calls for other: %zu is %.3f per op\n", distcalls_other, distcalls_other / div); + fprintf(stderr, "refill needed calls: %zu is %.3f per op\n", refill_needed_calls, refill_needed_calls / div); + fprintf(stderr, "shrink needed calls: %zu is %.3f per op\n", shrink_needed_calls, shrink_needed_calls / div); + fprintf(stderr, "disconnected weak links: %zu is %.3f per op\n", disconnected_weak_links, disconnected_weak_links / div); + fprintf(stderr, "disconnected for symmetry: %zu is %.3f per op\n", disconnected_for_symmetry, disconnected_for_symmetry / div); + fprintf(stderr, "select neighbors: partial %zu vs full %zu\n", select_n_partial, select_n_full); + } +} - void refill_ifneeded(uint32_t my_id, const LinkList &replacements, uint32_t level) { - LinkList &my_links = getLinkList(my_id, level); - if (my_links.size() < 8) { - ++refill_needed_calls; - for (uint32_t repl_id : replacements) { - if (repl_id == my_id) continue; - if (my_links.has_link_to(repl_id)) continue; - LinkList &other_links = getLinkList(repl_id, level); - if (other_links.size() + 1 >= _M) continue; - other_links.push_back(my_id); - my_links.push_back(repl_id); - if (my_links.size() >= _M) return; - } +void +HnswLikeNns::refill_ifneeded(uint32_t my_id, const LinkList &replacements, uint32_t level) { + LinkList &my_links = getLinkList(my_id, level); + if (my_links.size() < 8) { + ++refill_needed_calls; + for (uint32_t repl_id : replacements) { + if (repl_id == my_id) continue; + if (my_links.has_link_to(repl_id)) continue; + LinkList &other_links = getLinkList(repl_id, level); + if (other_links.size() + 1 >= _M) continue; + other_links.push_back(my_id); + my_links.push_back(repl_id); + if (my_links.size() >= _M) return; } } +} - void connect_new_node(uint32_t id, const LinkList &neighbors, uint32_t level); - - void shrink_links(uint32_t shrink_id, uint32_t maxLinks, uint32_t level) { - LinkList &links = getLinkList(shrink_id, level); - NearestList distances; - for (uint32_t n_id : links) { - double n_dist = distance(shrink_id, n_id); - ++distcalls_shrink; - distances.emplace_back(n_id, SqDist(n_dist)); - } - LinkList lostLinks; - LinkList oldLinks = links; - links = remove_weakest(distances, maxLinks, lostLinks); - for (uint32_t lost_id : lostLinks) { - remove_link_from(lost_id, shrink_id, level); - refill_ifneeded(lost_id, oldLinks, level); - } +void +HnswLikeNns::shrink_links(uint32_t shrink_id, uint32_t maxLinks, uint32_t level) { + LinkList &links = getLinkList(shrink_id, level); + NearestList distances; + for (uint32_t n_id : links) { + double n_dist = distance(shrink_id, n_id); + ++distcalls_shrink; + distances.emplace_back(n_id, SqDist(n_dist)); + } + LinkList lostLinks; + LinkList oldLinks = links; + links = remove_weakest(distances, maxLinks, lostLinks); +#define KEEP_SYM +#ifdef KEEP_SYM + for (uint32_t lost_id : lostLinks) { + ++disconnected_for_symmetry; + remove_link_from(lost_id, shrink_id, level); + } +#define DO_REFILL_AFTER_KEEP_SYM +#ifdef DO_REFILL_AFTER_KEEP_SYM + for (uint32_t lost_id : lostLinks) { + refill_ifneeded(lost_id, oldLinks, level); } +#endif +#endif +} - void each_shrink_ifneeded(const LinkList &neighbors, uint32_t level); - - void removeDoc(uint32_t docid) override { - Node &node = _nodes[docid]; - bool need_new_entrypoint = (docid == _entryId); - for (int level = node._links.size(); level-- > 0; ) { - LinkList my_links; - my_links.swap(node._links[level]); - for (uint32_t n_id : my_links) { - if (need_new_entrypoint) { - _entryId = n_id; - _entryLevel = level; - need_new_entrypoint = false; - } - remove_link_from(n_id, docid, level); - } - for (uint32_t n_id : my_links) { - refill_ifneeded(n_id, my_links, level); +void +HnswLikeNns::removeDoc(uint32_t docid) { + Node &node = _nodes[docid]; + bool need_new_entrypoint = (docid == _entryId); + for (int level = node._links.size(); level-- > 0; ) { + LinkList my_links; + my_links.swap(node._links[level]); + for (uint32_t n_id : my_links) { + if (need_new_entrypoint) { + _entryId = n_id; + _entryLevel = level; + need_new_entrypoint = false; } - } - node = Node(docid, 0, _M); - if (need_new_entrypoint) { - _entryLevel = -1; - _entryId = 0; - for (uint32_t i = 0; i < _nodes.size(); ++i) { - if (_nodes[i]._links.size() > 0) { - _entryId = i; - _entryLevel = _nodes[i]._links.size() - 1; - break; - } + remove_link_from(n_id, docid, level); + } + while (! my_links.empty()) { + uint32_t n_id = my_links.back(); + my_links.pop_back(); + refill_ifneeded(n_id, my_links, level); + } + } + node = Node(docid, 0, _M); + if (need_new_entrypoint) { + _entryLevel = -1; + _entryId = 0; + for (uint32_t i = 0; i < _nodes.size(); ++i) { + if (_nodes[i]._links.size() > 0) { + _entryId = i; + _entryLevel = _nodes[i]._links.size() - 1; + break; } } - track_ops(); } + track_ops(); +} - std::vector<NnsHit> topK(uint32_t k, Vector vector, uint32_t search_k) override { - std::vector<NnsHit> result; - if (_entryLevel < 0) return result; - double entryDist = distance(vector, _entryId); - ++distcalls_other; - HnswHit entryPoint(_entryId, SqDist(entryDist)); - int searchLevel = _entryLevel; - FurthestPriQ w; - w.push(entryPoint); - while (searchLevel > 0) { - search_layer(vector, w, std::min(k, search_k), searchLevel); - --searchLevel; - } - search_layer(vector, w, std::max(k, search_k), 0); - while (w.size() > k) { - w.pop(); - } - NearestList tmp = w.steal(); - std::sort(tmp.begin(), tmp.end(), LesserDist()); - result.reserve(tmp.size()); - for (const auto & hit : tmp) { - result.emplace_back(hit.docid, SqDist(hit.dist)); - } - return result; +std::vector<NnsHit> +HnswLikeNns::topK(uint32_t k, Vector vector, uint32_t search_k) { + std::vector<NnsHit> result; + if (_entryLevel < 0) return result; + double entryDist = distance(vector, _entryId); + ++distcalls_other; + HnswHit entryPoint(_entryId, SqDist(entryDist)); + int searchLevel = _entryLevel; + while (searchLevel > 0) { + entryPoint = search_layer_simple(vector, entryPoint, searchLevel); + --searchLevel; + } + FurthestPriQ w; + w.push(entryPoint); + search_layer(vector, w, std::max(k, search_k), 0); + while (w.size() > k) { + w.pop(); + } + NearestList tmp = w.steal(); + std::sort(tmp.begin(), tmp.end(), LesserDist()); + result.reserve(tmp.size()); + for (const auto & hit : tmp) { + result.emplace_back(hit.docid, SqDist(hit.dist)); } -}; + return result; +} + double HnswLikeNns::distance(Vector v, uint32_t b) const @@ -390,12 +252,40 @@ HnswLikeNns::distance(Vector v, uint32_t b) const return l2distCalc.l2sq_dist(v, w); } +std::vector<NnsHit> +HnswLikeNns::topKfilter(uint32_t k, Vector vector, uint32_t search_k, const BitVector &blacklist) +{ + std::vector<NnsHit> result; + if (_entryLevel < 0) return result; + double entryDist = distance(vector, _entryId); + ++distcalls_other; + HnswHit entryPoint(_entryId, SqDist(entryDist)); + int searchLevel = _entryLevel; + while (searchLevel > 0) { + entryPoint = search_layer_simple(vector, entryPoint, searchLevel); + --searchLevel; + } + FurthestPriQ w; + w.push(entryPoint); + search_layer_with_filter(vector, w, std::max(k, search_k), 0, blacklist); + NearestList tmp = w.steal(); + std::sort(tmp.begin(), tmp.end(), LesserDist()); + result.reserve(std::min((size_t)k, tmp.size())); + for (const auto & hit : tmp) { + if (blacklist.isSet(hit.docid)) continue; + result.emplace_back(hit.docid, SqDist(hit.dist)); + if (result.size() == k) break; + } + return result; +} + void HnswLikeNns::each_shrink_ifneeded(const LinkList &neighbors, uint32_t level) { uint32_t maxLinks = (level > 0) ? _M : (2 * _M); for (uint32_t old_id : neighbors) { LinkList &oldLinks = getLinkList(old_id, level); if (oldLinks.size() > maxLinks) { + ++shrink_needed_calls; shrink_links(old_id, maxLinks, level); } } @@ -437,6 +327,44 @@ HnswLikeNns::search_layer(Vector vector, FurthestPriQ &w, return; } +void +HnswLikeNns::search_layer_with_filter(Vector vector, FurthestPriQ &w, + uint32_t ef, uint32_t searchLevel, + const BitVector &blacklist) +{ + NearestPriQ candidates; + VisitedSet &visited = _visitedSetPool.get(_nodes.size()); + + for (const HnswHit & entry : w.peek()) { + candidates.push(entry); + visited.mark(entry.docid); + if (blacklist.isSet(entry.docid)) ++ef; + } + double limd = std::numeric_limits<double>::max(); + while (! candidates.empty()) { + HnswHit cand = candidates.top(); + if (cand.dist > limd) { + break; + } + candidates.pop(); + for (uint32_t e_id : getLinkList(cand.docid, searchLevel)) { + if (visited.isMarked(e_id)) continue; + visited.mark(e_id); + double e_dist = distance(vector, e_id); + ++distcalls_search_layer; + if (e_dist < limd) { + candidates.emplace(e_id, SqDist(e_dist)); + if (blacklist.isSet(e_id)) continue; + w.emplace(e_id, SqDist(e_dist)); + if (w.size() > ef) { + w.pop(); + limd = w.top().dist; + } + } + } + } +} + LinkList HnswLikeNns::remove_weakest(const NearestList &neighbors, uint32_t curMax, LinkList &lost) const { @@ -458,13 +386,13 @@ HnswLikeNns::remove_weakest(const NearestList &neighbors, uint32_t curMax, LinkL return result; } +#define NO_BACKFILL #ifdef NO_BACKFILL LinkList HnswLikeNns::select_neighbors(const NearestList &neighbors, uint32_t curMax) const { LinkList result; result.reserve(curMax+1); - bool needFiltering = (neighbors.size() > curMax); NearestPriQ w; for (const auto & entry : neighbors) { w.push(entry); @@ -472,12 +400,16 @@ HnswLikeNns::select_neighbors(const NearestList &neighbors, uint32_t curMax) con while (! w.empty()) { HnswHit e = w.top(); w.pop(); - if (needFiltering && haveCloserDistance(e, result)) { + if (haveCloserDistance(e, result)) { continue; } result.push_back(e.docid); - if (result.size() == curMax) return result; + if (result.size() == curMax) { + ++select_n_full; + return result; + } } + ++select_n_partial; return result; } #else @@ -502,10 +434,10 @@ HnswLikeNns::select_neighbors(const NearestList &neighbors, uint32_t curMax) con result.push_back(e.docid); if (result.size() == curMax) return result; } - if (result.size() * 4 < curMax) { + if (result.size() * 4 < _M) { for (uint32_t fill_id : backfill) { result.push_back(fill_id); - if (result.size() * 4 >= curMax) break; + if (result.size() * 2 >= _M) break; } } return result; @@ -576,7 +508,9 @@ HnswLikeNns::dumpStats() const { for (uint32_t n_id : link_list) { const LinkList &neigh_list = getLinkList(n_id, 0); if (! neigh_list.has_link_to(id)) { +#ifdef KEEP_SYM fprintf(stderr, "BAD: %u has link to neighbor %u, but backlink is missing\n", id, n_id); +#endif all_sym = false; } } |