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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#pragma once
#include "common.h"
#include <vespa/vespalib/btree/btreestore.h>
#include <vespa/vespalib/data/databuffer.h>
#include <vespa/vespalib/util/rcuvector.h>
#include <optional>
namespace search::predicate {
template <typename Key = uint64_t, typename DocId = uint32_t>
struct SimpleIndexDeserializeObserver {
virtual ~SimpleIndexDeserializeObserver() {}
virtual void notifyInsert(Key key, DocId docId, uint32_t k) = 0;
};
template <typename Posting>
struct PostingSerializer {
virtual ~PostingSerializer() {}
virtual void serialize(const Posting &posting, vespalib::DataBuffer &buffer) const = 0;
};
template <typename Posting>
struct PostingDeserializer {
virtual ~PostingDeserializer() {}
virtual Posting deserialize(vespalib::DataBuffer &buffer) = 0;
};
struct SimpleIndexConfig {
static constexpr double DEFAULT_UPPER_DOCID_FREQ_THRESHOLD = 0.40;
static constexpr double DEFAULT_LOWER_DOCID_FREQ_THRESHOLD = 0.8 * DEFAULT_UPPER_DOCID_FREQ_THRESHOLD;
static constexpr size_t DEFAULT_UPPER_VECTOR_SIZE_THRESHOLD = 10000;
static constexpr size_t DEFAULT_LOWER_VECTOR_SIZE_THRESHOLD = static_cast<size_t>(0.8 * DEFAULT_UPPER_VECTOR_SIZE_THRESHOLD);
static constexpr size_t DEFAULT_VECTOR_PRUNE_FREQUENCY = 20000;
static constexpr double DEFAULT_FOREACH_VECTOR_THRESHOLD = 0.25;
// Create vector posting list if doc frequency is above
double upper_docid_freq_threshold = DEFAULT_UPPER_DOCID_FREQ_THRESHOLD;
// Remove vector posting list if doc frequency is below
double lower_docid_freq_threshold = DEFAULT_LOWER_DOCID_FREQ_THRESHOLD;
// Threshold to create vector posting list
size_t upper_vector_size_threshold = DEFAULT_UPPER_VECTOR_SIZE_THRESHOLD;
// Threshold to remove vector posting list
size_t lower_vector_size_threshold = DEFAULT_LOWER_VECTOR_SIZE_THRESHOLD;
// How often to prune vector when add is called
size_t vector_prune_frequency = DEFAULT_VECTOR_PRUNE_FREQUENCY;
// Use vector posting list in foreach_frozen if doc frequency is above
double foreach_vector_threshold = DEFAULT_FOREACH_VECTOR_THRESHOLD;
// Grow strategy for the posting vectors
vespalib::GrowStrategy grow_strategy = vespalib::GrowStrategy();
SimpleIndexConfig() {}
SimpleIndexConfig(double upper_docid_freq_threshold_,
double lower_docid_freq_threshold_,
size_t upper_vector_size_threshold_,
size_t lower_vector_size_threshold_,
size_t vector_prune_frequency_,
double foreach_vector_threshold_,
vespalib::GrowStrategy grow_strategy_)
: upper_docid_freq_threshold(upper_docid_freq_threshold_),
lower_docid_freq_threshold(lower_docid_freq_threshold_),
upper_vector_size_threshold(upper_vector_size_threshold_),
lower_vector_size_threshold(lower_vector_size_threshold_),
vector_prune_frequency(vector_prune_frequency_),
foreach_vector_threshold(foreach_vector_threshold_),
grow_strategy(grow_strategy_) {}
SimpleIndexConfig(double upper_docid_freq_threshold_, vespalib::GrowStrategy grow_strategy_)
: upper_docid_freq_threshold(upper_docid_freq_threshold_),
lower_docid_freq_threshold(upper_docid_freq_threshold_ * 0.80),
grow_strategy(grow_strategy_) {}
};
template <typename Posting, typename Key, typename DocId>
class PostingVectorIterator {
using PostingVector = vespalib::RcuVectorBase<Posting>;
const Posting * const _vector;
const size_t _size;
size_t _pos;
Posting _data;
public:
// Handle both move and copy construction
PostingVectorIterator(PostingVectorIterator&&) = default;
PostingVectorIterator& operator=(PostingVectorIterator&&) = default;
PostingVectorIterator(const PostingVectorIterator&) = default;
PostingVectorIterator& operator=(const PostingVectorIterator&) = default;
explicit PostingVectorIterator(const PostingVector & vector, size_t size)
: _vector(&vector.acquire_elem_ref(0)),
_size(size)
{
assert(_size <= vector.get_size()); // Data race: not writer
linearSeek(1);
}
bool valid() const { return _pos < _size; }
DocId getKey() const { return _pos; }
Posting getData() const { return _data; }
void linearSeek(DocId doc_id) {
while (doc_id < _size) {
const Posting &p = _vector[doc_id];
if (p.valid()) {
_pos = doc_id;
_data = p;
return;
}
++doc_id;
}
_pos = _size;
}
PostingVectorIterator & operator++() {
linearSeek(_pos + 1);
return *this;
}
};
/**
* SimpleIndex holds a dictionary of Keys and posting lists of DocIds
* with Posting information.
*
* Serialization / deserialization assumes that Key fits in 64 bits
* and DocId fits in 32 bits.
*/
template <typename Posting,
typename Key = uint64_t, typename DocId = uint32_t>
class SimpleIndex {
public:
using Dictionary = vespalib::btree::BTree<Key, vespalib::datastore::EntryRef, vespalib::btree::NoAggregated>;
using DictionaryIterator = typename Dictionary::ConstIterator;
using BTreeStore = vespalib::btree::BTreeStore<
DocId, Posting, vespalib::btree::NoAggregated, std::less<DocId>, vespalib::btree::BTreeDefaultTraits>;
using BTreeIterator = typename BTreeStore::ConstIterator;
using PostingVector = vespalib::RcuVectorBase<Posting>;
using VectorStore = vespalib::btree::BTree<Key, std::shared_ptr<PostingVector>, vespalib::btree::NoAggregated>;
using VectorIterator = PostingVectorIterator<Posting, Key, DocId>;
private:
using GenerationHolder = vespalib::GenerationHolder;
using generation_t = vespalib::GenerationHandler::generation_t;
template <typename T>
using optional = std::optional<T>;
Dictionary _dictionary;
BTreeStore _btree_posting_lists;
VectorStore _vector_posting_lists;
GenerationHolder &_generation_holder;
uint32_t _insert_remove_counter = 0;
const SimpleIndexConfig _config;
const DocIdLimitProvider &_limit_provider;
void insertIntoPosting(vespalib::datastore::EntryRef &ref, Key key, DocId doc_id, const Posting &posting);
void insertIntoVectorPosting(vespalib::datastore::EntryRef ref, Key key, DocId doc_id, const Posting &posting);
void removeFromVectorPostingList(vespalib::datastore::EntryRef ref, Key key, DocId doc_id);
void pruneBelowThresholdVectors();
void createVectorIfOverThreshold(vespalib::datastore::EntryRef ref, Key key);
bool removeVectorIfBelowThreshold(vespalib::datastore::EntryRef ref, typename VectorStore::Iterator &it);
void logVector(const char *action, Key key, size_t document_count,
double ratio, size_t vector_length) const;
double getDocumentRatio(size_t document_count, uint32_t doc_id_limit) const;
size_t getDocumentCount(vespalib::datastore::EntryRef ref) const;
bool shouldCreateVectorPosting(size_t size, double ratio) const;
bool shouldRemoveVectorPosting(size_t size, double ratio) const;
size_t getVectorPostingSize(const PostingVector &vector) const {
return std::min(vector.get_size() /* Data race: not writer */,
static_cast<size_t>(_limit_provider.getCommittedDocIdLimit()));
}
public:
SimpleIndex(GenerationHolder &generation_holder,
const DocIdLimitProvider &provider, const SimpleIndexConfig &config)
: _generation_holder(generation_holder), _config(config), _limit_provider(provider) {}
~SimpleIndex();
void serialize(vespalib::DataBuffer &buffer,
const PostingSerializer<Posting> &serializer) const;
void deserialize(vespalib::DataBuffer &buffer,
PostingDeserializer<Posting> &deserializer,
SimpleIndexDeserializeObserver<Key, DocId> &observer, uint32_t version);
void addPosting(Key key, DocId doc_id, const Posting &posting);
std::pair<Posting, bool> removeFromPostingList(Key key, DocId doc_id);
// Call promoteOverThresholdVectors() after deserializing a SimpleIndex
// (and after doc id limits values are determined) to promote posting lists to vectors.
void promoteOverThresholdVectors();
void commit();
void reclaim_memory(generation_t oldest_used_gen);
void assign_generation(generation_t current_gen);
vespalib::MemoryUsage getMemoryUsage() const;
template <typename FunctionType>
void foreach_frozen_key(vespalib::datastore::EntryRef ref, Key key, FunctionType func) const;
DictionaryIterator lookup(Key key) const {
return _dictionary.getFrozenView().find(key);
}
size_t getPostingListSize(vespalib::datastore::EntryRef ref) const {
return _btree_posting_lists.frozenSize(ref);
}
BTreeIterator getBTreePostingList(vespalib::datastore::EntryRef ref) const {
return _btree_posting_lists.beginFrozen(ref);
}
optional<VectorIterator> getVectorPostingList(Key key) const {
auto it = _vector_posting_lists.getFrozenView().find(key);
if (it.valid()) {
auto &vector = *it.getData();
size_t size = getVectorPostingSize(vector);
return optional<VectorIterator>(VectorIterator(vector, size));
}
return optional<VectorIterator>();
}
};
template<typename Posting, typename Key, typename DocId>
template<typename FunctionType>
void
SimpleIndex<Posting, Key, DocId>::foreach_frozen_key(vespalib::datastore::EntryRef ref, Key key, FunctionType func) const {
auto it = _vector_posting_lists.getFrozenView().find(key);
double ratio = getDocumentRatio(getDocumentCount(ref), _limit_provider.getDocIdLimit());
if (it.valid() && ratio > _config.foreach_vector_threshold) {
auto &vector = *it.getData();
size_t size = getVectorPostingSize(vector);
for (DocId doc_id = 1; doc_id < size; ++doc_id) {
if (vector[doc_id].valid()) {
func(doc_id);
}
}
} else {
_btree_posting_lists.foreach_frozen_key(ref, func);
}
}
}
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