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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 <vespa/vespalib/datastore/atomic_entry_ref.h>
namespace search::memoryindex {
/**
* Class storing interleaved features for a posting list entry.
*/
class InterleavedFeatures {
protected:
uint16_t _num_occs;
uint16_t _field_length;
public:
InterleavedFeatures()
: _num_occs(0),
_field_length(1)
{
}
InterleavedFeatures(uint16_t num_occs, uint16_t field_length)
: _num_occs(num_occs),
_field_length(field_length)
{
}
uint16_t get_num_occs() const { return _num_occs; }
uint16_t get_field_length() const { return _field_length; }
};
/**
* Empty class used when posting list entry does not have interleaved features.
*/
class NoInterleavedFeatures {
public:
NoInterleavedFeatures() {}
NoInterleavedFeatures(uint16_t num_occs, uint16_t field_length) {
(void) num_occs;
(void) field_length;
}
uint16_t get_num_occs() const { return 0; }
uint16_t get_field_length() const { return 1; }
};
/**
* Entry per document in memory index posting list.
*/
template <bool interleaved_features>
class PostingListEntry : public std::conditional_t<interleaved_features, InterleavedFeatures, NoInterleavedFeatures> {
using ParentType = std::conditional_t<interleaved_features, InterleavedFeatures, NoInterleavedFeatures>;
mutable vespalib::datastore::AtomicEntryRef _features; // reference to compressed features
public:
explicit PostingListEntry(vespalib::datastore::EntryRef features, uint16_t num_occs, uint16_t field_length)
: ParentType(num_occs, field_length),
_features(features)
{
}
PostingListEntry()
: ParentType(),
_features()
{
}
vespalib::datastore::EntryRef get_features() const noexcept { return _features.load_acquire(); }
vespalib::datastore::EntryRef get_features_relaxed() const noexcept { return _features.load_relaxed(); }
/*
* Reference moved features (used when compacting FeatureStore).
* The moved features must have the same content as the original
* features.
*/
void update_features(vespalib::datastore::EntryRef features) const { _features.store_release(features); }
};
template class PostingListEntry<false>;
template class PostingListEntry<true>;
}
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