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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 "condensedbitvectors.h"
#include <vespa/vespalib/stllike/hash_set.h>
#include <vespa/vespalib/stllike/hash_map.h>
#include <shared_mutex>
namespace search {
class PopulateInterface
{
public:
class Iterator {
public:
using UP = std::unique_ptr<Iterator>;
virtual ~Iterator() = default;
virtual int32_t getNext() = 0;
};
virtual ~PopulateInterface() = default;
virtual Iterator::UP lookup(uint64_t key) const = 0;
};
class BitVectorCache
{
public:
using Key = uint64_t;
using KeySet = vespalib::hash_set<Key>;
using KeyAndCountSet = std::vector<std::pair<Key, size_t>>;
using CountVector = CondensedBitVector::CountVector;
using GenerationHolder = vespalib::GenerationHolder;
explicit BitVectorCache(GenerationHolder &genHolder);
~BitVectorCache();
void computeCountVector(KeySet & keys, CountVector & v) const;
KeySet lookupCachedSet(const KeyAndCountSet & keys);
void set(Key key, uint32_t index, bool v);
bool get(Key key, uint32_t index) const;
void removeIndex(uint32_t index);
void adjustDocIdLimit(uint32_t docId);
void populate(uint32_t count, const PopulateInterface &);
bool needPopulation() const { return _needPopulation.load(std::memory_order_relaxed); }
void requirePopulation() { _needPopulation = true; }
private:
class KeyMeta {
public:
KeyMeta() noexcept
: _lookupCount(0),
_bitCount(0),
_chunkId(-1),
_chunkIndex(0)
{ }
KeyMeta(const KeyMeta & rhs) noexcept
: _lookupCount(rhs.lookupCount()),
_bitCount(rhs._bitCount),
_chunkId(rhs._chunkId),
_chunkIndex(rhs._chunkIndex)
{}
KeyMeta & operator = (const KeyMeta & rhs) {
_lookupCount.store(rhs.lookupCount(), std::memory_order_release);
_bitCount = rhs._bitCount;
_chunkId = rhs._chunkId;
_chunkIndex = rhs._chunkIndex;
return *this;
}
double cost() const { return _bitCount * lookupCount(); }
bool isCached() const { return _chunkId >= 0; }
size_t bitCount() const { return _bitCount; }
size_t chunkIndex() const { return _chunkIndex; }
size_t chunkId() const { return _chunkId; }
size_t lookupCount() const { return _lookupCount.load(std::memory_order_relaxed); }
KeyMeta & lookup() { _lookupCount++; return *this; }
KeyMeta & bitCount(uint32_t v) { _bitCount = v; return *this; }
KeyMeta & chunkId(uint32_t v) { _chunkId = v; return *this; }
KeyMeta & chunkIndex(uint32_t v) { _chunkIndex = v; return *this; }
KeyMeta & unCache() { _chunkId = -1; return *this; }
private:
std::atomic<size_t> _lookupCount;
uint32_t _bitCount;
int32_t _chunkId;
uint32_t _chunkIndex;
};
using Key2Index = vespalib::hash_map<Key, KeyMeta>;
using SortedKeyMeta = std::vector<std::pair<Key, KeyMeta *>>;
using ChunkV = std::vector<CondensedBitVector::SP>;
VESPA_DLL_LOCAL static SortedKeyMeta getSorted(Key2Index & keys);
VESPA_DLL_LOCAL static void populate(Key2Index & newKeys, CondensedBitVector & chunk, const PopulateInterface & lookup);
VESPA_DLL_LOCAL bool hasCostChanged(const std::shared_lock<std::shared_mutex> &);
std::atomic<uint64_t> _lookupCount;
std::atomic<bool> _needPopulation;
mutable std::shared_mutex _mutex;
Key2Index _keys;
ChunkV _chunks;
GenerationHolder &_genHolder;
};
}
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