bloom.h

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// Copyright (c) 2012-present The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
#ifndef BITCOIN_COMMON_BLOOM_H
#define BITCOIN_COMMON_BLOOM_H
 
#include <serialize.h>
 
#include <cstdint>
#include <span>
#include <vector>
 
class COutPoint;
class CTransaction;

inline constexpr unsigned int MAX_BLOOM_FILTER_SIZE{36'000}; // bytes
inline constexpr unsigned int MAX_HASH_FUNCS = 50;

enum bloomflags
{
    BLOOM_UPDATE_NONE = 0,
    BLOOM_UPDATE_ALL = 1,
    // Only adds outpoints to the filter if the output is a pay-to-pubkey/pay-to-multisig script
    BLOOM_UPDATE_P2PUBKEY_ONLY = 2,
    BLOOM_UPDATE_MASK = 3,
};

class CBloomFilter
{
private:
    std::vector<unsigned char> vData;
    unsigned int nHashFuncs;
    unsigned int nTweak;
    unsigned char nFlags;
 
    unsigned int Hash(unsigned int nHashNum, std::span<const unsigned char> vDataToHash) const;
 
public:
    CBloomFilter(unsigned int nElements, double nFPRate, unsigned int nTweak, unsigned char nFlagsIn);
    CBloomFilter() : nHashFuncs(0), nTweak(0), nFlags(0) {}
 
    SERIALIZE_METHODS(CBloomFilter, obj) { READWRITE(obj.vData, obj.nHashFuncs, obj.nTweak, obj.nFlags); }
 
    void insert(std::span<const unsigned char> vKey);
    void insert(const COutPoint& outpoint);
 
    bool contains(std::span<const unsigned char> vKey) const;
    bool contains(const COutPoint& outpoint) const;

    bool IsWithinSizeConstraints() const;

    bool IsRelevantAndUpdate(const CTransaction& tx);
};

class CRollingBloomFilter
{
public:
    CRollingBloomFilter(unsigned int nElements, double nFPRate);
 
    void insert(std::span<const unsigned char> vKey);
    bool contains(std::span<const unsigned char> vKey) const;
 
    void reset();
 
private:
    int nEntriesPerGeneration;
    int nEntriesThisGeneration;
    int nGeneration;
    std::vector<uint64_t> data;
    unsigned int nTweak;
    int nHashFuncs;
};
 
#endif // BITCOIN_COMMON_BLOOM_H