coins.h

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// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2016 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_COINS_H
#define BITCOIN_COINS_H
 
#include <compressor.h>
#include <memusage.h>
#include <primitives/blockhash.h>
#include <serialize.h>
#include <support/allocators/pool.h>
#include <util/hasher.h>
 
#include <cassert>
#include <cstdint>
#include <functional>
#include <unordered_map>
 
class Coin {
    CTxOut out;
 
    uint32_t nHeightAndIsCoinBase;
 
public:
    Coin() : nHeightAndIsCoinBase(0) {}
 
    Coin(CTxOut outIn, uint32_t nHeightIn, bool IsCoinbase)
        : out(std::move(outIn)),
          nHeightAndIsCoinBase((nHeightIn << 1) | IsCoinbase) {}
 
    uint32_t GetHeight() const { return nHeightAndIsCoinBase >> 1; }
    bool IsCoinBase() const { return nHeightAndIsCoinBase & 0x01; }
    bool IsSpent() const { return out.IsNull(); }
 
    CTxOut &GetTxOut() { return out; }
    const CTxOut &GetTxOut() const { return out; }
 
    void Clear() {
        out.SetNull();
        nHeightAndIsCoinBase = 0;
    }
 
    template <typename Stream> void Serialize(Stream &s) const {
        assert(!IsSpent());
        ::Serialize(s, VARINT(nHeightAndIsCoinBase));
        ::Serialize(s, Using<TxOutCompression>(out));
    }
 
    template <typename Stream> void Unserialize(Stream &s) {
        ::Unserialize(s, VARINT(nHeightAndIsCoinBase));
        ::Unserialize(s, Using<TxOutCompression>(out));
    }
 
    size_t DynamicMemoryUsage() const {
        return memusage::DynamicUsage(out.scriptPubKey);
    }
};
 
struct CCoinsCacheEntry {
    // The actual cached data.
    Coin coin;
    uint8_t flags;
 
    enum Flags {
        DIRTY = (1 << 0),
        FRESH = (1 << 1),
    };
 
    CCoinsCacheEntry() : flags(0) {}
    explicit CCoinsCacheEntry(Coin coinIn)
        : coin(std::move(coinIn)), flags(0) {}
    CCoinsCacheEntry(Coin &&coin_, uint8_t flag)
        : coin(std::move(coin_)), flags(flag) {}
};
 
using CCoinsMap = std::unordered_map<
    COutPoint, CCoinsCacheEntry, SaltedOutpointHasher, std::equal_to<COutPoint>,
    PoolAllocator<std::pair<const COutPoint, CCoinsCacheEntry>,
                  sizeof(std::pair<const COutPoint, CCoinsCacheEntry>) +
                      sizeof(void *) * 4>>;
 
using CCoinsMapMemoryResource = CCoinsMap::allocator_type::ResourceType;
 
class CCoinsViewCursor {
public:
    CCoinsViewCursor(const BlockHash &hashBlockIn) : hashBlock(hashBlockIn) {}
    virtual ~CCoinsViewCursor() {}
 
    virtual bool GetKey(COutPoint &key) const = 0;
    virtual bool GetValue(Coin &coin) const = 0;
    virtual unsigned int GetValueSize() const = 0;
 
    virtual bool Valid() const = 0;
    virtual void Next() = 0;
 
    const BlockHash &GetBestBlock() const { return hashBlock; }
 
private:
    BlockHash hashBlock;
};
 
class CCoinsView {
public:
    virtual bool GetCoin(const COutPoint &outpoint, Coin &coin) const;
 
    virtual bool HaveCoin(const COutPoint &outpoint) const;
 
    virtual BlockHash GetBestBlock() const;
 
    virtual std::vector<BlockHash> GetHeadBlocks() const;
 
    virtual bool BatchWrite(CCoinsMap &mapCoins, const BlockHash &hashBlock,
                            bool erase = true);
 
    virtual CCoinsViewCursor *Cursor() const;
 
    virtual ~CCoinsView() {}
 
    virtual size_t EstimateSize() const { return 0; }
};
 
class CCoinsViewBacked : public CCoinsView {
protected:
    CCoinsView *base;
 
public:
    CCoinsViewBacked(CCoinsView *viewIn);
    bool GetCoin(const COutPoint &outpoint, Coin &coin) const override;
    bool HaveCoin(const COutPoint &outpoint) const override;
    BlockHash GetBestBlock() const override;
    std::vector<BlockHash> GetHeadBlocks() const override;
    void SetBackend(CCoinsView &viewIn);
    bool BatchWrite(CCoinsMap &mapCoins, const BlockHash &hashBlock,
                    bool erase = true) override;
    CCoinsViewCursor *Cursor() const override;
    size_t EstimateSize() const override;
};
 
class CCoinsViewCache : public CCoinsViewBacked {
private:
    const bool m_deterministic;
 
protected:
    mutable BlockHash hashBlock;
    mutable CCoinsMapMemoryResource m_cache_coins_memory_resource{};
    mutable CCoinsMap cacheCoins;
 
    /* Cached dynamic memory usage for the inner Coin objects. */
    mutable size_t cachedCoinsUsage;
 
public:
    CCoinsViewCache(CCoinsView *baseIn, bool deterministic = false);
 
    CCoinsViewCache(const CCoinsViewCache &) = delete;
 
    // Standard CCoinsView methods
    bool GetCoin(const COutPoint &outpoint, Coin &coin) const override;
    bool HaveCoin(const COutPoint &outpoint) const override;
    BlockHash GetBestBlock() const override;
    void SetBestBlock(const BlockHash &hashBlock);
    bool BatchWrite(CCoinsMap &mapCoins, const BlockHash &hashBlock,
                    bool erase = true) override;
    CCoinsViewCursor *Cursor() const override {
        throw std::logic_error(
            "CCoinsViewCache cursor iteration not supported.");
    }
 
    bool HaveCoinInCache(const COutPoint &outpoint) const;
 
    const Coin &AccessCoin(const COutPoint &output) const;
 
    void AddCoin(const COutPoint &outpoint, Coin coin, bool possible_overwrite);
 
    void EmplaceCoinInternalDANGER(COutPoint &&outpoint, Coin &&coin);
 
    bool SpendCoin(const COutPoint &outpoint, Coin *moveto = nullptr);
 
    bool Flush();
 
    bool Sync();
 
    void Uncache(const COutPoint &outpoint);
 
    unsigned int GetCacheSize() const;
 
    size_t DynamicMemoryUsage() const;
 
    bool HaveInputs(const CTransaction &tx) const;
 
    void ReallocateCache();
 
    void SanityCheck() const;
 
private:
    CCoinsMap::iterator FetchCoin(const COutPoint &outpoint) const;
};
 
// TODO: pass in a boolean to limit these possible overwrites to known
// (pre-BIP34) cases.
void AddCoins(CCoinsViewCache &cache, const CTransaction &tx, int nHeight,
              bool check = false);
 
const Coin &AccessByTxid(const CCoinsViewCache &cache, const TxId &txid);
 
class CCoinsViewErrorCatcher final : public CCoinsViewBacked {
public:
    explicit CCoinsViewErrorCatcher(CCoinsView *view)
        : CCoinsViewBacked(view) {}
 
    void AddReadErrCallback(std::function<void()> f) {
        m_err_callbacks.emplace_back(std::move(f));
    }
 
    bool GetCoin(const COutPoint &outpoint, Coin &coin) const override;
 
private:
    std::vector<std::function<void()>> m_err_callbacks;
};
 
#endif // BITCOIN_COINS_H