coins.h

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// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2014 The Bitcoin 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 "consensus/consensus.h"  // can be removed once policy/ established
#include "script/standard.h"
#include "serialize.h"
#include "uint256.h"
#include "undo.h"
 
#include <assert.h>
#include <stdint.h>
 
#include <boost/unordered_map.hpp>
 
extern bool GetTransaction(const uint256& hash, CTransaction& tx, uint256& hashBlock, bool fAllowSlow, CBlockIndex* blockIndex);
 
class CCoins
{
public:
    bool fCoinBase;
    bool fCoinStake;
 
    std::vector<CTxOut> vout;
 
    int nHeight;
 
    int nVersion;
 
    void FromTx(const CTransaction& tx, int nHeightIn)
    {
        fCoinBase = tx.IsCoinBase();
        fCoinStake = tx.IsCoinStake();
        vout = tx.vout;
        nHeight = nHeightIn;
        nVersion = tx.nVersion;
        ClearUnspendable();
    }
 
    CCoins(const CTransaction& tx, int nHeightIn)
    {
        FromTx(tx, nHeightIn);
    }
 
    void Clear()
    {
        fCoinBase = false;
        fCoinStake = false;
        std::vector<CTxOut>().swap(vout);
        nHeight = 0;
        nVersion = 0;
    }
 
    CCoins() : fCoinBase(false), fCoinStake(false), vout(0), nHeight(0), nVersion(0) {}
 
    void Cleanup()
    {
        while (vout.size() > 0 && vout.back().IsNull())
            vout.pop_back();
        if (vout.empty())
            std::vector<CTxOut>().swap(vout);
    }
 
    void ClearUnspendable()
    {
        for (CTxOut& txout : vout) {
            if (txout.scriptPubKey.IsUnspendable())
                txout.SetNull();
        }
        Cleanup();
    }
 
    void swap(CCoins& to)
    {
        std::swap(to.fCoinBase, fCoinBase);
        std::swap(to.fCoinStake, fCoinStake);
        to.vout.swap(vout);
        std::swap(to.nHeight, nHeight);
        std::swap(to.nVersion, nVersion);
    }
 
    friend bool operator==(const CCoins& a, const CCoins& b)
    {
        // Empty CCoins objects are always equal.
        if (a.IsPruned() && b.IsPruned())
            return true;
        return a.fCoinBase == b.fCoinBase &&
               a.fCoinStake == b.fCoinStake &&
               a.nHeight == b.nHeight &&
               a.nVersion == b.nVersion &&
               a.vout == b.vout;
    }
    friend bool operator!=(const CCoins& a, const CCoins& b)
    {
        return !(a == b);
    }
 
    void CalcMaskSize(unsigned int& nBytes, unsigned int& nNonzeroBytes) const;
 
    bool IsCoinBase() const
    {
        return fCoinBase;
    }
 
    bool IsCoinStake() const
    {
        return fCoinStake;
    }
 
    unsigned int GetSerializeSize(int nType, int nVersion) const
    {
        unsigned int nSize = 0;
        unsigned int nMaskSize = 0, nMaskCode = 0;
        CalcMaskSize(nMaskSize, nMaskCode);
        bool fFirst = vout.size() > 0 && !vout[0].IsNull();
        bool fSecond = vout.size() > 1 && !vout[1].IsNull();
        assert(fFirst || fSecond || nMaskCode);
        unsigned int nCode = 8 * (nMaskCode - (fFirst || fSecond ? 0 : 1)) + (fCoinBase ? 1 : 0) + (fCoinStake ? 2 : 0) + (fFirst ? 4 : 0) + (fSecond ? 8 : 0);
        // version
        nSize += ::GetSerializeSize(VARINT(this->nVersion), nType, nVersion);
        // size of header code
        nSize += ::GetSerializeSize(VARINT(nCode), nType, nVersion);
        // spentness bitmask
        nSize += nMaskSize;
        // txouts themself
        for (unsigned int i = 0; i < vout.size(); i++)
            if (!vout[i].IsNull())
                nSize += ::GetSerializeSize(CTxOutCompressor(REF(vout[i])), nType, nVersion);
        // height
        nSize += ::GetSerializeSize(VARINT(nHeight), nType, nVersion);
        return nSize;
    }
 
    template <typename Stream>
    void Serialize(Stream& s, int nType, int nVersion) const
    {
        unsigned int nMaskSize = 0, nMaskCode = 0;
        CalcMaskSize(nMaskSize, nMaskCode);
        bool fFirst = vout.size() > 0 && !vout[0].IsNull();
        bool fSecond = vout.size() > 1 && !vout[1].IsNull();
        assert(fFirst || fSecond || nMaskCode);
        unsigned int nCode = 16 * (nMaskCode - (fFirst || fSecond ? 0 : 1)) + (fCoinBase ? 1 : 0) + (fCoinStake ? 2 : 0) + (fFirst ? 4 : 0) + (fSecond ? 8 : 0);
        // version
        ::Serialize(s, VARINT(this->nVersion), nType, nVersion);
        // header code
        ::Serialize(s, VARINT(nCode), nType, nVersion);
        // spentness bitmask
        for (unsigned int b = 0; b < nMaskSize; b++) {
            unsigned char chAvail = 0;
            for (unsigned int i = 0; i < 8 && 2 + b * 8 + i < vout.size(); i++)
                if (!vout[2 + b * 8 + i].IsNull())
                    chAvail |= (1 << i);
            ::Serialize(s, chAvail, nType, nVersion);
        }
        // txouts themself
        for (unsigned int i = 0; i < vout.size(); i++) {
            if (!vout[i].IsNull())
                ::Serialize(s, CTxOutCompressor(REF(vout[i])), nType, nVersion);
        }
        // coinbase height
        ::Serialize(s, VARINT(nHeight), nType, nVersion);
    }
 
    template <typename Stream>
    void Unserialize(Stream& s, int nType, int nVersion)
    {
        unsigned int nCode = 0;
        // version
        ::Unserialize(s, VARINT(this->nVersion), nType, nVersion);
        // header code
        ::Unserialize(s, VARINT(nCode), nType, nVersion);
        fCoinBase = nCode & 1;         //0001 - means coinbase
        fCoinStake = (nCode & 2) != 0; //0010 coinstake
        std::vector<bool> vAvail(2, false);
        vAvail[0] = (nCode & 4) != 0; // 0100
        vAvail[1] = (nCode & 8) != 0; // 1000
        unsigned int nMaskCode = (nCode / 16) + ((nCode & 12) != 0 ? 0 : 1);
        // spentness bitmask
        while (nMaskCode > 0) {
            unsigned char chAvail = 0;
            ::Unserialize(s, chAvail, nType, nVersion);
            for (unsigned int p = 0; p < 8; p++) {
                bool f = (chAvail & (1 << p)) != 0;
                vAvail.push_back(f);
            }
            if (chAvail != 0)
                nMaskCode--;
        }
        // txouts themself
        vout.assign(vAvail.size(), CTxOut());
        for (unsigned int i = 0; i < vAvail.size(); i++) {
            if (vAvail[i])
                ::Unserialize(s, REF(CTxOutCompressor(vout[i])), nType, nVersion);
        }
        // coinbase height
        ::Unserialize(s, VARINT(nHeight), nType, nVersion);
        Cleanup();
    }
 
    bool Spend(const COutPoint& out, CTxInUndo& undo);
 
    bool Spend(int nPos);
 
    bool IsAvailable(unsigned int nPos) const
    {
        return (nPos < vout.size() && !vout[nPos].IsNull());
    }
 
    bool IsPruned() const
    {
        for (const CTxOut& out : vout)
            if (!out.IsNull())
                return false;
        return true;
    }
 
    size_t DynamicMemoryUsage() const {
        size_t ret = memusage::DynamicUsage(vout);
        for(const CTxOut &out : vout) {
            ret += memusage::DynamicUsage(*static_cast<const CScriptBase*>(&out.scriptPubKey));
        }
        return ret;
    }
};
 
class CCoinsKeyHasher
{
private:
    uint256 salt;
 
public:
    CCoinsKeyHasher();
 
    size_t operator()(const uint256& key) const
    {
        return key.GetHash(salt);
    }
};
 
struct CCoinsCacheEntry {
    CCoins coins; // The actual cached data.
    unsigned char flags;
 
    enum Flags {
        DIRTY = (1 << 0), // This cache entry is potentially different from the version in the parent view.
        FRESH = (1 << 1), // The parent view does not have this entry (or it is pruned).
    };
 
    CCoinsCacheEntry() : coins(), flags(0) {}
};
 
typedef boost::unordered_map<uint256, CCoinsCacheEntry, CCoinsKeyHasher> CCoinsMap;
 
struct CCoinsStats {
    int nHeight;
    uint256 hashBlock;
    uint64_t nTransactions;
    uint64_t nTransactionOutputs;
    uint64_t nSerializedSize;
    uint256 hashSerialized;
    CAmount nTotalAmount;
 
    CCoinsStats() : nHeight(0), nTransactions(0), nTransactionOutputs(0), nSerializedSize(0), nTotalAmount(0) {}
};
 
 
class CCoinsView
{
public:
    virtual bool GetCoins(const uint256& txid, CCoins& coins) const;
 
    virtual bool HaveCoins(const uint256& txid) const;
 
    virtual uint256 GetBestBlock() const;
 
    virtual bool BatchWrite(CCoinsMap& mapCoins, const uint256& hashBlock);
 
    virtual bool GetStats(CCoinsStats& stats) const;
 
    virtual ~CCoinsView() {}
};
 
 
class CCoinsViewBacked : public CCoinsView
{
protected:
    CCoinsView* base;
 
public:
    CCoinsViewBacked(CCoinsView* viewIn);
    bool GetCoins(const uint256& txid, CCoins& coins) const;
    bool HaveCoins(const uint256& txid) const;
    uint256 GetBestBlock() const;
    void SetBackend(CCoinsView& viewIn);
    bool BatchWrite(CCoinsMap& mapCoins, const uint256& hashBlock);
    bool GetStats(CCoinsStats& stats) const;
};
 
class CCoinsViewCache;
 
static const unsigned int STANDARD_LOCKTIME_VERIFY_FLAGS = LOCKTIME_VERIFY_SEQUENCE |
                                                           LOCKTIME_MEDIAN_TIME_PAST;
 
class CCoinsModifier
{
private:
    CCoinsViewCache& cache;
    CCoinsMap::iterator it;
    size_t cachedCoinUsage; // Cached memory usage of the CCoins object before modification
    CCoinsModifier(CCoinsViewCache& cache_, CCoinsMap::iterator it_, size_t usage);
 
public:
    CCoins* operator->() { return &it->second.coins; }
    CCoins& operator*() { return it->second.coins; }
    ~CCoinsModifier();
    friend class CCoinsViewCache;
};
 
class CCoinsViewCache : public CCoinsViewBacked
{
protected:
    /* Whether this cache has an active modifier. */
    bool hasModifier;
 
    mutable uint256 hashBlock;
    mutable CCoinsMap cacheCoins;
 
    /* Cached dynamic memory usage for the inner CCoins objects. */
    mutable size_t cachedCoinsUsage;
 
public:
    CCoinsViewCache(CCoinsView* baseIn);
    ~CCoinsViewCache();
 
    // Standard CCoinsView methods
    bool GetCoins(const uint256& txid, CCoins& coins) const;
    bool HaveCoins(const uint256& txid) const;
    uint256 GetBestBlock() const;
    void SetBestBlock(const uint256& hashBlock);
    bool BatchWrite(CCoinsMap& mapCoins, const uint256& hashBlock);
 
    const CCoins* AccessCoins(const uint256& txid) const;
 
    CCoinsModifier ModifyCoins(const uint256& txid);
 
    bool Flush();
 
    unsigned int GetCacheSize() const;
 
    size_t DynamicMemoryUsage() const;
 
    bool HaveInputs(const CTransaction& tx) const;
 
    const CTxOut& GetOutputFor(const CTxIn& input) const;
 
    friend class CCoinsModifier;
 
private:
    CCoinsMap::iterator FetchCoins(const uint256& txid);
    CCoinsMap::const_iterator FetchCoins(const uint256& txid) const;
};
 
#endif // BITCOIN_COINS_H