c9d1a81ce7
All direct modifications are now done through ModifyCoins, and BatchWrite is used for pushing batches of queued modifications up, so we don't need the low-level SetCoins and SetBestBlock anymore in the top-level CCoinsView class.
418 lines
15 KiB
C++
418 lines
15 KiB
C++
// Copyright (c) 2009-2010 Satoshi Nakamoto
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// Copyright (c) 2009-2013 The Bitcoin developers
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// Distributed under the MIT/X11 software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#ifndef BITCOIN_COINS_H
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#define BITCOIN_COINS_H
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#include "core.h"
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#include "serialize.h"
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#include "uint256.h"
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#include <assert.h>
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#include <stdint.h>
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#include <boost/foreach.hpp>
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#include <boost/unordered_map.hpp>
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/** pruned version of CTransaction: only retains metadata and unspent transaction outputs
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*
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* Serialized format:
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* - VARINT(nVersion)
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* - VARINT(nCode)
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* - unspentness bitvector, for vout[2] and further; least significant byte first
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* - the non-spent CTxOuts (via CTxOutCompressor)
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* - VARINT(nHeight)
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*
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* The nCode value consists of:
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* - bit 1: IsCoinBase()
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* - bit 2: vout[0] is not spent
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* - bit 4: vout[1] is not spent
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* - The higher bits encode N, the number of non-zero bytes in the following bitvector.
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* - In case both bit 2 and bit 4 are unset, they encode N-1, as there must be at
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* least one non-spent output).
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*
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* Example: 0104835800816115944e077fe7c803cfa57f29b36bf87c1d358bb85e
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* <><><--------------------------------------------><---->
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* | \ | /
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* version code vout[1] height
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*
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* - version = 1
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* - code = 4 (vout[1] is not spent, and 0 non-zero bytes of bitvector follow)
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* - unspentness bitvector: as 0 non-zero bytes follow, it has length 0
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* - vout[1]: 835800816115944e077fe7c803cfa57f29b36bf87c1d35
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* * 8358: compact amount representation for 60000000000 (600 BTC)
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* * 00: special txout type pay-to-pubkey-hash
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* * 816115944e077fe7c803cfa57f29b36bf87c1d35: address uint160
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* - height = 203998
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*
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*
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* Example: 0109044086ef97d5790061b01caab50f1b8e9c50a5057eb43c2d9563a4eebbd123008c988f1a4a4de2161e0f50aac7f17e7f9555caa486af3b
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* <><><--><--------------------------------------------------><----------------------------------------------><---->
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* / \ \ | | /
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* version code unspentness vout[4] vout[16] height
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*
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* - version = 1
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* - code = 9 (coinbase, neither vout[0] or vout[1] are unspent,
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* 2 (1, +1 because both bit 2 and bit 4 are unset) non-zero bitvector bytes follow)
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* - unspentness bitvector: bits 2 (0x04) and 14 (0x4000) are set, so vout[2+2] and vout[14+2] are unspent
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* - vout[4]: 86ef97d5790061b01caab50f1b8e9c50a5057eb43c2d9563a4ee
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* * 86ef97d579: compact amount representation for 234925952 (2.35 BTC)
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* * 00: special txout type pay-to-pubkey-hash
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* * 61b01caab50f1b8e9c50a5057eb43c2d9563a4ee: address uint160
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* - vout[16]: bbd123008c988f1a4a4de2161e0f50aac7f17e7f9555caa4
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* * bbd123: compact amount representation for 110397 (0.001 BTC)
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* * 00: special txout type pay-to-pubkey-hash
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* * 8c988f1a4a4de2161e0f50aac7f17e7f9555caa4: address uint160
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* - height = 120891
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*/
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class CCoins
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{
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public:
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// whether transaction is a coinbase
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bool fCoinBase;
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// unspent transaction outputs; spent outputs are .IsNull(); spent outputs at the end of the array are dropped
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std::vector<CTxOut> vout;
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// at which height this transaction was included in the active block chain
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int nHeight;
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// version of the CTransaction; accesses to this value should probably check for nHeight as well,
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// as new tx version will probably only be introduced at certain heights
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int nVersion;
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void FromTx(const CTransaction &tx, int nHeightIn) {
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fCoinBase = tx.IsCoinBase();
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vout = tx.vout;
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nHeight = nHeightIn;
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nVersion = tx.nVersion;
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ClearUnspendable();
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}
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// construct a CCoins from a CTransaction, at a given height
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CCoins(const CTransaction &tx, int nHeightIn) {
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FromTx(tx, nHeightIn);
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}
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void Clear() {
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fCoinBase = false;
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std::vector<CTxOut>().swap(vout);
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nHeight = 0;
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nVersion = 0;
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}
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// empty constructor
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CCoins() : fCoinBase(false), vout(0), nHeight(0), nVersion(0) { }
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// remove spent outputs at the end of vout
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void Cleanup() {
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while (vout.size() > 0 && vout.back().IsNull())
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vout.pop_back();
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if (vout.empty())
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std::vector<CTxOut>().swap(vout);
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}
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void ClearUnspendable() {
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BOOST_FOREACH(CTxOut &txout, vout) {
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if (txout.scriptPubKey.IsUnspendable())
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txout.SetNull();
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}
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Cleanup();
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}
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void swap(CCoins &to) {
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std::swap(to.fCoinBase, fCoinBase);
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to.vout.swap(vout);
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std::swap(to.nHeight, nHeight);
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std::swap(to.nVersion, nVersion);
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}
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// equality test
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friend bool operator==(const CCoins &a, const CCoins &b) {
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// Empty CCoins objects are always equal.
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if (a.IsPruned() && b.IsPruned())
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return true;
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return a.fCoinBase == b.fCoinBase &&
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a.nHeight == b.nHeight &&
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a.nVersion == b.nVersion &&
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a.vout == b.vout;
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}
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friend bool operator!=(const CCoins &a, const CCoins &b) {
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return !(a == b);
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}
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void CalcMaskSize(unsigned int &nBytes, unsigned int &nNonzeroBytes) const;
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bool IsCoinBase() const {
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return fCoinBase;
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}
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unsigned int GetSerializeSize(int nType, int nVersion) const {
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unsigned int nSize = 0;
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unsigned int nMaskSize = 0, nMaskCode = 0;
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CalcMaskSize(nMaskSize, nMaskCode);
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bool fFirst = vout.size() > 0 && !vout[0].IsNull();
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bool fSecond = vout.size() > 1 && !vout[1].IsNull();
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assert(fFirst || fSecond || nMaskCode);
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unsigned int nCode = 8*(nMaskCode - (fFirst || fSecond ? 0 : 1)) + (fCoinBase ? 1 : 0) + (fFirst ? 2 : 0) + (fSecond ? 4 : 0);
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// version
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nSize += ::GetSerializeSize(VARINT(this->nVersion), nType, nVersion);
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// size of header code
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nSize += ::GetSerializeSize(VARINT(nCode), nType, nVersion);
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// spentness bitmask
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nSize += nMaskSize;
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// txouts themself
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for (unsigned int i = 0; i < vout.size(); i++)
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if (!vout[i].IsNull())
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nSize += ::GetSerializeSize(CTxOutCompressor(REF(vout[i])), nType, nVersion);
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// height
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nSize += ::GetSerializeSize(VARINT(nHeight), nType, nVersion);
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return nSize;
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}
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template<typename Stream>
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void Serialize(Stream &s, int nType, int nVersion) const {
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unsigned int nMaskSize = 0, nMaskCode = 0;
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CalcMaskSize(nMaskSize, nMaskCode);
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bool fFirst = vout.size() > 0 && !vout[0].IsNull();
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bool fSecond = vout.size() > 1 && !vout[1].IsNull();
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assert(fFirst || fSecond || nMaskCode);
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unsigned int nCode = 8*(nMaskCode - (fFirst || fSecond ? 0 : 1)) + (fCoinBase ? 1 : 0) + (fFirst ? 2 : 0) + (fSecond ? 4 : 0);
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// version
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::Serialize(s, VARINT(this->nVersion), nType, nVersion);
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// header code
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::Serialize(s, VARINT(nCode), nType, nVersion);
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// spentness bitmask
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for (unsigned int b = 0; b<nMaskSize; b++) {
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unsigned char chAvail = 0;
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for (unsigned int i = 0; i < 8 && 2+b*8+i < vout.size(); i++)
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if (!vout[2+b*8+i].IsNull())
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chAvail |= (1 << i);
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::Serialize(s, chAvail, nType, nVersion);
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}
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// txouts themself
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for (unsigned int i = 0; i < vout.size(); i++) {
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if (!vout[i].IsNull())
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::Serialize(s, CTxOutCompressor(REF(vout[i])), nType, nVersion);
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}
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// coinbase height
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::Serialize(s, VARINT(nHeight), nType, nVersion);
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}
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template<typename Stream>
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void Unserialize(Stream &s, int nType, int nVersion) {
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unsigned int nCode = 0;
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// version
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::Unserialize(s, VARINT(this->nVersion), nType, nVersion);
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// header code
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::Unserialize(s, VARINT(nCode), nType, nVersion);
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fCoinBase = nCode & 1;
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std::vector<bool> vAvail(2, false);
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vAvail[0] = (nCode & 2) != 0;
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vAvail[1] = (nCode & 4) != 0;
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unsigned int nMaskCode = (nCode / 8) + ((nCode & 6) != 0 ? 0 : 1);
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// spentness bitmask
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while (nMaskCode > 0) {
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unsigned char chAvail = 0;
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::Unserialize(s, chAvail, nType, nVersion);
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for (unsigned int p = 0; p < 8; p++) {
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bool f = (chAvail & (1 << p)) != 0;
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vAvail.push_back(f);
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}
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if (chAvail != 0)
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nMaskCode--;
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}
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// txouts themself
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vout.assign(vAvail.size(), CTxOut());
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for (unsigned int i = 0; i < vAvail.size(); i++) {
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if (vAvail[i])
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::Unserialize(s, REF(CTxOutCompressor(vout[i])), nType, nVersion);
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}
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// coinbase height
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::Unserialize(s, VARINT(nHeight), nType, nVersion);
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Cleanup();
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}
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// mark an outpoint spent, and construct undo information
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bool Spend(const COutPoint &out, CTxInUndo &undo);
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// mark a vout spent
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bool Spend(int nPos);
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// check whether a particular output is still available
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bool IsAvailable(unsigned int nPos) const {
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return (nPos < vout.size() && !vout[nPos].IsNull());
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}
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// check whether the entire CCoins is spent
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// note that only !IsPruned() CCoins can be serialized
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bool IsPruned() const {
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BOOST_FOREACH(const CTxOut &out, vout)
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if (!out.IsNull())
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return false;
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return true;
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}
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};
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class CCoinsKeyHasher
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{
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private:
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uint256 salt;
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public:
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CCoinsKeyHasher();
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// This *must* return size_t. With Boost 1.46 on 32-bit systems the
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// unordered_map will behave unpredictably if the custom hasher returns a
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// uint64_t, resulting in failures when syncing the chain (#4634).
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size_t operator()(const uint256& key) const {
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return key.GetHash(salt);
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}
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};
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typedef boost::unordered_map<uint256, CCoins, CCoinsKeyHasher> CCoinsMap;
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struct CCoinsStats
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{
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int nHeight;
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uint256 hashBlock;
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uint64_t nTransactions;
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uint64_t nTransactionOutputs;
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uint64_t nSerializedSize;
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uint256 hashSerialized;
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int64_t nTotalAmount;
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CCoinsStats() : nHeight(0), hashBlock(0), nTransactions(0), nTransactionOutputs(0), nSerializedSize(0), hashSerialized(0), nTotalAmount(0) {}
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};
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/** Abstract view on the open txout dataset. */
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class CCoinsView
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{
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public:
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// Retrieve the CCoins (unspent transaction outputs) for a given txid
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virtual bool GetCoins(const uint256 &txid, CCoins &coins) const;
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// Just check whether we have data for a given txid.
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// This may (but cannot always) return true for fully spent transactions
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virtual bool HaveCoins(const uint256 &txid) const;
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// Retrieve the block hash whose state this CCoinsView currently represents
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virtual uint256 GetBestBlock() const;
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// Do a bulk modification (multiple CCoins changes + BestBlock change).
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// The passed mapCoins can be modified.
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virtual bool BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlock);
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// Calculate statistics about the unspent transaction output set
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virtual bool GetStats(CCoinsStats &stats) const;
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// As we use CCoinsViews polymorphically, have a virtual destructor
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virtual ~CCoinsView() {}
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};
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/** CCoinsView backed by another CCoinsView */
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class CCoinsViewBacked : public CCoinsView
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{
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protected:
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CCoinsView *base;
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public:
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CCoinsViewBacked(CCoinsView &viewIn);
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bool GetCoins(const uint256 &txid, CCoins &coins) const;
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bool HaveCoins(const uint256 &txid) const;
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uint256 GetBestBlock() const;
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void SetBackend(CCoinsView &viewIn);
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bool BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlock);
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bool GetStats(CCoinsStats &stats) const;
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};
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class CCoinsViewCache;
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/** A reference to a mutable cache entry. Encapsulating it allows us to run
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* cleanup code after the modification is finished, and keeping track of
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* concurrent modifications. */
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class CCoinsModifier
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{
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private:
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CCoinsViewCache& cache;
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CCoinsMap::iterator it;
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CCoinsModifier(CCoinsViewCache& cache_, CCoinsMap::iterator it_);
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public:
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CCoins* operator->() { return &it->second; }
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CCoins& operator*() { return it->second; }
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~CCoinsModifier();
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friend class CCoinsViewCache;
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};
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/** CCoinsView that adds a memory cache for transactions to another CCoinsView */
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class CCoinsViewCache : public CCoinsViewBacked
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{
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protected:
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/* Whether this cache has an active modifier. */
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bool hasModifier;
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/* Make mutable so that we can "fill the cache" even from Get-methods
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declared as "const". */
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mutable uint256 hashBlock;
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mutable CCoinsMap cacheCoins;
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public:
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CCoinsViewCache(CCoinsView &baseIn, bool fDummy = false);
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~CCoinsViewCache();
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// Standard CCoinsView methods
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bool GetCoins(const uint256 &txid, CCoins &coins) const;
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bool HaveCoins(const uint256 &txid) const;
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uint256 GetBestBlock() const;
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void SetBestBlock(const uint256 &hashBlock);
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bool BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlock);
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// Return a pointer to CCoins in the cache, or NULL if not found. This is
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// more efficient than GetCoins. Modifications to other cache entries are
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// allowed while accessing the returned pointer.
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const CCoins* AccessCoins(const uint256 &txid) const;
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// Return a modifiable reference to a CCoins. If no entry with the given
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// txid exists, a new one is created. Simultaneous modifications are not
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// allowed.
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CCoinsModifier ModifyCoins(const uint256 &txid);
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// Push the modifications applied to this cache to its base.
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// Failure to call this method before destruction will cause the changes to be forgotten.
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// If false is returned, the state of this cache (and its backing view) will be undefined.
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bool Flush();
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// Calculate the size of the cache (in number of transactions)
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unsigned int GetCacheSize() const;
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/** Amount of bitcoins coming in to a transaction
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Note that lightweight clients may not know anything besides the hash of previous transactions,
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so may not be able to calculate this.
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@param[in] tx transaction for which we are checking input total
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@return Sum of value of all inputs (scriptSigs)
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*/
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int64_t GetValueIn(const CTransaction& tx) const;
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// Check whether all prevouts of the transaction are present in the UTXO set represented by this view
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bool HaveInputs(const CTransaction& tx) const;
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// Return priority of tx at height nHeight
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double GetPriority(const CTransaction &tx, int nHeight) const;
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const CTxOut &GetOutputFor(const CTxIn& input) const;
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friend class CCoinsModifier;
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private:
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CCoinsMap::iterator FetchCoins(const uint256 &txid);
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CCoinsMap::const_iterator FetchCoins(const uint256 &txid) const;
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};
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#endif // BITCOIN_COINS_H
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