src/coins.cpp

   1 // Copyright (c) 2012-2013 The Bitcoin developers
   2 // Distributed under the MIT/X11 software license, see the accompanying
   3 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
   4
   5 #include "coins.h"
   6
   7 #include "random.h"
   8
   9 #include <assert.h>
  10
  11 // calculate number of bytes for the bitmask, and its number of non-zero bytes
  12 // each bit in the bitmask represents the availability of one output, but the
  13 // availabilities of the first two outputs are encoded separately
  14 void CCoins::CalcMaskSize(unsigned int &nBytes, unsigned int &nNonzeroBytes) const {
  15     unsigned int nLastUsedByte = 0;
  16     for (unsigned int b = 0; 2+b*8 < vout.size(); b++) {
  17         bool fZero = true;
  18         for (unsigned int i = 0; i < 8 && 2+b*8+i < vout.size(); i++) {
  19             if (!vout[2+b*8+i].IsNull()) {
  20                 fZero = false;
  21                 continue;
  22             }
  23         }
  24         if (!fZero) {
  25             nLastUsedByte = b + 1;
  26             nNonzeroBytes++;
  27         }
  28     }
  29     nBytes += nLastUsedByte;
  30 }
  31
  32 bool CCoins::Spend(const COutPoint &out, CTxInUndo &undo) {
  33     if (out.n >= vout.size())
  34         return false;
  35     if (vout[out.n].IsNull())
  36         return false;
  37     undo = CTxInUndo(vout[out.n]);
  38     vout[out.n].SetNull();
  39     Cleanup();
  40     if (vout.size() == 0) {
  41         undo.nHeight = nHeight;
  42         undo.fCoinBase = fCoinBase;
  43         undo.nVersion = this->nVersion;
  44     }
  45     return true;
  46 }
  47
  48 bool CCoins::Spend(int nPos) {
  49     CTxInUndo undo;
  50     COutPoint out(0, nPos);
  51     return Spend(out, undo);
  52 }
  53
  54
  55 bool CCoinsView::GetCoins(const uint256 &txid, CCoins &coins) { return false; }
  56 bool CCoinsView::SetCoins(const uint256 &txid, const CCoins &coins) { return false; }
  57 bool CCoinsView::HaveCoins(const uint256 &txid) { return false; }
  58 uint256 CCoinsView::GetBestBlock() { return uint256(0); }
  59 bool CCoinsView::SetBestBlock(const uint256 &hashBlock) { return false; }
  60 bool CCoinsView::BatchWrite(const CCoinsMap &mapCoins, const uint256 &hashBlock) { return false; }
  61 bool CCoinsView::GetStats(CCoinsStats &stats) { return false; }
  62
  63
  64 CCoinsViewBacked::CCoinsViewBacked(CCoinsView &viewIn) : base(&viewIn) { }
  65 bool CCoinsViewBacked::GetCoins(const uint256 &txid, CCoins &coins) { return base->GetCoins(txid, coins); }
  66 bool CCoinsViewBacked::SetCoins(const uint256 &txid, const CCoins &coins) { return base->SetCoins(txid, coins); }
  67 bool CCoinsViewBacked::HaveCoins(const uint256 &txid) { return base->HaveCoins(txid); }
  68 uint256 CCoinsViewBacked::GetBestBlock() { return base->GetBestBlock(); }
  69 bool CCoinsViewBacked::SetBestBlock(const uint256 &hashBlock) { return base->SetBestBlock(hashBlock); }
  70 void CCoinsViewBacked::SetBackend(CCoinsView &viewIn) { base = &viewIn; }
  71 bool CCoinsViewBacked::BatchWrite(const CCoinsMap &mapCoins, const uint256 &hashBlock) { return base->BatchWrite(mapCoins, hashBlock); }
  72 bool CCoinsViewBacked::GetStats(CCoinsStats &stats) { return base->GetStats(stats); }
  73
  74 CCoinsKeyHasher::CCoinsKeyHasher() : salt(GetRandHash()) {}
  75
  76 CCoinsViewCache::CCoinsViewCache(CCoinsView &baseIn, bool fDummy) : CCoinsViewBacked(baseIn), hashBlock(0) { }
  77
  78 bool CCoinsViewCache::GetCoins(const uint256 &txid, CCoins &coins) {
  79     if (cacheCoins.count(txid)) {
  80         coins = cacheCoins[txid];
  81         return true;
  82     }
  83     if (base->GetCoins(txid, coins)) {
  84         cacheCoins[txid] = coins;
  85         return true;
  86     }
  87     return false;
  88 }
  89
  90 CCoinsMap::iterator CCoinsViewCache::FetchCoins(const uint256 &txid) {
  91     CCoinsMap::iterator it = cacheCoins.find(txid);
  92     if (it != cacheCoins.end())
  93         return it;
  94     CCoins tmp;
  95     if (!base->GetCoins(txid,tmp))
  96         return cacheCoins.end();
  97     CCoinsMap::iterator ret = cacheCoins.insert(it, std::make_pair(txid, CCoins()));
  98     tmp.swap(ret->second);
  99     return ret;
 100 }
 101
 102 CCoins &CCoinsViewCache::GetCoins(const uint256 &txid) {
 103     CCoinsMap::iterator it = FetchCoins(txid);
 104     assert(it != cacheCoins.end());
 105     return it->second;
 106 }
 107
 108 bool CCoinsViewCache::SetCoins(const uint256 &txid, const CCoins &coins) {
 109     cacheCoins[txid] = coins;
 110     return true;
 111 }
 112
 113 bool CCoinsViewCache::HaveCoins(const uint256 &txid) {
 114     CCoinsMap::iterator it = FetchCoins(txid);
 115     // We're using vtx.empty() instead of IsPruned here for performance reasons,
 116     // as we only care about the case where an transaction was replaced entirely
 117     // in a reorganization (which wipes vout entirely, as opposed to spending
 118     // which just cleans individual outputs).
 119     return (it != cacheCoins.end() && !it->second.vout.empty());
 120 }
 121
 122 uint256 CCoinsViewCache::GetBestBlock() {
 123     if (hashBlock == uint256(0))
 124         hashBlock = base->GetBestBlock();
 125     return hashBlock;
 126 }
 127
 128 bool CCoinsViewCache::SetBestBlock(const uint256 &hashBlockIn) {
 129     hashBlock = hashBlockIn;
 130     return true;
 131 }
 132
 133 bool CCoinsViewCache::BatchWrite(const CCoinsMap &mapCoins, const uint256 &hashBlockIn) {
 134     for (CCoinsMap::const_iterator it = mapCoins.begin(); it != mapCoins.end(); it++)
 135         cacheCoins[it->first] = it->second;
 136     hashBlock = hashBlockIn;
 137     return true;
 138 }
 139
 140 bool CCoinsViewCache::Flush() {
 141     bool fOk = base->BatchWrite(cacheCoins, hashBlock);
 142     if (fOk)
 143         cacheCoins.clear();
 144     return fOk;
 145 }
 146
 147 unsigned int CCoinsViewCache::GetCacheSize() {
 148     return cacheCoins.size();
 149 }
 150
 151 const CTxOut &CCoinsViewCache::GetOutputFor(const CTxIn& input)
 152 {
 153     const CCoins &coins = GetCoins(input.prevout.hash);
 154     assert(coins.IsAvailable(input.prevout.n));
 155     return coins.vout[input.prevout.n];
 156 }
 157
 158 int64_t CCoinsViewCache::GetValueIn(const CTransaction& tx)
 159 {
 160     if (tx.IsCoinBase())
 161         return 0;
 162
 163     int64_t nResult = 0;
 164     for (unsigned int i = 0; i < tx.vin.size(); i++)
 165         nResult += GetOutputFor(tx.vin[i]).nValue;
 166
 167     return nResult;
 168 }
 169
 170 bool CCoinsViewCache::HaveInputs(const CTransaction& tx)
 171 {
 172     if (!tx.IsCoinBase()) {
 173         // first check whether information about the prevout hash is available
 174         for (unsigned int i = 0; i < tx.vin.size(); i++) {
 175             const COutPoint &prevout = tx.vin[i].prevout;
 176             if (!HaveCoins(prevout.hash))
 177                 return false;
 178         }
 179
 180         // then check whether the actual outputs are available
 181         for (unsigned int i = 0; i < tx.vin.size(); i++) {
 182             const COutPoint &prevout = tx.vin[i].prevout;
 183             const CCoins &coins = GetCoins(prevout.hash);
 184             if (!coins.IsAvailable(prevout.n))
 185                 return false;
 186         }
 187     }
 188     return true;
 189 }
 190
 191 double CCoinsViewCache::GetPriority(const CTransaction &tx, int nHeight)
 192 {
 193     if (tx.IsCoinBase())
 194         return 0.0;
 195     double dResult = 0.0;
 196     BOOST_FOREACH(const CTxIn& txin, tx.vin)
 197     {
 198         const CCoins &coins = GetCoins(txin.prevout.hash);
 199         if (!coins.IsAvailable(txin.prevout.n)) continue;
 200         if (coins.nHeight < nHeight) {
 201             dResult += coins.vout[txin.prevout.n].nValue * (nHeight-coins.nHeight);
 202         }
 203     }
 204     return tx.ComputePriority(dResult);
 205 }