src/coins.cpp

   1 // Copyright (c) 2012-2017 The Bitcoin Core developers
   2 // Distributed under the MIT 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 <consensus/consensus.h>
   8 #include <random.h>
   9
  10 bool CCoinsView::GetCoin(const COutPoint &outpoint, Coin &coin) const { return false; }
  11 uint256 CCoinsView::GetBestBlock() const { return uint256(); }
  12 std::vector<uint256> CCoinsView::GetHeadBlocks() const { return std::vector<uint256>(); }
  13 bool CCoinsView::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlock) { return false; }
  14 CCoinsViewCursor *CCoinsView::Cursor() const { return nullptr; }
  15
  16 bool CCoinsView::HaveCoin(const COutPoint &outpoint) const
  17 {
  18     Coin coin;
  19     return GetCoin(outpoint, coin);
  20 }
  21
  22 CCoinsViewBacked::CCoinsViewBacked(CCoinsView *viewIn) : base(viewIn) { }
  23 bool CCoinsViewBacked::GetCoin(const COutPoint &outpoint, Coin &coin) const { return base->GetCoin(outpoint, coin); }
  24 bool CCoinsViewBacked::HaveCoin(const COutPoint &outpoint) const { return base->HaveCoin(outpoint); }
  25 uint256 CCoinsViewBacked::GetBestBlock() const { return base->GetBestBlock(); }
  26 std::vector<uint256> CCoinsViewBacked::GetHeadBlocks() const { return base->GetHeadBlocks(); }
  27 void CCoinsViewBacked::SetBackend(CCoinsView &viewIn) { base = &viewIn; }
  28 bool CCoinsViewBacked::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlock) { return base->BatchWrite(mapCoins, hashBlock); }
  29 CCoinsViewCursor *CCoinsViewBacked::Cursor() const { return base->Cursor(); }
  30 size_t CCoinsViewBacked::EstimateSize() const { return base->EstimateSize(); }
  31
  32 SaltedOutpointHasher::SaltedOutpointHasher() : k0(GetRand(std::numeric_limits<uint64_t>::max())), k1(GetRand(std::numeric_limits<uint64_t>::max())) {}
  33
  34 CCoinsViewCache::CCoinsViewCache(CCoinsView *baseIn) : CCoinsViewBacked(baseIn), cachedCoinsUsage(0) {}
  35
  36 size_t CCoinsViewCache::DynamicMemoryUsage() const {
  37     return memusage::DynamicUsage(cacheCoins) + cachedCoinsUsage;
  38 }
  39
  40 CCoinsMap::iterator CCoinsViewCache::FetchCoin(const COutPoint &outpoint) const {
  41     CCoinsMap::iterator it = cacheCoins.find(outpoint);
  42     if (it != cacheCoins.end())
  43         return it;
  44     Coin tmp;
  45     if (!base->GetCoin(outpoint, tmp))
  46         return cacheCoins.end();
  47     CCoinsMap::iterator ret = cacheCoins.emplace(std::piecewise_construct, std::forward_as_tuple(outpoint), std::forward_as_tuple(std::move(tmp))).first;
  48     if (ret->second.coin.IsSpent()) {
  49         // The parent only has an empty entry for this outpoint; we can consider our
  50         // version as fresh.
  51         ret->second.flags = CCoinsCacheEntry::FRESH;
  52     }
  53     cachedCoinsUsage += ret->second.coin.DynamicMemoryUsage();
  54     return ret;
  55 }
  56
  57 bool CCoinsViewCache::GetCoin(const COutPoint &outpoint, Coin &coin) const {
  58     CCoinsMap::const_iterator it = FetchCoin(outpoint);
  59     if (it != cacheCoins.end()) {
  60         coin = it->second.coin;
  61         return !coin.IsSpent();
  62     }
  63     return false;
  64 }
  65
  66 void CCoinsViewCache::AddCoin(const COutPoint &outpoint, Coin&& coin, bool possible_overwrite) {
  67     assert(!coin.IsSpent());
  68     if (coin.out.scriptPubKey.IsUnspendable()) return;
  69     CCoinsMap::iterator it;
  70     bool inserted;
  71     std::tie(it, inserted) = cacheCoins.emplace(std::piecewise_construct, std::forward_as_tuple(outpoint), std::tuple<>());
  72     bool fresh = false;
  73     if (!inserted) {
  74         cachedCoinsUsage -= it->second.coin.DynamicMemoryUsage();
  75     }
  76     if (!possible_overwrite) {
  77         if (!it->second.coin.IsSpent()) {
  78             throw std::logic_error("Adding new coin that replaces non-pruned entry");
  79         }
  80         fresh = !(it->second.flags & CCoinsCacheEntry::DIRTY);
  81     }
  82     it->second.coin = std::move(coin);
  83     it->second.flags |= CCoinsCacheEntry::DIRTY | (fresh ? CCoinsCacheEntry::FRESH : 0);
  84     cachedCoinsUsage += it->second.coin.DynamicMemoryUsage();
  85 }
  86
  87 void AddCoins(CCoinsViewCache& cache, const CTransaction &tx, int nHeight, bool check) {
  88     bool fCoinbase = tx.IsCoinBase();
  89     const uint256& txid = tx.GetHash();
  90     for (size_t i = 0; i < tx.vout.size(); ++i) {
  91         bool overwrite = check ? cache.HaveCoin(COutPoint(txid, i)) : fCoinbase;
  92         // Always set the possible_overwrite flag to AddCoin for coinbase txn, in order to correctly
  93         // deal with the pre-BIP30 occurrences of duplicate coinbase transactions.
  94         cache.AddCoin(COutPoint(txid, i), Coin(tx.vout[i], nHeight, fCoinbase), overwrite);
  95     }
  96 }
  97
  98 bool CCoinsViewCache::SpendCoin(const COutPoint &outpoint, Coin* moveout) {
  99     CCoinsMap::iterator it = FetchCoin(outpoint);
 100     if (it == cacheCoins.end()) return false;
 101     cachedCoinsUsage -= it->second.coin.DynamicMemoryUsage();
 102     if (moveout) {
 103         *moveout = std::move(it->second.coin);
 104     }
 105     if (it->second.flags & CCoinsCacheEntry::FRESH) {
 106         cacheCoins.erase(it);
 107     } else {
 108         it->second.flags |= CCoinsCacheEntry::DIRTY;
 109         it->second.coin.Clear();
 110     }
 111     return true;
 112 }
 113
 114 static const Coin coinEmpty;
 115
 116 const Coin& CCoinsViewCache::AccessCoin(const COutPoint &outpoint) const {
 117     CCoinsMap::const_iterator it = FetchCoin(outpoint);
 118     if (it == cacheCoins.end()) {
 119         return coinEmpty;
 120     } else {
 121         return it->second.coin;
 122     }
 123 }
 124
 125 bool CCoinsViewCache::HaveCoin(const COutPoint &outpoint) const {
 126     CCoinsMap::const_iterator it = FetchCoin(outpoint);
 127     return (it != cacheCoins.end() && !it->second.coin.IsSpent());
 128 }
 129
 130 bool CCoinsViewCache::HaveCoinInCache(const COutPoint &outpoint) const {
 131     CCoinsMap::const_iterator it = cacheCoins.find(outpoint);
 132     return (it != cacheCoins.end() && !it->second.coin.IsSpent());
 133 }
 134
 135 uint256 CCoinsViewCache::GetBestBlock() const {
 136     if (hashBlock.IsNull())
 137         hashBlock = base->GetBestBlock();
 138     return hashBlock;
 139 }
 140
 141 void CCoinsViewCache::SetBestBlock(const uint256 &hashBlockIn) {
 142     hashBlock = hashBlockIn;
 143 }
 144
 145 bool CCoinsViewCache::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlockIn) {
 146     for (CCoinsMap::iterator it = mapCoins.begin(); it != mapCoins.end(); it = mapCoins.erase(it)) {
 147         // Ignore non-dirty entries (optimization).
 148         if (!(it->second.flags & CCoinsCacheEntry::DIRTY)) {
 149             continue;
 150         }
 151         CCoinsMap::iterator itUs = cacheCoins.find(it->first);
 152         if (itUs == cacheCoins.end()) {
 153             // The parent cache does not have an entry, while the child does
 154             // We can ignore it if it's both FRESH and pruned in the child
 155             if (!(it->second.flags & CCoinsCacheEntry::FRESH && it->second.coin.IsSpent())) {
 156                 // Otherwise we will need to create it in the parent
 157                 // and move the data up and mark it as dirty
 158                 CCoinsCacheEntry& entry = cacheCoins[it->first];
 159                 entry.coin = std::move(it->second.coin);
 160                 cachedCoinsUsage += entry.coin.DynamicMemoryUsage();
 161                 entry.flags = CCoinsCacheEntry::DIRTY;
 162                 // We can mark it FRESH in the parent if it was FRESH in the child
 163                 // Otherwise it might have just been flushed from the parent's cache
 164                 // and already exist in the grandparent
 165                 if (it->second.flags & CCoinsCacheEntry::FRESH) {
 166                     entry.flags |= CCoinsCacheEntry::FRESH;
 167                 }
 168             }
 169         } else {
 170             // Assert that the child cache entry was not marked FRESH if the
 171             // parent cache entry has unspent outputs. If this ever happens,
 172             // it means the FRESH flag was misapplied and there is a logic
 173             // error in the calling code.
 174             if ((it->second.flags & CCoinsCacheEntry::FRESH) && !itUs->second.coin.IsSpent()) {
 175                 throw std::logic_error("FRESH flag misapplied to cache entry for base transaction with spendable outputs");
 176             }
 177
 178             // Found the entry in the parent cache
 179             if ((itUs->second.flags & CCoinsCacheEntry::FRESH) && it->second.coin.IsSpent()) {
 180                 // The grandparent does not have an entry, and the child is
 181                 // modified and being pruned. This means we can just delete
 182                 // it from the parent.
 183                 cachedCoinsUsage -= itUs->second.coin.DynamicMemoryUsage();
 184                 cacheCoins.erase(itUs);
 185             } else {
 186                 // A normal modification.
 187                 cachedCoinsUsage -= itUs->second.coin.DynamicMemoryUsage();
 188                 itUs->second.coin = std::move(it->second.coin);
 189                 cachedCoinsUsage += itUs->second.coin.DynamicMemoryUsage();
 190                 itUs->second.flags |= CCoinsCacheEntry::DIRTY;
 191                 // NOTE: It is possible the child has a FRESH flag here in
 192                 // the event the entry we found in the parent is pruned. But
 193                 // we must not copy that FRESH flag to the parent as that
 194                 // pruned state likely still needs to be communicated to the
 195                 // grandparent.
 196             }
 197         }
 198     }
 199     hashBlock = hashBlockIn;
 200     return true;
 201 }
 202
 203 bool CCoinsViewCache::Flush() {
 204     bool fOk = base->BatchWrite(cacheCoins, hashBlock);
 205     cacheCoins.clear();
 206     cachedCoinsUsage = 0;
 207     return fOk;
 208 }
 209
 210 void CCoinsViewCache::Uncache(const COutPoint& hash)
 211 {
 212     CCoinsMap::iterator it = cacheCoins.find(hash);
 213     if (it != cacheCoins.end() && it->second.flags == 0) {
 214         cachedCoinsUsage -= it->second.coin.DynamicMemoryUsage();
 215         cacheCoins.erase(it);
 216     }
 217 }
 218
 219 unsigned int CCoinsViewCache::GetCacheSize() const {
 220     return cacheCoins.size();
 221 }
 222
 223 CAmount CCoinsViewCache::GetValueIn(const CTransaction& tx) const
 224 {
 225     if (tx.IsCoinBase())
 226         return 0;
 227
 228     CAmount nResult = 0;
 229     for (unsigned int i = 0; i < tx.vin.size(); i++)
 230         nResult += AccessCoin(tx.vin[i].prevout).out.nValue;
 231
 232     return nResult;
 233 }
 234
 235 bool CCoinsViewCache::HaveInputs(const CTransaction& tx) const
 236 {
 237     if (!tx.IsCoinBase()) {
 238         for (unsigned int i = 0; i < tx.vin.size(); i++) {
 239             if (!HaveCoin(tx.vin[i].prevout)) {
 240                 return false;
 241             }
 242         }
 243     }
 244     return true;
 245 }
 246
 247 static const size_t MIN_TRANSACTION_OUTPUT_WEIGHT = WITNESS_SCALE_FACTOR * ::GetSerializeSize(CTxOut(), SER_NETWORK, PROTOCOL_VERSION);
 248 static const size_t MAX_OUTPUTS_PER_BLOCK = MAX_BLOCK_WEIGHT / MIN_TRANSACTION_OUTPUT_WEIGHT;
 249
 250 const Coin& AccessByTxid(const CCoinsViewCache& view, const uint256& txid)
 251 {
 252     COutPoint iter(txid, 0);
 253     while (iter.n < MAX_OUTPUTS_PER_BLOCK) {
 254         const Coin& alternate = view.AccessCoin(iter);
 255         if (!alternate.IsSpent()) return alternate;
 256         ++iter.n;
 257     }
 258     return coinEmpty;
 259 }