src/coins.cpp

   1 // Copyright (c) 2012-2016 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 "memusage.h"
   9 #include "random.h"
  10
  11 #include <assert.h>
  12
  13 bool CCoinsView::GetCoins(const COutPoint &outpoint, Coin &coin) const { return false; }
  14 bool CCoinsView::HaveCoins(const COutPoint &outpoint) const { return false; }
  15 uint256 CCoinsView::GetBestBlock() const { return uint256(); }
  16 bool CCoinsView::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlock) { return false; }
  17 CCoinsViewCursor *CCoinsView::Cursor() const { return 0; }
  18
  19
  20 CCoinsViewBacked::CCoinsViewBacked(CCoinsView *viewIn) : base(viewIn) { }
  21 bool CCoinsViewBacked::GetCoins(const COutPoint &outpoint, Coin &coin) const { return base->GetCoins(outpoint, coin); }
  22 bool CCoinsViewBacked::HaveCoins(const COutPoint &outpoint) const { return base->HaveCoins(outpoint); }
  23 uint256 CCoinsViewBacked::GetBestBlock() const { return base->GetBestBlock(); }
  24 void CCoinsViewBacked::SetBackend(CCoinsView &viewIn) { base = &viewIn; }
  25 bool CCoinsViewBacked::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlock) { return base->BatchWrite(mapCoins, hashBlock); }
  26 CCoinsViewCursor *CCoinsViewBacked::Cursor() const { return base->Cursor(); }
  27 size_t CCoinsViewBacked::EstimateSize() const { return base->EstimateSize(); }
  28
  29 SaltedOutpointHasher::SaltedOutpointHasher() : k0(GetRand(std::numeric_limits<uint64_t>::max())), k1(GetRand(std::numeric_limits<uint64_t>::max())) {}
  30
  31 CCoinsViewCache::CCoinsViewCache(CCoinsView *baseIn) : CCoinsViewBacked(baseIn), cachedCoinsUsage(0) {}
  32
  33 size_t CCoinsViewCache::DynamicMemoryUsage() const {
  34     return memusage::DynamicUsage(cacheCoins) + cachedCoinsUsage;
  35 }
  36
  37 CCoinsMap::iterator CCoinsViewCache::FetchCoins(const COutPoint &outpoint) const {
  38     CCoinsMap::iterator it = cacheCoins.find(outpoint);
  39     if (it != cacheCoins.end())
  40         return it;
  41     Coin tmp;
  42     if (!base->GetCoins(outpoint, tmp))
  43         return cacheCoins.end();
  44     CCoinsMap::iterator ret = cacheCoins.emplace(std::piecewise_construct, std::forward_as_tuple(outpoint), std::forward_as_tuple(std::move(tmp))).first;
  45     if (ret->second.coin.IsPruned()) {
  46         // The parent only has an empty entry for this outpoint; we can consider our
  47         // version as fresh.
  48         ret->second.flags = CCoinsCacheEntry::FRESH;
  49     }
  50     cachedCoinsUsage += ret->second.coin.DynamicMemoryUsage();
  51     return ret;
  52 }
  53
  54 bool CCoinsViewCache::GetCoins(const COutPoint &outpoint, Coin &coin) const {
  55     CCoinsMap::const_iterator it = FetchCoins(outpoint);
  56     if (it != cacheCoins.end()) {
  57         coin = it->second.coin;
  58         return true;
  59     }
  60     return false;
  61 }
  62
  63 void CCoinsViewCache::AddCoin(const COutPoint &outpoint, Coin&& coin, bool possible_overwrite) {
  64     assert(!coin.IsPruned());
  65     if (coin.out.scriptPubKey.IsUnspendable()) return;
  66     CCoinsMap::iterator it;
  67     bool inserted;
  68     std::tie(it, inserted) = cacheCoins.emplace(std::piecewise_construct, std::forward_as_tuple(outpoint), std::tuple<>());
  69     bool fresh = false;
  70     if (!inserted) {
  71         cachedCoinsUsage -= it->second.coin.DynamicMemoryUsage();
  72     }
  73     if (!possible_overwrite) {
  74         if (!it->second.coin.IsPruned()) {
  75             throw std::logic_error("Adding new coin that replaces non-pruned entry");
  76         }
  77         fresh = !(it->second.flags & CCoinsCacheEntry::DIRTY);
  78     }
  79     it->second.coin = std::move(coin);
  80     it->second.flags |= CCoinsCacheEntry::DIRTY | (fresh ? CCoinsCacheEntry::FRESH : 0);
  81     cachedCoinsUsage += it->second.coin.DynamicMemoryUsage();
  82 }
  83
  84 void AddCoins(CCoinsViewCache& cache, const CTransaction &tx, int nHeight) {
  85     bool fCoinbase = tx.IsCoinBase();
  86     const uint256& txid = tx.GetHash();
  87     for (size_t i = 0; i < tx.vout.size(); ++i) {
  88         // Pass fCoinbase as the possible_overwrite flag to AddCoin, in order to correctly
  89         // deal with the pre-BIP30 occurrances of duplicate coinbase transactions.
  90         cache.AddCoin(COutPoint(txid, i), Coin(tx.vout[i], nHeight, fCoinbase), fCoinbase);
  91     }
  92 }
  93
  94 void CCoinsViewCache::SpendCoin(const COutPoint &outpoint, Coin* moveout) {
  95     CCoinsMap::iterator it = FetchCoins(outpoint);
  96     if (it == cacheCoins.end()) return;
  97     cachedCoinsUsage -= it->second.coin.DynamicMemoryUsage();
  98     if (moveout) {
  99         *moveout = std::move(it->second.coin);
 100     }
 101     if (it->second.flags & CCoinsCacheEntry::FRESH) {
 102         cacheCoins.erase(it);
 103     } else {
 104         it->second.flags |= CCoinsCacheEntry::DIRTY;
 105         it->second.coin.Clear();
 106     }
 107 }
 108
 109 static const Coin coinEmpty;
 110
 111 const Coin& CCoinsViewCache::AccessCoin(const COutPoint &outpoint) const {
 112     CCoinsMap::const_iterator it = FetchCoins(outpoint);
 113     if (it == cacheCoins.end()) {
 114         return coinEmpty;
 115     } else {
 116         return it->second.coin;
 117     }
 118 }
 119
 120 bool CCoinsViewCache::HaveCoins(const COutPoint &outpoint) const {
 121     CCoinsMap::const_iterator it = FetchCoins(outpoint);
 122     return (it != cacheCoins.end() && !it->second.coin.IsPruned());
 123 }
 124
 125 bool CCoinsViewCache::HaveCoinsInCache(const COutPoint &outpoint) const {
 126     CCoinsMap::const_iterator it = cacheCoins.find(outpoint);
 127     return it != cacheCoins.end();
 128 }
 129
 130 uint256 CCoinsViewCache::GetBestBlock() const {
 131     if (hashBlock.IsNull())
 132         hashBlock = base->GetBestBlock();
 133     return hashBlock;
 134 }
 135
 136 void CCoinsViewCache::SetBestBlock(const uint256 &hashBlockIn) {
 137     hashBlock = hashBlockIn;
 138 }
 139
 140 bool CCoinsViewCache::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlockIn) {
 141     for (CCoinsMap::iterator it = mapCoins.begin(); it != mapCoins.end();) {
 142         if (it->second.flags & CCoinsCacheEntry::DIRTY) { // Ignore non-dirty entries (optimization).
 143             CCoinsMap::iterator itUs = cacheCoins.find(it->first);
 144             if (itUs == cacheCoins.end()) {
 145                 // The parent cache does not have an entry, while the child does
 146                 // We can ignore it if it's both FRESH and pruned in the child
 147                 if (!(it->second.flags & CCoinsCacheEntry::FRESH && it->second.coin.IsPruned())) {
 148                     // Otherwise we will need to create it in the parent
 149                     // and move the data up and mark it as dirty
 150                     CCoinsCacheEntry& entry = cacheCoins[it->first];
 151                     entry.coin = std::move(it->second.coin);
 152                     cachedCoinsUsage += entry.coin.DynamicMemoryUsage();
 153                     entry.flags = CCoinsCacheEntry::DIRTY;
 154                     // We can mark it FRESH in the parent if it was FRESH in the child
 155                     // Otherwise it might have just been flushed from the parent's cache
 156                     // and already exist in the grandparent
 157                     if (it->second.flags & CCoinsCacheEntry::FRESH)
 158                         entry.flags |= CCoinsCacheEntry::FRESH;
 159                 }
 160             } else {
 161                 // Assert that the child cache entry was not marked FRESH if the
 162                 // parent cache entry has unspent outputs. If this ever happens,
 163                 // it means the FRESH flag was misapplied and there is a logic
 164                 // error in the calling code.
 165                 if ((it->second.flags & CCoinsCacheEntry::FRESH) && !itUs->second.coin.IsPruned())
 166                     throw std::logic_error("FRESH flag misapplied to cache entry for base transaction with spendable outputs");
 167
 168                 // Found the entry in the parent cache
 169                 if ((itUs->second.flags & CCoinsCacheEntry::FRESH) && it->second.coin.IsPruned()) {
 170                     // The grandparent does not have an entry, and the child is
 171                     // modified and being pruned. This means we can just delete
 172                     // it from the parent.
 173                     cachedCoinsUsage -= itUs->second.coin.DynamicMemoryUsage();
 174                     cacheCoins.erase(itUs);
 175                 } else {
 176                     // A normal modification.
 177                     cachedCoinsUsage -= itUs->second.coin.DynamicMemoryUsage();
 178                     itUs->second.coin = std::move(it->second.coin);
 179                     cachedCoinsUsage += itUs->second.coin.DynamicMemoryUsage();
 180                     itUs->second.flags |= CCoinsCacheEntry::DIRTY;
 181                     // NOTE: It is possible the child has a FRESH flag here in
 182                     // the event the entry we found in the parent is pruned. But
 183                     // we must not copy that FRESH flag to the parent as that
 184                     // pruned state likely still needs to be communicated to the
 185                     // grandparent.
 186                 }
 187             }
 188         }
 189         CCoinsMap::iterator itOld = it++;
 190         mapCoins.erase(itOld);
 191     }
 192     hashBlock = hashBlockIn;
 193     return true;
 194 }
 195
 196 bool CCoinsViewCache::Flush() {
 197     bool fOk = base->BatchWrite(cacheCoins, hashBlock);
 198     cacheCoins.clear();
 199     cachedCoinsUsage = 0;
 200     return fOk;
 201 }
 202
 203 void CCoinsViewCache::Uncache(const COutPoint& hash)
 204 {
 205     CCoinsMap::iterator it = cacheCoins.find(hash);
 206     if (it != cacheCoins.end() && it->second.flags == 0) {
 207         cachedCoinsUsage -= it->second.coin.DynamicMemoryUsage();
 208         cacheCoins.erase(it);
 209     }
 210 }
 211
 212 unsigned int CCoinsViewCache::GetCacheSize() const {
 213     return cacheCoins.size();
 214 }
 215
 216 CAmount CCoinsViewCache::GetValueIn(const CTransaction& tx) const
 217 {
 218     if (tx.IsCoinBase())
 219         return 0;
 220
 221     CAmount nResult = 0;
 222     for (unsigned int i = 0; i < tx.vin.size(); i++)
 223         nResult += AccessCoin(tx.vin[i].prevout).out.nValue;
 224
 225     return nResult;
 226 }
 227
 228 bool CCoinsViewCache::HaveInputs(const CTransaction& tx) const
 229 {
 230     if (!tx.IsCoinBase()) {
 231         for (unsigned int i = 0; i < tx.vin.size(); i++) {
 232             if (!HaveCoins(tx.vin[i].prevout)) {
 233                 return false;
 234             }
 235         }
 236     }
 237     return true;
 238 }
 239
 240 static const size_t MAX_OUTPUTS_PER_BLOCK = MAX_BLOCK_BASE_SIZE /  ::GetSerializeSize(CTxOut(), SER_NETWORK, PROTOCOL_VERSION); // TODO: merge with similar definition in undo.h.
 241
 242 const Coin& AccessByTxid(const CCoinsViewCache& view, const uint256& txid)
 243 {
 244     COutPoint iter(txid, 0);
 245     while (iter.n < MAX_OUTPUTS_PER_BLOCK) {
 246         const Coin& alternate = view.AccessCoin(iter);
 247         if (!alternate.IsPruned()) return alternate;
 248         ++iter.n;
 249     }
 250     return coinEmpty;
 251 }