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::GetCoin(const COutPoint &outpoint, Coin &coin) const { return false; }
  14 uint256 CCoinsView::GetBestBlock() const { return uint256(); }
  15 std::vector<uint256> CCoinsView::GetHeadBlocks() const { return std::vector<uint256>(); }
  16 bool CCoinsView::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlock) { return false; }
  17 CCoinsViewCursor *CCoinsView::Cursor() const { return nullptr; }
  18
  19 bool CCoinsView::HaveCoin(const COutPoint &outpoint) const
  20 {
  21     Coin coin;
  22     return GetCoin(outpoint, coin);
  23 }
  24
  25 CCoinsViewBacked::CCoinsViewBacked(CCoinsView *viewIn) : base(viewIn) { }
  26 bool CCoinsViewBacked::GetCoin(const COutPoint &outpoint, Coin &coin) const { return base->GetCoin(outpoint, coin); }
  27 bool CCoinsViewBacked::HaveCoin(const COutPoint &outpoint) const { return base->HaveCoin(outpoint); }
  28 uint256 CCoinsViewBacked::GetBestBlock() const { return base->GetBestBlock(); }
  29 std::vector<uint256> CCoinsViewBacked::GetHeadBlocks() const { return base->GetHeadBlocks(); }
  30 void CCoinsViewBacked::SetBackend(CCoinsView &viewIn) { base = &viewIn; }
  31 bool CCoinsViewBacked::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlock) { return base->BatchWrite(mapCoins, hashBlock); }
  32 CCoinsViewCursor *CCoinsViewBacked::Cursor() const { return base->Cursor(); }
  33 size_t CCoinsViewBacked::EstimateSize() const { return base->EstimateSize(); }
  34
  35 SaltedOutpointHasher::SaltedOutpointHasher() : k0(GetRand(std::numeric_limits<uint64_t>::max())), k1(GetRand(std::numeric_limits<uint64_t>::max())) {}
  36
  37 CCoinsViewCache::CCoinsViewCache(CCoinsView *baseIn) : CCoinsViewBacked(baseIn), cachedCoinsUsage(0) {}
  38
  39 size_t CCoinsViewCache::DynamicMemoryUsage() const {
  40     return memusage::DynamicUsage(cacheCoins) + cachedCoinsUsage;
  41 }
  42
  43 CCoinsMap::iterator CCoinsViewCache::FetchCoin(const COutPoint &outpoint) const {
  44     CCoinsMap::iterator it = cacheCoins.find(outpoint);
  45     if (it != cacheCoins.end())
  46         return it;
  47     Coin tmp;
  48     if (!base->GetCoin(outpoint, tmp))
  49         return cacheCoins.end();
  50     CCoinsMap::iterator ret = cacheCoins.emplace(std::piecewise_construct, std::forward_as_tuple(outpoint), std::forward_as_tuple(std::move(tmp))).first;
  51     if (ret->second.coin.IsSpent()) {
  52         // The parent only has an empty entry for this outpoint; we can consider our
  53         // version as fresh.
  54         ret->second.flags = CCoinsCacheEntry::FRESH;
  55     }
  56     cachedCoinsUsage += ret->second.coin.DynamicMemoryUsage();
  57     return ret;
  58 }
  59
  60 bool CCoinsViewCache::GetCoin(const COutPoint &outpoint, Coin &coin) const {
  61     CCoinsMap::const_iterator it = FetchCoin(outpoint);
  62     if (it != cacheCoins.end()) {
  63         coin = it->second.coin;
  64         return !coin.IsSpent();
  65     }
  66     return false;
  67 }
  68
  69 void CCoinsViewCache::AddCoin(const COutPoint &outpoint, Coin&& coin, bool possible_overwrite) {
  70     assert(!coin.IsSpent());
  71     if (coin.out.scriptPubKey.IsUnspendable()) return;
  72     CCoinsMap::iterator it;
  73     bool inserted;
  74     std::tie(it, inserted) = cacheCoins.emplace(std::piecewise_construct, std::forward_as_tuple(outpoint), std::tuple<>());
  75     bool fresh = false;
  76     if (!inserted) {
  77         cachedCoinsUsage -= it->second.coin.DynamicMemoryUsage();
  78     }
  79     if (!possible_overwrite) {
  80         if (!it->second.coin.IsSpent()) {
  81             throw std::logic_error("Adding new coin that replaces non-pruned entry");
  82         }
  83         fresh = !(it->second.flags & CCoinsCacheEntry::DIRTY);
  84     }
  85     it->second.coin = std::move(coin);
  86     it->second.flags |= CCoinsCacheEntry::DIRTY | (fresh ? CCoinsCacheEntry::FRESH : 0);
  87     cachedCoinsUsage += it->second.coin.DynamicMemoryUsage();
  88 }
  89
  90 void AddCoins(CCoinsViewCache& cache, const CTransaction &tx, int nHeight, bool check) {
  91     bool fCoinbase = tx.IsCoinBase();
  92     const uint256& txid = tx.GetHash();
  93     for (size_t i = 0; i < tx.vout.size(); ++i) {
  94         bool overwrite = check ? cache.HaveCoin(COutPoint(txid, i)) : fCoinbase;
  95         // Always set the possible_overwrite flag to AddCoin for coinbase txn, in order to correctly
  96         // deal with the pre-BIP30 occurrences of duplicate coinbase transactions.
  97         cache.AddCoin(COutPoint(txid, i), Coin(tx.vout[i], nHeight, fCoinbase), overwrite);
  98     }
  99 }
 100
 101 bool CCoinsViewCache::SpendCoin(const COutPoint &outpoint, Coin* moveout) {
 102     CCoinsMap::iterator it = FetchCoin(outpoint);
 103     if (it == cacheCoins.end()) return false;
 104     cachedCoinsUsage -= it->second.coin.DynamicMemoryUsage();
 105     if (moveout) {
 106         *moveout = std::move(it->second.coin);
 107     }
 108     if (it->second.flags & CCoinsCacheEntry::FRESH) {
 109         cacheCoins.erase(it);
 110     } else {
 111         it->second.flags |= CCoinsCacheEntry::DIRTY;
 112         it->second.coin.Clear();
 113     }
 114     return true;
 115 }
 116
 117 static const Coin coinEmpty;
 118
 119 const Coin& CCoinsViewCache::AccessCoin(const COutPoint &outpoint) const {
 120     CCoinsMap::const_iterator it = FetchCoin(outpoint);
 121     if (it == cacheCoins.end()) {
 122         return coinEmpty;
 123     } else {
 124         return it->second.coin;
 125     }
 126 }
 127
 128 bool CCoinsViewCache::HaveCoin(const COutPoint &outpoint) const {
 129     CCoinsMap::const_iterator it = FetchCoin(outpoint);
 130     return (it != cacheCoins.end() && !it->second.coin.IsSpent());
 131 }
 132
 133 bool CCoinsViewCache::HaveCoinInCache(const COutPoint &outpoint) const {
 134     CCoinsMap::const_iterator it = cacheCoins.find(outpoint);
 135     return (it != cacheCoins.end() && !it->second.coin.IsSpent());
 136 }
 137
 138 uint256 CCoinsViewCache::GetBestBlock() const {
 139     if (hashBlock.IsNull())
 140         hashBlock = base->GetBestBlock();
 141     return hashBlock;
 142 }
 143
 144 void CCoinsViewCache::SetBestBlock(const uint256 &hashBlockIn) {
 145     hashBlock = hashBlockIn;
 146 }
 147
 148 bool CCoinsViewCache::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlockIn) {
 149     for (CCoinsMap::iterator it = mapCoins.begin(); it != mapCoins.end(); it = mapCoins.erase(it)) {
 150         // Ignore non-dirty entries (optimization).
 151         if (!(it->second.flags & CCoinsCacheEntry::DIRTY)) {
 152             continue;
 153         }
 154         CCoinsMap::iterator itUs = cacheCoins.find(it->first);
 155         if (itUs == cacheCoins.end()) {
 156             // The parent cache does not have an entry, while the child does
 157             // We can ignore it if it's both FRESH and pruned in the child
 158             if (!(it->second.flags & CCoinsCacheEntry::FRESH && it->second.coin.IsSpent())) {
 159                 // Otherwise we will need to create it in the parent
 160                 // and move the data up and mark it as dirty
 161                 CCoinsCacheEntry& entry = cacheCoins[it->first];
 162                 entry.coin = std::move(it->second.coin);
 163                 cachedCoinsUsage += entry.coin.DynamicMemoryUsage();
 164                 entry.flags = CCoinsCacheEntry::DIRTY;
 165                 // We can mark it FRESH in the parent if it was FRESH in the child
 166                 // Otherwise it might have just been flushed from the parent's cache
 167                 // and already exist in the grandparent
 168                 if (it->second.flags & CCoinsCacheEntry::FRESH) {
 169                     entry.flags |= CCoinsCacheEntry::FRESH;
 170                 }
 171             }
 172         } else {
 173             // Assert that the child cache entry was not marked FRESH if the
 174             // parent cache entry has unspent outputs. If this ever happens,
 175             // it means the FRESH flag was misapplied and there is a logic
 176             // error in the calling code.
 177             if ((it->second.flags & CCoinsCacheEntry::FRESH) && !itUs->second.coin.IsSpent()) {
 178                 throw std::logic_error("FRESH flag misapplied to cache entry for base transaction with spendable outputs");
 179             }
 180
 181             // Found the entry in the parent cache
 182             if ((itUs->second.flags & CCoinsCacheEntry::FRESH) && it->second.coin.IsSpent()) {
 183                 // The grandparent does not have an entry, and the child is
 184                 // modified and being pruned. This means we can just delete
 185                 // it from the parent.
 186                 cachedCoinsUsage -= itUs->second.coin.DynamicMemoryUsage();
 187                 cacheCoins.erase(itUs);
 188             } else {
 189                 // A normal modification.
 190                 cachedCoinsUsage -= itUs->second.coin.DynamicMemoryUsage();
 191                 itUs->second.coin = std::move(it->second.coin);
 192                 cachedCoinsUsage += itUs->second.coin.DynamicMemoryUsage();
 193                 itUs->second.flags |= CCoinsCacheEntry::DIRTY;
 194                 // NOTE: It is possible the child has a FRESH flag here in
 195                 // the event the entry we found in the parent is pruned. But
 196                 // we must not copy that FRESH flag to the parent as that
 197                 // pruned state likely still needs to be communicated to the
 198                 // grandparent.
 199             }
 200         }
 201     }
 202     hashBlock = hashBlockIn;
 203     return true;
 204 }
 205
 206 bool CCoinsViewCache::Flush() {
 207     bool fOk = base->BatchWrite(cacheCoins, hashBlock);
 208     cacheCoins.clear();
 209     cachedCoinsUsage = 0;
 210     return fOk;
 211 }
 212
 213 void CCoinsViewCache::Uncache(const COutPoint& hash)
 214 {
 215     CCoinsMap::iterator it = cacheCoins.find(hash);
 216     if (it != cacheCoins.end() && it->second.flags == 0) {
 217         cachedCoinsUsage -= it->second.coin.DynamicMemoryUsage();
 218         cacheCoins.erase(it);
 219     }
 220 }
 221
 222 unsigned int CCoinsViewCache::GetCacheSize() const {
 223     return cacheCoins.size();
 224 }
 225
 226 CAmount CCoinsViewCache::GetValueIn(const CTransaction& tx) const
 227 {
 228     if (tx.IsCoinBase())
 229         return 0;
 230
 231     CAmount nResult = 0;
 232     for (unsigned int i = 0; i < tx.vin.size(); i++)
 233         nResult += AccessCoin(tx.vin[i].prevout).out.nValue;
 234
 235     return nResult;
 236 }
 237
 238 bool CCoinsViewCache::HaveInputs(const CTransaction& tx) const
 239 {
 240     if (!tx.IsCoinBase()) {
 241         for (unsigned int i = 0; i < tx.vin.size(); i++) {
 242             if (!HaveCoin(tx.vin[i].prevout)) {
 243                 return false;
 244             }
 245         }
 246     }
 247     return true;
 248 }
 249
 250 static const size_t MIN_TRANSACTION_OUTPUT_WEIGHT = WITNESS_SCALE_FACTOR * ::GetSerializeSize(CTxOut(), SER_NETWORK, PROTOCOL_VERSION);
 251 static const size_t MAX_OUTPUTS_PER_BLOCK = MAX_BLOCK_WEIGHT / MIN_TRANSACTION_OUTPUT_WEIGHT;
 252
 253 const Coin& AccessByTxid(const CCoinsViewCache& view, const uint256& txid)
 254 {
 255     COutPoint iter(txid, 0);
 256     while (iter.n < MAX_OUTPUTS_PER_BLOCK) {
 257         const Coin& alternate = view.AccessCoin(iter);
 258         if (!alternate.IsSpent()) return alternate;
 259         ++iter.n;
 260     }
 261     return coinEmpty;
 262 }