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 bool CCoinsView::HaveCoin(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::GetCoin(const COutPoint &outpoint, Coin &coin) const { return base->GetCoin(outpoint, coin); }
  22 bool CCoinsViewBacked::HaveCoin(const COutPoint &outpoint) const { return base->HaveCoin(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::FetchCoin(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->GetCoin(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.IsSpent()) {
  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::GetCoin(const COutPoint &outpoint, Coin &coin) const {
  55     CCoinsMap::const_iterator it = FetchCoin(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.IsSpent());
  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.IsSpent()) {
  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 occurrences of duplicate coinbase transactions.
  90         cache.AddCoin(COutPoint(txid, i), Coin(tx.vout[i], nHeight, fCoinbase), fCoinbase);
  91     }
  92 }
  93
  94 bool CCoinsViewCache::SpendCoin(const COutPoint &outpoint, Coin* moveout) {
  95     CCoinsMap::iterator it = FetchCoin(outpoint);
  96     if (it == cacheCoins.end()) return false;
  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     return true;
 108 }
 109
 110 static const Coin coinEmpty;
 111
 112 const Coin& CCoinsViewCache::AccessCoin(const COutPoint &outpoint) const {
 113     CCoinsMap::const_iterator it = FetchCoin(outpoint);
 114     if (it == cacheCoins.end()) {
 115         return coinEmpty;
 116     } else {
 117         return it->second.coin;
 118     }
 119 }
 120
 121 bool CCoinsViewCache::HaveCoin(const COutPoint &outpoint) const {
 122     CCoinsMap::const_iterator it = FetchCoin(outpoint);
 123     return (it != cacheCoins.end() && !it->second.coin.IsSpent());
 124 }
 125
 126 bool CCoinsViewCache::HaveCoinInCache(const COutPoint &outpoint) const {
 127     CCoinsMap::const_iterator it = cacheCoins.find(outpoint);
 128     return it != cacheCoins.end();
 129 }
 130
 131 uint256 CCoinsViewCache::GetBestBlock() const {
 132     if (hashBlock.IsNull())
 133         hashBlock = base->GetBestBlock();
 134     return hashBlock;
 135 }
 136
 137 void CCoinsViewCache::SetBestBlock(const uint256 &hashBlockIn) {
 138     hashBlock = hashBlockIn;
 139 }
 140
 141 bool CCoinsViewCache::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlockIn) {
 142     for (CCoinsMap::iterator it = mapCoins.begin(); it != mapCoins.end();) {
 143         if (it->second.flags & CCoinsCacheEntry::DIRTY) { // Ignore non-dirty entries (optimization).
 144             CCoinsMap::iterator itUs = cacheCoins.find(it->first);
 145             if (itUs == cacheCoins.end()) {
 146                 // The parent cache does not have an entry, while the child does
 147                 // We can ignore it if it's both FRESH and pruned in the child
 148                 if (!(it->second.flags & CCoinsCacheEntry::FRESH && it->second.coin.IsSpent())) {
 149                     // Otherwise we will need to create it in the parent
 150                     // and move the data up and mark it as dirty
 151                     CCoinsCacheEntry& entry = cacheCoins[it->first];
 152                     entry.coin = std::move(it->second.coin);
 153                     cachedCoinsUsage += entry.coin.DynamicMemoryUsage();
 154                     entry.flags = CCoinsCacheEntry::DIRTY;
 155                     // We can mark it FRESH in the parent if it was FRESH in the child
 156                     // Otherwise it might have just been flushed from the parent's cache
 157                     // and already exist in the grandparent
 158                     if (it->second.flags & CCoinsCacheEntry::FRESH)
 159                         entry.flags |= CCoinsCacheEntry::FRESH;
 160                 }
 161             } else {
 162                 // Assert that the child cache entry was not marked FRESH if the
 163                 // parent cache entry has unspent outputs. If this ever happens,
 164                 // it means the FRESH flag was misapplied and there is a logic
 165                 // error in the calling code.
 166                 if ((it->second.flags & CCoinsCacheEntry::FRESH) && !itUs->second.coin.IsSpent())
 167                     throw std::logic_error("FRESH flag misapplied to cache entry for base transaction with spendable outputs");
 168
 169                 // Found the entry in the parent cache
 170                 if ((itUs->second.flags & CCoinsCacheEntry::FRESH) && it->second.coin.IsSpent()) {
 171                     // The grandparent does not have an entry, and the child is
 172                     // modified and being pruned. This means we can just delete
 173                     // it from the parent.
 174                     cachedCoinsUsage -= itUs->second.coin.DynamicMemoryUsage();
 175                     cacheCoins.erase(itUs);
 176                 } else {
 177                     // A normal modification.
 178                     cachedCoinsUsage -= itUs->second.coin.DynamicMemoryUsage();
 179                     itUs->second.coin = std::move(it->second.coin);
 180                     cachedCoinsUsage += itUs->second.coin.DynamicMemoryUsage();
 181                     itUs->second.flags |= CCoinsCacheEntry::DIRTY;
 182                     // NOTE: It is possible the child has a FRESH flag here in
 183                     // the event the entry we found in the parent is pruned. But
 184                     // we must not copy that FRESH flag to the parent as that
 185                     // pruned state likely still needs to be communicated to the
 186                     // grandparent.
 187                 }
 188             }
 189         }
 190         CCoinsMap::iterator itOld = it++;
 191         mapCoins.erase(itOld);
 192     }
 193     hashBlock = hashBlockIn;
 194     return true;
 195 }
 196
 197 bool CCoinsViewCache::Flush() {
 198     bool fOk = base->BatchWrite(cacheCoins, hashBlock);
 199     cacheCoins.clear();
 200     cachedCoinsUsage = 0;
 201     return fOk;
 202 }
 203
 204 void CCoinsViewCache::Uncache(const COutPoint& hash)
 205 {
 206     CCoinsMap::iterator it = cacheCoins.find(hash);
 207     if (it != cacheCoins.end() && it->second.flags == 0) {
 208         cachedCoinsUsage -= it->second.coin.DynamicMemoryUsage();
 209         cacheCoins.erase(it);
 210     }
 211 }
 212
 213 unsigned int CCoinsViewCache::GetCacheSize() const {
 214     return cacheCoins.size();
 215 }
 216
 217 CAmount CCoinsViewCache::GetValueIn(const CTransaction& tx) const
 218 {
 219     if (tx.IsCoinBase())
 220         return 0;
 221
 222     CAmount nResult = 0;
 223     for (unsigned int i = 0; i < tx.vin.size(); i++)
 224         nResult += AccessCoin(tx.vin[i].prevout).out.nValue;
 225
 226     return nResult;
 227 }
 228
 229 bool CCoinsViewCache::HaveInputs(const CTransaction& tx) const
 230 {
 231     if (!tx.IsCoinBase()) {
 232         for (unsigned int i = 0; i < tx.vin.size(); i++) {
 233             if (!HaveCoin(tx.vin[i].prevout)) {
 234                 return false;
 235             }
 236         }
 237     }
 238     return true;
 239 }
 240
 241 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.
 242
 243 const Coin& AccessByTxid(const CCoinsViewCache& view, const uint256& txid)
 244 {
 245     COutPoint iter(txid, 0);
 246     while (iter.n < MAX_OUTPUTS_PER_BLOCK) {
 247         const Coin& alternate = view.AccessCoin(iter);
 248         if (!alternate.IsSpent()) return alternate;
 249         ++iter.n;
 250     }
 251     return coinEmpty;
 252 }