src/coins.cpp

   1 // Copyright (c) 2012-2014 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 "memusage.h"
   8 #include "random.h"
   9
  10 #include <assert.h>
  11
  12 /**
  13  * calculate number of bytes for the bitmask, and its number of non-zero bytes
  14  * each bit in the bitmask represents the availability of one output, but the
  15  * availabilities of the first two outputs are encoded separately
  16  */
  17 void CCoins::CalcMaskSize(unsigned int &nBytes, unsigned int &nNonzeroBytes) const {
  18     unsigned int nLastUsedByte = 0;
  19     for (unsigned int b = 0; 2+b*8 < vout.size(); b++) {
  20         bool fZero = true;
  21         for (unsigned int i = 0; i < 8 && 2+b*8+i < vout.size(); i++) {
  22             if (!vout[2+b*8+i].IsNull()) {
  23                 fZero = false;
  24                 continue;
  25             }
  26         }
  27         if (!fZero) {
  28             nLastUsedByte = b + 1;
  29             nNonzeroBytes++;
  30         }
  31     }
  32     nBytes += nLastUsedByte;
  33 }
  34
  35 bool CCoins::Spend(uint32_t nPos)
  36 {
  37     if (nPos >= vout.size() || vout[nPos].IsNull())
  38         return false;
  39     vout[nPos].SetNull();
  40     Cleanup();
  41     return true;
  42 }
  43
  44 bool CCoinsView::GetCoins(const uint256 &txid, CCoins &coins) const { return false; }
  45 bool CCoinsView::HaveCoins(const uint256 &txid) const { return false; }
  46 uint256 CCoinsView::GetBestBlock() const { return uint256(); }
  47 bool CCoinsView::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlock) { return false; }
  48 bool CCoinsView::GetStats(CCoinsStats &stats) const { return false; }
  49
  50
  51 CCoinsViewBacked::CCoinsViewBacked(CCoinsView *viewIn) : base(viewIn) { }
  52 bool CCoinsViewBacked::GetCoins(const uint256 &txid, CCoins &coins) const { return base->GetCoins(txid, coins); }
  53 bool CCoinsViewBacked::HaveCoins(const uint256 &txid) const { return base->HaveCoins(txid); }
  54 uint256 CCoinsViewBacked::GetBestBlock() const { return base->GetBestBlock(); }
  55 void CCoinsViewBacked::SetBackend(CCoinsView &viewIn) { base = &viewIn; }
  56 bool CCoinsViewBacked::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlock) { return base->BatchWrite(mapCoins, hashBlock); }
  57 bool CCoinsViewBacked::GetStats(CCoinsStats &stats) const { return base->GetStats(stats); }
  58
  59 CCoinsKeyHasher::CCoinsKeyHasher() : salt(GetRandHash()) {}
  60
  61 CCoinsViewCache::CCoinsViewCache(CCoinsView *baseIn) : CCoinsViewBacked(baseIn), hasModifier(false), cachedCoinsUsage(0) { }
  62
  63 CCoinsViewCache::~CCoinsViewCache()
  64 {
  65     assert(!hasModifier);
  66 }
  67
  68 size_t CCoinsViewCache::DynamicMemoryUsage() const {
  69     return memusage::DynamicUsage(cacheCoins) + cachedCoinsUsage;
  70 }
  71
  72 CCoinsMap::const_iterator CCoinsViewCache::FetchCoins(const uint256 &txid) const {
  73     CCoinsMap::iterator it = cacheCoins.find(txid);
  74     if (it != cacheCoins.end())
  75         return it;
  76     CCoins tmp;
  77     if (!base->GetCoins(txid, tmp))
  78         return cacheCoins.end();
  79     CCoinsMap::iterator ret = cacheCoins.insert(std::make_pair(txid, CCoinsCacheEntry())).first;
  80     tmp.swap(ret->second.coins);
  81     if (ret->second.coins.IsPruned()) {
  82         // The parent only has an empty entry for this txid; we can consider our
  83         // version as fresh.
  84         ret->second.flags = CCoinsCacheEntry::FRESH;
  85     }
  86     cachedCoinsUsage += ret->second.coins.DynamicMemoryUsage();
  87     return ret;
  88 }
  89
  90 bool CCoinsViewCache::GetCoins(const uint256 &txid, CCoins &coins) const {
  91     CCoinsMap::const_iterator it = FetchCoins(txid);
  92     if (it != cacheCoins.end()) {
  93         coins = it->second.coins;
  94         return true;
  95     }
  96     return false;
  97 }
  98
  99 CCoinsModifier CCoinsViewCache::ModifyCoins(const uint256 &txid) {
 100     assert(!hasModifier);
 101     std::pair<CCoinsMap::iterator, bool> ret = cacheCoins.insert(std::make_pair(txid, CCoinsCacheEntry()));
 102     size_t cachedCoinUsage = 0;
 103     if (ret.second) {
 104         if (!base->GetCoins(txid, ret.first->second.coins)) {
 105             // The parent view does not have this entry; mark it as fresh.
 106             ret.first->second.coins.Clear();
 107             ret.first->second.flags = CCoinsCacheEntry::FRESH;
 108         } else if (ret.first->second.coins.IsPruned()) {
 109             // The parent view only has a pruned entry for this; mark it as fresh.
 110             ret.first->second.flags = CCoinsCacheEntry::FRESH;
 111         }
 112     } else {
 113         cachedCoinUsage = ret.first->second.coins.DynamicMemoryUsage();
 114     }
 115     // Assume that whenever ModifyCoins is called, the entry will be modified.
 116     ret.first->second.flags |= CCoinsCacheEntry::DIRTY;
 117     return CCoinsModifier(*this, ret.first, cachedCoinUsage);
 118 }
 119
 120 CCoinsModifier CCoinsViewCache::ModifyNewCoins(const uint256 &txid) {
 121     assert(!hasModifier);
 122     std::pair<CCoinsMap::iterator, bool> ret = cacheCoins.insert(std::make_pair(txid, CCoinsCacheEntry()));
 123     ret.first->second.coins.Clear();
 124     ret.first->second.flags = CCoinsCacheEntry::FRESH;
 125     ret.first->second.flags |= CCoinsCacheEntry::DIRTY;
 126     return CCoinsModifier(*this, ret.first, 0);
 127 }
 128
 129 const CCoins* CCoinsViewCache::AccessCoins(const uint256 &txid) const {
 130     CCoinsMap::const_iterator it = FetchCoins(txid);
 131     if (it == cacheCoins.end()) {
 132         return NULL;
 133     } else {
 134         return &it->second.coins;
 135     }
 136 }
 137
 138 bool CCoinsViewCache::HaveCoins(const uint256 &txid) const {
 139     CCoinsMap::const_iterator it = FetchCoins(txid);
 140     // We're using vtx.empty() instead of IsPruned here for performance reasons,
 141     // as we only care about the case where a transaction was replaced entirely
 142     // in a reorganization (which wipes vout entirely, as opposed to spending
 143     // which just cleans individual outputs).
 144     return (it != cacheCoins.end() && !it->second.coins.vout.empty());
 145 }
 146
 147 uint256 CCoinsViewCache::GetBestBlock() const {
 148     if (hashBlock.IsNull())
 149         hashBlock = base->GetBestBlock();
 150     return hashBlock;
 151 }
 152
 153 void CCoinsViewCache::SetBestBlock(const uint256 &hashBlockIn) {
 154     hashBlock = hashBlockIn;
 155 }
 156
 157 bool CCoinsViewCache::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlockIn) {
 158     assert(!hasModifier);
 159     for (CCoinsMap::iterator it = mapCoins.begin(); it != mapCoins.end();) {
 160         if (it->second.flags & CCoinsCacheEntry::DIRTY) { // Ignore non-dirty entries (optimization).
 161             CCoinsMap::iterator itUs = cacheCoins.find(it->first);
 162             if (itUs == cacheCoins.end()) {
 163                 // The parent cache does not have an entry, while the child does
 164                 // We can ignore it if it's both FRESH and pruned in the child
 165                 if (!(it->second.flags & CCoinsCacheEntry::FRESH && it->second.coins.IsPruned())) {
 166                     // Otherwise we will need to create it in the parent
 167                     // and move the data up and mark it as dirty
 168                     CCoinsCacheEntry& entry = cacheCoins[it->first];
 169                     entry.coins.swap(it->second.coins);
 170                     cachedCoinsUsage += entry.coins.DynamicMemoryUsage();
 171                     entry.flags = CCoinsCacheEntry::DIRTY;
 172                     // We can mark it FRESH in the parent if it was FRESH in the child
 173                     // Otherwise it might have just been flushed from the parent's cache
 174                     // and already exist in the grandparent
 175                     if (it->second.flags & CCoinsCacheEntry::FRESH)
 176                         entry.flags |= CCoinsCacheEntry::FRESH;
 177                 }
 178             } else {
 179                 // Found the entry in the parent cache
 180                 if ((itUs->second.flags & CCoinsCacheEntry::FRESH) && it->second.coins.IsPruned()) {
 181                     // The grandparent does not have an entry, and the child is
 182                     // modified and being pruned. This means we can just delete
 183                     // it from the parent.
 184                     cachedCoinsUsage -= itUs->second.coins.DynamicMemoryUsage();
 185                     cacheCoins.erase(itUs);
 186                 } else {
 187                     // A normal modification.
 188                     cachedCoinsUsage -= itUs->second.coins.DynamicMemoryUsage();
 189                     itUs->second.coins.swap(it->second.coins);
 190                     cachedCoinsUsage += itUs->second.coins.DynamicMemoryUsage();
 191                     itUs->second.flags |= CCoinsCacheEntry::DIRTY;
 192                 }
 193             }
 194         }
 195         CCoinsMap::iterator itOld = it++;
 196         mapCoins.erase(itOld);
 197     }
 198     hashBlock = hashBlockIn;
 199     return true;
 200 }
 201
 202 bool CCoinsViewCache::Flush() {
 203     bool fOk = base->BatchWrite(cacheCoins, hashBlock);
 204     cacheCoins.clear();
 205     cachedCoinsUsage = 0;
 206     return fOk;
 207 }
 208
 209 unsigned int CCoinsViewCache::GetCacheSize() const {
 210     return cacheCoins.size();
 211 }
 212
 213 const CTxOut &CCoinsViewCache::GetOutputFor(const CTxIn& input) const
 214 {
 215     const CCoins* coins = AccessCoins(input.prevout.hash);
 216     assert(coins && coins->IsAvailable(input.prevout.n));
 217     return coins->vout[input.prevout.n];
 218 }
 219
 220 CAmount CCoinsViewCache::GetValueIn(const CTransaction& tx) const
 221 {
 222     if (tx.IsCoinBase())
 223         return 0;
 224
 225     CAmount nResult = 0;
 226     for (unsigned int i = 0; i < tx.vin.size(); i++)
 227         nResult += GetOutputFor(tx.vin[i]).nValue;
 228
 229     return nResult;
 230 }
 231
 232 bool CCoinsViewCache::HaveInputs(const CTransaction& tx) const
 233 {
 234     if (!tx.IsCoinBase()) {
 235         for (unsigned int i = 0; i < tx.vin.size(); i++) {
 236             const COutPoint &prevout = tx.vin[i].prevout;
 237             const CCoins* coins = AccessCoins(prevout.hash);
 238             if (!coins || !coins->IsAvailable(prevout.n)) {
 239                 return false;
 240             }
 241         }
 242     }
 243     return true;
 244 }
 245
 246 double CCoinsViewCache::GetPriority(const CTransaction &tx, int nHeight) const
 247 {
 248     if (tx.IsCoinBase())
 249         return 0.0;
 250     double dResult = 0.0;
 251     BOOST_FOREACH(const CTxIn& txin, tx.vin)
 252     {
 253         const CCoins* coins = AccessCoins(txin.prevout.hash);
 254         assert(coins);
 255         if (!coins->IsAvailable(txin.prevout.n)) continue;
 256         if (coins->nHeight < nHeight) {
 257             dResult += coins->vout[txin.prevout.n].nValue * (nHeight-coins->nHeight);
 258         }
 259     }
 260     return tx.ComputePriority(dResult);
 261 }
 262
 263 CCoinsModifier::CCoinsModifier(CCoinsViewCache& cache_, CCoinsMap::iterator it_, size_t usage) : cache(cache_), it(it_), cachedCoinUsage(usage) {
 264     assert(!cache.hasModifier);
 265     cache.hasModifier = true;
 266 }
 267
 268 CCoinsModifier::~CCoinsModifier()
 269 {
 270     assert(cache.hasModifier);
 271     cache.hasModifier = false;
 272     it->second.coins.Cleanup();
 273     cache.cachedCoinsUsage -= cachedCoinUsage; // Subtract the old usage
 274     if ((it->second.flags & CCoinsCacheEntry::FRESH) && it->second.coins.IsPruned()) {
 275         cache.cacheCoins.erase(it);
 276     } else {
 277         // If the coin still exists after the modification, add the new usage
 278         cache.cachedCoinsUsage += it->second.coins.DynamicMemoryUsage();
 279     }
 280 }