src/coins.cpp

   1 // Copyright (c) 2012-2015 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 CCoinsViewCursor *CCoinsView::Cursor() const { return 0; }
  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 CCoinsViewCursor *CCoinsViewBacked::Cursor() const { return base->Cursor(); }
  58
  59 SaltedTxidHasher::SaltedTxidHasher() : k0(GetRand(std::numeric_limits<uint64_t>::max())), k1(GetRand(std::numeric_limits<uint64_t>::max())) {}
  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 // ModifyNewCoins has to know whether the new outputs its creating are for a
 121 // coinbase or not.  If they are for a coinbase, it can not mark them as fresh.
 122 // This is to ensure that the historical duplicate coinbases before BIP30 was
 123 // in effect will still be properly overwritten when spent.
 124 CCoinsModifier CCoinsViewCache::ModifyNewCoins(const uint256 &txid, bool coinbase) {
 125     assert(!hasModifier);
 126     std::pair<CCoinsMap::iterator, bool> ret = cacheCoins.insert(std::make_pair(txid, CCoinsCacheEntry()));
 127     ret.first->second.coins.Clear();
 128     if (!coinbase) {
 129         ret.first->second.flags = CCoinsCacheEntry::FRESH;
 130     }
 131     ret.first->second.flags |= CCoinsCacheEntry::DIRTY;
 132     return CCoinsModifier(*this, ret.first, 0);
 133 }
 134
 135 const CCoins* CCoinsViewCache::AccessCoins(const uint256 &txid) const {
 136     CCoinsMap::const_iterator it = FetchCoins(txid);
 137     if (it == cacheCoins.end()) {
 138         return NULL;
 139     } else {
 140         return &it->second.coins;
 141     }
 142 }
 143
 144 bool CCoinsViewCache::HaveCoins(const uint256 &txid) const {
 145     CCoinsMap::const_iterator it = FetchCoins(txid);
 146     // We're using vtx.empty() instead of IsPruned here for performance reasons,
 147     // as we only care about the case where a transaction was replaced entirely
 148     // in a reorganization (which wipes vout entirely, as opposed to spending
 149     // which just cleans individual outputs).
 150     return (it != cacheCoins.end() && !it->second.coins.vout.empty());
 151 }
 152
 153 bool CCoinsViewCache::HaveCoinsInCache(const uint256 &txid) const {
 154     CCoinsMap::const_iterator it = cacheCoins.find(txid);
 155     return it != cacheCoins.end();
 156 }
 157
 158 uint256 CCoinsViewCache::GetBestBlock() const {
 159     if (hashBlock.IsNull())
 160         hashBlock = base->GetBestBlock();
 161     return hashBlock;
 162 }
 163
 164 void CCoinsViewCache::SetBestBlock(const uint256 &hashBlockIn) {
 165     hashBlock = hashBlockIn;
 166 }
 167
 168 bool CCoinsViewCache::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlockIn) {
 169     assert(!hasModifier);
 170     for (CCoinsMap::iterator it = mapCoins.begin(); it != mapCoins.end();) {
 171         if (it->second.flags & CCoinsCacheEntry::DIRTY) { // Ignore non-dirty entries (optimization).
 172             CCoinsMap::iterator itUs = cacheCoins.find(it->first);
 173             if (itUs == cacheCoins.end()) {
 174                 // The parent cache does not have an entry, while the child does
 175                 // We can ignore it if it's both FRESH and pruned in the child
 176                 if (!(it->second.flags & CCoinsCacheEntry::FRESH && it->second.coins.IsPruned())) {
 177                     // Otherwise we will need to create it in the parent
 178                     // and move the data up and mark it as dirty
 179                     CCoinsCacheEntry& entry = cacheCoins[it->first];
 180                     entry.coins.swap(it->second.coins);
 181                     cachedCoinsUsage += entry.coins.DynamicMemoryUsage();
 182                     entry.flags = CCoinsCacheEntry::DIRTY;
 183                     // We can mark it FRESH in the parent if it was FRESH in the child
 184                     // Otherwise it might have just been flushed from the parent's cache
 185                     // and already exist in the grandparent
 186                     if (it->second.flags & CCoinsCacheEntry::FRESH)
 187                         entry.flags |= CCoinsCacheEntry::FRESH;
 188                 }
 189             } else {
 190                 // Found the entry in the parent cache
 191                 if ((itUs->second.flags & CCoinsCacheEntry::FRESH) && it->second.coins.IsPruned()) {
 192                     // The grandparent does not have an entry, and the child is
 193                     // modified and being pruned. This means we can just delete
 194                     // it from the parent.
 195                     cachedCoinsUsage -= itUs->second.coins.DynamicMemoryUsage();
 196                     cacheCoins.erase(itUs);
 197                 } else {
 198                     // A normal modification.
 199                     cachedCoinsUsage -= itUs->second.coins.DynamicMemoryUsage();
 200                     itUs->second.coins.swap(it->second.coins);
 201                     cachedCoinsUsage += itUs->second.coins.DynamicMemoryUsage();
 202                     itUs->second.flags |= CCoinsCacheEntry::DIRTY;
 203                 }
 204             }
 205         }
 206         CCoinsMap::iterator itOld = it++;
 207         mapCoins.erase(itOld);
 208     }
 209     hashBlock = hashBlockIn;
 210     return true;
 211 }
 212
 213 bool CCoinsViewCache::Flush() {
 214     bool fOk = base->BatchWrite(cacheCoins, hashBlock);
 215     cacheCoins.clear();
 216     cachedCoinsUsage = 0;
 217     return fOk;
 218 }
 219
 220 void CCoinsViewCache::Uncache(const uint256& hash)
 221 {
 222     CCoinsMap::iterator it = cacheCoins.find(hash);
 223     if (it != cacheCoins.end() && it->second.flags == 0) {
 224         cachedCoinsUsage -= it->second.coins.DynamicMemoryUsage();
 225         cacheCoins.erase(it);
 226     }
 227 }
 228
 229 unsigned int CCoinsViewCache::GetCacheSize() const {
 230     return cacheCoins.size();
 231 }
 232
 233 const CTxOut &CCoinsViewCache::GetOutputFor(const CTxIn& input) const
 234 {
 235     const CCoins* coins = AccessCoins(input.prevout.hash);
 236     assert(coins && coins->IsAvailable(input.prevout.n));
 237     return coins->vout[input.prevout.n];
 238 }
 239
 240 CAmount CCoinsViewCache::GetValueIn(const CTransaction& tx) const
 241 {
 242     if (tx.IsCoinBase())
 243         return 0;
 244
 245     CAmount nResult = 0;
 246     for (unsigned int i = 0; i < tx.vin.size(); i++)
 247         nResult += GetOutputFor(tx.vin[i]).nValue;
 248
 249     return nResult;
 250 }
 251
 252 bool CCoinsViewCache::HaveInputs(const CTransaction& tx) const
 253 {
 254     if (!tx.IsCoinBase()) {
 255         for (unsigned int i = 0; i < tx.vin.size(); i++) {
 256             const COutPoint &prevout = tx.vin[i].prevout;
 257             const CCoins* coins = AccessCoins(prevout.hash);
 258             if (!coins || !coins->IsAvailable(prevout.n)) {
 259                 return false;
 260             }
 261         }
 262     }
 263     return true;
 264 }
 265
 266 double CCoinsViewCache::GetPriority(const CTransaction &tx, int nHeight, CAmount &inChainInputValue) const
 267 {
 268     inChainInputValue = 0;
 269     if (tx.IsCoinBase())
 270         return 0.0;
 271     double dResult = 0.0;
 272     BOOST_FOREACH(const CTxIn& txin, tx.vin)
 273     {
 274         const CCoins* coins = AccessCoins(txin.prevout.hash);
 275         assert(coins);
 276         if (!coins->IsAvailable(txin.prevout.n)) continue;
 277         if (coins->nHeight <= nHeight) {
 278             dResult += (double)(coins->vout[txin.prevout.n].nValue) * (nHeight-coins->nHeight);
 279             inChainInputValue += coins->vout[txin.prevout.n].nValue;
 280         }
 281     }
 282     return tx.ComputePriority(dResult);
 283 }
 284
 285 CCoinsModifier::CCoinsModifier(CCoinsViewCache& cache_, CCoinsMap::iterator it_, size_t usage) : cache(cache_), it(it_), cachedCoinUsage(usage) {
 286     assert(!cache.hasModifier);
 287     cache.hasModifier = true;
 288 }
 289
 290 CCoinsModifier::~CCoinsModifier()
 291 {
 292     assert(cache.hasModifier);
 293     cache.hasModifier = false;
 294     it->second.coins.Cleanup();
 295     cache.cachedCoinsUsage -= cachedCoinUsage; // Subtract the old usage
 296     if ((it->second.flags & CCoinsCacheEntry::FRESH) && it->second.coins.IsPruned()) {
 297         cache.cacheCoins.erase(it);
 298     } else {
 299         // If the coin still exists after the modification, add the new usage
 300         cache.cachedCoinsUsage += it->second.coins.DynamicMemoryUsage();
 301     }
 302 }
 303
 304 CCoinsViewCursor::~CCoinsViewCursor()
 305 {
 306 }