14470f9aa6
When processing a new transaction, in addition to spending the Coins of its txin's it creates a new Coins for its outputs. The existing ModifyCoins function will first make sure this Coins does not already exist. It can not exist due to BIP 30, but because of that the lookup can't be cached and always has to go to the database. Since we are creating the coins to match the new tx anyway, there is no point in checking if they exist first anyway. However this should not be used for coinbase tx's in order to preserve the historical behavior of overwriting the two existing duplicate tx pairs.
275 lines
10 KiB
C++
275 lines
10 KiB
C++
// Copyright (c) 2012-2014 The Bitcoin Core developers
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// Distributed under the MIT software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#include "coins.h"
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#include "memusage.h"
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#include "random.h"
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#include <assert.h>
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/**
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* calculate number of bytes for the bitmask, and its number of non-zero bytes
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* each bit in the bitmask represents the availability of one output, but the
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* availabilities of the first two outputs are encoded separately
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*/
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void CCoins::CalcMaskSize(unsigned int &nBytes, unsigned int &nNonzeroBytes) const {
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unsigned int nLastUsedByte = 0;
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for (unsigned int b = 0; 2+b*8 < vout.size(); b++) {
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bool fZero = true;
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for (unsigned int i = 0; i < 8 && 2+b*8+i < vout.size(); i++) {
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if (!vout[2+b*8+i].IsNull()) {
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fZero = false;
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continue;
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}
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}
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if (!fZero) {
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nLastUsedByte = b + 1;
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nNonzeroBytes++;
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}
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}
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nBytes += nLastUsedByte;
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}
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bool CCoins::Spend(uint32_t nPos)
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{
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if (nPos >= vout.size() || vout[nPos].IsNull())
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return false;
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vout[nPos].SetNull();
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Cleanup();
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return true;
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}
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bool CCoinsView::GetCoins(const uint256 &txid, CCoins &coins) const { return false; }
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bool CCoinsView::HaveCoins(const uint256 &txid) const { return false; }
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uint256 CCoinsView::GetBestBlock() const { return uint256(); }
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bool CCoinsView::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlock) { return false; }
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bool CCoinsView::GetStats(CCoinsStats &stats) const { return false; }
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CCoinsViewBacked::CCoinsViewBacked(CCoinsView *viewIn) : base(viewIn) { }
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bool CCoinsViewBacked::GetCoins(const uint256 &txid, CCoins &coins) const { return base->GetCoins(txid, coins); }
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bool CCoinsViewBacked::HaveCoins(const uint256 &txid) const { return base->HaveCoins(txid); }
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uint256 CCoinsViewBacked::GetBestBlock() const { return base->GetBestBlock(); }
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void CCoinsViewBacked::SetBackend(CCoinsView &viewIn) { base = &viewIn; }
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bool CCoinsViewBacked::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlock) { return base->BatchWrite(mapCoins, hashBlock); }
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bool CCoinsViewBacked::GetStats(CCoinsStats &stats) const { return base->GetStats(stats); }
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CCoinsKeyHasher::CCoinsKeyHasher() : salt(GetRandHash()) {}
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CCoinsViewCache::CCoinsViewCache(CCoinsView *baseIn) : CCoinsViewBacked(baseIn), hasModifier(false), cachedCoinsUsage(0) { }
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CCoinsViewCache::~CCoinsViewCache()
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{
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assert(!hasModifier);
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}
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size_t CCoinsViewCache::DynamicMemoryUsage() const {
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return memusage::DynamicUsage(cacheCoins) + cachedCoinsUsage;
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}
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CCoinsMap::const_iterator CCoinsViewCache::FetchCoins(const uint256 &txid) const {
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CCoinsMap::iterator it = cacheCoins.find(txid);
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if (it != cacheCoins.end())
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return it;
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CCoins tmp;
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if (!base->GetCoins(txid, tmp))
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return cacheCoins.end();
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CCoinsMap::iterator ret = cacheCoins.insert(std::make_pair(txid, CCoinsCacheEntry())).first;
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tmp.swap(ret->second.coins);
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if (ret->second.coins.IsPruned()) {
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// The parent only has an empty entry for this txid; we can consider our
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// version as fresh.
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ret->second.flags = CCoinsCacheEntry::FRESH;
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}
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cachedCoinsUsage += ret->second.coins.DynamicMemoryUsage();
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return ret;
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}
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bool CCoinsViewCache::GetCoins(const uint256 &txid, CCoins &coins) const {
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CCoinsMap::const_iterator it = FetchCoins(txid);
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if (it != cacheCoins.end()) {
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coins = it->second.coins;
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return true;
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}
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return false;
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}
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CCoinsModifier CCoinsViewCache::ModifyCoins(const uint256 &txid) {
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assert(!hasModifier);
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std::pair<CCoinsMap::iterator, bool> ret = cacheCoins.insert(std::make_pair(txid, CCoinsCacheEntry()));
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size_t cachedCoinUsage = 0;
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if (ret.second) {
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if (!base->GetCoins(txid, ret.first->second.coins)) {
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// The parent view does not have this entry; mark it as fresh.
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ret.first->second.coins.Clear();
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ret.first->second.flags = CCoinsCacheEntry::FRESH;
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} else if (ret.first->second.coins.IsPruned()) {
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// The parent view only has a pruned entry for this; mark it as fresh.
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ret.first->second.flags = CCoinsCacheEntry::FRESH;
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}
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} else {
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cachedCoinUsage = ret.first->second.coins.DynamicMemoryUsage();
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}
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// Assume that whenever ModifyCoins is called, the entry will be modified.
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ret.first->second.flags |= CCoinsCacheEntry::DIRTY;
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return CCoinsModifier(*this, ret.first, cachedCoinUsage);
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}
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CCoinsModifier CCoinsViewCache::ModifyNewCoins(const uint256 &txid) {
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assert(!hasModifier);
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std::pair<CCoinsMap::iterator, bool> ret = cacheCoins.insert(std::make_pair(txid, CCoinsCacheEntry()));
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ret.first->second.coins.Clear();
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ret.first->second.flags = CCoinsCacheEntry::FRESH;
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ret.first->second.flags |= CCoinsCacheEntry::DIRTY;
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return CCoinsModifier(*this, ret.first, 0);
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}
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const CCoins* CCoinsViewCache::AccessCoins(const uint256 &txid) const {
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CCoinsMap::const_iterator it = FetchCoins(txid);
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if (it == cacheCoins.end()) {
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return NULL;
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} else {
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return &it->second.coins;
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}
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}
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bool CCoinsViewCache::HaveCoins(const uint256 &txid) const {
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CCoinsMap::const_iterator it = FetchCoins(txid);
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// We're using vtx.empty() instead of IsPruned here for performance reasons,
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// as we only care about the case where a transaction was replaced entirely
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// in a reorganization (which wipes vout entirely, as opposed to spending
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// which just cleans individual outputs).
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return (it != cacheCoins.end() && !it->second.coins.vout.empty());
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}
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uint256 CCoinsViewCache::GetBestBlock() const {
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if (hashBlock.IsNull())
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hashBlock = base->GetBestBlock();
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return hashBlock;
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}
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void CCoinsViewCache::SetBestBlock(const uint256 &hashBlockIn) {
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hashBlock = hashBlockIn;
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}
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bool CCoinsViewCache::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlockIn) {
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assert(!hasModifier);
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for (CCoinsMap::iterator it = mapCoins.begin(); it != mapCoins.end();) {
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if (it->second.flags & CCoinsCacheEntry::DIRTY) { // Ignore non-dirty entries (optimization).
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CCoinsMap::iterator itUs = cacheCoins.find(it->first);
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if (itUs == cacheCoins.end()) {
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if (!it->second.coins.IsPruned()) {
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// The parent cache does not have an entry, while the child
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// cache does have (a non-pruned) one. Move the data up, and
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// mark it as fresh (if the grandparent did have it, we
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// would have pulled it in at first GetCoins).
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assert(it->second.flags & CCoinsCacheEntry::FRESH);
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CCoinsCacheEntry& entry = cacheCoins[it->first];
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entry.coins.swap(it->second.coins);
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cachedCoinsUsage += entry.coins.DynamicMemoryUsage();
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entry.flags = CCoinsCacheEntry::DIRTY | CCoinsCacheEntry::FRESH;
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}
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} else {
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if ((itUs->second.flags & CCoinsCacheEntry::FRESH) && it->second.coins.IsPruned()) {
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// The grandparent does not have an entry, and the child is
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// modified and being pruned. This means we can just delete
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// it from the parent.
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cachedCoinsUsage -= itUs->second.coins.DynamicMemoryUsage();
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cacheCoins.erase(itUs);
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} else {
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// A normal modification.
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cachedCoinsUsage -= itUs->second.coins.DynamicMemoryUsage();
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itUs->second.coins.swap(it->second.coins);
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cachedCoinsUsage += itUs->second.coins.DynamicMemoryUsage();
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itUs->second.flags |= CCoinsCacheEntry::DIRTY;
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}
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}
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}
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CCoinsMap::iterator itOld = it++;
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mapCoins.erase(itOld);
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}
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hashBlock = hashBlockIn;
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return true;
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}
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bool CCoinsViewCache::Flush() {
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bool fOk = base->BatchWrite(cacheCoins, hashBlock);
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cacheCoins.clear();
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cachedCoinsUsage = 0;
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return fOk;
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}
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unsigned int CCoinsViewCache::GetCacheSize() const {
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return cacheCoins.size();
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}
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const CTxOut &CCoinsViewCache::GetOutputFor(const CTxIn& input) const
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{
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const CCoins* coins = AccessCoins(input.prevout.hash);
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assert(coins && coins->IsAvailable(input.prevout.n));
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return coins->vout[input.prevout.n];
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}
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CAmount CCoinsViewCache::GetValueIn(const CTransaction& tx) const
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{
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if (tx.IsCoinBase())
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return 0;
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CAmount nResult = 0;
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for (unsigned int i = 0; i < tx.vin.size(); i++)
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nResult += GetOutputFor(tx.vin[i]).nValue;
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return nResult;
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}
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bool CCoinsViewCache::HaveInputs(const CTransaction& tx) const
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{
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if (!tx.IsCoinBase()) {
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for (unsigned int i = 0; i < tx.vin.size(); i++) {
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const COutPoint &prevout = tx.vin[i].prevout;
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const CCoins* coins = AccessCoins(prevout.hash);
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if (!coins || !coins->IsAvailable(prevout.n)) {
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return false;
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}
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}
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}
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return true;
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}
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double CCoinsViewCache::GetPriority(const CTransaction &tx, int nHeight) const
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{
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if (tx.IsCoinBase())
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return 0.0;
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double dResult = 0.0;
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BOOST_FOREACH(const CTxIn& txin, tx.vin)
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{
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const CCoins* coins = AccessCoins(txin.prevout.hash);
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assert(coins);
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if (!coins->IsAvailable(txin.prevout.n)) continue;
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if (coins->nHeight < nHeight) {
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dResult += coins->vout[txin.prevout.n].nValue * (nHeight-coins->nHeight);
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}
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}
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return tx.ComputePriority(dResult);
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}
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CCoinsModifier::CCoinsModifier(CCoinsViewCache& cache_, CCoinsMap::iterator it_, size_t usage) : cache(cache_), it(it_), cachedCoinUsage(usage) {
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assert(!cache.hasModifier);
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cache.hasModifier = true;
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}
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CCoinsModifier::~CCoinsModifier()
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{
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assert(cache.hasModifier);
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cache.hasModifier = false;
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it->second.coins.Cleanup();
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cache.cachedCoinsUsage -= cachedCoinUsage; // Subtract the old usage
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if ((it->second.flags & CCoinsCacheEntry::FRESH) && it->second.coins.IsPruned()) {
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cache.cacheCoins.erase(it);
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} else {
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// If the coin still exists after the modification, add the new usage
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cache.cachedCoinsUsage += it->second.coins.DynamicMemoryUsage();
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}
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}
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