339 lines
14 KiB
C++
339 lines
14 KiB
C++
// Copyright (c) 2012-2016 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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CCoinsViewCursor *CCoinsView::Cursor() const { return 0; }
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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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CCoinsViewCursor *CCoinsViewBacked::Cursor() const { return base->Cursor(); }
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SaltedTxidHasher::SaltedTxidHasher() : k0(GetRand(std::numeric_limits<uint64_t>::max())), k1(GetRand(std::numeric_limits<uint64_t>::max())) {}
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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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/* ModifyNewCoins allows for faster coin modification when creating the new
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* outputs from a transaction. It assumes that BIP 30 (no duplicate txids)
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* applies and has already been tested for (or the test is not required due to
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* BIP 34, height in coinbase). If we can assume BIP 30 then we know that any
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* non-coinbase transaction we are adding to the UTXO must not already exist in
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* the utxo unless it is fully spent. Thus we can check only if it exists DIRTY
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* at the current level of the cache, in which case it is not safe to mark it
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* FRESH (b/c then its spentness still needs to flushed). If it's not dirty and
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* doesn't exist or is pruned in the current cache, we know it either doesn't
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* exist or is pruned in parent caches, which is the definition of FRESH. The
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* exception to this is the two historical violations of BIP 30 in the chain,
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* both of which were coinbases. We do not mark these fresh so we we can ensure
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* that they will still be properly overwritten when spent.
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*/
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CCoinsModifier CCoinsViewCache::ModifyNewCoins(const uint256 &txid, bool coinbase) {
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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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if (!coinbase) {
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// New coins must not already exist.
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if (!ret.first->second.coins.IsPruned())
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throw std::logic_error("ModifyNewCoins should not find pre-existing coins on a non-coinbase unless they are pruned!");
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if (!(ret.first->second.flags & CCoinsCacheEntry::DIRTY)) {
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// If the coin is known to be pruned (have no unspent outputs) in
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// the current view and the cache entry is not dirty, we know the
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// coin also must be pruned in the parent view as well, so it is safe
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// to mark this fresh.
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ret.first->second.flags |= CCoinsCacheEntry::FRESH;
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}
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}
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ret.first->second.coins.Clear();
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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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bool CCoinsViewCache::HaveCoinsInCache(const uint256 &txid) const {
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CCoinsMap::const_iterator it = cacheCoins.find(txid);
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return it != cacheCoins.end();
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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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// The parent cache does not have an entry, while the child does
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// We can ignore it if it's both FRESH and pruned in the child
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if (!(it->second.flags & CCoinsCacheEntry::FRESH && it->second.coins.IsPruned())) {
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// Otherwise we will need to create it in the parent
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// and move the data up and mark it as dirty
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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;
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// We can mark it FRESH in the parent if it was FRESH in the child
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// Otherwise it might have just been flushed from the parent's cache
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// and already exist in the grandparent
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if (it->second.flags & CCoinsCacheEntry::FRESH)
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entry.flags |= CCoinsCacheEntry::FRESH;
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}
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} else {
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// Assert that the child cache entry was not marked FRESH if the
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// parent cache entry has unspent outputs. If this ever happens,
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// it means the FRESH flag was misapplied and there is a logic
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// error in the calling code.
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if ((it->second.flags & CCoinsCacheEntry::FRESH) && !itUs->second.coins.IsPruned())
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throw std::logic_error("FRESH flag misapplied to cache entry for base transaction with spendable outputs");
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// Found the entry in the parent cache
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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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// NOTE: It is possible the child has a FRESH flag here in
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// the event the entry we found in the parent is pruned. But
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// we must not copy that FRESH flag to the parent as that
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// pruned state likely still needs to be communicated to the
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// grandparent.
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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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void CCoinsViewCache::Uncache(const uint256& hash)
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{
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CCoinsMap::iterator it = cacheCoins.find(hash);
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if (it != cacheCoins.end() && it->second.flags == 0) {
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cachedCoinsUsage -= it->second.coins.DynamicMemoryUsage();
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cacheCoins.erase(it);
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}
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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, CAmount &inChainInputValue) const
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{
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inChainInputValue = 0;
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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 += (double)(coins->vout[txin.prevout.n].nValue) * (nHeight-coins->nHeight);
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inChainInputValue += coins->vout[txin.prevout.n].nValue;
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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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CCoinsViewCursor::~CCoinsViewCursor()
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{
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}
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