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// Copyright (c) 2012-2014 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#include "coins.h"
#include "memusage.h"
#include "random.h"
#include <assert.h>
/**
* calculate number of bytes for the bitmask, and its number of non-zero bytes
* each bit in the bitmask represents the availability of one output, but the
* availabilities of the first two outputs are encoded separately
*/
void CCoins::CalcMaskSize(unsigned int &nBytes, unsigned int &nNonzeroBytes) const {
unsigned int nLastUsedByte = 0;
for (unsigned int b = 0; 2+b*8 < vout.size(); b++) {
bool fZero = true;
for (unsigned int i = 0; i < 8 && 2+b*8+i < vout.size(); i++) {
if (!vout[2+b*8+i].IsNull()) {
fZero = false;
continue;
}
}
if (!fZero) {
nLastUsedByte = b + 1;
nNonzeroBytes++;
}
}
nBytes += nLastUsedByte;
}
bool CCoins::Spend(uint32_t nPos)
{
if (nPos >= vout.size() || vout[nPos].IsNull())
return false;
vout[nPos].SetNull();
Cleanup();
return true;
}
bool CCoinsView::GetCoins(const uint256 &txid, CCoins &coins) const { return false; }
bool CCoinsView::HaveCoins(const uint256 &txid) const { return false; }
uint256 CCoinsView::GetBestBlock() const { return uint256(); }
bool CCoinsView::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlock) { return false; }
bool CCoinsView::GetStats(CCoinsStats &stats) const { return false; }
CCoinsViewBacked::CCoinsViewBacked(CCoinsView *viewIn) : base(viewIn) { }
bool CCoinsViewBacked::GetCoins(const uint256 &txid, CCoins &coins) const { return base->GetCoins(txid, coins); }
bool CCoinsViewBacked::HaveCoins(const uint256 &txid) const { return base->HaveCoins(txid); }
uint256 CCoinsViewBacked::GetBestBlock() const { return base->GetBestBlock(); }
void CCoinsViewBacked::SetBackend(CCoinsView &viewIn) { base = &viewIn; }
bool CCoinsViewBacked::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlock) { return base->BatchWrite(mapCoins, hashBlock); }
bool CCoinsViewBacked::GetStats(CCoinsStats &stats) const { return base->GetStats(stats); }
CCoinsKeyHasher::CCoinsKeyHasher() : salt(GetRandHash()) {}
CCoinsViewCache::CCoinsViewCache(CCoinsView *baseIn) : CCoinsViewBacked(baseIn), hasModifier(false), cachedCoinsUsage(0) { }
CCoinsViewCache::~CCoinsViewCache()
{
assert(!hasModifier);
}
size_t CCoinsViewCache::DynamicMemoryUsage() const {
return memusage::DynamicUsage(cacheCoins) + cachedCoinsUsage;
}
CCoinsMap::const_iterator CCoinsViewCache::FetchCoins(const uint256 &txid) const {
CCoinsMap::iterator it = cacheCoins.find(txid);
if (it != cacheCoins.end())
return it;
CCoins tmp;
if (!base->GetCoins(txid, tmp))
return cacheCoins.end();
CCoinsMap::iterator ret = cacheCoins.insert(std::make_pair(txid, CCoinsCacheEntry())).first;
tmp.swap(ret->second.coins);
if (ret->second.coins.IsPruned()) {
// The parent only has an empty entry for this txid; we can consider our
// version as fresh.
ret->second.flags = CCoinsCacheEntry::FRESH;
}
cachedCoinsUsage += ret->second.coins.DynamicMemoryUsage();
return ret;
}
bool CCoinsViewCache::GetCoins(const uint256 &txid, CCoins &coins) const {
CCoinsMap::const_iterator it = FetchCoins(txid);
if (it != cacheCoins.end()) {
coins = it->second.coins;
return true;
}
return false;
}
CCoinsModifier CCoinsViewCache::ModifyCoins(const uint256 &txid) {
assert(!hasModifier);
std::pair<CCoinsMap::iterator, bool> ret = cacheCoins.insert(std::make_pair(txid, CCoinsCacheEntry()));
size_t cachedCoinUsage = 0;
if (ret.second) {
if (!base->GetCoins(txid, ret.first->second.coins)) {
// The parent view does not have this entry; mark it as fresh.
ret.first->second.coins.Clear();
ret.first->second.flags = CCoinsCacheEntry::FRESH;
} else if (ret.first->second.coins.IsPruned()) {
// The parent view only has a pruned entry for this; mark it as fresh.
ret.first->second.flags = CCoinsCacheEntry::FRESH;
}
} else {
cachedCoinUsage = ret.first->second.coins.DynamicMemoryUsage();
}
// Assume that whenever ModifyCoins is called, the entry will be modified.
ret.first->second.flags |= CCoinsCacheEntry::DIRTY;
return CCoinsModifier(*this, ret.first, cachedCoinUsage);
}
const CCoins* CCoinsViewCache::AccessCoins(const uint256 &txid) const {
CCoinsMap::const_iterator it = FetchCoins(txid);
if (it == cacheCoins.end()) {
return NULL;
} else {
return &it->second.coins;
}
}
bool CCoinsViewCache::HaveCoins(const uint256 &txid) const {
CCoinsMap::const_iterator it = FetchCoins(txid);
// We're using vtx.empty() instead of IsPruned here for performance reasons,
// as we only care about the case where a transaction was replaced entirely
// in a reorganization (which wipes vout entirely, as opposed to spending
// which just cleans individual outputs).
return (it != cacheCoins.end() && !it->second.coins.vout.empty());
}
uint256 CCoinsViewCache::GetBestBlock() const {
if (hashBlock.IsNull())
hashBlock = base->GetBestBlock();
return hashBlock;
}
void CCoinsViewCache::SetBestBlock(const uint256 &hashBlockIn) {
hashBlock = hashBlockIn;
}
bool CCoinsViewCache::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlockIn) {
assert(!hasModifier);
for (CCoinsMap::iterator it = mapCoins.begin(); it != mapCoins.end();) {
if (it->second.flags & CCoinsCacheEntry::DIRTY) { // Ignore non-dirty entries (optimization).
CCoinsMap::iterator itUs = cacheCoins.find(it->first);
if (itUs == cacheCoins.end()) {
if (!it->second.coins.IsPruned()) {
// The parent cache does not have an entry, while the child
// cache does have (a non-pruned) one. Move the data up, and
// mark it as fresh (if the grandparent did have it, we
// would have pulled it in at first GetCoins).
assert(it->second.flags & CCoinsCacheEntry::FRESH);
CCoinsCacheEntry& entry = cacheCoins[it->first];
entry.coins.swap(it->second.coins);
cachedCoinsUsage += entry.coins.DynamicMemoryUsage();
entry.flags = CCoinsCacheEntry::DIRTY | CCoinsCacheEntry::FRESH;
}
} else {
if ((itUs->second.flags & CCoinsCacheEntry::FRESH) && it->second.coins.IsPruned()) {
// The grandparent does not have an entry, and the child is
// modified and being pruned. This means we can just delete
// it from the parent.
cachedCoinsUsage -= itUs->second.coins.DynamicMemoryUsage();
cacheCoins.erase(itUs);
} else {
// A normal modification.
cachedCoinsUsage -= itUs->second.coins.DynamicMemoryUsage();
itUs->second.coins.swap(it->second.coins);
cachedCoinsUsage += itUs->second.coins.DynamicMemoryUsage();
itUs->second.flags |= CCoinsCacheEntry::DIRTY;
}
}
}
CCoinsMap::iterator itOld = it++;
mapCoins.erase(itOld);
}
hashBlock = hashBlockIn;
return true;
}
bool CCoinsViewCache::Flush() {
bool fOk = base->BatchWrite(cacheCoins, hashBlock);
cacheCoins.clear();
cachedCoinsUsage = 0;
return fOk;
}
unsigned int CCoinsViewCache::GetCacheSize() const {
return cacheCoins.size();
}
const CTxOut &CCoinsViewCache::GetOutputFor(const CTxIn& input) const
{
const CCoins* coins = AccessCoins(input.prevout.hash);
assert(coins && coins->IsAvailable(input.prevout.n));
return coins->vout[input.prevout.n];
}
CAmount CCoinsViewCache::GetValueIn(const CTransaction& tx) const
{
if (tx.IsCoinBase())
return 0;
CAmount nResult = 0;
for (unsigned int i = 0; i < tx.vin.size(); i++)
nResult += GetOutputFor(tx.vin[i]).nValue;
return nResult;
}
bool CCoinsViewCache::HaveInputs(const CTransaction& tx) const
{
if (!tx.IsCoinBase()) {
for (unsigned int i = 0; i < tx.vin.size(); i++) {
const COutPoint &prevout = tx.vin[i].prevout;
const CCoins* coins = AccessCoins(prevout.hash);
if (!coins || !coins->IsAvailable(prevout.n)) {
return false;
}
}
}
return true;
}
double CCoinsViewCache::GetPriority(const CTransaction &tx, int nHeight) const
{
if (tx.IsCoinBase())
return 0.0;
double dResult = 0.0;
BOOST_FOREACH(const CTxIn& txin, tx.vin)
{
const CCoins* coins = AccessCoins(txin.prevout.hash);
assert(coins);
if (!coins->IsAvailable(txin.prevout.n)) continue;
if (coins->nHeight < nHeight) {
dResult += coins->vout[txin.prevout.n].nValue * (nHeight-coins->nHeight);
}
}
return tx.ComputePriority(dResult);
}
CCoinsModifier::CCoinsModifier(CCoinsViewCache& cache_, CCoinsMap::iterator it_, size_t usage) : cache(cache_), it(it_), cachedCoinUsage(usage) {
assert(!cache.hasModifier);
cache.hasModifier = true;
}
CCoinsModifier::~CCoinsModifier()
{
assert(cache.hasModifier);
cache.hasModifier = false;
it->second.coins.Cleanup();
cache.cachedCoinsUsage -= cachedCoinUsage; // Subtract the old usage
if ((it->second.flags & CCoinsCacheEntry::FRESH) && it->second.coins.IsPruned()) {
cache.cacheCoins.erase(it);
} else {
// If the coin still exists after the modification, add the new usage
cache.cachedCoinsUsage += it->second.coins.DynamicMemoryUsage();
}
}