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Allow BatchWrite to destroy its input, reducing copying

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sipa committed Aug 24, 2014
1 parent 5cd00bc commit b0875eb3fea0934f3a6651fbc22aac12e33e15e5
Showing with 21 additions and 14 deletions.
  1. +9 −7 src/coins.cpp
  2. +6 −4 src/coins.h
  3. +5 −2 src/txdb.cpp
  4. +1 −1 src/txdb.h
@@ -57,7 +57,7 @@ bool CCoinsView::SetCoins(const uint256 &txid, const CCoins &coins) { return fal
bool CCoinsView::HaveCoins(const uint256 &txid) { return false; }
uint256 CCoinsView::GetBestBlock() { return uint256(0); }
bool CCoinsView::SetBestBlock(const uint256 &hashBlock) { return false; }
bool CCoinsView::BatchWrite(const CCoinsMap &mapCoins, const uint256 &hashBlock) { return false; }
bool CCoinsView::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlock) { return false; }
bool CCoinsView::GetStats(CCoinsStats &stats) { return false; }


@@ -68,7 +68,7 @@ bool CCoinsViewBacked::HaveCoins(const uint256 &txid) { return base->HaveCoins(t
uint256 CCoinsViewBacked::GetBestBlock() { return base->GetBestBlock(); }
bool CCoinsViewBacked::SetBestBlock(const uint256 &hashBlock) { return base->SetBestBlock(hashBlock); }
void CCoinsViewBacked::SetBackend(CCoinsView &viewIn) { base = &viewIn; }
bool CCoinsViewBacked::BatchWrite(const CCoinsMap &mapCoins, const uint256 &hashBlock) { return base->BatchWrite(mapCoins, hashBlock); }
bool CCoinsViewBacked::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlock) { return base->BatchWrite(mapCoins, hashBlock); }
bool CCoinsViewBacked::GetStats(CCoinsStats &stats) { return base->GetStats(stats); }

CCoinsKeyHasher::CCoinsKeyHasher() : salt(GetRandHash()) {}
@@ -130,17 +130,19 @@ bool CCoinsViewCache::SetBestBlock(const uint256 &hashBlockIn) {
return true;
}

bool CCoinsViewCache::BatchWrite(const CCoinsMap &mapCoins, const uint256 &hashBlockIn) {
for (CCoinsMap::const_iterator it = mapCoins.begin(); it != mapCoins.end(); it++)
cacheCoins[it->first] = it->second;
bool CCoinsViewCache::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlockIn) {
for (CCoinsMap::iterator it = mapCoins.begin(); it != mapCoins.end();) {
cacheCoins[it->first].swap(it->second);
CCoinsMap::iterator itOld = it++;
mapCoins.erase(itOld);
}
hashBlock = hashBlockIn;
return true;
}

bool CCoinsViewCache::Flush() {
bool fOk = base->BatchWrite(cacheCoins, hashBlock);
if (fOk)
cacheCoins.clear();
cacheCoins.clear();
return fOk;
}

@@ -291,8 +291,9 @@ class CCoinsView
// Modify the currently active block hash
virtual bool SetBestBlock(const uint256 &hashBlock);

// Do a bulk modification (multiple SetCoins + one SetBestBlock)
virtual bool BatchWrite(const CCoinsMap &mapCoins, const uint256 &hashBlock);
// Do a bulk modification (multiple SetCoins + one SetBestBlock).
// The passed mapCoins can be modified.
virtual bool BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlock);

// Calculate statistics about the unspent transaction output set
virtual bool GetStats(CCoinsStats &stats);
@@ -316,7 +317,7 @@ class CCoinsViewBacked : public CCoinsView
uint256 GetBestBlock();
bool SetBestBlock(const uint256 &hashBlock);
void SetBackend(CCoinsView &viewIn);
bool BatchWrite(const CCoinsMap &mapCoins, const uint256 &hashBlock);
bool BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlock);
bool GetStats(CCoinsStats &stats);
};

@@ -337,7 +338,7 @@ class CCoinsViewCache : public CCoinsViewBacked
bool HaveCoins(const uint256 &txid);
uint256 GetBestBlock();
bool SetBestBlock(const uint256 &hashBlock);
bool BatchWrite(const CCoinsMap &mapCoins, const uint256 &hashBlock);
bool BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlock);

// Return a modifiable reference to a CCoins. Check HaveCoins first.
// Many methods explicitly require a CCoinsViewCache because of this method, to reduce
@@ -346,6 +347,7 @@ class CCoinsViewCache : public CCoinsViewBacked

// Push the modifications applied to this cache to its base.
// Failure to call this method before destruction will cause the changes to be forgotten.
// If false is returned, the state of this cache (and its backing view) will be undefined.
bool Flush();

// Calculate the size of the cache (in number of transactions)
@@ -54,12 +54,15 @@ bool CCoinsViewDB::SetBestBlock(const uint256 &hashBlock) {
return db.WriteBatch(batch);
}

bool CCoinsViewDB::BatchWrite(const CCoinsMap &mapCoins, const uint256 &hashBlock) {
bool CCoinsViewDB::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlock) {
LogPrint("coindb", "Committing %u changed transactions to coin database...\n", (unsigned int)mapCoins.size());

CLevelDBBatch batch;
for (CCoinsMap::const_iterator it = mapCoins.begin(); it != mapCoins.end(); it++)
for (CCoinsMap::iterator it = mapCoins.begin(); it != mapCoins.end();) {
BatchWriteCoins(batch, it->first, it->second);
CCoinsMap::iterator itOld = it++;
mapCoins.erase(itOld);
}
if (hashBlock != uint256(0))
BatchWriteHashBestChain(batch, hashBlock);

@@ -37,7 +37,7 @@ class CCoinsViewDB : public CCoinsView
bool HaveCoins(const uint256 &txid);
uint256 GetBestBlock();
bool SetBestBlock(const uint256 &hashBlock);
bool BatchWrite(const CCoinsMap &mapCoins, const uint256 &hashBlock);
bool BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlock);
bool GetStats(CCoinsStats &stats);
};

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