From f28aec014edd29cfc669cf1c3f795c0f1e2ae7e2 Mon Sep 17 00:00:00 2001 From: Pieter Wuille Date: Wed, 3 Sep 2014 09:01:24 +0200 Subject: [PATCH] Use ModifyCoins instead of mutable GetCoins. Replace the mutable non-copying GetCoins method with a ModifyCoins, which returns an encapsulated iterator, so we can keep track of concurrent modifications (as iterators can be invalidated by those) and run cleanup code after a modification is finished. This also removes the overloading of the 'GetCoins' name. --- src/bitcoin-tx.cpp | 18 +++++++------- src/coins.cpp | 36 +++++++++++++++++++--------- src/coins.h | 49 +++++++++++++++++++++++++++++++++++---- src/main.cpp | 49 ++++++++++++++++++--------------------- src/rpcrawtransaction.cpp | 18 +++++++------- 5 files changed, 108 insertions(+), 62 deletions(-) diff --git a/src/bitcoin-tx.cpp b/src/bitcoin-tx.cpp index b6e7a6c54..4d6dbc1df 100644 --- a/src/bitcoin-tx.cpp +++ b/src/bitcoin-tx.cpp @@ -384,21 +384,19 @@ static void MutateTxSign(CMutableTransaction& tx, const string& flagStr) vector pkData(ParseHexUV(prevOut, "scriptPubKey")); CScript scriptPubKey(pkData.begin(), pkData.end()); - CCoins coins; - if (view.GetCoins(txid, coins)) { - if (coins.IsAvailable(nOut) && coins.vout[nOut].scriptPubKey != scriptPubKey) { + { + CCoinsModifier coins = view.ModifyCoins(txid); + if (coins->IsAvailable(nOut) && coins->vout[nOut].scriptPubKey != scriptPubKey) { string err("Previous output scriptPubKey mismatch:\n"); - err = err + coins.vout[nOut].scriptPubKey.ToString() + "\nvs:\n"+ + err = err + coins->vout[nOut].scriptPubKey.ToString() + "\nvs:\n"+ scriptPubKey.ToString(); throw runtime_error(err); } - // what todo if txid is known, but the actual output isn't? + if ((unsigned int)nOut >= coins->vout.size()) + coins->vout.resize(nOut+1); + coins->vout[nOut].scriptPubKey = scriptPubKey; + coins->vout[nOut].nValue = 0; // we don't know the actual output value } - if ((unsigned int)nOut >= coins.vout.size()) - coins.vout.resize(nOut+1); - coins.vout[nOut].scriptPubKey = scriptPubKey; - coins.vout[nOut].nValue = 0; // we don't know the actual output value - view.SetCoins(txid, coins); // if redeemScript given and private keys given, // add redeemScript to the tempKeystore so it can be signed: diff --git a/src/coins.cpp b/src/coins.cpp index 34485db2b..2b93c74c3 100644 --- a/src/coins.cpp +++ b/src/coins.cpp @@ -73,7 +73,7 @@ bool CCoinsViewBacked::GetStats(CCoinsStats &stats) const { return base->GetStat CCoinsKeyHasher::CCoinsKeyHasher() : salt(GetRandHash()) {} -CCoinsViewCache::CCoinsViewCache(CCoinsView &baseIn, bool fDummy) : CCoinsViewBacked(baseIn), hashBlock(0) { } +CCoinsViewCache::CCoinsViewCache(CCoinsView &baseIn, bool fDummy) : CCoinsViewBacked(baseIn), hasModifier(false), hashBlock(0) { } bool CCoinsViewCache::GetCoins(const uint256 &txid, CCoins &coins) const { if (cacheCoins.count(txid)) { @@ -87,7 +87,12 @@ bool CCoinsViewCache::GetCoins(const uint256 &txid, CCoins &coins) const { return false; } -CCoinsMap::iterator CCoinsViewCache::FetchCoins(const uint256 &txid) { +CCoinsViewCache::~CCoinsViewCache() +{ + assert(!hasModifier); +} + +CCoinsMap::const_iterator CCoinsViewCache::FetchCoins(const uint256 &txid) const { CCoinsMap::iterator it = cacheCoins.find(txid); if (it != cacheCoins.end()) return it; @@ -99,15 +104,15 @@ CCoinsMap::iterator CCoinsViewCache::FetchCoins(const uint256 &txid) { return ret; } -CCoinsMap::const_iterator CCoinsViewCache::FetchCoins(const uint256 &txid) const { - /* Avoid redundant implementation with the const-cast. */ - return const_cast(this)->FetchCoins(txid); -} - -CCoins &CCoinsViewCache::GetCoins(const uint256 &txid) { - CCoinsMap::iterator it = FetchCoins(txid); - assert(it != cacheCoins.end()); - return it->second; +CCoinsModifier CCoinsViewCache::ModifyCoins(const uint256 &txid) { + assert(!hasModifier); + hasModifier = true; + std::pair ret = cacheCoins.insert(std::make_pair(txid, CCoins())); + if (ret.second) { + if (!base->GetCoins(txid, ret.first->second)) + ret.first->second.Clear(); + } + return CCoinsModifier(*this, ret.first); } const CCoins* CCoinsViewCache::AccessCoins(const uint256 &txid) const { @@ -145,6 +150,7 @@ bool CCoinsViewCache::SetBestBlock(const uint256 &hashBlockIn) { } bool CCoinsViewCache::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlockIn) { + assert(!hasModifier); for (CCoinsMap::iterator it = mapCoins.begin(); it != mapCoins.end();) { cacheCoins[it->first].swap(it->second); CCoinsMap::iterator itOld = it++; @@ -213,3 +219,11 @@ double CCoinsViewCache::GetPriority(const CTransaction &tx, int nHeight) const } return tx.ComputePriority(dResult); } + +CCoinsModifier::CCoinsModifier(CCoinsViewCache& cache_, CCoinsMap::iterator it_) : cache(cache_), it(it_) {} + +CCoinsModifier::~CCoinsModifier() { + assert(cache.hasModifier); + cache.hasModifier = false; + it->second.Cleanup(); +} diff --git a/src/coins.h b/src/coins.h index bf61f55aa..62beea3c2 100644 --- a/src/coins.h +++ b/src/coins.h @@ -83,11 +83,26 @@ public: // as new tx version will probably only be introduced at certain heights int nVersion; - // construct a CCoins from a CTransaction, at a given height - CCoins(const CTransaction &tx, int nHeightIn) : fCoinBase(tx.IsCoinBase()), vout(tx.vout), nHeight(nHeightIn), nVersion(tx.nVersion) { + void FromTx(const CTransaction &tx, int nHeightIn) { + fCoinBase = tx.IsCoinBase(); + vout = tx.vout; + nHeight = nHeightIn; + nVersion = tx.nVersion; ClearUnspendable(); } + // construct a CCoins from a CTransaction, at a given height + CCoins(const CTransaction &tx, int nHeightIn) { + FromTx(tx, nHeightIn); + } + + void Clear() { + fCoinBase = false; + std::vector().swap(vout); + nHeight = 0; + nVersion = 0; + } + // empty constructor CCoins() : fCoinBase(false), vout(0), nHeight(0), nVersion(0) { } @@ -323,10 +338,31 @@ public: }; +class CCoinsViewCache; + +/** A reference to a mutable cache entry. Encapsulating it allows us to run + * cleanup code after the modification is finished, and keeping track of + * concurrent modifications. */ +class CCoinsModifier +{ +private: + CCoinsViewCache& cache; + CCoinsMap::iterator it; + CCoinsModifier(CCoinsViewCache& cache_, CCoinsMap::iterator it_); + +public: + CCoins* operator->() { return &it->second; } + CCoins& operator*() { return it->second; } + ~CCoinsModifier(); + friend class CCoinsViewCache; +}; + /** CCoinsView that adds a memory cache for transactions to another CCoinsView */ class CCoinsViewCache : public CCoinsViewBacked { protected: + /* Whether this cache has an active modifier. */ + bool hasModifier; /* Make mutable so that we can "fill the cache" even from Get-methods declared as "const". */ @@ -335,6 +371,7 @@ protected: public: CCoinsViewCache(CCoinsView &baseIn, bool fDummy = false); + ~CCoinsViewCache(); // Standard CCoinsView methods bool GetCoins(const uint256 &txid, CCoins &coins) const; @@ -349,8 +386,10 @@ public: // allowed while accessing the returned pointer. const CCoins* AccessCoins(const uint256 &txid) const; - // Return a modifiable reference to a CCoins. Check HaveCoins first. - CCoins &GetCoins(const uint256 &txid); + // Return a modifiable reference to a CCoins. If no entry with the given + // txid exists, a new one is created. Simultaneous modifications are not + // allowed. + CCoinsModifier ModifyCoins(const uint256 &txid); // Push the modifications applied to this cache to its base. // Failure to call this method before destruction will cause the changes to be forgotten. @@ -377,6 +416,8 @@ public: const CTxOut &GetOutputFor(const CTxIn& input) const; + friend class CCoinsModifier; + private: CCoinsMap::iterator FetchCoins(const uint256 &txid); CCoinsMap::const_iterator FetchCoins(const uint256 &txid) const; diff --git a/src/main.cpp b/src/main.cpp index 15c3916a6..5aed3a252 100644 --- a/src/main.cpp +++ b/src/main.cpp @@ -1348,22 +1348,18 @@ void static InvalidBlockFound(CBlockIndex *pindex, const CValidationState &state void UpdateCoins(const CTransaction& tx, CValidationState &state, CCoinsViewCache &inputs, CTxUndo &txundo, int nHeight) { - bool ret; // mark inputs spent if (!tx.IsCoinBase()) { txundo.vprevout.reserve(tx.vin.size()); - for (unsigned int i = 0; i < tx.vin.size(); i++) { - const CTxIn &txin = tx.vin[i]; - CCoins &coins = inputs.GetCoins(txin.prevout.hash); + BOOST_FOREACH(const CTxIn &txin, tx.vin) { txundo.vprevout.push_back(CTxInUndo()); - ret = coins.Spend(txin.prevout, txundo.vprevout.back()); + bool ret = inputs.ModifyCoins(txin.prevout.hash)->Spend(txin.prevout, txundo.vprevout.back()); assert(ret); } } // add outputs - ret = inputs.SetCoins(tx.GetHash(), CCoins(tx, nHeight)); - assert(ret); + inputs.ModifyCoins(tx.GetHash())->FromTx(tx, nHeight); } bool CScriptCheck::operator()() const { @@ -1504,21 +1500,23 @@ bool DisconnectBlock(CBlock& block, CValidationState& state, CBlockIndex* pindex // exactly. Note that transactions with only provably unspendable outputs won't // have outputs available even in the block itself, so we handle that case // specially with outsEmpty. + { CCoins outsEmpty; - CCoins &outs = view.HaveCoins(hash) ? view.GetCoins(hash) : outsEmpty; - outs.ClearUnspendable(); + CCoinsModifier outs = view.ModifyCoins(hash); + outs->ClearUnspendable(); - CCoins outsBlock = CCoins(tx, pindex->nHeight); + CCoins outsBlock(tx, pindex->nHeight); // The CCoins serialization does not serialize negative numbers. // No network rules currently depend on the version here, so an inconsistency is harmless // but it must be corrected before txout nversion ever influences a network rule. if (outsBlock.nVersion < 0) - outs.nVersion = outsBlock.nVersion; - if (outs != outsBlock) + outs->nVersion = outsBlock.nVersion; + if (*outs != outsBlock) fClean = fClean && error("DisconnectBlock() : added transaction mismatch? database corrupted"); // remove outputs - outs = CCoins(); + outs->Clear(); + } // restore inputs if (i > 0) { // not coinbases @@ -1528,27 +1526,24 @@ bool DisconnectBlock(CBlock& block, CValidationState& state, CBlockIndex* pindex for (unsigned int j = tx.vin.size(); j-- > 0;) { const COutPoint &out = tx.vin[j].prevout; const CTxInUndo &undo = txundo.vprevout[j]; - CCoins coins; - view.GetCoins(out.hash, coins); // this can fail if the prevout was already entirely spent + CCoinsModifier coins = view.ModifyCoins(out.hash); if (undo.nHeight != 0) { // undo data contains height: this is the last output of the prevout tx being spent - if (!coins.IsPruned()) + if (!coins->IsPruned()) fClean = fClean && error("DisconnectBlock() : undo data overwriting existing transaction"); - coins = CCoins(); - coins.fCoinBase = undo.fCoinBase; - coins.nHeight = undo.nHeight; - coins.nVersion = undo.nVersion; + coins->Clear(); + coins->fCoinBase = undo.fCoinBase; + coins->nHeight = undo.nHeight; + coins->nVersion = undo.nVersion; } else { - if (coins.IsPruned()) + if (coins->IsPruned()) fClean = fClean && error("DisconnectBlock() : undo data adding output to missing transaction"); } - if (coins.IsAvailable(out.n)) + if (coins->IsAvailable(out.n)) fClean = fClean && error("DisconnectBlock() : undo data overwriting existing output"); - if (coins.vout.size() < out.n+1) - coins.vout.resize(out.n+1); - coins.vout[out.n] = undo.txout; - if (!view.SetCoins(out.hash, coins)) - return error("DisconnectBlock() : cannot restore coin inputs"); + if (coins->vout.size() < out.n+1) + coins->vout.resize(out.n+1); + coins->vout[out.n] = undo.txout; } } } diff --git a/src/rpcrawtransaction.cpp b/src/rpcrawtransaction.cpp index dbb0966ae..da2421f38 100644 --- a/src/rpcrawtransaction.cpp +++ b/src/rpcrawtransaction.cpp @@ -612,21 +612,19 @@ Value signrawtransaction(const Array& params, bool fHelp) vector pkData(ParseHexO(prevOut, "scriptPubKey")); CScript scriptPubKey(pkData.begin(), pkData.end()); - CCoins coins; - if (view.GetCoins(txid, coins)) { - if (coins.IsAvailable(nOut) && coins.vout[nOut].scriptPubKey != scriptPubKey) { + { + CCoinsModifier coins = view.ModifyCoins(txid); + if (coins->IsAvailable(nOut) && coins->vout[nOut].scriptPubKey != scriptPubKey) { string err("Previous output scriptPubKey mismatch:\n"); - err = err + coins.vout[nOut].scriptPubKey.ToString() + "\nvs:\n"+ + err = err + coins->vout[nOut].scriptPubKey.ToString() + "\nvs:\n"+ scriptPubKey.ToString(); throw JSONRPCError(RPC_DESERIALIZATION_ERROR, err); } - // what todo if txid is known, but the actual output isn't? + if ((unsigned int)nOut >= coins->vout.size()) + coins->vout.resize(nOut+1); + coins->vout[nOut].scriptPubKey = scriptPubKey; + coins->vout[nOut].nValue = 0; // we don't know the actual output value } - if ((unsigned int)nOut >= coins.vout.size()) - coins.vout.resize(nOut+1); - coins.vout[nOut].scriptPubKey = scriptPubKey; - coins.vout[nOut].nValue = 0; // we don't know the actual output value - view.SetCoins(txid, coins); // if redeemScript given and not using the local wallet (private keys // given), add redeemScript to the tempKeystore so it can be signed: