Merge #13011: Cache witness hash in CTransaction

fac1223 Cache witness hash in CTransaction (MarcoFalke)
faab55f Make CMutableTransaction constructor explicit (MarcoFalke)

Pull request description:

  This speeds up:
  * compactblocks (v2)
  * ATMP
  * validation and miner (via `BlockWitnessMerkleRoot`)
  * sigcache (see also unrelated #13204)
  * rpc and rest (nice, but irrelevant)

  This presumably slows down rescan, which uses a `CTransaction` and its `GetHash`, but never uses the `GetWitnessHash`. The slow down is proportional to the number of witness transactions in the rescan window. I.e. early in the chain there should be no measurable slow down. Later in the chain, there should be a slow down, but acceptable given the speedups in the modules mentioned above.

Tree-SHA512: 443e86acfcceb5af2163e68840c581d44159af3fd1fce266cab3504b29fcd74c50812b69a00d41582e7e1c5ea292f420ce5e892cdfab691da9c24ed1c44536c7

Author: laanwj

src/bitcoin-tx.cpp

@@ -546,7 +546,7 @@ static void MutateTxSign(CMutableTransaction& tx, const std::string& flagStr)
     // mergedTx will end up with all the signatures; it
     // starts as a clone of the raw tx:
     CMutableTransaction mergedTx{tx};
-    const CTransaction txv{tx};
+    const CMutableTransaction txv{tx};
     CCoinsView viewDummy;
     CCoinsViewCache view(&viewDummy);
 

src/primitives/transaction.cpp

@@ -67,18 +67,18 @@ uint256 CTransaction::ComputeHash() const
     return SerializeHash(*this, SER_GETHASH, SERIALIZE_TRANSACTION_NO_WITNESS);
 }
 
-uint256 CTransaction::GetWitnessHash() const
+uint256 CTransaction::ComputeWitnessHash() const
 {
     if (!HasWitness()) {
-        return GetHash();
+        return hash;
     }
     return SerializeHash(*this, SER_GETHASH, 0);
 }
 
 /* For backward compatibility, the hash is initialized to 0. TODO: remove the need for this default constructor entirely. */
-CTransaction::CTransaction() : vin(), vout(), nVersion(CTransaction::CURRENT_VERSION), nLockTime(0), hash() {}
-CTransaction::CTransaction(const CMutableTransaction &tx) : vin(tx.vin), vout(tx.vout), nVersion(tx.nVersion), nLockTime(tx.nLockTime), hash(ComputeHash()) {}
-CTransaction::CTransaction(CMutableTransaction &&tx) : vin(std::move(tx.vin)), vout(std::move(tx.vout)), nVersion(tx.nVersion), nLockTime(tx.nLockTime), hash(ComputeHash()) {}
+CTransaction::CTransaction() : vin(), vout(), nVersion(CTransaction::CURRENT_VERSION), nLockTime(0), hash{}, m_witness_hash{} {}
+CTransaction::CTransaction(const CMutableTransaction& tx) : vin(tx.vin), vout(tx.vout), nVersion(tx.nVersion), nLockTime(tx.nLockTime), hash{ComputeHash()}, m_witness_hash{ComputeWitnessHash()} {}
+CTransaction::CTransaction(CMutableTransaction&& tx) : vin(std::move(tx.vin)), vout(std::move(tx.vout)), nVersion(tx.nVersion), nLockTime(tx.nLockTime), hash{ComputeHash()}, m_witness_hash{ComputeWitnessHash()} {}
 
 CAmount CTransaction::GetValueOut() const
 {

src/primitives/transaction.h

@@ -286,8 +286,10 @@ class CTransaction
 private:
     /** Memory only. */
     const uint256 hash;
+    const uint256 m_witness_hash;
 
     uint256 ComputeHash() const;
+    uint256 ComputeWitnessHash() const;
 
 public:
     /** Construct a CTransaction that qualifies as IsNull() */
@@ -311,12 +313,8 @@ class CTransaction
         return vin.empty() && vout.empty();
     }
 
-    const uint256& GetHash() const {
-        return hash;
-    }
-
-    // Compute a hash that includes both transaction and witness data
-    uint256 GetWitnessHash() const;
+    const uint256& GetHash() const { return hash; }
+    const uint256& GetWitnessHash() const { return m_witness_hash; };
 
     // Return sum of txouts.
     CAmount GetValueOut() const;
@@ -367,7 +365,7 @@ struct CMutableTransaction
     uint32_t nLockTime;
 
     CMutableTransaction();
-    CMutableTransaction(const CTransaction& tx);
+    explicit CMutableTransaction(const CTransaction& tx);
 
     template <typename Stream>
     inline void Serialize(Stream& s) const {

src/test/coins_tests.cpp

@@ -312,7 +312,7 @@ BOOST_AUTO_TEST_CASE(updatecoins_simulation_test)
                 if (InsecureRandRange(10) == 0 && coinbase_coins.size()) {
                     auto utxod = FindRandomFrom(coinbase_coins);
                     // Reuse the exact same coinbase
-                    tx = std::get<0>(utxod->second);
+                    tx = CMutableTransaction{std::get<0>(utxod->second)};
                     // shouldn't be available for reconnection if it's been duplicated
                     disconnected_coins.erase(utxod->first);
 
@@ -331,7 +331,7 @@ BOOST_AUTO_TEST_CASE(updatecoins_simulation_test)
                 // 1/20 times reconnect a previously disconnected tx
                 if (randiter % 20 == 2 && disconnected_coins.size()) {
                     auto utxod = FindRandomFrom(disconnected_coins);
-                    tx = std::get<0>(utxod->second);
+                    tx = CMutableTransaction{std::get<0>(utxod->second)};
                     prevout = tx.vin[0].prevout;
                     if (!CTransaction(tx).IsCoinBase() && !utxoset.count(prevout)) {
                         disconnected_coins.erase(utxod->first);

src/test/script_tests.cpp

@@ -137,7 +137,7 @@ CMutableTransaction BuildCreditingTransaction(const CScript& scriptPubKey, int n
     return txCredit;
 }
 
-CMutableTransaction BuildSpendingTransaction(const CScript& scriptSig, const CScriptWitness& scriptWitness, const CMutableTransaction& txCredit)
+CMutableTransaction BuildSpendingTransaction(const CScript& scriptSig, const CScriptWitness& scriptWitness, const CTransaction& txCredit)
 {
     CMutableTransaction txSpend;
     txSpend.nVersion = 1;
@@ -163,7 +163,7 @@ void DoTest(const CScript& scriptPubKey, const CScript& scriptSig, const CScript
         flags |= SCRIPT_VERIFY_WITNESS;
     }
     ScriptError err;
-    CMutableTransaction txCredit = BuildCreditingTransaction(scriptPubKey, nValue);
+    const CTransaction txCredit{BuildCreditingTransaction(scriptPubKey, nValue)};
     CMutableTransaction tx = BuildSpendingTransaction(scriptSig, scriptWitness, txCredit);
     CMutableTransaction tx2 = tx;
     BOOST_CHECK_MESSAGE(VerifyScript(scriptSig, scriptPubKey, &scriptWitness, flags, MutableTransactionSignatureChecker(&tx, 0, txCredit.vout[0].nValue), &err) == expect, message);
@@ -1073,7 +1073,7 @@ BOOST_AUTO_TEST_CASE(script_CHECKMULTISIG12)
     CScript scriptPubKey12;
     scriptPubKey12 << OP_1 << ToByteVector(key1.GetPubKey()) << ToByteVector(key2.GetPubKey()) << OP_2 << OP_CHECKMULTISIG;
 
-    CMutableTransaction txFrom12 = BuildCreditingTransaction(scriptPubKey12);
+    const CTransaction txFrom12{BuildCreditingTransaction(scriptPubKey12)};
     CMutableTransaction txTo12 = BuildSpendingTransaction(CScript(), CScriptWitness(), txFrom12);
 
     CScript goodsig1 = sign_multisig(scriptPubKey12, key1, txTo12);
@@ -1104,7 +1104,7 @@ BOOST_AUTO_TEST_CASE(script_CHECKMULTISIG23)
     CScript scriptPubKey23;
     scriptPubKey23 << OP_2 << ToByteVector(key1.GetPubKey()) << ToByteVector(key2.GetPubKey()) << ToByteVector(key3.GetPubKey()) << OP_3 << OP_CHECKMULTISIG;
 
-    CMutableTransaction txFrom23 = BuildCreditingTransaction(scriptPubKey23);
+    const CTransaction txFrom23{BuildCreditingTransaction(scriptPubKey23)};
     CMutableTransaction txTo23 = BuildSpendingTransaction(CScript(), CScriptWitness(), txFrom23);
 
     std::vector<CKey> keys;

src/test/txvalidationcache_tests.cpp

@@ -24,7 +24,7 @@ bool CheckInputs(const CTransaction& tx, CValidationState &state, const CCoinsVi
 BOOST_AUTO_TEST_SUITE(tx_validationcache_tests)
 
 static bool
-ToMemPool(CMutableTransaction& tx)
+ToMemPool(const CMutableTransaction& tx)
 {
     LOCK(cs_main);
 

src/wallet/feebumper.cpp

@@ -185,7 +185,7 @@ Result CreateTransaction(const CWallet* wallet, const uint256& txid, const CCoin
     // If the output is not large enough to pay the fee, fail.
     CAmount nDelta = new_fee - old_fee;
     assert(nDelta > 0);
-    mtx =  *wtx.tx;
+    mtx = CMutableTransaction{*wtx.tx};
     CTxOut* poutput = &(mtx.vout[nOutput]);
     if (poutput->nValue < nDelta) {
         errors.push_back("Change output is too small to bump the fee");

src/wallet/wallet.cpp

@@ -2075,8 +2075,8 @@ bool CWalletTx::IsTrusted() const
 
 bool CWalletTx::IsEquivalentTo(const CWalletTx& _tx) const
 {
-        CMutableTransaction tx1 = *this->tx;
-        CMutableTransaction tx2 = *_tx.tx;
+        CMutableTransaction tx1 {*this->tx};
+        CMutableTransaction tx2 {*_tx.tx};
         for (auto& txin : tx1.vin) txin.scriptSig = CScript();
         for (auto& txin : tx2.vin) txin.scriptSig = CScript();
         return CTransaction(tx1) == CTransaction(tx2);