Merge bitcoin/bitcoin#28766: Improve peformance of CTransaction::HasWitness (28107 follow-up)

af1d2ff88344e1545ac8d9ad09f8e37e264da712 [primitives] Precompute result of CTransaction::HasWitness (dergoegge)

Pull request description:

  This addresses https://github.com/bitcoin/bitcoin/pull/28107#discussion_r1364961590 from #28107.

ACKs for top commit:
  theStack:
    ACK af1d2ff88344e1545ac8d9ad09f8e37e264da712
  achow101:
    ACK af1d2ff88344e1545ac8d9ad09f8e37e264da712
  stickies-v:
    ACK af1d2ff88344e1545ac8d9ad09f8e37e264da712
  TheCharlatan:
    ACK af1d2ff88344e1545ac8d9ad09f8e37e264da712

Tree-SHA512: a77654ae429d0d7ce12daa309770e75beec4f8984734f80ed203156199425af43b50ad3d8aab85a89371a71356464ebd4503a0248fd0103579adfc74a55aaf51

2 files changed, 14 insertions, 11 deletions

diff --git a/src/primitives/transaction.cpp b/src/primitives/transaction.cpp
index 002c922c0d..b4a860dd9e 100644
--- a/src/primitives/transaction.cpp
+++ b/src/primitives/transaction.cpp
@@ -14,6 +14,7 @@
 #include <util/strencodings.h>
 #include <util/transaction_identifier.h>
 
+#include <algorithm>
 #include <cassert>
 #include <stdexcept>
 
@@ -70,6 +71,13 @@ Txid CMutableTransaction::GetHash() const
     return Txid::FromUint256((HashWriter{} << TX_NO_WITNESS(*this)).GetHash());
 }
 
+bool CTransaction::ComputeHasWitness() const
+{
+    return std::any_of(vin.begin(), vin.end(), [](const auto& input) {
+        return !input.scriptWitness.IsNull();
+    });
+}
+
 Txid CTransaction::ComputeHash() const
 {
     return Txid::FromUint256((HashWriter{} << TX_NO_WITNESS(*this)).GetHash());
@@ -84,8 +92,8 @@ Wtxid CTransaction::ComputeWitnessHash() const
     return Wtxid::FromUint256((HashWriter{} << TX_WITH_WITNESS(*this)).GetHash());
 }
 
-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()} {}
+CTransaction::CTransaction(const CMutableTransaction& tx) : vin(tx.vin), vout(tx.vout), nVersion(tx.nVersion), nLockTime(tx.nLockTime), m_has_witness{ComputeHasWitness()}, 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), m_has_witness{ComputeHasWitness()}, hash{ComputeHash()}, m_witness_hash{ComputeWitnessHash()} {}
 
 CAmount CTransaction::GetValueOut() const
 {
diff --git a/src/primitives/transaction.h b/src/primitives/transaction.h
index e0c0c860c6..ccbeb3ec49 100644
--- a/src/primitives/transaction.h
+++ b/src/primitives/transaction.h
@@ -310,12 +310,15 @@ public:
 
 private:
     /** Memory only. */
+    const bool m_has_witness;
     const Txid hash;
     const Wtxid m_witness_hash;
 
     Txid ComputeHash() const;
     Wtxid ComputeWitnessHash() const;
 
+    bool ComputeHasWitness() const;
+
 public:
     /** Convert a CMutableTransaction into a CTransaction. */
     explicit CTransaction(const CMutableTransaction& tx);
@@ -367,15 +370,7 @@ public:
 
     std::string ToString() const;
 
-    bool HasWitness() const
-    {
-        for (size_t i = 0; i < vin.size(); i++) {
-            if (!vin[i].scriptWitness.IsNull()) {
-                return true;
-            }
-        }
-        return false;
-    }
+    bool HasWitness() const { return m_has_witness; }
 };
 
 /** A mutable version of CTransaction. */