validation: Pass in chain tip to ::CheckFinalTx

Author: dongcarl

src/validation.cpp

@@ -205,8 +205,14 @@ static FlatFileSeq BlockFileSeq();
 static FlatFileSeq UndoFileSeq();
 
 bool CheckFinalTx(const CTransaction &tx, int flags)
+{
+    return CheckFinalTx(::ChainActive().Tip(), tx, flags);
+}
+
+bool CheckFinalTx(const CBlockIndex* active_chain_tip, const CTransaction &tx, int flags)
 {
     AssertLockHeld(cs_main);
+    assert(std::addressof(*::ChainActive().Tip()) == std::addressof(*active_chain_tip));
 
     // By convention a negative value for flags indicates that the
     // current network-enforced consensus rules should be used. In
@@ -222,15 +228,15 @@ bool CheckFinalTx(const CTransaction &tx, int flags)
     // evaluated is what is used. Thus if we want to know if a
     // transaction can be part of the *next* block, we need to call
     // IsFinalTx() with one more than ::ChainActive().Height().
-    const int nBlockHeight = ::ChainActive().Height() + 1;
+    const int nBlockHeight = active_chain_tip->nHeight + 1;
 
     // BIP113 requires that time-locked transactions have nLockTime set to
     // less than the median time of the previous block they're contained in.
     // When the next block is created its previous block will be the current
     // chain tip, so we use that to calculate the median time passed to
     // IsFinalTx() if LOCKTIME_MEDIAN_TIME_PAST is set.
     const int64_t nBlockTime = (flags & LOCKTIME_MEDIAN_TIME_PAST)
-                             ? ::ChainActive().Tip()->GetMedianTimePast()
+                             ? active_chain_tip->GetMedianTimePast()
                              : GetAdjustedTime();
 
     return IsFinalTx(tx, nBlockHeight, nBlockTime);
@@ -599,7 +605,7 @@ bool MemPoolAccept::PreChecks(ATMPArgs& args, Workspace& ws)
     // Only accept nLockTime-using transactions that can be mined in the next
     // block; we don't want our mempool filled up with transactions that can't
     // be mined yet.
-    if (!CheckFinalTx(tx, STANDARD_LOCKTIME_VERIFY_FLAGS))
+    if (!CheckFinalTx(::ChainActive().Tip(), tx, STANDARD_LOCKTIME_VERIFY_FLAGS))
         return state.Invalid(TxValidationResult::TX_PREMATURE_SPEND, "non-final");
 
     // is it already in the memory pool?

src/validation.h

@@ -249,6 +249,7 @@ void UpdateCoins(const CTransaction& tx, CCoinsViewCache& inputs, int nHeight);
  * See consensus/consensus.h for flag definitions.
  */
 bool CheckFinalTx(const CTransaction &tx, int flags = -1) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
+bool CheckFinalTx(const CBlockIndex* active_chain_tip, const CTransaction &tx, int flags = -1) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
 
 /**
  * Test whether the LockPoints height and time are still valid on the current chain