Repository: bitcoin/bitcoin
File: src/validation.cpp (C++)

Code before:
    LogDebug(BCLog::BENCH, "    - Fork checks: %.2fms [%.2fs (%.2fms/blk)]\n",
             Ticks<MillisecondsDouble>(time_2 - time_1),
             Ticks<SecondsDouble>(m_chainman.time_forks),
             Ticks<MillisecondsDouble>(m_chainman.time_forks) / m_chainman.num_blocks_total);

    CBlockUndo blockundo;

    // Precomputed transaction data pointers must not be invalidated
    // until after `control` has run the script checks (potentially
    // in multiple threads). Preallocate the vector size so a new allocation
    // doesn't invalidate pointers into the vector, and keep txsdata in scope
    // for as long as `control`.
    std::optional<CCheckQueueControl<CScriptCheck>> control;
    if (auto& queue = m_chainman.GetCheckQueue(); queue.HasThreads() && fScriptChecks) control.emplace(queue);

    std::vector<PrecomputedTransactionData> txsdata(block.vtx.size());

    std::vector<int> prevheights;
    CAmount nFees = 0;
    int nInputs = 0;
    int64_t nSigOpsCost = 0;
    blockundo.vtxundo.reserve(block.vtx.size() - 1);
    for (unsigned int i = 0; i < block.vtx.size(); i++)
    {
        if (!state.IsValid()) break;
        const CTransaction &tx = *(block.vtx[i]);

        nInputs += tx.vin.size();

        if (!tx.IsCoinBase())
        {
            CAmount txfee = 0;
            TxValidationState tx_state;
            if (!Consensus::CheckTxInputs(tx, tx_state, view, pindex->nHeight, txfee)) {
                // Any transaction validation failure in ConnectBlock is a block consensus failure
                state.Invalid(BlockValidationResult::BLOCK_CONSENSUS,
                              tx_state.GetRejectReason(),
                              tx_state.GetDebugMessage() + " in transaction " + tx.GetHash().ToString());
                break;
            }
            nFees += txfee;
            if (!MoneyRange(nFees)) {
                state.Invalid(BlockValidationResult::BLOCK_CONSENSUS, "bad-txns-accumulated-fee-outofrange",
                              "accumulated fee in the block out of range");
                break;
            }

            // Check that transaction is BIP68 final
            // BIP68 lock checks (as opposed to nLockTime checks) must
            // be in ConnectBlock because they require the UTXO set
            prevheights.resize(tx.vin.size());

Review comment (bug):
Seems dangerous to have an inline static variable, particularly with no lock annotations, and in kernel code.

Maybe better to do:

```c++
static bool g_script_checks_enabled GUARDED_BY(::cs_main) {false};
...
    if (pindex == nullptr || pindex->nHeight == 0 || g_script_checks_enable != fScriptchecks) {
        LogInfo("%s signature validations...", ...);
        g_script_checks_enable = fScriptChecks;
    }
```

I think this will give weird output with assumeutxo though -- repeatedly reporting enabled for new blocks on the assumeutxo chain, and disabled for the IBD chain. Might be better to associate the bool with `class Chainstate` in that case?

Code after:
    LogDebug(BCLog::BENCH, "    - Fork checks: %.2fms [%.2fs (%.2fms/blk)]\n",
             Ticks<MillisecondsDouble>(time_2 - time_1),
             Ticks<SecondsDouble>(m_chainman.time_forks),
             Ticks<MillisecondsDouble>(m_chainman.time_forks) / m_chainman.num_blocks_total);

    if (fScriptChecks != m_prev_script_checks_logged && GetRole() == ChainstateRole::NORMAL) {
        LogInfo("%s signature validations at block #%d (%s).", fScriptChecks ? "Enabling" : "Disabling", pindex->nHeight, block_hash.ToString());
        m_prev_script_checks_logged = fScriptChecks;
    }

    CBlockUndo blockundo;

    // Precomputed transaction data pointers must not be invalidated
    // until after `control` has run the script checks (potentially
    // in multiple threads). Preallocate the vector size so a new allocation
    // doesn't invalidate pointers into the vector, and keep txsdata in scope
    // for as long as `control`.
    std::optional<CCheckQueueControl<CScriptCheck>> control;
    if (auto& queue = m_chainman.GetCheckQueue(); queue.HasThreads() && fScriptChecks) control.emplace(queue);

    std::vector<PrecomputedTransactionData> txsdata(block.vtx.size());

    std::vector<int> prevheights;
    CAmount nFees = 0;
    int nInputs = 0;
    int64_t nSigOpsCost = 0;
    blockundo.vtxundo.reserve(block.vtx.size() - 1);
    for (unsigned int i = 0; i < block.vtx.size(); i++)
    {
        if (!state.IsValid()) break;
        const CTransaction &tx = *(block.vtx[i]);

        nInputs += tx.vin.size();

        if (!tx.IsCoinBase())
        {
            CAmount txfee = 0;
            TxValidationState tx_state;
            if (!Consensus::CheckTxInputs(tx, tx_state, view, pindex->nHeight, txfee)) {
                // Any transaction validation failure in ConnectBlock is a block consensus failure
                state.Invalid(BlockValidationResult::BLOCK_CONSENSUS,
                              tx_state.GetRejectReason(),
                              tx_state.GetDebugMessage() + " in transaction " + tx.GetHash().ToString());
                break;
            }
            nFees += txfee;
            if (!MoneyRange(nFees)) {
                state.Invalid(BlockValidationResult::BLOCK_CONSENSUS, "bad-txns-accumulated-fee-outofrange",
                              "accumulated fee in the block out of range");
                break;
            }