Method DisconnectTip

src/validation.cpp:2349–2398

Disconnect chainActive's tip. * After calling, the mempool will be in an inconsistent state, with * transactions from disconnected blocks being added to disconnectpool. You * should make the mempool consistent again by calling UpdateMempoolForReorg. * with cs_main held. * * If disconnectpool is nullptr, then no disconnected transactions are added to * disconnectpool (note that the c

  * in any case).
  */
bool CChainState::DisconnectTip(CValidationState& state, const CChainParams& chainparams, DisconnectedBlockTransactions *disconnectpool)
{
    CBlockIndex *pindexDelete = chainActive.Tip();
    assert(pindexDelete);
    // Read block from disk.
    std::shared_ptr<CBlock> pblock = std::make_shared<CBlock>();
    CBlock& block = *pblock;
    if (!ReadBlockFromDisk(block, pindexDelete, chainparams.GetConsensus()))
        return AbortNode(state, "Failed to read block");
    // Apply the block atomically to the chain state.
    int64_t nStart = GetTimeMicros();
    {
        CCoinsViewCache view(pcoinsTip.get());
        assert(view.GetBestBlock() == pindexDelete->GetBlockHash());
        if (DisconnectBlock(block, pindexDelete, view) != DISCONNECT_OK)
            return error("DisconnectTip(): DisconnectBlock %s failed", pindexDelete->GetBlockHash().ToString());
        bool flushed = view.Flush();
        assert(flushed);
    }
    LogPrint(BCLog::BENCH, "- Disconnect block: %.2fms\n", (GetTimeMicros() - nStart) * MILLI);
    // Write the chain state to disk, if necessary.
    if (!FlushStateToDisk(chainparams, state, FlushStateMode::IF_NEEDED))
        return false;

    if (disconnectpool) {
        // Save transactions to re-add to mempool at end of reorg
        for (auto it = block.vtx.rbegin(); it != block.vtx.rend(); ++it) {
            disconnectpool->addTransaction(*it);
        }
        while (disconnectpool->DynamicMemoryUsage() > MAX_DISCONNECTED_TX_POOL_SIZE * 1000) {
            // Drop the earliest entry, and remove its children from the mempool.
            auto it = disconnectpool->queuedTx.get<insertion_order>().begin();
            mempool.removeRecursive(**it, MemPoolRemovalReason::REORG);
            disconnectpool->removeEntry(it);
        }
    }

    // If the tip is finalized, then undo it.
    if (pindexFinalized == pindexDelete) {
        pindexFinalized = pindexDelete->pprev;
    }

    chainActive.SetTip(pindexDelete->pprev);

    UpdateTip(pindexDelete->pprev, chainparams);
    // Let wallets know transactions went from 1-confirmed to
    // 0-confirmed or conflicted:
    GetMainSignals().BlockDisconnected(pblock);
    return true;
}

static int64_t nTimeReadFromDisk = 0;
static int64_t nTimeConnectTotal = 0;