Function StartIndexBackgroundSync

src/init.cpp:2362–2437

}

bool StartIndexBackgroundSync(NodeContext& node)
{
    ChainstateManager& chainman = *Assert(node.chainman);
    const Chainstate& chainstate = WITH_LOCK(::cs_main, return chainman.ValidatedChainstate());
    const CChain& index_chain = chainstate.m_chain;
    const int current_height = WITH_LOCK(::cs_main, return index_chain.Height());

    // Skip checking data availability if we have not synced any blocks yet
    if (current_height > 0) {
        // Before starting index sync, verify that all required block data is available
        // on disk from each index's current sync position up to the chain tip.
        //
        // This is done separately for undo and block data: First we verify block + undo
        // data existence from tip down to the lowest height required by any index that
        // needs undo data (e.g., coinstatsindex, blockfilterindex). Then, if any
        // block-only index needs to sync from a lower height than previously covered,
        // verify block data existence down to that lower height.
        //
        // This avoids checking undo data for blocks where no index requires it,
        // though currently block and undo data availability are synchronized on disk
        // under normal circumstances.
        std::optional<const CBlockIndex*> block_start;
        std::string block_start_name;
        std::optional<const CBlockIndex*> undo_start;
        std::string undo_start_name;

        for (const auto& index : node.indexes) {
            const IndexSummary& summary = index->GetSummary();
            if (summary.synced) continue;

            // Get the last common block between the index best block and the active chain
            const CBlockIndex* pindex = nullptr;
            {
                LOCK(::cs_main);
                pindex = chainman.m_blockman.LookupBlockIndex(summary.best_block_hash);
                if (!pindex) {
                    LogWarning("Failed to find block manager entry for best block %s from %s, falling back to genesis for index sync",
                        summary.best_block_hash.ToString(), summary.name);
                } else if (!index_chain.Contains(*pindex)) {
                    pindex = index_chain.FindFork(*pindex);
                }
            }
            if (!pindex) {
                pindex = index_chain.Genesis();
            }

            bool need_undo = index->CustomOptions().connect_undo_data;
            auto& op_start_index = need_undo ? undo_start : block_start;
            auto& name_index = need_undo ? undo_start_name : block_start_name;

            if (op_start_index && pindex->nHeight >= op_start_index.value()->nHeight) continue;
            op_start_index = pindex;
            name_index = summary.name;
        }

        // Verify all blocks needed to sync to current tip are present including undo data.
        if (undo_start) {
            LOCK(::cs_main);