Method ActivateSnapshot

src/validation.cpp:5607–5713

}

util::Result<CBlockIndex*> ChainstateManager::ActivateSnapshot(
        AutoFile& coins_file,
        const SnapshotMetadata& metadata,
        bool in_memory)
{
    uint256 base_blockhash = metadata.m_base_blockhash;

    CBlockIndex* snapshot_start_block{};

    {
        LOCK(::cs_main);

        if (this->CurrentChainstate().m_from_snapshot_blockhash) {
            return util::Error{Untranslated("Can't activate a snapshot-based chainstate more than once")};
        }
        if (!GetParams().AssumeutxoForBlockhash(base_blockhash).has_value()) {
            auto available_heights = GetParams().GetAvailableSnapshotHeights();
            std::string heights_formatted = util::Join(available_heights, ", ", [&](const auto& i) { return util::ToString(i); });
            return util::Error{Untranslated(strprintf("assumeutxo block hash in snapshot metadata not recognized (hash: %s). The following snapshot heights are available: %s",
                base_blockhash.ToString(),
                heights_formatted))};
        }

        snapshot_start_block = m_blockman.LookupBlockIndex(base_blockhash);
        if (!snapshot_start_block) {
            return util::Error{Untranslated(strprintf("The base block header (%s) must appear in the headers chain. Make sure all headers are syncing, and call loadtxoutset again",
                          base_blockhash.ToString()))};
        }

        bool start_block_invalid = snapshot_start_block->nStatus & BLOCK_FAILED_VALID;
        if (start_block_invalid) {
            return util::Error{Untranslated(strprintf("The base block header (%s) is part of an invalid chain", base_blockhash.ToString()))};
        }

        if (!m_best_header || m_best_header->GetAncestor(snapshot_start_block->nHeight) != snapshot_start_block) {
            return util::Error{Untranslated("A forked headers-chain with more work than the chain with the snapshot base block header exists. Please proceed to sync without AssumeUtxo.")};
        }

        auto mempool{CurrentChainstate().GetMempool()};
        if (mempool && mempool->size() > 0) {
            return util::Error{Untranslated("Can't activate a snapshot when mempool not empty")};
        }
    }

    int64_t current_coinsdb_cache_size{0};
    int64_t current_coinstip_cache_size{0};

    // Cache percentages to allocate to each chainstate.
    //
    // These particular percentages don't matter so much since they will only be
    // relevant during snapshot activation; caches are rebalanced at the conclusion of
    // this function. We want to give (essentially) all available cache capacity to the
    // snapshot to aid the bulk load later in this function.
    static constexpr double IBD_CACHE_PERC = 0.01;
    static constexpr double SNAPSHOT_CACHE_PERC = 0.99;

    {
        LOCK(::cs_main);