Function getchaintips

src/rpc/blockchain.cpp:1588–1685

};

static RPCMethod getchaintips()
{
    return RPCMethod{"getchaintips",
                "Return information about all known tips in the block tree,"
                " including the main chain as well as orphaned branches.\n",
                {},
                RPCResult{
                    RPCResult::Type::ARR, "", "",
                    {{RPCResult::Type::OBJ, "", "",
                        {
                            {RPCResult::Type::NUM, "height", "height of the chain tip"},
                            {RPCResult::Type::STR_HEX, "hash", "block hash of the tip"},
                            {RPCResult::Type::NUM, "branchlen", "zero for main chain, otherwise length of branch connecting the tip to the main chain"},
                            {RPCResult::Type::STR, "status", "status of the chain, \"active\" for the main chain\n"
            "Possible values for status:\n"
            "1.  \"invalid\"               This branch contains at least one invalid block\n"
            "2.  \"headers-only\"          Not all blocks for this branch are available, but the headers are valid\n"
            "3.  \"valid-headers\"         All blocks are available for this branch, but they were never fully validated\n"
            "4.  \"valid-fork\"            This branch is not part of the active chain, but is fully validated\n"
            "5.  \"active\"                This is the tip of the active main chain, which is certainly valid"},
                        }}}},
                RPCExamples{
                    HelpExampleCli("getchaintips", "")
            + HelpExampleRpc("getchaintips", "")
                },
        [](const RPCMethod& self, const JSONRPCRequest& request) -> UniValue
{
    ChainstateManager& chainman = EnsureAnyChainman(request.context);
    LOCK(cs_main);
    CChain& active_chain = chainman.ActiveChain();

    /*
     * Idea: The set of chain tips is the active chain tip, plus orphan blocks which do not have another orphan building off of them.
     * Algorithm:
     *  - Make one pass through BlockIndex(), picking out the orphan blocks, and also storing a set of the orphan block's pprev pointers.
     *  - Iterate through the orphan blocks. If the block isn't pointed to by another orphan, it is a chain tip.
     *  - Add the active chain tip
     */
    std::set<const CBlockIndex*, CompareBlocksByHeight> setTips;
    std::set<const CBlockIndex*> setOrphans;
    std::set<const CBlockIndex*> setPrevs;

    for (const auto& [_, block_index] : chainman.BlockIndex()) {
        if (!active_chain.Contains(block_index)) {
            setOrphans.insert(&block_index);
            setPrevs.insert(block_index.pprev);
        }
    }

    for (std::set<const CBlockIndex*>::iterator it = setOrphans.begin(); it != setOrphans.end(); ++it) {
        if (setPrevs.erase(*it) == 0) {
            setTips.insert(*it);
        }
    }

    // Always report the currently active tip.
    setTips.insert(active_chain.Tip());