[bitcoin] headerssync-paramsって何?

A script to generate optimal parameters for the headerssync module (src/headerssync.cpp). It takes no command-line
options, as all its configuration is set at the top of the file. It runs many times faster inside PyPy. Invocation:
つまり、node間でのヘッダー情報のやり取りのことだ。c++ファイルのヘッダではない。stateで、 PRESYNC、REDOWNLOAD、FINALとある。

src/headerssync.h, src/headerssync.cpp を見てみる。
### headerssync.h
A compressed CBlockHeader, which leaves out the prevhash
We wish to download a peer’s headers chain in a DoS-resistant way.
* – In the first download phase, called pre-synchronization, we can calculate
* the work on the chain as we go (just by checking the nBits value on each
* header, and validating the proof-of-work).
In phase 1 (presync)
In phase 2 (redownload)

#### headerssync.cpp
// The two constants below are computed using the simulation script in
// contrib/devtools/headerssync-params.py.
m_max_commitments = 6*(Ticks(NodeClock::now() – NodeSeconds{std::chrono::seconds{chain_start->GetMedianTimePast()}}) + MAX_FUTURE_BLOCK_TIME) / HEADER_COMMITMENT_PERIOD;


    if (m_current_chain_work >= m_minimum_required_work) {
        m_redownload_buffer_last_height = m_chain_start->nHeight;
        m_redownload_buffer_first_prev_hash = m_chain_start->GetBlockHash();
        m_redownload_buffer_last_hash = m_chain_start->GetBlockHash();
        m_redownload_chain_work = m_chain_start->nChainWork;
        m_download_state = State::REDOWNLOAD;
        LogPrint(BCLog::NET, "Initial headers sync transition with peer=%d: reached sufficient work at height=%i, redownloading from height=%i\n", m_id, m_current_height, m_redownload_buffer_last_height);