ConsensusParms.h

//------------------------------------------------------------------------------
/*
    This file is part of rippled: https://github.com/ripple/rippled
    Copyright (c) 2012-2017 Ripple Labs Inc.
 
    Permission to use, copy, modify, and/or distribute this software for any
    purpose  with  or without fee is hereby granted, provided that the above
    copyright notice and this permission notice appear in all copies.
 
    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
//==============================================================================
 
#ifndef RIPPLE_CONSENSUS_CONSENSUS_PARMS_H_INCLUDED
#define RIPPLE_CONSENSUS_CONSENSUS_PARMS_H_INCLUDED
 
#include <xrpl/beast/utility/instrumentation.h>
 
#include <chrono>
#include <cstddef>
#include <functional>
#include <map>
#include <optional>
 
namespace ripple {
 
struct ConsensusParms
{
    explicit ConsensusParms() = default;
 
    //-------------------------------------------------------------------------
    // Validation and proposal durations are relative to NetClock times, so use
    // second resolution
    std::chrono::seconds const validationVALID_WALL = std::chrono::minutes{5};
 
    std::chrono::seconds const validationVALID_LOCAL = std::chrono::minutes{3};
 
    std::chrono::seconds const validationVALID_EARLY = std::chrono::minutes{3};
 
    std::chrono::seconds const proposeFRESHNESS = std::chrono::seconds{20};
 
    std::chrono::seconds const proposeINTERVAL = std::chrono::seconds{12};
 
    //-------------------------------------------------------------------------
    // Consensus durations are relative to the internal Consensus clock and use
    // millisecond resolution.
 
    std::size_t const minCONSENSUS_PCT = 80;
 
    std::chrono::milliseconds const ledgerIDLE_INTERVAL =
        std::chrono::seconds{15};
 
    std::chrono::milliseconds const ledgerMIN_CONSENSUS =
        std::chrono::milliseconds{1950};
 
    std::chrono::milliseconds const ledgerMAX_CONSENSUS =
        std::chrono::seconds{15};
 
    std::chrono::milliseconds const ledgerMIN_CLOSE = std::chrono::seconds{2};
 
    std::chrono::milliseconds const ledgerGRANULARITY = std::chrono::seconds{1};
 
    std::size_t const ledgerABANDON_CONSENSUS_FACTOR = 10;
 
    std::chrono::milliseconds const ledgerABANDON_CONSENSUS =
        std::chrono::seconds{120};
 
    std::chrono::milliseconds const avMIN_CONSENSUS_TIME =
        std::chrono::seconds{5};
 
    //------------------------------------------------------------------------------
    // Avalanche tuning
    // As a function of the percent this round's duration is of the prior round,
    // we increase the threshold for yes votes to add a transaction to our
    // position.
    enum AvalancheState { init, mid, late, stuck };
    struct AvalancheCutoff
    {
        int const consensusTime;
        std::size_t const consensusPct;
        AvalancheState const next;
    };
    std::map<AvalancheState, AvalancheCutoff> const avalancheCutoffs{
        // {state, {time, percent, nextState}},
        // Initial state: 50% of nodes must vote yes
        {init, {0, 50, mid}},
        // mid-consensus starts after 50% of the previous round time, and
        // requires 65% yes
        {mid, {50, 65, late}},
        // late consensus starts after 85% time, and requires 70% yes
        {late, {85, 70, stuck}},
        // we're stuck after 2x time, requires 95% yes votes
        {stuck, {200, 95, stuck}},
    };
 
    std::size_t const avCT_CONSENSUS_PCT = 75;
 
    // (Moving to the next avalanche level, considering that votes are stalled
    // without consensus.)
    std::size_t const avMIN_ROUNDS = 2;
 
    std::size_t const avSTALLED_ROUNDS = 4;
};
 
inline std::pair<std::size_t, std::optional<ConsensusParms::AvalancheState>>
getNeededWeight(
    ConsensusParms const& p,
    ConsensusParms::AvalancheState currentState,
    int percentTime,
    std::size_t currentRounds,
    std::size_t minimumRounds)
{
    // at() can throw, but the map is built by hand to ensure all valid
    // values are available.
    auto const& currentCutoff = p.avalancheCutoffs.at(currentState);
    // Should we consider moving to the next state?
    if (currentCutoff.next != currentState && currentRounds >= minimumRounds)
    {
        // at() can throw, but the map is built by hand to ensure all
        // valid values are available.
        auto const& nextCutoff = p.avalancheCutoffs.at(currentCutoff.next);
        // See if enough time has passed to move on to the next.
        XRPL_ASSERT(
            nextCutoff.consensusTime >= currentCutoff.consensusTime,
            "ripple::getNeededWeight : next state valid");
        if (percentTime >= nextCutoff.consensusTime)
        {
            return {nextCutoff.consensusPct, currentCutoff.next};
        }
    }
    return {currentCutoff.consensusPct, {}};
}
 
}  // namespace ripple
#endif