/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
Copyright (C) 2008-2014 Marco Costalba, Joona Kiiski, Tord Romstad
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
Stockfish is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see .
*/
#include
#include
#include
#include "search.h"
#include "timeman.h"
#include "uci.h"
namespace {
enum TimeType { OptimumTime, MaxTime };
const int MoveHorizon = 50; // Plan time management at most this many moves ahead
const double MaxRatio = 7.0; // When in trouble, we can step over reserved time with this ratio
const double StealRatio = 0.33; // However we must not steal time from remaining moves over this ratio
const double xscale = 9.3;
const double xshift = 59.8;
const double skewfactor = 0.172;
// move_importance() is a skew-logistic function based on naive statistical
// analysis of "how many games are still undecided after n half-moves". Game
// is considered "undecided" as long as neither side has >275cp advantage.
// Data was extracted from CCRL game database with some simple filtering criteria.
double move_importance(int ply) {
return pow((1 + exp((ply - xshift) / xscale)), -skewfactor) + DBL_MIN; // Ensure non-zero
}
template
int remaining(int myTime, int movesToGo, int currentPly, int slowMover)
{
const double TMaxRatio = (T == OptimumTime ? 1 : MaxRatio);
const double TStealRatio = (T == OptimumTime ? 0 : StealRatio);
double thisMoveImportance = (move_importance(currentPly) * slowMover) / 100;
double otherMovesImportance = 0;
for (int i = 1; i < movesToGo; ++i)
otherMovesImportance += move_importance(currentPly + 2 * i);
double ratio1 = (TMaxRatio * thisMoveImportance) / (TMaxRatio * thisMoveImportance + otherMovesImportance);
double ratio2 = (thisMoveImportance + TStealRatio * otherMovesImportance) / (thisMoveImportance + otherMovesImportance);
return int(myTime * std::min(ratio1, ratio2));
}
} // namespace
void TimeManager::init(const Search::LimitsType& limits, int currentPly, Color us)
{
/* We support four different kinds of time controls:
increment == 0 && movesToGo == 0 means: x basetime [sudden death!]
increment == 0 && movesToGo != 0 means: x moves in y minutes
increment > 0 && movesToGo == 0 means: x basetime + z increment
increment > 0 && movesToGo != 0 means: x moves in y minutes + z increment
Time management is adjusted by following parameters:
emergencyMoveHorizon: Be prepared to always play at least this many moves
emergencyBaseTime : Always attempt to keep at least this much time (in ms) at clock
emergencyMoveTime : Plus attempt to keep at least this much time for each remaining emergency move
minThinkingTime : No matter what, use at least this much thinking before doing the move
*/
int hypMTG, hypMyTime, t1, t2;
// Read uci parameters
int moveOverhead = Options["Move Overhead"];
int minThinkingTime = Options["Minimum Thinking Time"];
int slowMover = Options["Slow Mover"];
// Initialize unstablePvFactor to 1 and search times to maximum values
unstablePvFactor = 1;
optimumSearchTime = maximumSearchTime = std::max(limits.time[us], minThinkingTime);
// We calculate optimum time usage for different hypothetical "moves to go"-values and choose the
// minimum of calculated search time values. Usually the greatest hypMTG gives the minimum values.
for (hypMTG = 1; hypMTG <= (limits.movestogo ? std::min(limits.movestogo, MoveHorizon) : MoveHorizon); ++hypMTG)
{
// Calculate thinking time for hypothetical "moves to go"-value
hypMyTime = limits.time[us]
+ limits.inc[us] * (hypMTG - 1)
- moveOverhead * (2 + std::min(hypMTG, 40));
hypMyTime = std::max(hypMyTime, 0);
t1 = minThinkingTime + remaining(hypMyTime, hypMTG, currentPly, slowMover);
t2 = minThinkingTime + remaining(hypMyTime, hypMTG, currentPly, slowMover);
optimumSearchTime = std::min(optimumSearchTime, t1);
maximumSearchTime = std::min(maximumSearchTime, t2);
}
if (Options["Ponder"])
optimumSearchTime += optimumSearchTime / 4;
// Make sure that maxSearchTime is not over absoluteMaxSearchTime
optimumSearchTime = std::min(optimumSearchTime, maximumSearchTime);
}