/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
- Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
- Copyright (C) 2015-2016 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+ Copyright (C) 2004-2020 The Stockfish developers (see AUTHORS file)
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
TimeManagement Time; // Our global time management object
-namespace {
- enum TimeType { OptimumTime, MaxTime };
-
- const int MoveHorizon = 50; // Plan time management at most this many moves ahead
- const double MaxRatio = 7.09; // When in trouble, we can step over reserved time with this ratio
- const double StealRatio = 0.35; // However we must not steal time from remaining moves over this ratio
-
-
- // 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 the CCRL game database with some simple filtering criteria.
-
- double move_importance(int ply) {
-
- const double XScale = 7.64;
- const double XShift = 58.4;
- const double Skew = 0.183;
-
- return pow((1 + exp((ply - XShift) / XScale)), -Skew) + DBL_MIN; // Ensure non-zero
- }
-
- template<TimeType T>
- int remaining(int myTime, int movesToGo, int ply, int slowMover) {
-
- const double TMaxRatio = (T == OptimumTime ? 1 : MaxRatio);
- const double TStealRatio = (T == OptimumTime ? 0 : StealRatio);
-
- double moveImportance = (move_importance(ply) * slowMover) / 100;
- double otherMovesImportance = 0;
-
- for (int i = 1; i < movesToGo; ++i)
- otherMovesImportance += move_importance(ply + 2 * i);
-
- double ratio1 = (TMaxRatio * moveImportance) / (TMaxRatio * moveImportance + otherMovesImportance);
- double ratio2 = (moveImportance + TStealRatio * otherMovesImportance) / (moveImportance + otherMovesImportance);
-
- return int(myTime * std::min(ratio1, ratio2)); // Intel C++ asks for an explicit cast
- }
-
-} // namespace
-
-
-/// init() is called at the beginning of the search and calculates the allowed
-/// thinking time out of the time control and current game ply. We support four
-/// different kinds of time controls, passed in 'limits':
-///
-/// inc == 0 && movestogo == 0 means: x basetime [sudden death!]
-/// inc == 0 && movestogo != 0 means: x moves in y minutes
-/// inc > 0 && movestogo == 0 means: x basetime + z increment
-/// inc > 0 && movestogo != 0 means: x moves in y minutes + z increment
+/// TimeManagement::init() is called at the beginning of the search and calculates
+/// the bounds of time allowed for the current game ply. We currently support:
+// 1) x basetime (+ z increment)
+// 2) x moves in y seconds (+ z increment)
void TimeManagement::init(Search::LimitsType& limits, Color us, int ply) {
- int minThinkingTime = Options["Minimum Thinking Time"];
- int moveOverhead = Options["Move Overhead"];
- int slowMover = Options["Slow Mover"];
- int npmsec = Options["nodestime"];
+ TimePoint moveOverhead = TimePoint(Options["Move Overhead"]);
+ TimePoint slowMover = TimePoint(Options["Slow Mover"]);
+ TimePoint npmsec = TimePoint(Options["nodestime"]);
+
+ // optScale is a percentage of available time to use for the current move.
+ // maxScale is a multiplier applied to optimumTime.
+ double optScale, maxScale;
// If we have to play in 'nodes as time' mode, then convert from time
// to nodes, and use resulting values in time management formulas.
- // WARNING: Given npms (nodes per millisecond) must be much lower then
- // the real engine speed to avoid time losses.
+ // WARNING: to avoid time losses, the given npmsec (nodes per millisecond)
+ // must be much lower than the real engine speed.
if (npmsec)
{
if (!availableNodes) // Only once at game start
availableNodes = npmsec * limits.time[us]; // Time is in msec
- // Convert from millisecs to nodes
- limits.time[us] = (int)availableNodes;
+ // Convert from milliseconds to nodes
+ limits.time[us] = TimePoint(availableNodes);
limits.inc[us] *= npmsec;
limits.npmsec = npmsec;
}
startTime = limits.startTime;
- optimumTime = maximumTime = std::max(limits.time[us], minThinkingTime);
- const int MaxMTG = limits.movestogo ? std::min(limits.movestogo, MoveHorizon) : MoveHorizon;
+ // Maximum move horizon of 50 moves
+ int mtg = limits.movestogo ? std::min(limits.movestogo, 50) : 50;
- // 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 (int hypMTG = 1; hypMTG <= MaxMTG; ++hypMTG)
- {
- // Calculate thinking time for hypothetical "moves to go"-value
- int hypMyTime = limits.time[us]
- + limits.inc[us] * (hypMTG - 1)
- - moveOverhead * (2 + std::min(hypMTG, 40));
+ // Make sure timeLeft is > 0 since we may use it as a divisor
+ TimePoint timeLeft = std::max(TimePoint(1),
+ limits.time[us] + limits.inc[us] * (mtg - 1) - moveOverhead * (2 + mtg));
- hypMyTime = std::max(hypMyTime, 0);
+ // A user may scale time usage by setting UCI option "Slow Mover"
+ // Default is 100 and changing this value will probably lose elo.
+ timeLeft = slowMover * timeLeft / 100;
- int t1 = minThinkingTime + remaining<OptimumTime>(hypMyTime, hypMTG, ply, slowMover);
- int t2 = minThinkingTime + remaining<MaxTime >(hypMyTime, hypMTG, ply, slowMover);
+ // x basetime (+ z increment)
+ // If there is a healthy increment, timeLeft can exceed actual available
+ // game time for the current move, so also cap to 20% of available game time.
+ if (limits.movestogo == 0)
+ {
+ optScale = std::min(0.0084 + std::pow(ply + 3.0, 0.5) * 0.0042,
+ 0.2 * limits.time[us] / double(timeLeft));
+ maxScale = std::min(7.0, 4.0 + ply / 12.0);
+ }
- optimumTime = std::min(t1, optimumTime);
- maximumTime = std::min(t2, maximumTime);
+ // x moves in y seconds (+ z increment)
+ else
+ {
+ optScale = std::min((0.8 + ply / 128.0) / mtg,
+ 0.8 * limits.time[us] / double(timeLeft));
+ maxScale = std::min(6.3, 1.5 + 0.11 * mtg);
}
+ // Never use more than 80% of the available time for this move
+ optimumTime = TimePoint(optScale * timeLeft);
+ maximumTime = TimePoint(std::min(0.8 * limits.time[us] - moveOverhead, maxScale * optimumTime));
+
if (Options["Ponder"])
optimumTime += optimumTime / 4;
}
projects / stockfish / blobdiff