/*
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
+ 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
#include "timeman.h"
#include "uci.h"
-namespace {
+TimeManagement Time; // Our global time management object
- 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
+/// 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)
- const double xscale = 9.3;
- const double xshift = 59.8;
- const double skewfactor = 0.172;
+void TimeManagement::init(Search::LimitsType& limits, Color us, int ply) {
+ TimePoint moveOverhead = TimePoint(Options["Move Overhead"]);
+ TimePoint slowMover = TimePoint(Options["Slow Mover"]);
+ TimePoint npmsec = TimePoint(Options["nodestime"]);
- // 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.
+ // optScale is a percentage of available time to use for the current move.
+ // maxScale is a multiplier applied to optimumTime.
+ double optScale, maxScale;
- double move_importance(int ply) {
-
- return pow((1 + exp((ply - xshift) / xscale)), -skewfactor) + DBL_MIN; // Ensure non-zero
- }
-
- template<TimeType T>
- int remaining(int myTime, int movesToGo, int currentPly, int slowMover)
+ // 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: to avoid time losses, the given npmsec (nodes per millisecond)
+ // must be much lower than the real engine speed.
+ if (npmsec)
{
- const double TMaxRatio = (T == OptimumTime ? 1 : MaxRatio);
- const double TStealRatio = (T == OptimumTime ? 0 : StealRatio);
-
- double thisMoveImportance = (move_importance(currentPly) * slowMover) / 100;
- double otherMovesImportance = 0;
+ if (!availableNodes) // Only once at game start
+ availableNodes = npmsec * limits.time[us]; // Time is in msec
- 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));
+ // Convert from milliseconds to nodes
+ limits.time[us] = TimePoint(availableNodes);
+ limits.inc[us] *= npmsec;
+ limits.npmsec = npmsec;
}
-} // namespace
-
-
-void TimeManager::init(const Search::LimitsType& limits, int currentPly, Color us)
-{
- /* We support four different kinds of time controls:
+ startTime = limits.startTime;
- 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
- */
+ // Maximum move horizon of 50 moves
+ int mtg = limits.movestogo ? std::min(limits.movestogo, 50) : 50;
- int hypMTG, hypMyTime, t1, t2;
+ // 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));
- // Read uci parameters
- int moveOverhead = Options["Move Overhead"];
- int minThinkingTime = Options["Minimum Thinking Time"];
- int slowMover = Options["Slow Mover"];
+ // 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;
- // 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)
+ // 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)
{
- // 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<OptimumTime>(hypMyTime, hypMTG, currentPly, slowMover);
- t2 = minThinkingTime + remaining<MaxTime>(hypMyTime, hypMTG, currentPly, slowMover);
+ 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);
+ }
- optimumSearchTime = std::min(optimumSearchTime, t1);
- maximumSearchTime = std::min(maximumSearchTime, t2);
+ // 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);
}
- if (Options["Ponder"])
- optimumSearchTime += optimumSearchTime / 4;
+ // 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));
- // Make sure that maxSearchTime is not over absoluteMaxSearchTime
- optimumSearchTime = std::min(optimumSearchTime, maximumSearchTime);
+ if (Options["Ponder"])
+ optimumTime += optimumTime / 4;
}
projects / stockfish / blobdiff