/*
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) 2004-2023 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
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
+#include "timeman.h"
+
#include <algorithm>
-#include <cfloat>
#include <cmath>
#include "search.h"
-#include "timeman.h"
#include "uci.h"
-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 = 7.0; // 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
-
-
- // 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) {
-
- const double XScale = 9.3;
- const double XShift = 59.8;
- const double Skew = 0.172;
-
- 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 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
-
-void TimeManagement::init(Search::LimitsType& limits, Color us, int ply, TimePoint now)
-{
- int minThinkingTime = Options["Minimum Thinking Time"];
- int moveOverhead = Options["Move Overhead"];
- int slowMover = Options["Slow Mover"];
- int npmsec = Options["nodestime"];
-
- // 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
- // real engine speed to avoid time losses.
- 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;
- limits.inc[us] *= npmsec;
- limits.npmsec = npmsec;
- }
-
- start = now;
- unstablePvFactor = 1;
- optimumTime = maximumTime = std::max(limits.time[us], minThinkingTime);
-
- const int MaxMTG = limits.movestogo ? std::min(limits.movestogo, MoveHorizon) : MoveHorizon;
-
- // 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));
-
- hypMyTime = std::max(hypMyTime, 0);
-
- int t1 = minThinkingTime + remaining<OptimumTime>(hypMyTime, hypMTG, ply, slowMover);
- int t2 = minThinkingTime + remaining<MaxTime >(hypMyTime, hypMTG, ply, slowMover);
-
- optimumTime = std::min(t1, optimumTime);
- maximumTime = std::min(t2, maximumTime);
- }
-
- if (Options["Ponder"])
- optimumTime += optimumTime / 4;
-
- optimumTime = std::min(optimumTime, maximumTime);
+namespace Stockfish {
+
+TimeManagement Time; // Our global time management object
+
+
+// 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) {
+
+ // If we have no time, no need to initialize TM, except for the start time,
+ // which is used by movetime.
+ startTime = limits.startTime;
+ if (limits.time[us] == 0)
+ return;
+
+ TimePoint moveOverhead = TimePoint(Options["Move Overhead"]);
+ 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: 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 milliseconds to nodes
+ limits.time[us] = TimePoint(availableNodes);
+ limits.inc[us] *= npmsec;
+ limits.npmsec = npmsec;
+ }
+
+ // Maximum move horizon of 50 moves
+ int mtg = limits.movestogo ? std::min(limits.movestogo, 50) : 50;
+
+ // 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));
+
+ // Use extra time with larger increments
+ double optExtra = std::clamp(1.0 + 12.5 * limits.inc[us] / limits.time[us], 1.0, 1.11);
+
+ // Calculate time constants based on current time left.
+ double optConstant = std::min(0.00334 + 0.0003 * std::log10(limits.time[us] / 1000.0), 0.0049);
+ double maxConstant = std::max(3.4 + 3.0 * std::log10(limits.time[us] / 1000.0), 2.76);
+
+ // 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(0.0120 + std::pow(ply + 3.1, 0.44) * optConstant,
+ 0.21 * limits.time[us] / double(timeLeft))
+ * optExtra;
+ maxScale = std::min(6.9, maxConstant + ply / 12.2);
+ }
+
+ // x moves in y seconds (+ z increment)
+ else
+ {
+ optScale = std::min((0.88 + ply / 116.4) / mtg, 0.88 * limits.time[us] / double(timeLeft));
+ maxScale = std::min(6.3, 1.5 + 0.11 * mtg);
+ }
+
+ // Limit the maximum possible time for this move
+ optimumTime = TimePoint(optScale * timeLeft);
+ maximumTime =
+ TimePoint(std::min(0.84 * limits.time[us] - moveOverhead, maxScale * optimumTime)) - 10;
+
+ if (Options["Ponder"])
+ optimumTime += optimumTime / 4;
}
+
+} // namespace Stockfish
projects / stockfish / blobdiff