X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Ftimeman.cpp;h=035fe33511db8669f5a2b4634bd92af5fb5ecc22;hp=55d98c1fa98b693a0b948d2d1175e8017d466e6c;hb=aa88261a8f509fdabfe235042de1c1ea7a39a399;hpb=01d97521fd675ed157ff7d61e6057916abbcc56c

diff --git a/src/timeman.cpp b/src/timeman.cpp
index 55d98c1f..035fe335 100644
--- a/src/timeman.cpp
+++ b/src/timeman.cpp
@@ -2,7 +2,7 @@
   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) 2015-2017 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2015-2018 Marco Costalba, Joona Kiiski, Gary Linscott, 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
@@ -32,40 +32,41 @@ namespace {
 
   enum TimeType { OptimumTime, MaxTime };
 
-  int remaining(int myTime, int myInc, int moveOverhead,
-                int movesToGo, int ply, TimeType type) {
+  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
 
-    if (myTime <= 0)
-        return 0;
 
-    int moveNumber = (ply + 1) / 2;
-    double ratio;    // Which ratio of myTime we are going to use. It is <= 1
-    double sd = 8.5;
+  // 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.
 
-    // Usage of increment follows quadratic distribution with the maximum at move 25
-    double inc = myInc * std::max(55.0, 120.0 - 0.12 * (moveNumber - 25) * (moveNumber - 25));
+  double move_importance(int ply) {
 
-    // In moves-to-go we distribute time according to a quadratic function with
-    // the maximum around move 20 for 40 moves in y time case.
-    if (movesToGo)
-    {
-        ratio = (type == OptimumTime ? 1.0 : 6.0) / std::min(50, movesToGo);
+    const double XScale = 7.64;
+    const double XShift = 58.4;
+    const double Skew   = 0.183;
 
-        if (moveNumber <= 40)
-            ratio *= 1.1 - 0.001 * (moveNumber - 20) * (moveNumber - 20);
-        else
-            ratio *= 1.5;
-    }
-    // Otherwise we increase usage of remaining time as the game goes on
-    else
-    {
-        sd = 1 + 20 * moveNumber / (500.0 + moveNumber);
-        ratio = (type == OptimumTime ? 0.017 : 0.07) * sd;
-    }
+    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;
 
-    ratio = std::min(1.0, ratio * (1 + inc / (myTime * sd)));
+    for (int i = 1; i < movesToGo; ++i)
+        otherMovesImportance += move_importance(ply + 2 * i);
 
-    return int(ratio * std::max(0, myTime - moveOverhead));
+    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
@@ -80,9 +81,11 @@ namespace {
 ///  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)
-{
+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"];
 
   // If we have to play in 'nodes as time' mode, then convert from time
@@ -101,8 +104,28 @@ void TimeManagement::init(Search::LimitsType& limits, Color us, int ply)
   }
 
   startTime = limits.startTime;
-  optimumTime = remaining(limits.time[us], limits.inc[us], moveOverhead, limits.movestogo, ply, OptimumTime);
-  maximumTime = remaining(limits.time[us], limits.inc[us], moveOverhead, limits.movestogo, ply, MaxTime);
+  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;