Fix sending of best move during an infinite search

According to UCI standard once engine receives 'go infinite'
command it should search until the "stop" command and do not exit
the search without being told so, even if PLY_MAX has been reached.

Patch is quite invasive because it cleanups some hacks used
by fixed depth and fixed nodes modes, mainly during benchmarks.

Bug found by Pascal Georges.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>

src/benchmark.cpp

@@ -155,7 +155,7 @@ void benchmark(const string& commandLine) {
       cerr << "\nBench position: " << cnt << '/' << positions.size() << endl << endl;
       if (limitType == "perft")
           totalNodes += perft(pos, maxDepth * OnePly);
-      else if (!think(pos, true, false, 0, dummy, dummy, 0, maxDepth, maxNodes, secsPerPos, moves))
+      else if (!think(pos, false, false, 0, dummy, dummy, 0, maxDepth, maxNodes, secsPerPos, moves))
           break;
       totalNodes += nodes_searched();
   }

src/search.cpp

@@ -231,7 +231,7 @@ namespace {
   int SearchStartTime;
   int MaxNodes, MaxDepth;
   int MaxSearchTime, AbsoluteMaxSearchTime, ExtraSearchTime, ExactMaxTime;
-  bool InfiniteSearch, PonderSearch, StopOnPonderhit;
+  bool UseTimeManagement, InfiniteSearch, PonderSearch, StopOnPonderhit;
   bool AbortSearch, Quit;
   bool FailHigh, FailLow, Problem;
 
@@ -373,8 +373,20 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move,
            int time[], int increment[], int movesToGo, int maxDepth,
            int maxNodes, int maxTime, Move searchMoves[]) {
 
-  // Look for a book move
+  // Initialize global search variables
-  if (!infinite && !ponder && get_option_value_bool("OwnBook"))
+  Idle = StopOnPonderhit = AbortSearch = Quit = false;
+  FailHigh = FailLow = Problem = false;
+  NodesSincePoll = 0;
+  SearchStartTime = get_system_time();
+  ExactMaxTime = maxTime;
+  MaxDepth = maxDepth;
+  MaxNodes = maxNodes;
+  InfiniteSearch = infinite;
+  PonderSearch = ponder;
+  UseTimeManagement = !ExactMaxTime && !MaxDepth && !MaxNodes && !InfiniteSearch;
+
+  // Look for a book move, only during games, not tests
+  if (UseTimeManagement && !ponder && get_option_value_bool("OwnBook"))
   {
       Move bookMove;
       if (get_option_value_string("Book File") != OpeningBook.file_name())
@@ -388,15 +400,6 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move,
       }
   }
 
-  // Initialize global search variables
-  Idle = StopOnPonderhit = AbortSearch = Quit = false;
-  FailHigh = FailLow = Problem = false;
-  SearchStartTime = get_system_time();
-  ExactMaxTime = maxTime;
-  NodesSincePoll = 0;
-  InfiniteSearch = infinite;
-  PonderSearch = ponder;
-
   for (int i = 0; i < THREAD_MAX; i++)
   {
       Threads[i].nodes = 0ULL;
@@ -464,51 +467,45 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move,
   // Set thinking time
   int myTime = time[side_to_move];
   int myIncrement = increment[side_to_move];
+  if (UseTimeManagement)
+  {
+      if (!movesToGo) // Sudden death time control
+      {
+          if (myIncrement)
+          {
+              MaxSearchTime = myTime / 30 + myIncrement;
+              AbsoluteMaxSearchTime = Max(myTime / 4, myIncrement - 100);
+          }
+          else // Blitz game without increment
+          {
+              MaxSearchTime = myTime / 30;
+              AbsoluteMaxSearchTime = myTime / 8;
+          }
+      }
+      else // (x moves) / (y minutes)
+      {
+          if (movesToGo == 1)
+          {
+              MaxSearchTime = myTime / 2;
+              AbsoluteMaxSearchTime = (myTime > 3000)? (myTime - 500) : ((myTime * 3) / 4);
+          }
+          else
+          {
+              MaxSearchTime = myTime / Min(movesToGo, 20);
+              AbsoluteMaxSearchTime = Min((4 * myTime) / movesToGo, myTime / 3);
+          }
+      }
 
-  if (!movesToGo) // Sudden death time control
+      if (PonderingEnabled)
-  {
-      if (myIncrement)
       {
-          MaxSearchTime = myTime / 30 + myIncrement;
+          MaxSearchTime += MaxSearchTime / 4;
-          AbsoluteMaxSearchTime = Max(myTime / 4, myIncrement - 100);
+          MaxSearchTime = Min(MaxSearchTime, AbsoluteMaxSearchTime);
-      }
-      else // Blitz game without increment
-      {
-          MaxSearchTime = myTime / 30;
-          AbsoluteMaxSearchTime = myTime / 8;
-      }
-  }
-  else // (x moves) / (y minutes)
-  {
-      if (movesToGo == 1)
-      {
-          MaxSearchTime = myTime / 2;
-          AbsoluteMaxSearchTime = (myTime > 3000)? (myTime - 500) : ((myTime * 3) / 4);
-      }
-      else
-      {
-          MaxSearchTime = myTime / Min(movesToGo, 20);
-          AbsoluteMaxSearchTime = Min((4 * myTime) / movesToGo, myTime / 3);
       }
   }
 
-  if (PonderingEnabled)
+  // Set best NodesBetweenPolls interval
-  {
-      MaxSearchTime += MaxSearchTime / 4;
-      MaxSearchTime = Min(MaxSearchTime, AbsoluteMaxSearchTime);
-  }
-
-  // Fixed depth or fixed number of nodes?
-  MaxDepth = maxDepth;
-  if (MaxDepth)
-      InfiniteSearch = true; // HACK
-
-  MaxNodes = maxNodes;
   if (MaxNodes)
-  {
       NodesBetweenPolls = Min(MaxNodes, 30000);
-      InfiniteSearch = true; // HACK
-  }
   else if (myTime && myTime < 1000)
       NodesBetweenPolls = 1000;
   else if (myTime && myTime < 5000)
@@ -791,7 +788,7 @@ namespace {
 
         Problem = false;
 
-        if (!InfiniteSearch)
+        if (UseTimeManagement)
         {
             // Time to stop?
             bool stopSearch = false;
@@ -845,9 +842,9 @@ namespace {
 
     rml.sort();
 
-    // If we are pondering, we shouldn't print the best move before we
+    // If we are pondering or in infinite search, we shouldn't print the
-    // are told to do so
+    // best move before we are told to do so.
-    if (PonderSearch)
+    if (PonderSearch || InfiniteSearch)
         wait_for_stop_or_ponderhit();
     else
         // Print final search statistics
@@ -2680,7 +2677,7 @@ namespace {
                      || stillAtFirstMove //FIXME: We are not checking any problem flags, BUG?
                      || noProblemFound;
 
-    if (   (Iteration >= 3 && !InfiniteSearch && noMoreTime)
+    if (   (Iteration >= 3 && UseTimeManagement && noMoreTime)
         || (ExactMaxTime && t >= ExactMaxTime)
         || (Iteration >= 3 && MaxNodes && nodes_searched() >= MaxNodes))
         AbortSearch = true;
@@ -2710,7 +2707,7 @@ namespace {
                      || stillAtFirstMove
                      || noProblemFound;
 
-    if (Iteration >= 3 && !InfiniteSearch && (noMoreTime || StopOnPonderhit))
+    if (Iteration >= 3 && UseTimeManagement && (noMoreTime || StopOnPonderhit))
         AbortSearch = true;
   }