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Member "stockfish-11-linux/src/thread.cpp" (18 Jan 2020, 6692 Bytes) of package /linux/privat/stockfish-11-linux.zip:


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    1 /*
    2   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
    3   Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
    4   Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
    5   Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
    6 
    7   Stockfish is free software: you can redistribute it and/or modify
    8   it under the terms of the GNU General Public License as published by
    9   the Free Software Foundation, either version 3 of the License, or
   10   (at your option) any later version.
   11 
   12   Stockfish is distributed in the hope that it will be useful,
   13   but WITHOUT ANY WARRANTY; without even the implied warranty of
   14   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   15   GNU General Public License for more details.
   16 
   17   You should have received a copy of the GNU General Public License
   18   along with this program.  If not, see <http://www.gnu.org/licenses/>.
   19 */
   20 
   21 #include <cassert>
   22 
   23 #include <algorithm> // For std::count
   24 #include "movegen.h"
   25 #include "search.h"
   26 #include "thread.h"
   27 #include "uci.h"
   28 #include "syzygy/tbprobe.h"
   29 #include "tt.h"
   30 
   31 ThreadPool Threads; // Global object
   32 
   33 
   34 /// Thread constructor launches the thread and waits until it goes to sleep
   35 /// in idle_loop(). Note that 'searching' and 'exit' should be already set.
   36 
   37 Thread::Thread(size_t n) : idx(n), stdThread(&Thread::idle_loop, this) {
   38 
   39   wait_for_search_finished();
   40 }
   41 
   42 
   43 /// Thread destructor wakes up the thread in idle_loop() and waits
   44 /// for its termination. Thread should be already waiting.
   45 
   46 Thread::~Thread() {
   47 
   48   assert(!searching);
   49 
   50   exit = true;
   51   start_searching();
   52   stdThread.join();
   53 }
   54 
   55 /// Thread::bestMoveCount(Move move) return best move counter for the given root move
   56 
   57 int Thread::best_move_count(Move move) {
   58 
   59   auto rm = std::find(rootMoves.begin() + pvIdx,
   60                       rootMoves.begin() + pvLast, move);
   61 
   62   return rm != rootMoves.begin() + pvLast ? rm->bestMoveCount : 0;
   63 }
   64 
   65 /// Thread::clear() reset histories, usually before a new game
   66 
   67 void Thread::clear() {
   68 
   69   counterMoves.fill(MOVE_NONE);
   70   mainHistory.fill(0);
   71   captureHistory.fill(0);
   72 
   73   for (bool inCheck : { false, true })
   74     for (StatsType c : { NoCaptures, Captures })
   75       for (auto& to : continuationHistory[inCheck][c])
   76         for (auto& h : to)
   77           h->fill(0);
   78 
   79   for (bool inCheck : { false, true })
   80     for (StatsType c : { NoCaptures, Captures })
   81       continuationHistory[inCheck][c][NO_PIECE][0]->fill(Search::CounterMovePruneThreshold - 1);
   82 }
   83 
   84 /// Thread::start_searching() wakes up the thread that will start the search
   85 
   86 void Thread::start_searching() {
   87 
   88   std::lock_guard<std::mutex> lk(mutex);
   89   searching = true;
   90   cv.notify_one(); // Wake up the thread in idle_loop()
   91 }
   92 
   93 
   94 /// Thread::wait_for_search_finished() blocks on the condition variable
   95 /// until the thread has finished searching.
   96 
   97 void Thread::wait_for_search_finished() {
   98 
   99   std::unique_lock<std::mutex> lk(mutex);
  100   cv.wait(lk, [&]{ return !searching; });
  101 }
  102 
  103 
  104 /// Thread::idle_loop() is where the thread is parked, blocked on the
  105 /// condition variable, when it has no work to do.
  106 
  107 void Thread::idle_loop() {
  108 
  109   // If OS already scheduled us on a different group than 0 then don't overwrite
  110   // the choice, eventually we are one of many one-threaded processes running on
  111   // some Windows NUMA hardware, for instance in fishtest. To make it simple,
  112   // just check if running threads are below a threshold, in this case all this
  113   // NUMA machinery is not needed.
  114   if (Options["Threads"] > 8)
  115       WinProcGroup::bindThisThread(idx);
  116 
  117   while (true)
  118   {
  119       std::unique_lock<std::mutex> lk(mutex);
  120       searching = false;
  121       cv.notify_one(); // Wake up anyone waiting for search finished
  122       cv.wait(lk, [&]{ return searching; });
  123 
  124       if (exit)
  125           return;
  126 
  127       lk.unlock();
  128 
  129       search();
  130   }
  131 }
  132 
  133 /// ThreadPool::set() creates/destroys threads to match the requested number.
  134 /// Created and launched threads will immediately go to sleep in idle_loop.
  135 /// Upon resizing, threads are recreated to allow for binding if necessary.
  136 
  137 void ThreadPool::set(size_t requested) {
  138 
  139   if (size() > 0) { // destroy any existing thread(s)
  140       main()->wait_for_search_finished();
  141 
  142       while (size() > 0)
  143           delete back(), pop_back();
  144   }
  145 
  146   if (requested > 0) { // create new thread(s)
  147       push_back(new MainThread(0));
  148 
  149       while (size() < requested)
  150           push_back(new Thread(size()));
  151       clear();
  152 
  153       // Reallocate the hash with the new threadpool size
  154       TT.resize(Options["Hash"]);
  155 
  156       // Init thread number dependent search params.
  157       Search::init();
  158   }
  159 }
  160 
  161 /// ThreadPool::clear() sets threadPool data to initial values.
  162 
  163 void ThreadPool::clear() {
  164 
  165   for (Thread* th : *this)
  166       th->clear();
  167 
  168   main()->callsCnt = 0;
  169   main()->previousScore = VALUE_INFINITE;
  170   main()->previousTimeReduction = 1.0;
  171 }
  172 
  173 /// ThreadPool::start_thinking() wakes up main thread waiting in idle_loop() and
  174 /// returns immediately. Main thread will wake up other threads and start the search.
  175 
  176 void ThreadPool::start_thinking(Position& pos, StateListPtr& states,
  177                                 const Search::LimitsType& limits, bool ponderMode) {
  178 
  179   main()->wait_for_search_finished();
  180 
  181   main()->stopOnPonderhit = stop = false;
  182   increaseDepth = true;
  183   main()->ponder = ponderMode;
  184   Search::Limits = limits;
  185   Search::RootMoves rootMoves;
  186 
  187   for (const auto& m : MoveList<LEGAL>(pos))
  188       if (   limits.searchmoves.empty()
  189           || std::count(limits.searchmoves.begin(), limits.searchmoves.end(), m))
  190           rootMoves.emplace_back(m);
  191 
  192   if (!rootMoves.empty())
  193       Tablebases::rank_root_moves(pos, rootMoves);
  194 
  195   // After ownership transfer 'states' becomes empty, so if we stop the search
  196   // and call 'go' again without setting a new position states.get() == NULL.
  197   assert(states.get() || setupStates.get());
  198 
  199   if (states.get())
  200       setupStates = std::move(states); // Ownership transfer, states is now empty
  201 
  202   // We use Position::set() to set root position across threads. But there are
  203   // some StateInfo fields (previous, pliesFromNull, capturedPiece) that cannot
  204   // be deduced from a fen string, so set() clears them and to not lose the info
  205   // we need to backup and later restore setupStates->back(). Note that setupStates
  206   // is shared by threads but is accessed in read-only mode.
  207   StateInfo tmp = setupStates->back();
  208 
  209   for (Thread* th : *this)
  210   {
  211       th->nodes = th->tbHits = th->nmpMinPly = 0;
  212       th->rootDepth = th->completedDepth = 0;
  213       th->rootMoves = rootMoves;
  214       th->rootPos.set(pos.fen(), pos.is_chess960(), &setupStates->back(), th);
  215   }
  216 
  217   setupStates->back() = tmp;
  218 
  219   main()->start_searching();
  220 }