Convert project to Android Studio.

DroidFishApp/src/main/cpp/stockfish/thread.cpp

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+/*
+  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) 2015-2019 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
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  Stockfish is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <algorithm> // For std::count
+#include <cassert>
+
+#include "movegen.h"
+#include "search.h"
+#include "thread.h"
+#include "uci.h"
+#include "syzygy/tbprobe.h"
+#include "tt.h"
+
+ThreadPool Threads; // Global object
+
+
+/// Thread constructor launches the thread and waits until it goes to sleep
+/// in idle_loop(). Note that 'searching' and 'exit' should be alredy set.
+
+Thread::Thread(size_t n) : idx(n), stdThread(&Thread::idle_loop, this) {
+
+  wait_for_search_finished();
+}
+
+
+/// Thread destructor wakes up the thread in idle_loop() and waits
+/// for its termination. Thread should be already waiting.
+
+Thread::~Thread() {
+
+  assert(!searching);
+
+  exit = true;
+  start_searching();
+  stdThread.join();
+}
+
+
+/// Thread::clear() reset histories, usually before a new game
+
+void Thread::clear() {
+
+  counterMoves.fill(MOVE_NONE);
+  mainHistory.fill(0);
+  captureHistory.fill(0);
+
+  for (auto& to : continuationHistory)
+      for (auto& h : to)
+          h->fill(0);
+
+  continuationHistory[NO_PIECE][0]->fill(Search::CounterMovePruneThreshold - 1);
+}
+
+/// Thread::start_searching() wakes up the thread that will start the search
+
+void Thread::start_searching() {
+
+  std::lock_guard<Mutex> lk(mutex);
+  searching = true;
+  cv.notify_one(); // Wake up the thread in idle_loop()
+}
+
+
+/// Thread::wait_for_search_finished() blocks on the condition variable
+/// until the thread has finished searching.
+
+void Thread::wait_for_search_finished() {
+
+  std::unique_lock<Mutex> lk(mutex);
+  cv.wait(lk, [&]{ return !searching; });
+}
+
+
+/// Thread::idle_loop() is where the thread is parked, blocked on the
+/// condition variable, when it has no work to do.
+
+void Thread::idle_loop() {
+
+  // If OS already scheduled us on a different group than 0 then don't overwrite
+  // the choice, eventually we are one of many one-threaded processes running on
+  // some Windows NUMA hardware, for instance in fishtest. To make it simple,
+  // just check if running threads are below a threshold, in this case all this
+  // NUMA machinery is not needed.
+  if (Options["Threads"] > 8)
+      WinProcGroup::bindThisThread(idx);
+
+  while (true)
+  {
+      std::unique_lock<Mutex> lk(mutex);
+      searching = false;
+      cv.notify_one(); // Wake up anyone waiting for search finished
+      cv.wait(lk, [&]{ return searching; });
+
+      if (exit)
+          return;
+
+      lk.unlock();
+
+      search();
+  }
+}
+
+/// ThreadPool::set() creates/destroys threads to match the requested number.
+/// Created and launched threads will go immediately to sleep in idle_loop.
+/// Upon resizing, threads are recreated to allow for binding if necessary.
+
+void ThreadPool::set(size_t requested) {
+
+  if (size() > 0) { // destroy any existing thread(s)
+      main()->wait_for_search_finished();
+
+      while (size() > 0)
+          delete back(), pop_back();
+  }
+
+  if (requested > 0) { // create new thread(s)
+      push_back(new MainThread(0));
+
+      while (size() < requested)
+          push_back(new Thread(size()));
+      clear();
+  }
+
+  // Reallocate the hash with the new threadpool size
+  TT.resize(Options["Hash"]);
+}
+
+/// ThreadPool::clear() sets threadPool data to initial values.
+
+void ThreadPool::clear() {
+
+  for (Thread* th : *this)
+      th->clear();
+
+  main()->callsCnt = 0;
+  main()->previousScore = VALUE_INFINITE;
+  main()->previousTimeReduction = 1.0;
+}
+
+/// ThreadPool::start_thinking() wakes up main thread waiting in idle_loop() and
+/// returns immediately. Main thread will wake up other threads and start the search.
+
+void ThreadPool::start_thinking(Position& pos, StateListPtr& states,
+                                const Search::LimitsType& limits, bool ponderMode) {
+
+  main()->wait_for_search_finished();
+
+  stopOnPonderhit = stop = false;
+  ponder = ponderMode;
+  Search::Limits = limits;
+  Search::RootMoves rootMoves;
+
+  for (const auto& m : MoveList<LEGAL>(pos))
+      if (   limits.searchmoves.empty()
+          || std::count(limits.searchmoves.begin(), limits.searchmoves.end(), m))
+          rootMoves.emplace_back(m);
+
+  if (!rootMoves.empty())
+      Tablebases::rank_root_moves(pos, rootMoves);
+
+  // After ownership transfer 'states' becomes empty, so if we stop the search
+  // and call 'go' again without setting a new position states.get() == NULL.
+  assert(states.get() || setupStates.get());
+
+  if (states.get())
+      setupStates = std::move(states); // Ownership transfer, states is now empty
+
+  // We use Position::set() to set root position across threads. But there are
+  // some StateInfo fields (previous, pliesFromNull, capturedPiece) that cannot
+  // be deduced from a fen string, so set() clears them and to not lose the info
+  // we need to backup and later restore setupStates->back(). Note that setupStates
+  // is shared by threads but is accessed in read-only mode.
+  StateInfo tmp = setupStates->back();
+
+  for (Thread* th : *this)
+  {
+      th->nodes = th->tbHits = th->nmpMinPly = 0;
+      th->rootDepth = th->completedDepth = DEPTH_ZERO;
+      th->rootMoves = rootMoves;
+      th->rootPos.set(pos.fen(), pos.is_chess960(), &setupStates->back(), th);
+  }
+
+  setupStates->back() = tmp;
+
+  main()->start_searching();
+}