X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fthread.cpp;h=6516192d3700cc4dea05ba26f396cc09a6e37594;hp=858a09d9c011bbe57a5b80feef21fe1c1d2eb670;hb=4c57cf0ead29536504ca452b876d350a8e2edbdc;hpb=76ed0ab5015f41715453a7efcedd57a7a5c962da

diff --git a/src/thread.cpp b/src/thread.cpp
index 858a09d9..6516192d 100644
--- a/src/thread.cpp
+++ b/src/thread.cpp
@@ -2,6 +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) 2015-2018 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
@@ -24,172 +25,175 @@
 #include "search.h"
 #include "thread.h"
 #include "uci.h"
-
-using namespace Search;
+#include "syzygy/tbprobe.h"
 
 ThreadPool Threads; // Global object
 
-// Thread constructor makes some init and launches the thread that will go to
-// sleep in idle_loop().
 
-Thread::Thread() {
+/// 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) {
 
-  searching = true; // Avoid a race with start_thinking()
-  exit = resetCalls = false;
-  maxPly = callsCnt = 0;
-  history.clear();
-  counterMoves.clear();
-  idx = Threads.size(); // Starts from 0
-  std::thread::operator=(std::thread(&Thread::idle_loop, this));
+  wait_for_search_finished();
 }
 
 
-// Thread destructor waits for thread termination before deleting
+/// Thread destructor wakes up the thread in idle_loop() and waits
+/// for its termination. Thread should be already waiting.
 
 Thread::~Thread() {
 
-  mutex.lock();
-  exit = true; // Search must be already finished
-  mutex.unlock();
+  assert(!searching);
 
-  notify_one();
-  std::thread::join(); // Wait for thread termination
+  exit = true;
+  start_searching();
+  stdThread.join();
 }
 
 
-// Thread::join() waits for the thread to finish searching
-void Thread::join() {
+/// Thread::clear() reset histories, usually before a new game
 
-  std::unique_lock<Mutex> lk(mutex);
-  sleepCondition.wait(lk, [&]{ return !searching; });
-}
+void Thread::clear() {
 
+  counterMoves.fill(MOVE_NONE);
+  mainHistory.fill(0);
+  captureHistory.fill(0);
 
-// Thread::notify_one() wakes up the thread when there is some work to do
+  for (auto& to : contHistory)
+      for (auto& h : to)
+          h.fill(0);
 
-void Thread::notify_one() {
+  contHistory[NO_PIECE][0].fill(Search::CounterMovePruneThreshold - 1);
+}
 
-  std::unique_lock<Mutex> lk(mutex);
-  sleepCondition.notify_one();
+/// 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() set the thread to sleep until 'condition' turns true
+/// Thread::wait_for_search_finished() blocks on the condition variable
+/// until the thread has finished searching.
 
-void Thread::wait(std::atomic_bool& condition) {
+void Thread::wait_for_search_finished() {
 
   std::unique_lock<Mutex> lk(mutex);
-  sleepCondition.wait(lk, [&]{ return bool(condition); });
+  cv.wait(lk, [&]{ return !searching; });
 }
 
 
-// Thread::idle_loop() is where the thread is parked when it has no work to do
+/// 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() {
 
-  while (!exit)
+  // 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; });
 
-      while (!searching && !exit)
-      {
-          sleepCondition.notify_one(); // Wake up main thread if needed
-          sleepCondition.wait(lk);
-      }
+      if (exit)
+          return;
 
       lk.unlock();
 
-      if (!exit && searching)
-          search();
+      search();
   }
 }
 
+/// ThreadPool::set() creates/destroys threads to match the requested number.
+/// Created and launced threads wil go immediately to sleep in idle_loop.
+/// Upon resizing, threads are recreated to allow for binding if necessary.
 
-// ThreadPool::init() is called at startup to create and launch requested threads,
-// that will go immediately to sleep. We cannot use a constructor because Threads
-// is a static object and we need a fully initialized engine at this point due to
-// allocation of Endgames in the Thread constructor.
-
-void ThreadPool::init() {
-
-  push_back(new MainThread);
-  read_uci_options();
-}
-
+void ThreadPool::set(size_t requested) {
 
-// ThreadPool::exit() terminates the threads before the program exits. Cannot be
-// done in destructor because threads must be terminated before freeing us.
+  if (size() > 0) { // destroy any existing thread(s)
+      main()->wait_for_search_finished();
 
-void ThreadPool::exit() {
+      while (size() > 0)
+          delete back(), pop_back();
+  }
 
-  for (Thread* th : *this)
-      delete th;
+  if (requested > 0) { // create new thread(s)
+      push_back(new MainThread(0));
 
-  clear(); // Get rid of stale pointers
+      while (size() < requested)
+          push_back(new Thread(size()));
+      clear();
+  }
 }
 
+/// ThreadPool::clear() sets threadPool data to initial values.
 
-// ThreadPool::read_uci_options() updates internal threads parameters from the
-// corresponding UCI options and creates/destroys threads to match the requested
-// number. Thread objects are dynamically allocated to avoid creating all possible
-// threads in advance (which include pawns and material tables), even if only a
-// few are to be used.
-
-void ThreadPool::read_uci_options() {
-
-  size_t requested  = Options["Threads"];
-
-  assert(requested > 0);
+void ThreadPool::clear() {
 
-  while (size() < requested)
-      push_back(new Thread);
+  for (Thread* th : *this)
+      th->clear();
 
-  while (size() > requested)
-  {
-      delete back();
-      pop_back();
-  }
+  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.
 
-// ThreadPool::nodes_searched() returns the number of nodes searched
+void ThreadPool::start_thinking(Position& pos, StateListPtr& states,
+                                const Search::LimitsType& limits, bool ponderMode) {
 
-int64_t ThreadPool::nodes_searched() {
+  main()->wait_for_search_finished();
 
-  int64_t nodes = 0;
-  for (Thread *th : *this)
-      nodes += th->rootPos.nodes_searched();
-  return nodes;
-}
+  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::filter_root_moves(pos, rootMoves);
 
-// ThreadPool::start_thinking() wakes up the main thread sleeping in
-// MainThread::idle_loop() and starts a new search, then returns immediately.
+  // 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());
 
-void ThreadPool::start_thinking(const Position& pos, const LimitsType& limits,
-                                StateStackPtr& states) {
-  for (Thread* th : Threads)
-      th->join();
+  if (states.get())
+      setupStates = std::move(states); // Ownership transfer, states is now empty
 
-  Signals.stopOnPonderhit = Signals.firstRootMove = false;
-  Signals.stop = Signals.failedLowAtRoot = false;
+  // 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();
 
-  main()->rootMoves.clear();
-  main()->rootPos = pos;
-  Limits = limits;
-  if (states.get()) // If we don't set a new position, preserve current state
+  for (Thread* th : *this)
   {
-      SetupStates = std::move(states); // Ownership transfer here
-      assert(!states.get());
+      th->nodes = th->tbHits = th->nmp_ply = th->nmp_odd = 0;
+      th->rootDepth = th->completedDepth = DEPTH_ZERO;
+      th->rootMoves = rootMoves;
+      th->rootPos.set(pos.fen(), pos.is_chess960(), &setupStates->back(), th);
   }
 
-  for (const auto& m : MoveList<LEGAL>(pos))
-      if (   limits.searchmoves.empty()
-          || std::count(limits.searchmoves.begin(), limits.searchmoves.end(), m))
-          main()->rootMoves.push_back(RootMove(m));
+  setupStates->back() = tmp;
 
-  main()->searching = true;
-  main()->notify_one(); // Wake up main thread: 'searching' must be already set
+  main()->start_searching();
 }