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
#include "search.h"
#include "thread.h"
#include "uci.h"
-
-using namespace Search;
+#include "syzygy/tbprobe.h"
+#include "tt.h"
ThreadPool Threads; // Global object
-namespace {
- // Helpers to launch a thread after creation and joining before delete. Outside the
- // Thread constructor and destructor because the object must be fully initialized
- // when start_routine (and hence virtual idle_loop) is called and when joining.
+/// Thread constructor launches the thread and waits until it goes to sleep
+/// in idle_loop(). Note that 'searching' and 'exit' should be alredy set.
- template<typename T> T* new_thread() {
- std::thread* th = new T;
- *th = std::thread(&T::idle_loop, (T*)th); // Will go to sleep
- return (T*)th;
- }
+Thread::Thread(size_t n) : idx(n), stdThread(&Thread::idle_loop, this) {
- void delete_thread(ThreadBase* th) {
+ wait_for_search_finished();
+}
- th->mutex.lock();
- th->exit = true; // Search must be already finished
- th->mutex.unlock();
- th->notify_one();
- th->join(); // Wait for thread termination
- delete th;
- }
+/// Thread destructor wakes up the thread in idle_loop() and waits
+/// for its termination. Thread should be already waiting.
-}
+Thread::~Thread() {
+ assert(!searching);
-// ThreadBase::notify_one() wakes up the thread when there is some work to do
+ exit = true;
+ start_searching();
+ stdThread.join();
+}
-void ThreadBase::notify_one() {
- std::unique_lock<Mutex> lk(mutex);
- sleepCondition.notify_one();
-}
+/// Thread::clear() reset histories, usually before a new game
+void Thread::clear() {
-// ThreadBase::wait() set the thread to sleep until 'condition' turns true
+ counterMoves.fill(MOVE_NONE);
+ mainHistory.fill(0);
+ captureHistory.fill(0);
-void ThreadBase::wait(std::atomic_bool& condition) {
+ for (auto& to : continuationHistory)
+ for (auto& h : to)
+ h->fill(0);
- std::unique_lock<Mutex> lk(mutex);
- sleepCondition.wait(lk, [&]{ return bool(condition); });
+ continuationHistory[NO_PIECE][0]->fill(Search::CounterMovePruneThreshold - 1);
}
+/// Thread::start_searching() wakes up the thread that will start the search
-// ThreadBase::wait_while() set the thread to sleep until 'condition' turns false
-void ThreadBase::wait_while(std::atomic_bool& condition) {
+void Thread::start_searching() {
- std::unique_lock<Mutex> lk(mutex);
- sleepCondition.wait(lk, [&]{ return !condition; });
+ std::lock_guard<Mutex> lk(mutex);
+ searching = true;
+ cv.notify_one(); // Wake up the thread in idle_loop()
}
-// Thread constructor makes some init but does not launch any execution thread,
-// which will be started only when the constructor returns.
+/// Thread::wait_for_search_finished() blocks on the condition variable
+/// until the thread has finished searching.
-Thread::Thread() {
+void Thread::wait_for_search_finished() {
- searching = resetCallsCnt = false;
- maxPly = callsCnt = 0;
- history.clear();
- counterMoves.clear();
- idx = Threads.size(); // Starts from 0
+ std::unique_lock<Mutex> lk(mutex);
+ 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)
- {
- std::unique_lock<Mutex> lk(mutex);
-
- while (!searching && !exit)
- sleepCondition.wait(lk);
-
- lk.unlock();
-
- if (!exit && searching)
- search();
- }
-}
+ // 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);
-
-// MainThread::idle_loop() is where the main thread is parked waiting to be started
-// when there is a new search. The main thread will launch all the slave threads.
-
-void MainThread::idle_loop() {
-
- while (!exit)
+ 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; });
- thinking = false;
-
- while (!thinking && !exit)
- {
- sleepCondition.notify_one(); // Wake up the UI thread if needed
- sleepCondition.wait(lk);
- }
+ if (exit)
+ return;
lk.unlock();
- if (!exit)
- think();
+ 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.
-// MainThread::join() waits for main thread to finish thinking
-
-void MainThread::join() {
+void ThreadPool::set(size_t requested) {
- std::unique_lock<Mutex> lk(mutex);
- sleepCondition.wait(lk, [&]{ return !thinking; });
-}
+ if (size() > 0) { // destroy any existing thread(s)
+ main()->wait_for_search_finished();
+ while (size() > 0)
+ delete back(), pop_back();
+ }
-// 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.
+ if (requested > 0) { // create new thread(s)
+ push_back(new MainThread(0));
-void ThreadPool::init() {
+ while (size() < requested)
+ push_back(new Thread(size()));
+ clear();
+ }
- push_back(new_thread<MainThread>());
- read_uci_options();
+ // Reallocate the hash with the new threadpool size
+ TT.resize(Options["Hash"]);
}
+/// ThreadPool::clear() sets threadPool data to initial values.
-// ThreadPool::exit() terminates the threads before the program exits. Cannot be
-// done in destructor because threads must be terminated before freeing us.
-
-void ThreadPool::exit() {
+void ThreadPool::clear() {
for (Thread* th : *this)
- delete_thread(th);
+ th->clear();
- clear(); // Get rid of stale pointers
+ 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::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);
-
- while (size() < requested)
- push_back(new_thread<Thread>());
-
- while (size() > requested)
- {
- delete_thread(back());
- pop_back();
- }
-}
-
+void ThreadPool::start_thinking(Position& pos, StateListPtr& states,
+ const Search::LimitsType& limits, bool ponderMode) {
-// ThreadPool::nodes_searched() returns the number of nodes searched
+ main()->wait_for_search_finished();
-int64_t ThreadPool::nodes_searched() {
+ stopOnPonderhit = stop = false;
+ ponder = ponderMode;
+ Search::Limits = limits;
+ Search::RootMoves rootMoves;
- int64_t nodes = 0;
- for (Thread *th : *this)
- nodes += th->rootPos.nodes_searched();
- return nodes;
-}
+ 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);
-// 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) {
- main()->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->nmpMinPly = 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()->thinking = true;
- main()->notify_one(); // Wake up main thread: 'thinking' must be already set
+ main()->start_searching();
}
projects / stockfish / blobdiff