X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fthread.cpp;h=3b6074acf0f84a0e5b397254afc0da14535f6068;hp=12a9527131b6f73bbb8f46a7b8cb6a219f2e994b;hb=ed72a1e9ba37a9fa2674da8f46bb0597a1721c2d;hpb=91427c824280d71eaf27f39a4bfdd2188cbdb4ec diff --git a/src/thread.cpp b/src/thread.cpp index 12a95271..3b6074ac 100644 --- a/src/thread.cpp +++ b/src/thread.cpp @@ -1,7 +1,7 @@ /* Stockfish, a UCI chess playing engine derived from Glaurung 2.1 Copyright (C) 2004-2008 Tord Romstad (Glaurung author) - Copyright (C) 2008-2012 Marco Costalba, Joona Kiiski, Tord Romstad + Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, 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 @@ -19,360 +19,176 @@ #include // For std::count #include -#include #include "movegen.h" #include "search.h" #include "thread.h" -#include "ucioption.h" +#include "uci.h" using namespace Search; ThreadPool Threads; // Global object -namespace { extern "C" { +/// Thread constructor launch the thread and then wait until it goes to sleep +/// in idle_loop(). - // start_routine() is the C function which is called when a new thread - // is launched. It is a wrapper to the virtual function idle_loop(). +Thread::Thread() { - long start_routine(Thread* th) { th->idle_loop(); return 0; } + resetCalls = exit = false; + maxPly = callsCnt = 0; + history.clear(); + counterMoves.clear(); + idx = Threads.size(); // Start from 0 -} } - - -// Thread c'tor starts a newly-created thread of execution that will call -// the the virtual function idle_loop(), going immediately to sleep. - -Thread::Thread() : splitPoints() { - - searching = exit = false; - maxPly = splitPointsSize = 0; - activeSplitPoint = NULL; - idx = Threads.size(); - - if (!thread_create(handle, start_routine, this)) - { - std::cerr << "Failed to create thread number " << idx << std::endl; - ::exit(EXIT_FAILURE); - } + std::unique_lock lk(mutex); + searching = true; + nativeThread = std::thread(&Thread::idle_loop, this); + sleepCondition.wait(lk, [&]{ return !searching; }); } -// Thread d'tor waits for thread termination before to return +/// Thread destructor wait for thread termination before returning Thread::~Thread() { - exit = true; // Search must be already finished - notify_one(); - thread_join(handle); // Wait for thread termination + mutex.lock(); + exit = true; + sleepCondition.notify_one(); + mutex.unlock(); + nativeThread.join(); } -// TimerThread::idle_loop() is where the timer thread waits msec milliseconds -// and then calls check_time(). If msec is 0 thread sleeps until is woken up. -extern void check_time(); - -void TimerThread::idle_loop() { - - while (!exit) - { - mutex.lock(); - - if (!exit) - sleepCondition.wait_for(mutex, msec ? msec : INT_MAX); +/// Thread::wait_for_search_finished() wait on sleep condition until not searching - mutex.unlock(); +void Thread::wait_for_search_finished() { - if (msec) - check_time(); - } + std::unique_lock lk(mutex); + sleepCondition.wait(lk, [&]{ return !searching; }); } -// MainThread::idle_loop() is where the main thread is parked waiting to be started -// when there is a new search. Main thread will launch all the slave threads. +/// Thread::wait() wait on sleep condition until condition is true -void MainThread::idle_loop() { +void Thread::wait(std::atomic_bool& condition) { - while (true) - { - mutex.lock(); + std::unique_lock lk(mutex); + sleepCondition.wait(lk, [&]{ return bool(condition); }); +} - thinking = false; - while (!thinking && !exit) - { - Threads.sleepCondition.notify_one(); // Wake up UI thread if needed - sleepCondition.wait(mutex); - } +/// Thread::start_searching() wake up the thread that will start the search - mutex.unlock(); +void Thread::start_searching(bool resume) { - if (exit) - return; + std::unique_lock lk(mutex); + if (!resume) searching = true; - Search::think(); - - assert(searching); - - searching = false; - } -} - - -// Thread::notify_one() wakes up the thread when there is some search to do - -void Thread::notify_one() { - - mutex.lock(); sleepCondition.notify_one(); - mutex.unlock(); -} - - -// Thread::wait_for() set the thread to sleep until condition 'b' turns true - -void Thread::wait_for(volatile const bool& b) { - - mutex.lock(); - while (!b) sleepCondition.wait(mutex); - mutex.unlock(); } -// Thread::cutoff_occurred() checks whether a beta cutoff has occurred in the -// current active split point, or in some ancestor of the split point. - -bool Thread::cutoff_occurred() const { - - for (SplitPoint* sp = activeSplitPoint; sp; sp = sp->parentSplitPoint) - if (sp->cutoff) - return true; - - return false; -} +/// Thread::idle_loop() is where the thread is parked when it has no work to do +void Thread::idle_loop() { -// Thread::is_available_to() checks whether the thread is available to help the -// thread 'master' at a split point. An obvious requirement is that thread must -// be idle. With more than two threads, this is not sufficient: If the thread is -// the master of some split point, it is only available as a slave to the slaves -// which are busy searching the split point at the top of slaves split point -// stack (the "helpful master concept" in YBWC terminology). + while (!exit) + { + std::unique_lock lk(mutex); -bool Thread::is_available_to(Thread* master) const { + searching = false; - if (searching) - return false; + while (!searching && !exit) + { + sleepCondition.notify_one(); // Wake up any waiting thread + sleepCondition.wait(lk); + } - // Make a local copy to be sure doesn't become zero under our feet while - // testing next condition and so leading to an out of bound access. - int size = splitPointsSize; + lk.unlock(); - // No split points means that the thread is available as a slave for any - // other thread otherwise apply the "helpful master" concept if possible. - return !size || (splitPoints[size - 1].slavesMask & (1ULL << master->idx)); + if (!exit) + search(); + } } -// init() is called at startup to create and launch requested threads, that will -// go immediately to sleep due to 'sleepWhileIdle' set to true. We cannot use -// a c'tor becuase Threads is a static object and we need a fully initialized -// engine at this point due to allocation of Endgames in Thread c'tor. +/// ThreadPool::init() 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() { - sleepWhileIdle = true; - timer = new TimerThread(); - threads.push_back(new MainThread()); + push_back(new MainThread); read_uci_options(); } -// exit() cleanly terminates the threads before the program exits +/// ThreadPool::exit() terminate threads before the program exits. Cannot be +/// done in destructor because threads must be terminated before deleting any +/// static objects, so while still in main(). void ThreadPool::exit() { - delete timer; // As first because check_time() accesses threads data - - for (size_t i = 0; i < threads.size(); i++) - delete threads[i]; + while (size()) + delete back(), pop_back(); } -// 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 in advance all possible -// threads, with included pawns and material tables, if only few are used. +/// ThreadPool::read_uci_options() updates internal threads parameters from the +/// corresponding UCI options and creates/destroys threads to match requested +/// number. Thread objects are dynamically allocated. void ThreadPool::read_uci_options() { - maxThreadsPerSplitPoint = Options["Max Threads per Split Point"]; - minimumSplitDepth = Options["Min Split Depth"] * ONE_PLY; - size_t requested = Options["Threads"]; + size_t requested = Options["Threads"]; assert(requested > 0); - while (threads.size() < requested) - threads.push_back(new Thread()); + while (size() < requested) + push_back(new Thread); - while (threads.size() > requested) - { - delete threads.back(); - threads.pop_back(); - } + while (size() > requested) + delete back(), pop_back(); } -// slave_available() tries to find an idle thread which is available as a slave -// for the thread 'master'. +/// ThreadPool::nodes_searched() return the number of nodes searched -bool ThreadPool::slave_available(Thread* master) const { +int64_t ThreadPool::nodes_searched() { - for (size_t i = 0; i < threads.size(); i++) - if (threads[i]->is_available_to(master)) - return true; - - return false; + int64_t nodes = 0; + for (Thread* th : *this) + nodes += th->rootPos.nodes_searched(); + return nodes; } -// split() does the actual work of distributing the work at a node between -// several available threads. If it does not succeed in splitting the node -// (because no idle threads are available), the function immediately returns. -// If splitting is possible, a SplitPoint object is initialized with all the -// data that must be copied to the helper threads and then helper threads are -// told that they have been assigned work. This will cause them to instantly -// leave their idle loops and call search(). When all threads have returned from -// search() then split() returns. - -template -Value Thread::split(Position& pos, Stack* ss, Value alpha, Value beta, - Value bestValue, Move* bestMove, Depth depth, Move threatMove, - int moveCount, MovePicker& mp, int nodeType) { - - assert(pos.pos_is_ok()); - assert(bestValue <= alpha && alpha < beta && beta <= VALUE_INFINITE); - assert(bestValue > -VALUE_INFINITE); - assert(depth >= Threads.minimumSplitDepth); - - assert(searching); - assert(splitPointsSize < MAX_SPLITPOINTS_PER_THREAD); - - // Pick the next available split point from the split point stack - SplitPoint& sp = splitPoints[splitPointsSize]; - - sp.masterThread = this; - sp.parentSplitPoint = activeSplitPoint; - sp.slavesMask = 1ULL << idx; - sp.depth = depth; - sp.bestMove = *bestMove; - sp.threatMove = threatMove; - sp.alpha = alpha; - sp.beta = beta; - sp.nodeType = nodeType; - sp.bestValue = bestValue; - sp.movePicker = ∓ - sp.moveCount = moveCount; - sp.pos = &pos; - sp.nodes = 0; - sp.cutoff = false; - sp.ss = ss; - - // Try to allocate available threads and ask them to start searching setting - // 'searching' flag. This must be done under lock protection to avoid concurrent - // allocation of the same slave by another master. - Threads.mutex.lock(); - sp.mutex.lock(); - - splitPointsSize++; - activeSplitPoint = &sp; - - size_t slavesCnt = 1; // Master is always included - - for (size_t i = 0; i < Threads.size() && !Fake; ++i) - if (Threads[i].is_available_to(this) && ++slavesCnt <= Threads.maxThreadsPerSplitPoint) - { - sp.slavesMask |= 1ULL << Threads[i].idx; - Threads[i].activeSplitPoint = &sp; - Threads[i].searching = true; // Slave leaves idle_loop() - Threads[i].notify_one(); // Could be sleeping - } - - sp.mutex.unlock(); - Threads.mutex.unlock(); - - // Everything is set up. The master thread enters the idle loop, from which - // it will instantly launch a search, because its 'searching' flag is set. - // The thread will return from the idle loop when all slaves have finished - // their work at this split point. - if (slavesCnt > 1 || Fake) - { - Thread::idle_loop(); // Force a call to base class idle_loop() - - // In helpful master concept a master can help only a sub-tree of its split - // point, and because here is all finished is not possible master is booked. - assert(!searching); - } - - // We have returned from the idle loop, which means that all threads are - // finished. Note that setting 'searching' and decreasing splitPointsSize is - // done under lock protection to avoid a race with Thread::is_available_to(). - Threads.mutex.lock(); - sp.mutex.lock(); - - searching = true; - splitPointsSize--; - activeSplitPoint = sp.parentSplitPoint; - pos.set_nodes_searched(pos.nodes_searched() + sp.nodes); - *bestMove = sp.bestMove; - - sp.mutex.unlock(); - Threads.mutex.unlock(); - - return sp.bestValue; -} - -// Explicit template instantiations -template Value Thread::split(Position&, Stack*, Value, Value, Value, Move*, Depth, Move, int, MovePicker&, int); -template Value Thread::split(Position&, Stack*, Value, Value, Value, Move*, Depth, Move, int, MovePicker&, int); - - -// wait_for_think_finished() waits for main thread to go to sleep then returns - -void ThreadPool::wait_for_think_finished() { - - MainThread* t = main_thread(); - t->mutex.lock(); - while (t->thinking) sleepCondition.wait(t->mutex); - t->mutex.unlock(); -} - - -// start_thinking() wakes up the main thread sleeping in MainThread::idle_loop() -// so to start a new search, then returns immediately. +/// ThreadPool::start_thinking() wake up the main thread sleeping in idle_loop() +/// and start a new search, then return immediately. void ThreadPool::start_thinking(const Position& pos, const LimitsType& limits, - const std::vector& searchMoves, StateStackPtr& states) { - wait_for_think_finished(); + StateStackPtr& states) { - SearchTime = Time::now(); // As early as possible + main()->wait_for_search_finished(); - Signals.stopOnPonderhit = Signals.firstRootMove = false; - Signals.stop = Signals.failedLowAtRoot = false; + Signals.stopOnPonderhit = Signals.stop = false; - RootPos = pos; + main()->rootMoves.clear(); + main()->rootPos = pos; Limits = limits; - SetupStates = states; // Ownership transfer here - RootMoves.clear(); + if (states.get()) // If we don't set a new position, preserve current state + { + SetupStates = std::move(states); // Ownership transfer here + assert(!states.get()); + } - for (MoveList ml(pos); !ml.end(); ++ml) - if ( searchMoves.empty() - || std::count(searchMoves.begin(), searchMoves.end(), ml.move())) - RootMoves.push_back(RootMove(ml.move())); + for (const auto& m : MoveList(pos)) + if ( limits.searchmoves.empty() + || std::count(limits.searchmoves.begin(), limits.searchmoves.end(), m)) + main()->rootMoves.push_back(RootMove(m)); - main_thread()->thinking = true; - main_thread()->notify_one(); // Starts main thread + main()->start_searching(); }