X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fthread.cpp;h=440b8bf0e4f06b5ea6087aa76c2e9aec3ca02cc0;hp=bd20361daff658cd31a9e955fe585d3473a1c7e4;hb=29b5842da8d5477c0aea924cfd364c9e619456a2;hpb=5cbcff55cc3a2ff78dd83e7a3f94c5414946f82c diff --git a/src/thread.cpp b/src/thread.cpp index bd20361d..440b8bf0 100644 --- a/src/thread.cpp +++ b/src/thread.cpp @@ -1,7 +1,8 @@ /* Stockfish, a UCI chess playing engine derived from Glaurung 2.1 Copyright (C) 2004-2008 Tord Romstad (Glaurung author) - Copyright (C) 2008-2014 Marco Costalba, Joona Kiiski, Tord Romstad + Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad + Copyright (C) 2015-2016 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 @@ -29,351 +30,167 @@ using namespace Search; ThreadPool Threads; // Global object -extern void check_time(); +/// Thread constructor launches the thread and then waits until it goes to sleep +/// in idle_loop(). -namespace { +Thread::Thread() { - // 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(). - - extern "C" { long start_routine(ThreadBase* th) { th->idle_loop(); return 0; } } - - - // Helpers to launch a thread after creation and joining before delete. Must be - // outside Thread c'tor and d'tor because the object will be fully initialized - // when start_routine (and hence virtual idle_loop) is called and when joining. - - template T* new_thread() { - T* th = new T(); - thread_create(th->handle, start_routine, th); // Will go to sleep - return th; - } - - void delete_thread(ThreadBase* th) { - th->exit = true; // Search must be already finished - th->notify_one(); - thread_join(th->handle); // Wait for thread termination - delete th; - } + resetCalls = exit = false; + maxPly = callsCnt = 0; + history.clear(); + counterMoves.clear(); + idx = Threads.size(); // Start from 0 + std::unique_lock lk(mutex); + searching = true; + nativeThread = std::thread(&Thread::idle_loop, this); + sleepCondition.wait(lk, [&]{ return !searching; }); } -// notify_one() wakes up the thread when there is some work to do +/// Thread destructor waits for thread termination before returning -void ThreadBase::notify_one() { +Thread::~Thread() { mutex.lock(); + exit = true; sleepCondition.notify_one(); mutex.unlock(); + nativeThread.join(); } -// wait_for() set the thread to sleep until condition 'b' turns true - -void ThreadBase::wait_for(volatile const bool& b) { - - mutex.lock(); - while (!b) sleepCondition.wait(mutex); - mutex.unlock(); -} - - -// Thread c'tor just inits data and does not launch any execution thread. -// Such a thread will only be started when c'tor returns. +/// Thread::wait_for_search_finished() waits on sleep condition +/// until not searching -Thread::Thread() /* : splitPoints() */ { // Value-initialization bug in MSVC +void Thread::wait_for_search_finished() { - searching = false; - maxPly = splitPointsSize = 0; - activeSplitPoint = NULL; - activePosition = NULL; - idx = Threads.size(); // Starts from 0 + std::unique_lock lk(mutex); + sleepCondition.wait(lk, [&]{ return !searching; }); } -// 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 { +/// Thread::wait() waits on sleep condition until condition is true - for (SplitPoint* sp = activeSplitPoint; sp; sp = sp->parentSplitPoint) - if (sp->cutoff) - return true; +void Thread::wait(std::atomic_bool& condition) { - return false; + std::unique_lock lk(mutex); + sleepCondition.wait(lk, [&]{ return bool(condition); }); } -// Thread::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 slave's split point -// stack (the "helpful master concept" in YBWC terminology). +/// Thread::start_searching() wakes up the thread that will start the search -bool Thread::available_to(const Thread* master) const { +void Thread::start_searching(bool resume) { - if (searching) - return false; + std::unique_lock lk(mutex); - // Make a local copy to be sure it doesn't become zero under our feet while - // testing next condition and so leading to an out of bounds access. - const int size = splitPointsSize; + if (!resume) + searching = true; - // 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.test(master->idx); + sleepCondition.notify_one(); } -// TimerThread::idle_loop() is where the timer thread waits msec milliseconds -// and then calls check_time(). If msec is 0 thread sleeps until it's woken up. +/// Thread::idle_loop() is where the thread is parked when it has no work to do -void TimerThread::idle_loop() { +void Thread::idle_loop() { while (!exit) { - mutex.lock(); - - if (!exit) - sleepCondition.wait_for(mutex, run ? Resolution : INT_MAX); - - mutex.unlock(); - - if (run) - check_time(); - } -} - - -// 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 (true) - { - mutex.lock(); + std::unique_lock lk(mutex); - thinking = false; + searching = false; - while (!thinking && !exit) + while (!searching && !exit) { - Threads.sleepCondition.notify_one(); // Wake up the UI thread if needed - sleepCondition.wait(mutex); + sleepCondition.notify_one(); // Wake up any waiting thread + sleepCondition.wait(lk); } - mutex.unlock(); + lk.unlock(); - if (exit) - return; - - searching = true; - - Search::think(); - - assert(searching); - - searching = false; + if (!exit) + search(); } } -// init() is called at startup to create and launch requested threads, that will -// go immediately to sleep. We cannot use a c'tor because 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() creates and launches 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() { - timer = new_thread(); - push_back(new_thread()); + push_back(new MainThread); read_uci_options(); } -// exit() cleanly terminates the threads before the program exits. Cannot be done in -// d'tor because we have to terminate the threads before to free ThreadPool object. +/// ThreadPool::exit() terminates threads before the program exits. Cannot be +/// done in destructor because threads must be terminated before deleting any +/// static objects while still in main(). void ThreadPool::exit() { - delete_thread(timer); // As first because check_time() accesses threads data - - for (iterator it = begin(); it != end(); ++it) - delete_thread(*it); + 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 all possible threads -// in advance (which include pawns and material tables), even if only a few -// are to be 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() { - minimumSplitDepth = Options["Min Split Depth"] * ONE_PLY; - size_t requested = Options["Threads"]; + size_t requested = Options["Threads"]; assert(requested > 0); - // If zero (default) then set best minimum split depth automatically - if (!minimumSplitDepth) - minimumSplitDepth = requested < 8 ? 4 * ONE_PLY : 7 * ONE_PLY; - while (size() < requested) - push_back(new_thread()); + push_back(new Thread); while (size() > requested) - { - delete_thread(back()); - pop_back(); - } -} - - -// available_slave() tries to find an idle thread which is available as a slave -// for the thread 'master'. - -Thread* ThreadPool::available_slave(const Thread* master) const { - - for (const_iterator it = begin(); it != end(); ++it) - if ((*it)->available_to(master)) - return *it; - - return NULL; + delete back(), pop_back(); } -// 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. - -void Thread::split(Position& pos, const Stack* ss, Value alpha, Value beta, Value* bestValue, - Move* bestMove, Depth depth, int moveCount, - MovePicker* movePicker, int nodeType, bool cutNode) { - - assert(pos.pos_is_ok()); - assert(-VALUE_INFINITE < *bestValue && *bestValue <= alpha && alpha < beta && beta <= 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 = 0, sp.slavesMask.set(idx); - sp.depth = depth; - sp.bestValue = *bestValue; - sp.bestMove = *bestMove; - sp.alpha = alpha; - sp.beta = beta; - sp.nodeType = nodeType; - sp.cutNode = cutNode; - sp.movePicker = 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(); - - sp.allSlavesSearching = true; // Must be set under lock protection - ++splitPointsSize; - activeSplitPoint = &sp; - activePosition = NULL; - - for (Thread* slave; (slave = Threads.available_slave(this)) != NULL; ) - { - sp.slavesMask.set(slave->idx); - slave->activeSplitPoint = &sp; - slave->searching = true; // Slave leaves idle_loop() - slave->notify_one(); // Could be sleeping - } - - // 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. - sp.mutex.unlock(); - Threads.mutex.unlock(); - - Thread::idle_loop(); // Force a call to base class idle_loop() +/// ThreadPool::nodes_searched() returns the number of nodes searched - // In the helpful master concept, a master can help only a sub-tree of its - // split point and because everything is finished here, it's not possible - // for the master to be booked. - assert(!searching); - assert(!activePosition); +int64_t ThreadPool::nodes_searched() { - // 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::available_to(). - Threads.mutex.lock(); - sp.mutex.lock(); - - searching = true; - --splitPointsSize; - activeSplitPoint = sp.parentSplitPoint; - activePosition = &pos; - pos.set_nodes_searched(pos.nodes_searched() + sp.nodes); - *bestMove = sp.bestMove; - *bestValue = sp.bestValue; - - sp.mutex.unlock(); - Threads.mutex.unlock(); + int64_t nodes = 0; + for (Thread* th : *this) + nodes += th->rootPos.nodes_searched(); + return nodes; } -// wait_for_think_finished() waits for main thread to go to sleep then returns - -void ThreadPool::wait_for_think_finished() { - - MainThread* t = main(); - 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. -void ThreadPool::start_thinking(const Position& pos, const LimitsType& limits, StateStackPtr& states) { +/// ThreadPool::start_thinking() wakes up the main thread sleeping in idle_loop() +/// and starts a new search, then returns immediately. - wait_for_think_finished(); +void ThreadPool::start_thinking(const Position& pos, const LimitsType& limits, + 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; - RootMoves.clear(); - RootPos = pos; + main()->rootMoves.clear(); + main()->rootPos = pos; Limits = limits; if (states.get()) // If we don't set a new position, preserve current state { - SetupStates = states; // Ownership transfer here + SetupStates = std::move(states); // Ownership transfer here assert(!states.get()); } - for (MoveList it(pos); *it; ++it) + for (const auto& m : MoveList(pos)) if ( limits.searchmoves.empty() - || std::count(limits.searchmoves.begin(), limits.searchmoves.end(), *it)) - RootMoves.push_back(RootMove(*it)); + || std::count(limits.searchmoves.begin(), limits.searchmoves.end(), m)) + main()->rootMoves.push_back(RootMove(m)); - main()->thinking = true; - main()->notify_one(); // Starts main thread + main()->start_searching(); }