X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fthread.cpp;h=c76b4b707e9f97dfe641670de06021b982481287;hp=1a39651673c2212aa40bb39a3d5b2c7b00ca694e;hb=9c9205860c5ab0e4f3180298e3f7082be259772c;hpb=ddbe6082c47befcfe2bd2e778866c8fbda33b8e2 diff --git a/src/thread.cpp b/src/thread.cpp index 1a396516..c76b4b70 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 @@ -19,362 +19,216 @@ #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" { +namespace { - // 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(). + // 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. - long start_routine(Thread* th) { th->idle_loop(); return 0; } + template T* new_thread() { + std::thread* th = new T; + *th = std::thread(&T::idle_loop, (T*)th); // Will go to sleep + return (T*)th; + } -} } + void delete_thread(ThreadBase* th) { + th->mutex.lock(); + th->exit = true; // Search must be already finished + th->mutex.unlock(); -// Thread c'tor starts a newly-created thread of execution that will call -// the the virtual function idle_loop(), going immediately to sleep. + th->notify_one(); + th->join(); // Wait for thread termination + delete th; + } -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); - } } -// Thread d'tor waits for thread termination before to return +// ThreadBase::notify_one() wakes up the thread when there is some work to do -Thread::~Thread() { +void ThreadBase::notify_one() { - exit = true; // Search must be already finished - notify_one(); - thread_join(handle); // Wait for thread termination + std::unique_lock lk(mutex); + 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 is woken up. -extern void check_time(); +// ThreadBase::wait() set the thread to sleep until 'condition' turns true -void TimerThread::idle_loop() { +void ThreadBase::wait(std::atomic_bool& condition) { - while (!exit) - { - mutex.lock(); + std::unique_lock lk(mutex); + sleepCondition.wait(lk, [&]{ return bool(condition); }); +} - if (!exit) - sleepCondition.wait_for(mutex, msec ? msec : INT_MAX); - mutex.unlock(); +// ThreadBase::wait_while() set the thread to sleep until 'condition' turns false +void ThreadBase::wait_while(std::atomic_bool& condition) { - if (msec) - check_time(); - } + std::unique_lock lk(mutex); + sleepCondition.wait(lk, [&]{ return !condition; }); } -// 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 constructor makes some init but does not launch any execution thread, +// which will be started only when the constructor returns. -void MainThread::idle_loop() { +Thread::Thread() { - while (true) - { - mutex.lock(); + searching = resetCallsCnt = false; + maxPly = callsCnt = 0; + history.clear(); + counterMoves.clear(); + idx = Threads.size(); // Starts from 0 +} - thinking = false; - while (!thinking && !exit) - { - Threads.sleepCondition.notify_one(); // Wake up UI thread if needed - sleepCondition.wait(mutex); - } - - mutex.unlock(); +// Thread::idle_loop() is where the thread is parked when it has no work to do - if (exit) - return; +void Thread::idle_loop() { - searching = true; + while (!exit) + { + std::unique_lock lk(mutex); - Search::think(); + while (!searching && !exit) + sleepCondition.wait(lk); - assert(searching); + lk.unlock(); - searching = false; + if (!exit && searching) + search(); } } -// 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) { +// 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. - mutex.lock(); - while (!b) sleepCondition.wait(mutex); - mutex.unlock(); -} +void MainThread::idle_loop() { + while (!exit) + { + std::unique_lock lk(mutex); -// Thread::cutoff_occurred() checks whether a beta cutoff has occurred in the -// current active split point, or in some ancestor of the split point. + thinking = false; -bool Thread::cutoff_occurred() const { + while (!thinking && !exit) + { + sleepCondition.notify_one(); // Wake up the UI thread if needed + sleepCondition.wait(lk); + } - for (SplitPoint* sp = activeSplitPoint; sp; sp = sp->parent) - if (sp->cutoff) - return true; + lk.unlock(); - return false; + if (!exit) + think(); + } } -// 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). - -bool Thread::is_available_to(Thread* master) const { - - if (searching) - return false; +// MainThread::join() waits for main thread to finish thinking - // 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; +void MainThread::join() { - // 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)); + std::unique_lock lk(mutex); + sleepCondition.wait(lk, [&]{ return !thinking; }); } -// 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() 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() { - sleepWhileIdle = true; - timer = new TimerThread(); - threads.push_back(new MainThread()); + push_back(new_thread()); read_uci_options(); } -// exit() cleanly terminates the threads before the program exits +// 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() { - delete timer; // As first because check_time() accesses threads data + for (Thread* th : *this) + delete_thread(th); - for (size_t i = 0; i < threads.size(); i++) - delete threads[i]; + clear(); // Get rid of stale pointers } -// 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 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() { - 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 (threads.size() > requested) - { - delete threads.back(); - threads.pop_back(); - } -} - - -// slave_available() tries to find an idle thread which is available as a slave -// for the thread 'master'. - -bool ThreadPool::slave_available(Thread* master) const { - - for (size_t i = 0; i < threads.size(); i++) - if (threads[i]->is_available_to(master)) - return true; + while (size() < requested) + push_back(new_thread()); - return false; -} - - -// 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 ThreadPool::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); - - Thread* master = pos.this_thread(); - - assert(master->searching); - assert(master->splitPointsSize < MAX_SPLITPOINTS_PER_THREAD); - - // Pick the next available split point from the split point stack - SplitPoint& sp = master->splitPoints[master->splitPointsSize]; - - sp.master = master; - sp.parent = master->activeSplitPoint; - sp.slavesMask = 1ULL << master->idx; - sp.depth = depth; - sp.bestMove = *bestMove; - sp.threatMove = threatMove; - sp.alpha = alpha; - sp.beta = beta; - sp.nodeType = nodeType; - sp.bestValue = bestValue; - sp.mp = ∓ - 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. - mutex.lock(); - sp.mutex.lock(); - - master->splitPointsSize++; - master->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(master) && ++slavesCnt <= 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(); - 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) + while (size() > requested) { - master->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(!master->searching); + delete_thread(back()); + pop_back(); } - - // 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(). - mutex.lock(); - sp.mutex.lock(); - - master->searching = true; - master->splitPointsSize--; - master->activeSplitPoint = sp.parent; - pos.set_nodes_searched(pos.nodes_searched() + sp.nodes); - *bestMove = sp.bestMove; - - sp.mutex.unlock(); - mutex.unlock(); - - return sp.bestValue; } -// Explicit template instantiations -template Value ThreadPool::split(Position&, Stack*, Value, Value, Value, Move*, Depth, Move, int, MovePicker&, int); -template Value ThreadPool::split(Position&, Stack*, Value, Value, Value, Move*, Depth, Move, int, MovePicker&, int); +// ThreadPool::nodes_searched() returns the number of nodes searched -// wait_for_think_finished() waits for main thread to go to sleep then returns +int64_t ThreadPool::nodes_searched() { -void ThreadPool::wait_for_think_finished() { - - MainThread* t = main_thread(); - t->mutex.lock(); - while (t->thinking) sleepCondition.wait(t->mutex); - t->mutex.unlock(); + int64_t nodes = 0; + for (Thread *th : *this) + nodes += th->rootPos.nodes_searched(); + return nodes; } -// start_thinking() wakes up the main thread sleeping in MainThread::idle_loop() -// so to start a new search, then returns immediately. +// ThreadPool::start_thinking() wakes up the main thread sleeping in +// MainThread::idle_loop() and starts a new search, then returns immediately. void ThreadPool::start_thinking(const Position& pos, const LimitsType& limits, - const std::vector& searchMoves, StateStackPtr& states) { - wait_for_think_finished(); - - SearchTime = Time::now(); // As early as possible + StateStackPtr& states) { + main()->join(); Signals.stopOnPonderhit = Signals.firstRootMove = false; Signals.stop = Signals.failedLowAtRoot = 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()->thinking = true; + main()->notify_one(); // Wake up main thread: 'thinking' must be already set }