X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fthread.cpp;h=4ae268eb77b9ae885554bf4e60c78ef1e2ebf032;hp=031ee848e6343ea44c33835198a9411320b10a32;hb=0439a79566d03065317b2025b9b479b9ae9f2d65;hpb=41561c9bb80a176f9fce169975fcb553340499fc diff --git a/src/thread.cpp b/src/thread.cpp index 031ee848..4ae268eb 100644 --- a/src/thread.cpp +++ b/src/thread.cpp @@ -32,37 +32,25 @@ ThreadsManager Threads; // Global object namespace { extern "C" { // start_routine() is the C function which is called when a new thread - // is launched. It simply calls idle_loop() of the supplied thread. The first - // and last thread are special. First one is the main search thread while the - // last one mimics a timer, they run in main_loop() and timer_loop(). + // is launched. It is a wrapper to member function pointed by start_fn. - long start_routine(Thread* th) { - - if (th->threadID == 0) - th->main_loop(); - - else if (th->threadID == MAX_THREADS) - th->timer_loop(); - - else - th->idle_loop(NULL); - - return 0; - } + long start_routine(Thread* th) { (th->*(th->start_fn))(); return 0; } } } -// Thread c'tor creates and launches the OS thread, that will go immediately to -// sleep. +// Thread c'tor starts a newly-created thread of execution that will call +// the idle loop function pointed by start_fn going immediately to sleep. -Thread::Thread(int id) { +Thread::Thread(Fn fn) { is_searching = do_exit = false; maxPly = splitPointsCnt = 0; curSplitPoint = NULL; - threadID = id; - do_sleep = (id != 0); // Avoid a race with start_thinking() + start_fn = fn; + threadID = Threads.size(); + + do_sleep = (fn != &Thread::main_loop); // Avoid a race with start_searching() lock_init(sleepLock); cond_init(sleepCond); @@ -72,13 +60,13 @@ Thread::Thread(int id) { if (!thread_create(handle, start_routine, this)) { - std::cerr << "Failed to create thread number " << id << std::endl; + std::cerr << "Failed to create thread number " << threadID << std::endl; ::exit(EXIT_FAILURE); } } -// Thread d'tor will wait for thread termination before to return. +// Thread d'tor waits for thread termination before to return. Thread::~Thread() { @@ -98,7 +86,7 @@ Thread::~Thread() { // Thread::timer_loop() is where the timer thread waits maxPly milliseconds and -// then calls do_timer_event(). If maxPly is 0 thread sleeps until is woken up. +// then calls check_time(). If maxPly is 0 thread sleeps until is woken up. extern void check_time(); void Thread::timer_loop() { @@ -144,7 +132,7 @@ void Thread::main_loop() { // Thread::wake_up() wakes up the thread, normally at the beginning of the search -// or, if "sleeping threads" is used, when there is some work to do. +// or, if "sleeping threads" is used at split time. void Thread::wake_up() { @@ -166,16 +154,13 @@ void Thread::wait_for_stop_or_ponderhit() { Signals.stopOnPonderhit = true; lock_grab(sleepLock); - - while (!Signals.stop) - cond_wait(sleepCond, sleepLock); - + while (!Signals.stop) cond_wait(sleepCond, sleepLock); lock_release(sleepLock); } -// cutoff_occurred() checks whether a beta cutoff has occurred in the current -// active split point, or in some ancestor of the split point. +// 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 { @@ -187,12 +172,12 @@ bool Thread::cutoff_occurred() const { } -// is_available_to() checks whether the thread is available to help the thread with -// threadID "master" at a split point. An obvious requirement is that thread must be -// idle. With more than two threads, this is not by itself sufficient: If the thread -// is the master of some active split point, it is only available as a slave to the -// threads which are busy searching the split point at the top of "slave"'s split -// point stack (the "helpful master concept" in YBWC terminology). +// Thread::is_available_to() checks whether the thread is available to help the +// thread with threadID "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 active split point, it is only available as a +// slave to the threads which are busy searching the split point at the top of +// "slave"'s split point stack (the "helpful master concept" in YBWC terminology). bool Thread::is_available_to(int master) const { @@ -209,6 +194,34 @@ bool Thread::is_available_to(int master) const { } +// init() is called at startup. Initializes lock and condition variable and +// launches requested threads sending them immediately to sleep. 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. + +void ThreadsManager::init() { + + cond_init(sleepCond); + lock_init(splitLock); + timer = new Thread(&Thread::timer_loop); + threads.push_back(new Thread(&Thread::main_loop)); + read_uci_options(); +} + + +// d'tor cleanly terminates the threads when the program exits. + +ThreadsManager::~ThreadsManager() { + + for (int i = 0; i < size(); i++) + delete threads[i]; + + delete timer; + lock_destroy(splitLock); + cond_destroy(sleepCond); +} + + // 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 @@ -221,8 +234,10 @@ void ThreadsManager::read_uci_options() { useSleepingThreads = Options["Use Sleeping Threads"]; int requested = Options["Threads"]; + assert(requested > 0); + while (size() < requested) - threads.push_back(new Thread(size())); + threads.push_back(new Thread(&Thread::idle_loop)); while (size() > requested) { @@ -233,13 +248,14 @@ void ThreadsManager::read_uci_options() { // wake_up() is called before a new search to start the threads that are waiting -// on the sleep condition. If useSleepingThreads is set threads will be woken up -// at split time. +// on the sleep condition and to reset maxPly. When useSleepingThreads is set +// threads will be woken up at split time. -void ThreadsManager::wake_up() { +void ThreadsManager::wake_up() const { for (int i = 0; i < size(); i++) { + threads[i]->maxPly = 0; threads[i]->do_sleep = false; if (!useSleepingThreads) @@ -248,37 +264,13 @@ void ThreadsManager::wake_up() { } -// sleep() is called after the search to ask threads to wait on sleep condition - -void ThreadsManager::sleep() { - - for (int i = 0; i < size(); i++) - threads[i]->do_sleep = true; -} - - -// init() is called during startup. Initializes locks and condition variables -// and launches all threads sending them immediately to sleep. +// sleep() is called after the search finishes to ask all the threads but the +// main one to go waiting on a sleep condition. -void ThreadsManager::init() { +void ThreadsManager::sleep() const { - cond_init(sleepCond); - lock_init(splitLock); - timer = new Thread(MAX_THREADS); - read_uci_options(); // Creates at least the main thread -} - - -// exit() is called to cleanly terminate the threads before the program finishes - -void ThreadsManager::exit() { - - for (int i = 0; i < size(); i++) - delete threads[i]; - - delete timer; - lock_destroy(splitLock); - cond_destroy(sleepCond); + for (int i = 1; i < size(); i++) // Main thread will go to sleep by itself + threads[i]->do_sleep = true; // to avoid a race with start_searching() } @@ -317,7 +309,7 @@ Value ThreadsManager::split(Position& pos, Stack* ss, Value alpha, Value beta, assert(beta <= VALUE_INFINITE); assert(depth > DEPTH_ZERO); - int master = pos.thread(); + int master = pos.this_thread(); Thread& masterThread = *threads[master]; if (masterThread.splitPointsCnt >= MAX_SPLITPOINTS_PER_THREAD) @@ -420,63 +412,39 @@ void ThreadsManager::set_timer(int msec) { } -// ThreadsManager::start_thinking() is used by UI thread to wake up the main -// thread parked in main_loop() and starting a new search. If asyncMode is true -// then function returns immediately, otherwise caller is blocked waiting for -// the search to finish. - -void ThreadsManager::start_thinking(const Position& pos, const LimitsType& limits, - const std::set& searchMoves, bool async) { - Thread& main = *threads.front(); - - lock_grab(main.sleepLock); +// ThreadsManager::wait_for_search_finished() waits for main thread to go to +// sleep, this means search is finished. Then returns. - // Wait main thread has finished before to launch a new search - while (!main.do_sleep) - cond_wait(sleepCond, main.sleepLock); - - // Copy input arguments to initialize the search - RootPosition.copy(pos, 0); - Limits = limits; - RootMoves.clear(); +void ThreadsManager::wait_for_search_finished() { - // Populate RootMoves with all the legal moves (default) or, if a searchMoves - // set is given, with the subset of legal moves to search. - for (MoveList ml(pos); !ml.end(); ++ml) - if (searchMoves.empty() || searchMoves.count(ml.move())) - RootMoves.push_back(RootMove(ml.move())); - - // Reset signals before to start the new search - Signals.stopOnPonderhit = Signals.firstRootMove = false; - Signals.stop = Signals.failedLowAtRoot = false; - - main.do_sleep = false; - cond_signal(main.sleepCond); // Wake up main thread and start searching - - if (!async) - while (!main.do_sleep) - cond_wait(sleepCond, main.sleepLock); - - lock_release(main.sleepLock); + Thread* main = threads[0]; + lock_grab(main->sleepLock); + cond_signal(main->sleepCond); // In case is waiting for stop or ponderhit + while (!main->do_sleep) cond_wait(sleepCond, main->sleepLock); + lock_release(main->sleepLock); } -// ThreadsManager::stop_thinking() is used by UI thread to raise a stop request -// and to wait for the main thread finishing the search. Needed to wait exiting -// and terminate the threads after a 'quit' command. +// ThreadsManager::start_searching() wakes up the main thread sleeping in +// main_loop() so to start a new search, then returns immediately. -void ThreadsManager::stop_thinking() { +void ThreadsManager::start_searching(const Position& pos, const LimitsType& limits, + const std::vector& searchMoves) { + wait_for_search_finished(); - Thread& main = *threads.front(); + SearchTime.restart(); // As early as possible - Search::Signals.stop = true; - - lock_grab(main.sleepLock); + Signals.stopOnPonderhit = Signals.firstRootMove = false; + Signals.stop = Signals.failedLowAtRoot = false; - cond_signal(main.sleepCond); // In case is waiting for stop or ponderhit + RootPosition.copy(pos, 0); + Limits = limits; + RootMoves.clear(); - while (!main.do_sleep) - cond_wait(sleepCond, main.sleepLock); + for (MoveList ml(pos); !ml.end(); ++ml) + if (searchMoves.empty() || count(searchMoves.begin(), searchMoves.end(), ml.move())) + RootMoves.push_back(RootMove(ml.move())); - lock_release(main.sleepLock); + threads[0]->do_sleep = false; + threads[0]->wake_up(); }