X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fthread.cpp;h=65d01d9100a874e19db9addea3772bafa735dd69;hp=0d11a2d5330d1b3a720bd67faf56e58689e46130;hb=3aa471f2a9cb;hpb=553655eb073cdd59c726dd77fcf368d499029467 diff --git a/src/thread.cpp b/src/thread.cpp index 0d11a2d5..65d01d91 100644 --- a/src/thread.cpp +++ b/src/thread.cpp @@ -32,34 +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::Thread(int id) { +// 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(Fn fn) { - threadID = id; - do_sleep = (id != 0); // Avoid a race with start_thinking() is_searching = do_exit = false; maxPly = splitPointsCnt = 0; curSplitPoint = NULL; + start_fn = fn; + threadID = Threads.size(); + + do_sleep = (fn != &Thread::main_loop); // Avoid a race with start_searching() lock_init(sleepLock); cond_init(sleepCond); @@ -69,12 +60,14 @@ 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 waits for thread termination before to return. + Thread::~Thread() { assert(do_sleep); @@ -93,7 +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() { @@ -139,11 +132,12 @@ 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() { lock_grab(sleepLock); + do_sleep = false; cond_signal(sleepCond); lock_release(sleepLock); } @@ -161,16 +155,13 @@ 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 { @@ -182,12 +173,12 @@ 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 { @@ -204,70 +195,82 @@ 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. It is called before to start a new search. +// 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. void ThreadsManager::read_uci_options() { maxThreadsPerSplitPoint = Options["Max Threads per Split Point"]; minimumSplitDepth = Options["Min Split Depth"] * ONE_PLY; useSleepingThreads = Options["Use Sleeping Threads"]; - activeThreads = Options["Threads"]; - - // Dynamically allocate Thread object according to the number of - // active threads. This avoids preallocating memory for all possible - // threads if only few are used. - for (int i = 0; i < MAX_THREADS; i++) - if (i < activeThreads && !threads[i]) - threads[i] = new Thread(i); - else if (i >= activeThreads && threads[i]) - { - delete threads[i]; - threads[i] = NULL; - } -} + int requested = Options["Threads"]; + assert(requested > 0); -void ThreadsManager::wake_up() { + while (size() < requested) + threads.push_back(new Thread(&Thread::idle_loop)); - for (int i = 0; i < activeThreads; i++) + while (size() > requested) { - threads[i]->do_sleep = false; - threads[i]->wake_up(); + delete threads.back(); + threads.pop_back(); } } -void ThreadsManager::sleep() { - - for (int i = 0; i < activeThreads; i++) - threads[i]->do_sleep = true; -} +// wake_up() is called before a new search to start the threads that are waiting +// on the sleep condition and to reset maxPly. When useSleepingThreads is set +// threads will be woken up at split time. +void ThreadsManager::wake_up() const { -// init() is called during startup. Initializes locks and condition variables -// and launches all threads sending them immediately to sleep. - -void ThreadsManager::init() { + for (int i = 0; i < size(); i++) + { + threads[i]->maxPly = 0; - cond_init(sleepCond); - lock_init(splitLock); - timer = new Thread(MAX_THREADS); - read_uci_options(); // Creates at least main thread + if (!useSleepingThreads) + threads[i]->wake_up(); + } } -// exit() is called to cleanly terminate the threads when the program finishes +// 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::exit() { +void ThreadsManager::sleep() const { - for (int i = 0; i < MAX_THREADS; i++) - if (threads[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() } @@ -276,9 +279,9 @@ void ThreadsManager::exit() { bool ThreadsManager::available_slave_exists(int master) const { - assert(master >= 0 && master < activeThreads); + assert(master >= 0 && master < size()); - for (int i = 0; i < activeThreads; i++) + for (int i = 0; i < size(); i++) if (threads[i]->is_available_to(master)) return true; @@ -305,8 +308,6 @@ Value ThreadsManager::split(Position& pos, Stack* ss, Value alpha, Value beta, assert(alpha < beta); assert(beta <= VALUE_INFINITE); assert(depth > DEPTH_ZERO); - assert(pos.thread() >= 0 && pos.thread() < activeThreads); - assert(activeThreads > 1); int master = pos.thread(); Thread& masterThread = *threads[master]; @@ -345,7 +346,7 @@ Value ThreadsManager::split(Position& pos, Stack* ss, Value alpha, Value beta, lock_grab(sp->lock); lock_grab(splitLock); - for (int i = 0; i < activeThreads && !Fake; i++) + for (int i = 0; i < size() && !Fake; ++i) if (threads[i]->is_available_to(master)) { sp->slavesMask |= 1ULL << i; @@ -411,63 +412,40 @@ 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 +// ThreadsManager::wait_for_search_finished() waits for main thread to go to +// sleep, this means search is finished. Then returns. + +void ThreadsManager::wait_for_search_finished() { + + Thread* main = threads[0]; + lock_grab(main->sleepLock); + while (!main->do_sleep) cond_wait(sleepCond, main->sleepLock); + lock_release(main->sleepLock); +} + + +// ThreadsManager::start_searching() is used by UI thread to wake up the main +// thread parked in main_loop() and starting a new search. If async 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[0]; - - lock_grab(main.sleepLock); +void ThreadsManager::start_searching(const Position& pos, const LimitsType& limits, + const std::set& searchMoves, bool async) { + wait_for_search_finished(); - // Wait main thread has finished before to launch a new search - while (!main.do_sleep) - cond_wait(sleepCond, main.sleepLock); + Signals.stopOnPonderhit = Signals.firstRootMove = false; + Signals.stop = Signals.failedLowAtRoot = false; - // Copy input arguments to initialize the search RootPosition.copy(pos, 0); Limits = limits; RootMoves.clear(); - // 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 + threads[0]->wake_up(); // Start main thread if (!async) - 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. - -void ThreadsManager::stop_thinking() { - - Thread& main = *threads[0]; - - Search::Signals.stop = true; - - 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); + wait_for_search_finished(); }