X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fthread.cpp;h=440b8bf0e4f06b5ea6087aa76c2e9aec3ca02cc0;hb=24dac5ccd309837c6767dcf6b145be385eea2e21;hp=dee37d0dd740b7f6bb784c8cdf8eb0115282ff91;hpb=05cfb00f26ca075ac972e320aaeabefe20599aea;p=stockfish diff --git a/src/thread.cpp b/src/thread.cpp index dee37d0d..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) 2008-2010 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 @@ -17,330 +18,179 @@ along with this program. If not, see . */ -#include +#include // For std::count +#include +#include "movegen.h" +#include "search.h" #include "thread.h" -#include "ucioption.h" +#include "uci.h" -ThreadsManager Threads; // Global object definition +using namespace Search; -namespace { +ThreadPool Threads; // Global object - // init_thread() is the function which is called when a new thread is - // launched. It simply calls the idle_loop() function with the supplied - // threadID. There are two versions of this function; one for POSIX - // threads and one for Windows threads. +/// Thread constructor launches the thread and then waits until it goes to sleep +/// in idle_loop(). -#if !defined(_MSC_VER) +Thread::Thread() { - void* init_thread(void* threadID) { - - Threads.idle_loop(*(int*)threadID, NULL); - return NULL; - } - -#else - - DWORD WINAPI init_thread(LPVOID threadID) { - - Threads.idle_loop(*(int*)threadID, NULL); - return 0; - } - -#endif + 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; }); } -// 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. +/// Thread destructor waits for thread termination before returning -void Thread::wake_up() { +Thread::~Thread() { - lock_grab(&sleepLock); - cond_signal(&sleepCond); - lock_release(&sleepLock); + mutex.lock(); + exit = true; + sleepCondition.notify_one(); + mutex.unlock(); + nativeThread.join(); } -// cutoff_occurred() checks whether a beta cutoff has occurred in -// the thread's currently active split point, or in some ancestor of -// the current split point. +/// Thread::wait_for_search_finished() waits on sleep condition +/// until not searching -bool Thread::cutoff_occurred() const { +void Thread::wait_for_search_finished() { - for (SplitPoint* sp = splitPoint; sp; sp = sp->parent) - if (sp->is_betaCutoff) - return true; - return false; + std::unique_lock lk(mutex); + sleepCondition.wait(lk, [&]{ return !searching; }); } -// 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). - -bool Thread::is_available_to(int master) const { - - if (state != AVAILABLE) - return false; - - // 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 localActiveSplitPoints = activeSplitPoints; +/// Thread::wait() waits on sleep condition until condition is true - // No active split points means that the thread is available as a slave for any - // other thread otherwise apply the "helpful master" concept if possible. - if ( !localActiveSplitPoints - || splitPoints[localActiveSplitPoints - 1].is_slave[master]) - return true; +void Thread::wait(std::atomic_bool& condition) { - return false; + std::unique_lock lk(mutex); + sleepCondition.wait(lk, [&]{ return bool(condition); }); } -// read_uci_options() updates number of active threads and other internal -// parameters according to the UCI options values. It is called before -// to start a new search. +/// Thread::start_searching() wakes up the thread that will start the search -void ThreadsManager::read_uci_options() { +void Thread::start_searching(bool resume) { - maxThreadsPerSplitPoint = Options["Maximum Number of Threads per Split Point"].value(); - minimumSplitDepth = Options["Minimum Split Depth"].value() * ONE_PLY; - useSleepingThreads = Options["Use Sleeping Threads"].value(); - activeThreads = Options["Threads"].value(); -} - - -// init_threads() is called during startup. Initializes locks and condition -// variables and launches all threads sending them immediately to sleep. + std::unique_lock lk(mutex); -void ThreadsManager::init() { + if (!resume) + searching = true; - int arg[MAX_THREADS]; - - // This flag is needed to properly end the threads when program exits - allThreadsShouldExit = false; + sleepCondition.notify_one(); +} - // Threads will sent to sleep as soon as created, only main thread is kept alive - activeThreads = 1; - threads[0].state = Thread::SEARCHING; - // Allocate pawn and material hash tables for main thread - init_hash_tables(); +/// Thread::idle_loop() is where the thread is parked when it has no work to do - lock_init(&mpLock); +void Thread::idle_loop() { - // Initialize thread and split point locks - for (int i = 0; i < MAX_THREADS; i++) + while (!exit) { - lock_init(&threads[i].sleepLock); - cond_init(&threads[i].sleepCond); + std::unique_lock lk(mutex); - for (int j = 0; j < MAX_ACTIVE_SPLIT_POINTS; j++) - lock_init(&(threads[i].splitPoints[j].lock)); - } + searching = false; - // Create and startup all the threads but the main that is already running - for (int i = 1; i < MAX_THREADS; i++) - { - threads[i].state = Thread::INITIALIZING; - arg[i] = i; - -#if !defined(_MSC_VER) - pthread_t pthread[1]; - bool ok = (pthread_create(pthread, NULL, init_thread, (void*)(&arg[i])) == 0); - pthread_detach(pthread[0]); -#else - bool ok = (CreateThread(NULL, 0, init_thread, (LPVOID)(&arg[i]), 0, NULL) != NULL); -#endif - if (!ok) + while (!searching && !exit) { - std::cout << "Failed to create thread number " << i << std::endl; - ::exit(EXIT_FAILURE); + sleepCondition.notify_one(); // Wake up any waiting thread + sleepCondition.wait(lk); } - // Wait until the thread has finished launching and is gone to sleep - while (threads[i].state == Thread::INITIALIZING) {} + lk.unlock(); + + if (!exit) + search(); } } -// exit_threads() is called when the program exits. It makes all the -// helper threads exit cleanly. +/// 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 ThreadsManager::exit() { +void ThreadPool::init() { - // Force the woken up threads to exit idle_loop() and hence terminate - allThreadsShouldExit = true; - - for (int i = 0; i < MAX_THREADS; i++) - { - // Wake up all the threads and waits for termination - if (i != 0) - { - threads[i].wake_up(); - while (threads[i].state != Thread::TERMINATED) {} - } - - // Now we can safely destroy the locks and wait conditions - lock_destroy(&threads[i].sleepLock); - cond_destroy(&threads[i].sleepCond); - - for (int j = 0; j < MAX_ACTIVE_SPLIT_POINTS; j++) - lock_destroy(&(threads[i].splitPoints[j].lock)); - } - - lock_destroy(&mpLock); + push_back(new MainThread); + read_uci_options(); } -// init_hash_tables() dynamically allocates pawn and material hash tables -// according to the number of active threads. This avoids preallocating -// memory for all possible threads if only few are used as, for instance, -// on mobile devices where memory is scarce and allocating for MAX_THREADS -// threads could even result in a crash. +/// 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 ThreadsManager::init_hash_tables() { +void ThreadPool::exit() { - for (int i = 0; i < activeThreads; i++) - { - threads[i].pawnTable.init(); - threads[i].materialTable.init(); - } + while (size()) + delete back(), pop_back(); } -// available_slave_exists() tries to find an idle thread which is available as -// a slave for the thread with threadID "master". +/// 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. -bool ThreadsManager::available_slave_exists(int master) const { +void ThreadPool::read_uci_options() { - assert(master >= 0 && master < activeThreads); + size_t requested = Options["Threads"]; - for (int i = 0; i < activeThreads; i++) - if (i != master && threads[i].is_available_to(master)) - return true; + assert(requested > 0); - return false; + while (size() < requested) + push_back(new Thread); + + while (size() > requested) + 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, or because we have no unused -// split point objects), 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 we tell our helper threads 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 -void ThreadsManager::split(Position& pos, SearchStack* ss, Value* alpha, const Value beta, - Value* bestValue, Depth depth, Move threatMove, - int moveCount, MovePicker* mp, bool pvNode) { - assert(pos.is_ok()); - assert(*bestValue >= -VALUE_INFINITE); - assert(*bestValue <= *alpha); - assert(*alpha < beta); - assert(beta <= VALUE_INFINITE); - assert(depth > DEPTH_ZERO); - assert(pos.thread() >= 0 && pos.thread() < activeThreads); - assert(activeThreads > 1); - - int i, master = pos.thread(); - Thread& masterThread = threads[master]; - - lock_grab(&mpLock); - - // If no other thread is available to help us, or if we have too many - // active split points, don't split. - if ( !available_slave_exists(master) - || masterThread.activeSplitPoints >= MAX_ACTIVE_SPLIT_POINTS) - { - lock_release(&mpLock); - return; - } +/// ThreadPool::nodes_searched() returns the number of nodes searched - // Pick the next available split point object from the split point stack - SplitPoint& splitPoint = masterThread.splitPoints[masterThread.activeSplitPoints++]; - - // Initialize the split point object - splitPoint.parent = masterThread.splitPoint; - splitPoint.master = master; - splitPoint.is_betaCutoff = false; - splitPoint.depth = depth; - splitPoint.threatMove = threatMove; - splitPoint.alpha = *alpha; - splitPoint.beta = beta; - splitPoint.pvNode = pvNode; - splitPoint.bestValue = *bestValue; - splitPoint.mp = mp; - splitPoint.moveCount = moveCount; - splitPoint.pos = &pos; - splitPoint.nodes = 0; - splitPoint.ss = ss; - for (i = 0; i < activeThreads; i++) - splitPoint.is_slave[i] = false; - - masterThread.splitPoint = &splitPoint; - - // If we are here it means we are not available - assert(masterThread.state != Thread::AVAILABLE); - - int workersCnt = 1; // At least the master is included - - // Allocate available threads setting state to THREAD_BOOKED - for (i = 0; !Fake && i < activeThreads && workersCnt < maxThreadsPerSplitPoint; i++) - if (i != master && threads[i].is_available_to(master)) - { - threads[i].state = Thread::BOOKED; - threads[i].splitPoint = &splitPoint; - splitPoint.is_slave[i] = true; - workersCnt++; - } +int64_t ThreadPool::nodes_searched() { - assert(Fake || workersCnt > 1); + int64_t nodes = 0; + for (Thread* th : *this) + nodes += th->rootPos.nodes_searched(); + return nodes; +} - // We can release the lock because slave threads are already booked and master is not available - lock_release(&mpLock); - // Tell the threads that they have work to do. This will make them leave - // their idle loop. - for (i = 0; i < activeThreads; i++) - if (i == master || splitPoint.is_slave[i]) - { - assert(i == master || threads[i].state == Thread::BOOKED); +/// ThreadPool::start_thinking() wakes up the main thread sleeping in idle_loop() +/// and starts a new search, then returns immediately. - threads[i].state = Thread::WORKISWAITING; // This makes the slave to exit from idle_loop() +void ThreadPool::start_thinking(const Position& pos, const LimitsType& limits, + StateStackPtr& states) { - if (useSleepingThreads && i != master) - threads[i].wake_up(); - } + main()->wait_for_search_finished(); - // Everything is set up. The master thread enters the idle loop, from - // which it will instantly launch a search, because its state is - // THREAD_WORKISWAITING. We send the split point as a second parameter to the - // idle loop, which means that the main thread will return from the idle - // loop when all threads have finished their work at this split point. - idle_loop(master, &splitPoint); + Signals.stopOnPonderhit = Signals.stop = false; - // We have returned from the idle loop, which means that all threads are - // finished. Update alpha and bestValue, and return. - lock_grab(&mpLock); + main()->rootMoves.clear(); + main()->rootPos = pos; + Limits = limits; + if (states.get()) // If we don't set a new position, preserve current state + { + SetupStates = std::move(states); // Ownership transfer here + assert(!states.get()); + } - *alpha = splitPoint.alpha; - *bestValue = splitPoint.bestValue; - masterThread.activeSplitPoints--; - masterThread.splitPoint = splitPoint.parent; - pos.set_nodes_searched(pos.nodes_searched() + splitPoint.nodes); + 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)); - lock_release(&mpLock); + main()->start_searching(); } - -// Explicit template instantiations -template void ThreadsManager::split(Position&, SearchStack*, Value*, const Value, Value*, Depth, Move, int, MovePicker*, bool); -template void ThreadsManager::split(Position&, SearchStack*, Value*, const Value, Value*, Depth, Move, int, MovePicker*, bool);