/*
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
+ 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
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
+#include <algorithm> // For std::count
#include <cassert>
-#include <iostream>
#include "movegen.h"
#include "search.h"
#include "thread.h"
-#include "ucioption.h"
+#include "uci.h"
-using namespace Search;
+ThreadPool Threads; // Global object
-ThreadsManager Threads; // Global object
+/// Thread constructor launches the thread and then waits until it goes to sleep
+/// in idle_loop().
-namespace { extern "C" {
+Thread::Thread() {
- // 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().
+ resetCalls = exit = false;
+ maxPly = callsCnt = 0;
+ history.clear();
+ counterMoves.clear();
+ idx = Threads.size(); // Start from 0
-#if defined(_WIN32) || defined(_WIN64)
- DWORD WINAPI start_routine(LPVOID thread) {
-#else
- void* start_routine(void* thread) {
-#endif
-
- Thread* th = (Thread*)thread;
-
- if (th->threadID == 0)
- th->main_loop();
-
- else if (th->threadID == MAX_THREADS)
- th->timer_loop();
-
- else
- th->idle_loop(NULL);
-
- return 0;
- }
-
-} }
-
-
-// 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.
-extern void check_time();
-
-void Thread::timer_loop() {
-
- while (!do_exit)
- {
- lock_grab(sleepLock);
- timed_wait(sleepCond, sleepLock, maxPly ? maxPly : INT_MAX);
- lock_release(sleepLock);
- check_time();
- }
-}
-
-
-// Thread::main_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.
-
-void Thread::main_loop() {
-
- while (true)
- {
- lock_grab(sleepLock);
-
- do_sleep = true; // Always return to sleep after a search
- is_searching = false;
-
- while (do_sleep && !do_exit)
- {
- cond_signal(Threads.sleepCond); // Wake up UI thread if needed
- cond_wait(sleepCond, sleepLock);
- }
-
- lock_release(sleepLock);
-
- if (do_exit)
- return;
-
- is_searching = true;
-
- Search::think();
- }
+ std::unique_lock<Mutex> lk(mutex);
+ searching = true;
+ nativeThread = std::thread(&Thread::idle_loop, this);
+ sleepCondition.wait(lk, [&]{ return !searching; });
}
-// 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.
+/// 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();
}
-// Thread::wait_for_stop_or_ponderhit() is called when the maximum depth is
-// reached while the program is pondering. The point is to work around a wrinkle
-// in the UCI protocol: When pondering, the engine is not allowed to give a
-// "bestmove" before the GUI sends it a "stop" or "ponderhit" command. We simply
-// wait here until one of these commands (that raise StopRequest) is sent and
-// then return, after which the bestmove and pondermove will be printed.
-
-void Thread::wait_for_stop_or_ponderhit() {
-
- Signals.stopOnPonderhit = true;
+/// Thread::wait_for_search_finished() waits on sleep condition
+/// until not searching
- lock_grab(sleepLock);
+void Thread::wait_for_search_finished() {
- while (!Signals.stop)
- cond_wait(sleepCond, sleepLock);
-
- lock_release(sleepLock);
+ std::unique_lock<Mutex> 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 = curSplitPoint; sp; sp = sp->parent)
- if (sp->cutoff)
- return true;
+void Thread::wait(std::atomic_bool& condition) {
- return false;
+ std::unique_lock<Mutex> lk(mutex);
+ sleepCondition.wait(lk, [&]{ return bool(condition); });
}
-// 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::start_searching() wakes up the thread that will start the search
-bool Thread::is_available_to(int master) const {
+void Thread::start_searching(bool resume) {
- if (is_searching)
- return false;
+ std::unique_lock<Mutex> lk(mutex);
- // 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 spCnt = splitPointsCnt;
+ if (!resume)
+ searching = 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.
- return !spCnt || (splitPoints[spCnt - 1].slavesMask & (1ULL << master));
+ sleepCondition.notify_one();
}
-// read_uci_options() updates internal threads parameters from the corresponding
-// UCI options. It is called before to start a new search.
-
-void ThreadsManager::read_uci_options() {
-
- maxThreadsPerSplitPoint = Options["Max Threads per Split Point"];
- minimumSplitDepth = Options["Min Split Depth"] * ONE_PLY;
- useSleepingThreads = Options["Use Sleeping Threads"];
-}
-
-
-// set_size() changes the number of active threads and raises do_sleep flag for
-// all the unused threads that will go immediately to sleep.
-
-void ThreadsManager::set_size(int cnt) {
-
- assert(cnt > 0 && cnt < MAX_THREADS);
-
- activeThreads = cnt;
-
- for (int i = 0; i < MAX_THREADS; i++)
- if (i < activeThreads)
- {
- // Dynamically allocate 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.
- threads[i].pawnTable.init();
- threads[i].materialTable.init();
- threads[i].maxPly = 0;
+/// Thread::idle_loop() is where the thread is parked when it has no work to do
- threads[i].do_sleep = false;
+void Thread::idle_loop() {
- if (!useSleepingThreads)
- threads[i].wake_up();
- }
- else
- threads[i].do_sleep = true;
-}
-
-
-// init() is called during startup. Initializes locks and condition variables
-// and launches all threads sending them immediately to sleep.
-
-void ThreadsManager::init() {
-
- cond_init(sleepCond);
- lock_init(splitLock);
-
- for (int i = 0; i <= MAX_THREADS; i++)
+ while (!exit)
{
- lock_init(threads[i].sleepLock);
- cond_init(threads[i].sleepCond);
-
- for (int j = 0; j < MAX_SPLITPOINTS_PER_THREAD; j++)
- lock_init(threads[i].splitPoints[j].lock);
- }
+ std::unique_lock<Mutex> lk(mutex);
- // Allocate main thread tables to call evaluate() also when not searching
- threads[0].pawnTable.init();
- threads[0].materialTable.init();
-
- // Create and launch all the threads, threads will go immediately to sleep
- for (int i = 0; i <= MAX_THREADS; i++)
- {
- threads[i].is_searching = false;
- threads[i].do_sleep = (i != 0); // Avoid a race with start_thinking()
- threads[i].threadID = i;
+ searching = false;
- if (!thread_create(threads[i].handle, start_routine, threads[i]))
+ while (!searching && !exit)
{
- std::cerr << "Failed to create thread number " << i << std::endl;
- ::exit(EXIT_FAILURE);
+ sleepCondition.notify_one(); // Wake up any waiting thread
+ sleepCondition.wait(lk);
}
- }
-}
-
-
-// exit() is called to cleanly terminate the threads when the program finishes
-
-void ThreadsManager::exit() {
- for (int i = 0; i <= MAX_THREADS; i++)
- {
- assert(threads[i].do_sleep);
-
- threads[i].do_exit = true; // Search must be already finished
- threads[i].wake_up();
-
- thread_join(threads[i].handle); // Wait for thread termination
+ lk.unlock();
- lock_destroy(threads[i].sleepLock);
- cond_destroy(threads[i].sleepCond);
-
- for (int j = 0; j < MAX_SPLITPOINTS_PER_THREAD; j++)
- lock_destroy(threads[i].splitPoints[j].lock);
+ if (!exit)
+ search();
}
-
- lock_destroy(splitLock);
- cond_destroy(sleepCond);
}
-// available_slave_exists() tries to find an idle thread which is available as
-// a slave for the thread with threadID 'master'.
+/// 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.
-bool ThreadsManager::available_slave_exists(int master) const {
+void ThreadPool::init() {
- assert(master >= 0 && master < activeThreads);
-
- for (int i = 0; i < activeThreads; i++)
- if (threads[i].is_available_to(master))
- return true;
-
- return false;
+ push_back(new MainThread);
+ read_uci_options();
}
-// 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 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 <bool Fake>
-Value ThreadsManager::split(Position& pos, Stack* ss, Value alpha, Value beta,
- Value bestValue, Depth depth, Move threatMove,
- int moveCount, MovePicker* mp, int nodeType) {
- assert(pos.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 master = pos.thread();
- Thread& masterThread = threads[master];
-
- if (masterThread.splitPointsCnt >= MAX_SPLITPOINTS_PER_THREAD)
- return bestValue;
-
- // Pick the next available split point from the split point stack
- SplitPoint* sp = &masterThread.splitPoints[masterThread.splitPointsCnt++];
-
- sp->parent = masterThread.curSplitPoint;
- sp->master = master;
- sp->cutoff = false;
- sp->slavesMask = 1ULL << master;
- sp->depth = depth;
- sp->threatMove = threatMove;
- sp->alpha = alpha;
- sp->beta = beta;
- sp->nodeType = nodeType;
- sp->bestValue = bestValue;
- sp->mp = mp;
- sp->moveCount = moveCount;
- sp->pos = &pos;
- sp->nodes = 0;
- sp->ss = ss;
-
- assert(masterThread.is_searching);
-
- masterThread.curSplitPoint = sp;
- int slavesCnt = 0;
-
- // Try to allocate available threads and ask them to start searching setting
- // is_searching flag. This must be done under lock protection to avoid concurrent
- // allocation of the same slave by another master.
- lock_grab(sp->lock);
- lock_grab(splitLock);
-
- for (int i = 0; i < activeThreads && !Fake; i++)
- if (threads[i].is_available_to(master))
- {
- sp->slavesMask |= 1ULL << i;
- threads[i].curSplitPoint = sp;
- threads[i].is_searching = true; // Slave leaves idle_loop()
+/// 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().
- if (useSleepingThreads)
- threads[i].wake_up();
+void ThreadPool::exit() {
- if (++slavesCnt + 1 >= maxThreadsPerSplitPoint) // Master is always included
- break;
- }
+ while (size())
+ delete back(), pop_back();
+}
- lock_release(splitLock);
- lock_release(sp->lock);
- // Everything is set up. The master thread enters the idle loop, from which
- // it will instantly launch a search, because its is_searching flag is set.
- // We pass the split point as a parameter to the idle loop, which means that
- // the thread will return from the idle loop when all slaves have finished
- // their work at this split point.
- if (slavesCnt || Fake)
- {
- masterThread.idle_loop(sp);
+/// 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.
- // 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(!masterThread.is_searching);
- }
+void ThreadPool::read_uci_options() {
- // We have returned from the idle loop, which means that all threads are
- // finished. Note that setting is_searching and decreasing splitPointsCnt is
- // done under lock protection to avoid a race with Thread::is_available_to().
- lock_grab(sp->lock); // To protect sp->nodes
- lock_grab(splitLock);
+ size_t requested = Options["Threads"];
- masterThread.is_searching = true;
- masterThread.splitPointsCnt--;
- masterThread.curSplitPoint = sp->parent;
- pos.set_nodes_searched(pos.nodes_searched() + sp->nodes);
+ assert(requested > 0);
- lock_release(splitLock);
- lock_release(sp->lock);
+ while (size() < requested)
+ push_back(new Thread);
- return sp->bestValue;
+ while (size() > requested)
+ delete back(), pop_back();
}
-// Explicit template instantiations
-template Value ThreadsManager::split<false>(Position&, Stack*, Value, Value, Value, Depth, Move, int, MovePicker*, int);
-template Value ThreadsManager::split<true>(Position&, Stack*, Value, Value, Value, Depth, Move, int, MovePicker*, int);
-
-// ThreadsManager::set_timer() is used to set the timer to trigger after msec
-// milliseconds. If msec is 0 then timer is stopped.
+/// ThreadPool::nodes_searched() returns the number of nodes searched
-void ThreadsManager::set_timer(int msec) {
+int64_t ThreadPool::nodes_searched() {
- Thread& timer = threads[MAX_THREADS];
-
- lock_grab(timer.sleepLock);
- timer.maxPly = msec;
- cond_signal(timer.sleepCond); // Wake up and restart the timer
- lock_release(timer.sleepLock);
+ int64_t nodes = 0;
+ for (Thread* th : *this)
+ nodes += th->rootPos.nodes_searched();
+ return nodes;
}
-// 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<Move>& searchMoves, bool async) {
- Thread& main = threads[0];
+/// ThreadPool::start_thinking() wakes up the main thread sleeping in idle_loop()
+/// and starts a new search, then returns immediately.
- lock_grab(main.sleepLock);
+void ThreadPool::start_thinking(const Position& pos, StateListPtr& states,
+ const Search::LimitsType& limits) {
- // Wait main thread has finished before to launch a new search
- while (!main.do_sleep)
- cond_wait(sleepCond, main.sleepLock);
+ main()->wait_for_search_finished();
- // Copy input arguments to initialize the search
- RootPosition.copy(pos, 0);
- Limits = limits;
- RootMoves.clear();
+ Search::Signals.stopOnPonderhit = Search::Signals.stop = false;
+ Search::Limits = limits;
+ Search::RootMoves rootMoves;
- // 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<MV_LEGAL> ml(pos); !ml.end(); ++ml)
- if (searchMoves.empty() || searchMoves.count(ml.move()))
- RootMoves.push_back(RootMove(ml.move()));
+ for (const auto& m : MoveList<LEGAL>(pos))
+ if ( limits.searchmoves.empty()
+ || std::count(limits.searchmoves.begin(), limits.searchmoves.end(), m))
+ rootMoves.push_back(Search::RootMove(m));
- // Reset signals before to start the new search
- Signals.stopOnPonderhit = Signals.firstRootMove = false;
- Signals.stop = Signals.failedLowAtRoot = false;
+ // After ownership transfer 'states' becomes empty, so if we stop the search
+ // and call 'go' again without setting a new position states.get() == NULL.
+ assert(states.get() || setupStates.get());
- main.do_sleep = false;
- cond_signal(main.sleepCond); // Wake up main thread and start searching
+ if (states.get())
+ setupStates = std::move(states); // Ownership transfer, states is now empty
- if (!async)
- while (!main.do_sleep)
- cond_wait(sleepCond, main.sleepLock);
+ StateInfo tmp = setupStates->back();
- 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
+ for (Thread* th : Threads)
+ {
+ th->maxPly = 0;
+ th->rootDepth = DEPTH_ZERO;
+ th->rootMoves = rootMoves;
+ th->rootPos.set(pos.fen(), pos.is_chess960(), &setupStates->back(), th);
+ }
- while (!main.do_sleep)
- cond_wait(sleepCond, main.sleepLock);
+ setupStates->back() = tmp; // Restore st->previous, cleared by Position::set()
- lock_release(main.sleepLock);
+ main()->start_searching();
}
projects / stockfish / blobdiff