using namespace Search;
-ThreadsManager Threads; // Global object
+ThreadPool 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.
-#if defined(_WIN32) || defined(_WIN64)
- DWORD WINAPI start_routine(LPVOID thread) {
-#else
- void* start_routine(void* thread) {
-#endif
+ long start_routine(Thread* th) { (th->*(th->start_fn))(); return 0; }
- Thread* th = (Thread*)thread;
+} }
+
+
+// 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.
- if (th->threadID == 0)
- th->main_loop();
+Thread::Thread(Fn fn) : splitPoints() {
- else if (th->threadID == MAX_THREADS)
- th->timer_loop();
+ is_searching = do_exit = false;
+ maxPly = splitPointsCnt = 0;
+ curSplitPoint = NULL;
+ start_fn = fn;
+ idx = Threads.size();
- else
- th->idle_loop(NULL);
+ do_sleep = (fn != &Thread::main_loop); // Avoid a race with start_searching()
- return 0;
+ 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.
+
+Thread::~Thread() {
+
+ assert(do_sleep);
+
+ do_exit = true; // Search must be already finished
+ wake_up();
+ thread_join(handle); // Wait for thread termination
+}
-// 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::timer_loop() is where the timer thread waits maxPly milliseconds and
+// then calls check_time(). If maxPly is 0 thread sleeps until is woken up.
+extern void check_time();
+
+void Thread::timer_loop() {
+
+ while (!do_exit)
+ {
+ mutex.lock();
+ sleepCondition.wait_for(mutex, maxPly ? maxPly : INT_MAX);
+ mutex.unlock();
+ 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)
+ {
+ mutex.lock();
+
+ do_sleep = true; // Always return to sleep after a search
+ is_searching = false;
+
+ while (do_sleep && !do_exit)
+ {
+ Threads.sleepCondition.notify_one(); // Wake up UI thread if needed
+ sleepCondition.wait(mutex);
+ }
+
+ mutex.unlock();
+
+ if (do_exit)
+ return;
+
+ is_searching = true;
+
+ Search::think();
+
+ assert(is_searching);
+ }
+}
+
+
+// Thread::wake_up() wakes up the thread, normally at the beginning of the search
+// or, if "sleeping threads" is used at split time.
void Thread::wake_up() {
- lock_grab(sleepLock);
- cond_signal(sleepCond);
- lock_release(sleepLock);
+ mutex.lock();
+ sleepCondition.notify_one();
+ mutex.unlock();
+}
+
+
+// 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;
+
+ mutex.lock();
+ while (!Signals.stop) sleepCondition.wait(mutex);;
+ mutex.unlock();
}
-// 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 {
- for (SplitPoint* sp = splitPoint; sp; sp = sp->parent)
- if (sp->is_betaCutoff)
+ for (SplitPoint* sp = curSplitPoint; sp; sp = sp->parent)
+ if (sp->cutoff)
return true;
return false;
}
-// 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
+// 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 active 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(int master) const {
+bool Thread::is_available_to(Thread* master) const {
if (is_searching)
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 sp_count = activeSplitPoints;
+ int spCnt = splitPointsCnt;
// 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 !sp_count || (splitPoints[sp_count - 1].slavesMask & (1ULL << master));
+ return !spCnt || (splitPoints[spCnt - 1].slavesMask & (1ULL << master->idx));
}
-// read_uci_options() updates number of active threads and other parameters
-// according to the UCI options values. It is called before to start a new search.
+// 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::read_uci_options() {
-
- maxThreadsPerSplitPoint = Options["Max Threads per Split Point"];
- minimumSplitDepth = Options["Min Split Depth"] * ONE_PLY;
- useSleepingThreads = Options["Use Sleeping Threads"];
+void ThreadPool::init() {
- set_size(Options["Threads"]);
+ timer = new Thread(&Thread::timer_loop);
+ threads.push_back(new Thread(&Thread::main_loop));
+ read_uci_options();
}
-// 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) {
+// exit() cleanly terminates the threads before the program exits.
- assert(cnt > 0 && cnt <= MAX_THREADS);
+void ThreadPool::exit() {
- activeThreads = cnt;
-
- for (int i = 1; i < MAX_THREADS; i++) // Ignore main thread
- 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();
+ delete timer; // As first becuase check_time() accesses threads data
- threads[i].do_sleep = false;
- }
- else
- threads[i].do_sleep = true;
+ for (size_t i = 0; i < threads.size(); i++)
+ delete threads[i];
}
-// init() is called during startup. Initializes locks and condition variables
-// and launches all threads sending them immediately to sleep.
-
-void ThreadsManager::init() {
+// 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.
- cond_init(sleepCond);
- lock_init(splitLock);
+void ThreadPool::read_uci_options() {
- for (int i = 0; i <= MAX_THREADS; i++)
- {
- lock_init(threads[i].sleepLock);
- cond_init(threads[i].sleepCond);
+ maxThreadsPerSplitPoint = Options["Max Threads per Split Point"];
+ minimumSplitDepth = Options["Min Split Depth"] * ONE_PLY;
+ useSleepingThreads = Options["Use Sleeping Threads"];
+ size_t requested = Options["Threads"];
- for (int j = 0; j < MAX_ACTIVE_SPLIT_POINTS; j++)
- lock_init(threads[i].splitPoints[j].lock);
- }
+ assert(requested > 0);
- // Allocate main thread tables to call evaluate() also when not searching
- threads[0].pawnTable.init();
- threads[0].materialTable.init();
+ while (threads.size() < requested)
+ threads.push_back(new Thread(&Thread::idle_loop));
- // Create and launch all the threads, threads will go immediately to sleep
- for (int i = 0; i <= MAX_THREADS; i++)
+ while (threads.size() > requested)
{
- threads[i].is_searching = false;
- threads[i].do_sleep = (i != 0); // Avoid a race with start_thinking()
- threads[i].threadID = i;
-
- if (!thread_create(threads[i].handle, start_routine, threads[i]))
- {
- std::cerr << "Failed to create thread number " << i << std::endl;
- ::exit(EXIT_FAILURE);
- }
+ delete threads.back();
+ threads.pop_back();
}
}
-// exit() is called to cleanly terminate the threads when the program finishes
-
-void ThreadsManager::exit() {
+// 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.
- assert(threads[0].is_searching == false);
+void ThreadPool::wake_up() const {
- for (int i = 0; i <= MAX_THREADS; i++)
+ for (size_t i = 0; i < threads.size(); i++)
{
- threads[i].do_exit = true; // Search must be already finished
- threads[i].wake_up();
+ threads[i]->maxPly = 0;
+ threads[i]->do_sleep = false;
- thread_join(threads[i].handle); // Wait for thread termination
+ if (!useSleepingThreads)
+ threads[i]->wake_up();
+ }
+}
- 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);
- }
+// sleep() is called after the search finishes to ask all the threads but the
+// main one to go waiting on a sleep condition.
- lock_destroy(splitLock);
- cond_destroy(sleepCond);
+void ThreadPool::sleep() const {
+
+ // Main thread will go to sleep by itself to avoid a race with start_searching()
+ for (size_t i = 1; i < threads.size(); i++)
+ threads[i]->do_sleep = true;
}
// available_slave_exists() tries to find an idle thread which is available as
-// a slave for the thread with threadID 'master'.
-
-bool ThreadsManager::available_slave_exists(int master) const {
+// a slave for the thread 'master'.
- assert(master >= 0 && master < activeThreads);
+bool ThreadPool::available_slave_exists(Thread* master) const {
- for (int i = 0; i < activeThreads; i++)
- if (threads[i].is_available_to(master))
+ for (size_t i = 0; i < threads.size(); i++)
+ if (threads[i]->is_available_to(master))
return true;
return false;
// 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) {
+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 > -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];
+ Thread* master = pos.this_thread();
- if (masterThread.activeSplitPoints >= MAX_ACTIVE_SPLIT_POINTS)
+ if (master->splitPointsCnt >= MAX_SPLITPOINTS_PER_THREAD)
return bestValue;
// Pick the next available split point from the split point stack
- SplitPoint* sp = &masterThread.splitPoints[masterThread.activeSplitPoints];
-
- sp->parent = masterThread.splitPoint;
- sp->master = master;
- sp->is_betaCutoff = 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);
-
+ SplitPoint& sp = master->splitPoints[master->splitPointsCnt];
+
+ sp.parent = master->curSplitPoint;
+ sp.master = master;
+ sp.cutoff = false;
+ 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.ss = ss;
+
+ assert(master->is_searching);
+
+ master->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);
+ mutex.lock();
+ sp.mutex.lock();
- for (int i = 0; i < activeThreads && !Fake; i++)
- if (threads[i].is_available_to(master))
+ for (size_t i = 0; i < threads.size() && !Fake; ++i)
+ if (threads[i]->is_available_to(master))
{
- sp->slavesMask |= 1ULL << i;
- threads[i].splitPoint = sp;
- threads[i].is_searching = true; // Slave leaves idle_loop()
+ sp.slavesMask |= 1ULL << i;
+ threads[i]->curSplitPoint = &sp;
+ threads[i]->is_searching = true; // Slave leaves idle_loop()
if (useSleepingThreads)
- threads[i].wake_up();
+ threads[i]->wake_up();
if (++slavesCnt + 1 >= maxThreadsPerSplitPoint) // Master is always included
break;
}
- masterThread.splitPoint = sp;
- masterThread.activeSplitPoints++;
+ master->splitPointsCnt++;
- lock_release(splitLock);
- lock_release(sp->lock);
+ 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 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
+ // 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);
+ {
+ master->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->is_searching);
+ }
// We have returned from the idle loop, which means that all threads are
- // finished. Note that setting is_searching and decreasing activeSplitPoints is
+ // 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);
+ mutex.lock();
+ sp.mutex.lock();
- masterThread.is_searching = true;
- masterThread.activeSplitPoints--;
- masterThread.splitPoint = sp->parent;
- pos.set_nodes_searched(pos.nodes_searched() + sp->nodes);
+ master->is_searching = true;
+ master->splitPointsCnt--;
+ master->curSplitPoint = sp.parent;
+ pos.set_nodes_searched(pos.nodes_searched() + sp.nodes);
+ *bestMove = sp.bestMove;
- lock_release(splitLock);
- lock_release(sp->lock);
+ sp.mutex.unlock();
+ mutex.unlock();
- return sp->bestValue;
+ return sp.bestValue;
}
// 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);
+template Value ThreadPool::split<false>(Position&, Stack*, Value, Value, Value, Move*, Depth, Move, int, MovePicker&, int);
+template Value ThreadPool::split<true>(Position&, Stack*, Value, Value, Value, Move*, Depth, Move, int, MovePicker&, int);
-// 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();
+// set_timer() is used to set the timer to trigger after msec milliseconds.
+// If msec is 0 then timer is stopped.
-void Thread::timer_loop() {
+void ThreadPool::set_timer(int msec) {
- while (!do_exit)
- {
- lock_grab(sleepLock);
- timed_wait(sleepCond, sleepLock, maxPly ? maxPly : INT_MAX);
- lock_release(sleepLock);
- check_time();
- }
+ timer->mutex.lock();
+ timer->maxPly = msec;
+ timer->sleepCondition.notify_one(); // Wake up and restart the timer
+ timer->mutex.unlock();
}
-// ThreadsManager::set_timer() is used to set the timer to trigger after msec
-// milliseconds. If msec is 0 then timer is stopped.
-
-void ThreadsManager::set_timer(int msec) {
+// wait_for_search_finished() waits for main thread to go to sleep, this means
+// search is finished. Then returns.
- Thread& timer = threads[MAX_THREADS];
+void ThreadPool::wait_for_search_finished() {
- lock_grab(timer.sleepLock);
- timer.maxPly = msec;
- cond_signal(timer.sleepCond); // Wake up and restart the timer
- lock_release(timer.sleepLock);
+ Thread* t = main_thread();
+ t->mutex.lock();
+ t->sleepCondition.notify_one(); // In case is waiting for stop or ponderhit
+ while (!t->do_sleep) sleepCondition.wait(t->mutex);
+ t->mutex.unlock();
}
-// 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.
+// start_searching() wakes up the main thread sleeping in main_loop() so to start
+// a new search, then returns immediately.
-void Thread::main_loop() {
-
- while (true)
- {
- lock_grab(sleepLock);
+void ThreadPool::start_searching(const Position& pos, const LimitsType& limits,
+ const std::vector<Move>& searchMoves, StateStackPtr& states) {
+ wait_for_search_finished();
- do_sleep = true; // Always return to sleep after a search
- is_searching = false;
+ SearchTime = Time::now(); // As early as possible
- while (do_sleep && !do_exit)
- {
- cond_signal(Threads.sleepCond); // Wake up UI thread if needed
- cond_wait(sleepCond, sleepLock);
- }
-
- is_searching = true;
-
- lock_release(sleepLock);
-
- if (do_exit)
- return;
-
- Search::think();
- }
-}
-
-
-// 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];
-
- lock_grab(main.sleepLock);
-
- // 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);
+ RootPosition = pos;
Limits = limits;
+ SetupStates = states; // Ownership transfer here
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<MV_LEGAL> ml(pos); !ml.end(); ++ml)
- if (searchMoves.empty() || searchMoves.count(ml.move()))
+ for (MoveList<LEGAL> ml(pos); !ml.end(); ++ml)
+ if (searchMoves.empty() || count(searchMoves.begin(), searchMoves.end(), 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);
-}
-
-
-// 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);
-}
-
-
-// ThreadsManager::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 ThreadsManager::wait_for_stop_or_ponderhit() {
-
- Signals.stopOnPonderhit = true;
-
- Thread& main = threads[0];
-
- lock_grab(main.sleepLock);
-
- while (!Signals.stop)
- cond_wait(main.sleepCond, main.sleepLock);
-
- lock_release(main.sleepLock);
+ main_thread()->do_sleep = false;
+ main_thread()->wake_up();
}
projects / stockfish / blobdiff