ThreadPool Threads; // Global object
-extern void check_time();
-
namespace {
- // Helpers to launch a thread after creation and joining before delete. Must be
- // outside Thread c'tor and d'tor because the object must be fully initialized
+ // Helpers to launch a thread after creation and joining before delete. Outside the
+ // Thread constructor and destructor because the object must be fully initialized
// when start_routine (and hence virtual idle_loop) is called and when joining.
template<typename T> T* new_thread() {
- T* th = new T();
- th->nativeThread = std::thread(&ThreadBase::idle_loop, th); // Will go to sleep
- return th;
+ std::thread* th = new T;
+ *th = std::thread(&T::idle_loop, (T*)th); // Will go to sleep
+ return (T*)th;
}
void delete_thread(ThreadBase* th) {
th->mutex.unlock();
th->notify_one();
- th->nativeThread.join(); // Wait for thread termination
+ th->join(); // Wait for thread termination
delete th;
}
void ThreadBase::notify_one() {
- std::unique_lock<Mutex>(this->mutex);
+ std::unique_lock<Mutex> lk(mutex);
sleepCondition.notify_one();
}
-// ThreadBase::wait_for() set the thread to sleep until 'condition' turns true
+// ThreadBase::wait() set the thread to sleep until 'condition' turns true
-void ThreadBase::wait_for(volatile const bool& condition) {
+void ThreadBase::wait(std::atomic_bool& condition) {
std::unique_lock<Mutex> lk(mutex);
- sleepCondition.wait(lk, [&]{ return condition; });
-}
-
-
-// Thread c'tor makes some init but does not launch any execution thread that
-// will be started only when c'tor returns.
-
-Thread::Thread() /* : splitPoints() */ { // Initialization of non POD broken in MSVC
-
- searching = false;
- maxPly = 0;
- splitPointsSize = 0;
- activeSplitPoint = nullptr;
- activePosition = nullptr;
- idx = Threads.size(); // Starts from 0
-}
-
-
-// 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 = activeSplitPoint; sp; sp = sp->parentSplitPoint)
- if (sp->cutoff)
- return true;
-
- return false;
+ sleepCondition.wait(lk, [&]{ return bool(condition); });
}
-// Thread::can_join() checks whether the thread is available to join the split
-// point 'sp'. 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 split
-// point, it is only available as a slave for the split points below his active
-// one (the "helpful master" concept in YBWC terminology).
-
-bool Thread::can_join(const SplitPoint* sp) const {
-
- if (searching)
- return false;
-
- // Make a local copy to be sure it doesn't become zero under our feet while
- // testing next condition and so leading to an out of bounds access.
- const size_t size = splitPointsSize;
+// ThreadBase::wait_while() set the thread to sleep until 'condition' turns false
+void ThreadBase::wait_while(std::atomic_bool& condition) {
- // No split points means that the thread is available as a slave for any
- // other thread otherwise apply the "helpful master" concept if possible.
- return !size || splitPoints[size - 1].slavesMask.test(sp->master->idx);
+ std::unique_lock<Mutex> lk(mutex);
+ sleepCondition.wait(lk, [&]{ return !condition; });
}
-// Thread::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), 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
-// informed 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.
-
-void Thread::split(Position& pos, Stack* ss, Value alpha, Value beta, Value* bestValue,
- Move* bestMove, Depth depth, int moveCount,
- MovePicker* movePicker, int nodeType, bool cutNode) {
-
- assert(searching);
- assert(-VALUE_INFINITE < *bestValue && *bestValue <= alpha && alpha < beta && beta <= VALUE_INFINITE);
- assert(depth >= Threads.minimumSplitDepth);
- assert(splitPointsSize < MAX_SPLITPOINTS_PER_THREAD);
-
- // Pick and init the next available split point
- SplitPoint& sp = splitPoints[splitPointsSize];
-
- sp.mutex.lock(); // No contention here until we don't increment splitPointsSize
-
- sp.master = this;
- sp.parentSplitPoint = activeSplitPoint;
- sp.slavesMask = 0, sp.slavesMask.set(idx);
- sp.depth = depth;
- sp.bestValue = *bestValue;
- sp.bestMove = *bestMove;
- sp.alpha = alpha;
- sp.beta = beta;
- sp.nodeType = nodeType;
- sp.cutNode = cutNode;
- sp.movePicker = movePicker;
- sp.moveCount = moveCount;
- sp.pos = &pos;
- sp.nodes = 0;
- sp.cutoff = false;
- sp.ss = ss;
- sp.allSlavesSearching = true; // Must be set under lock protection
-
- ++splitPointsSize;
- activeSplitPoint = &sp;
- activePosition = nullptr;
-
- // Try to allocate available threads
- Thread* slave;
-
- while ( sp.slavesMask.count() < MAX_SLAVES_PER_SPLITPOINT
- && (slave = Threads.available_slave(&sp)) != nullptr)
- {
- slave->allocMutex.lock();
-
- if (slave->can_join(activeSplitPoint))
- {
- activeSplitPoint->slavesMask.set(slave->idx);
- slave->activeSplitPoint = activeSplitPoint;
- slave->searching = true;
- }
-
- slave->allocMutex.unlock();
-
- slave->notify_one(); // Could be sleeping
- }
-
- // Everything is set up. The master thread enters the idle loop, from which
- // it will instantly launch a search, because its 'searching' flag is set.
- // The thread will return from the idle loop when all slaves have finished
- // their work at this split point.
- sp.mutex.unlock();
+// Thread constructor makes some init but does not launch any execution thread,
+// which will be started only when the constructor returns.
- Thread::idle_loop(); // Force a call to base class idle_loop()
+Thread::Thread() {
- // In the helpful master concept, a master can help only a sub-tree of its
- // split point and because everything is finished here, it's not possible
- // for the master to be booked.
- assert(!searching);
- assert(!activePosition);
-
- searching = true;
-
- // We have returned from the idle loop, which means that all threads are
- // finished. Note that decreasing splitPointsSize must be done under lock
- // protection to avoid a race with Thread::can_join().
- sp.mutex.lock();
-
- --splitPointsSize;
- activeSplitPoint = sp.parentSplitPoint;
- activePosition = &pos;
- pos.set_nodes_searched(pos.nodes_searched() + sp.nodes);
- *bestMove = sp.bestMove;
- *bestValue = sp.bestValue;
-
- sp.mutex.unlock();
+ searching = resetCallsCnt = false;
+ maxPly = callsCnt = 0;
+ history.clear();
+ counterMoves.clear();
+ idx = Threads.size(); // Starts from 0
}
-// TimerThread::idle_loop() is where the timer thread waits Resolution milliseconds
-// and then calls check_time(). When not searching, thread sleeps until it's woken up.
+// Thread::idle_loop() is where the thread is parked when it has no work to do
-void TimerThread::idle_loop() {
+void Thread::idle_loop() {
while (!exit)
{
std::unique_lock<Mutex> lk(mutex);
- if (!exit)
- sleepCondition.wait_for(lk, std::chrono::milliseconds(run ? Resolution : INT_MAX));
+ while (!searching && !exit)
+ sleepCondition.wait(lk);
lk.unlock();
- if (run)
- check_time();
+ if (!exit && searching)
+ search();
}
}
while (!thinking && !exit)
{
- Threads.sleepCondition.notify_one(); // Wake up the UI thread if needed
+ sleepCondition.notify_one(); // Wake up the UI thread if needed
sleepCondition.wait(lk);
}
lk.unlock();
if (!exit)
- {
- searching = true;
+ think();
+ }
+}
- Search::think();
- assert(searching);
+// MainThread::join() waits for main thread to finish thinking
- searching = false;
- }
- }
+void MainThread::join() {
+
+ std::unique_lock<Mutex> lk(mutex);
+ sleepCondition.wait(lk, [&]{ return !thinking; });
}
// ThreadPool::init() is called at startup to create and launch requested threads,
-// that will go immediately to sleep. We cannot use a c'tor because Threads is a
-// static object and we need a fully initialized engine at this point due to
-// allocation of Endgames in Thread c'tor.
+// 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 ThreadPool::init() {
- timer = new_thread<TimerThread>();
push_back(new_thread<MainThread>());
read_uci_options();
}
// ThreadPool::exit() terminates the threads before the program exits. Cannot be
-// done in d'tor because threads must be terminated before freeing us.
+// done in destructor because threads must be terminated before freeing us.
void ThreadPool::exit() {
- delete_thread(timer); // As first because check_time() accesses threads data
-
for (Thread* th : *this)
delete_thread(th);
+
+ clear(); // Get rid of stale pointers
}
void ThreadPool::read_uci_options() {
- minimumSplitDepth = Options["Min Split Depth"] * ONE_PLY;
size_t requested = Options["Threads"];
assert(requested > 0);
- // If zero (default) then set best minimum split depth automatically
- if (!minimumSplitDepth)
- minimumSplitDepth = requested < 8 ? 4 * ONE_PLY : 7 * ONE_PLY;
-
while (size() < requested)
push_back(new_thread<Thread>());
}
-// ThreadPool::available_slave() tries to find an idle thread which is available
-// to join SplitPoint 'sp'.
-
-Thread* ThreadPool::available_slave(const SplitPoint* sp) const {
-
- for (Thread* th : *this)
- if (th->can_join(sp))
- return th;
-
- return nullptr;
-}
-
-
-// ThreadPool::wait_for_think_finished() waits for main thread to finish the search
+// ThreadPool::nodes_searched() returns the number of nodes searched
-void ThreadPool::wait_for_think_finished() {
+int64_t ThreadPool::nodes_searched() {
- std::unique_lock<Mutex> lk(main()->mutex);
- sleepCondition.wait(lk, [&]{ return !main()->thinking; });
+ int64_t nodes = 0;
+ for (Thread *th : *this)
+ nodes += th->rootPos.nodes_searched();
+ return nodes;
}
void ThreadPool::start_thinking(const Position& pos, const LimitsType& limits,
StateStackPtr& states) {
- wait_for_think_finished();
-
- SearchTime = now(); // As early as possible
+ main()->join();
Signals.stopOnPonderhit = Signals.firstRootMove = false;
Signals.stop = Signals.failedLowAtRoot = false;
- RootMoves.clear();
- RootPos = pos;
+ main()->rootMoves.clear();
+ main()->rootPos = pos;
Limits = limits;
if (states.get()) // If we don't set a new position, preserve current state
{
for (const auto& m : MoveList<LEGAL>(pos))
if ( limits.searchmoves.empty()
|| std::count(limits.searchmoves.begin(), limits.searchmoves.end(), m))
- RootMoves.push_back(RootMove(m));
+ main()->rootMoves.push_back(RootMove(m));
main()->thinking = true;
- main()->notify_one(); // Starts main thread
+ main()->notify_one(); // Wake up main thread: 'thinking' must be already set
}