void ThreadBase::notify_one() {
- std::unique_lock<std::mutex>(this->mutex);
+ std::unique_lock<Mutex>(this->mutex);
sleepCondition.notify_one();
}
void ThreadBase::wait_for(volatile const bool& condition) {
- std::unique_lock<std::mutex> lk(mutex);
+ std::unique_lock<Mutex> lk(mutex);
sleepCondition.wait(lk, [&]{ return condition; });
}
}
-// Thread::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 split point, it is only available as a slave to the slaves
-// which are busy searching the split point at the top of slave's split point
-// stack (the "helpful master concept" in YBWC terminology).
+// 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::available_to(const Thread* master) const {
+bool Thread::can_join(const SplitPoint* sp) const {
if (searching)
return false;
// 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(master->idx);
+ return !size || splitPoints[size - 1].slavesMask.test(sp->master->idx);
}
// Pick and init the next available split point
SplitPoint& sp = splitPoints[splitPointsSize];
+ sp.spinlock.acquire(); // No contention here until we don't increment splitPointsSize
+
sp.master = this;
sp.parentSplitPoint = activeSplitPoint;
sp.slavesMask = 0, sp.slavesMask.set(idx);
sp.nodes = 0;
sp.cutoff = false;
sp.ss = ss;
-
- // Try to allocate available threads and ask them to start searching setting
- // 'searching' flag. This must be done under lock protection to avoid concurrent
- // allocation of the same slave by another master.
- Threads.mutex.lock();
- sp.mutex.lock();
-
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(this)) != nullptr)
+ && (slave = Threads.available_slave(&sp)) != nullptr)
{
- sp.slavesMask.set(slave->idx);
- slave->activeSplitPoint = &sp;
- slave->searching = true; // Slave leaves idle_loop()
- slave->notify_one(); // Could be sleeping
+ slave->spinlock.acquire();
+
+ if (slave->can_join(activeSplitPoint))
+ {
+ activeSplitPoint->slavesMask.set(slave->idx);
+ slave->activeSplitPoint = activeSplitPoint;
+ slave->searching = true;
+ }
+
+ slave->spinlock.release();
}
// 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();
- Threads.mutex.unlock();
+ sp.spinlock.release();
Thread::idle_loop(); // Force a call to base class idle_loop()
assert(!searching);
assert(!activePosition);
+ searching = true;
+
// We have returned from the idle loop, which means that all threads are
- // finished. Note that setting 'searching' and decreasing splitPointsSize must
- // be done under lock protection to avoid a race with Thread::available_to().
- Threads.mutex.lock();
- sp.mutex.lock();
+ // finished. Note that decreasing splitPointsSize must be done under lock
+ // protection to avoid a race with Thread::can_join().
+ sp.spinlock.acquire();
- searching = true;
--splitPointsSize;
activeSplitPoint = sp.parentSplitPoint;
activePosition = &pos;
*bestMove = sp.bestMove;
*bestValue = sp.bestValue;
- sp.mutex.unlock();
- Threads.mutex.unlock();
+ sp.spinlock.release();
}
while (!exit)
{
- std::unique_lock<std::mutex> lk(mutex);
+ std::unique_lock<Mutex> lk(mutex);
if (!exit)
sleepCondition.wait_for(lk, std::chrono::milliseconds(run ? Resolution : INT_MAX));
while (!exit)
{
- std::unique_lock<std::mutex> lk(mutex);
+ std::unique_lock<Mutex> lk(mutex);
thinking = false;
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);
}
}
+// MainThread::join() waits for main thread to finish the search
+
+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
// ThreadPool::available_slave() tries to find an idle thread which is available
-// as a slave for the thread 'master'.
+// to join SplitPoint 'sp'.
-Thread* ThreadPool::available_slave(const Thread* master) const {
+Thread* ThreadPool::available_slave(const SplitPoint* sp) const {
for (Thread* th : *this)
- if (th->available_to(master))
+ if (th->can_join(sp))
return th;
return nullptr;
}
-// ThreadPool::wait_for_think_finished() waits for main thread to finish the search
-
-void ThreadPool::wait_for_think_finished() {
-
- std::unique_lock<std::mutex> lk(main()->mutex);
- sleepCondition.wait(lk, [&]{ return !main()->thinking; });
-}
-
-
// ThreadPool::start_thinking() wakes up the main thread sleeping in
// MainThread::idle_loop() and starts a new search, then returns immediately.
void ThreadPool::start_thinking(const Position& pos, const LimitsType& limits,
StateStackPtr& states) {
- wait_for_think_finished();
+ main()->join();
- SearchTime = Time::now(); // As early as possible
+ SearchTime = now(); // As early as possible
Signals.stopOnPonderhit = Signals.firstRootMove = false;
Signals.stop = Signals.failedLowAtRoot = false;
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
}
projects / stockfish / blobdiff