// call search().When all threads have returned from search() then split() returns.
template <bool Fake>
-void ThreadsManager::split(Position& pos, SearchStack* ss, Value* alpha, const Value beta,
- Value* bestValue, Depth depth, Move threatMove,
- int moveCount, MovePicker* mp, int nodeType) {
+Value ThreadsManager::split(Position& pos, SearchStack* ss, Value alpha, Value beta,
+ Value bestValue, Depth depth, Move threatMove,
+ int moveCount, MovePicker* mp, int nodeType) {
assert(pos.is_ok());
- assert(*bestValue >= -VALUE_INFINITE);
- assert(*bestValue <= *alpha);
- assert(*alpha < beta);
+ 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);
// If we already have too many active split points, don't split
if (masterThread.activeSplitPoints >= MAX_ACTIVE_SPLIT_POINTS)
- return;
+ return bestValue;
// Pick the next available split point object from the split point stack
SplitPoint& splitPoint = masterThread.splitPoints[masterThread.activeSplitPoints];
splitPoint.is_betaCutoff = false;
splitPoint.depth = depth;
splitPoint.threatMove = threatMove;
- splitPoint.alpha = *alpha;
+ splitPoint.alpha = alpha;
splitPoint.beta = beta;
splitPoint.nodeType = nodeType;
- splitPoint.bestValue = *bestValue;
+ splitPoint.bestValue = bestValue;
splitPoint.mp = mp;
splitPoint.moveCount = moveCount;
splitPoint.pos = &pos;
// If we are here it means we are not available
assert(masterThread.state == Thread::SEARCHING);
- int booked = 0;
+ int workersCnt = 1; // At least the master is included
- // Try to allocate available threads setting state to Thread::BOOKED, this
- // must be done under lock protection to avoid concurrent allocation of
- // the same slave by another master.
+ // Try to allocate available threads and ask them to start searching setting
+ // the state to Thread::WORKISWAITING, this must be done under lock protection
+ // to avoid concurrent allocation of the same slave by another master.
lock_grab(&threadsLock);
- for (i = 0; !Fake && i < activeThreads && booked < maxThreadsPerSplitPoint; i++)
+ 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;
+ workersCnt++;
splitPoint.is_slave[i] = true;
- booked++;
+ threads[i].splitPoint = &splitPoint;
+
+ // This makes the slave to exit from idle_loop()
+ threads[i].state = Thread::WORKISWAITING;
+
+ if (useSleepingThreads)
+ threads[i].wake_up();
}
lock_release(&threadsLock);
// We failed to allocate even one slave, return
- if (!Fake && !booked)
- return;
+ if (!Fake && workersCnt == 1)
+ return bestValue;
- masterThread.activeSplitPoints++;
masterThread.splitPoint = &splitPoint;
-
- // 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);
-
- // This makes the slave to exit from idle_loop()
- threads[i].state = Thread::WORKISWAITING;
-
- if (useSleepingThreads && i != master)
- threads[i].wake_up();
- }
+ masterThread.activeSplitPoints++;
+ masterThread.state = Thread::WORKISWAITING;
// 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
+ // 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);
// We have returned from the idle loop, which means that all threads are
- // finished. Update alpha and bestValue, and return. Note that changing
- // state and decreasing activeSplitPoints is done under lock protection
- // to avoid a race with Thread::is_available_to().
+ // finished. Note that changing state and decreasing activeSplitPoints is done
+ // under lock protection to avoid a race with Thread::is_available_to().
lock_grab(&threadsLock);
masterThread.state = Thread::SEARCHING;
lock_release(&threadsLock);
- *alpha = splitPoint.alpha;
- *bestValue = splitPoint.bestValue;
pos.set_nodes_searched(pos.nodes_searched() + splitPoint.nodes);
+ return splitPoint.bestValue;
}
// Explicit template instantiations
-template void ThreadsManager::split<false>(Position&, SearchStack*, Value*, const Value, Value*, Depth, Move, int, MovePicker*, int);
-template void ThreadsManager::split<true>(Position&, SearchStack*, Value*, const Value, Value*, Depth, Move, int, MovePicker*, int);
+template Value ThreadsManager::split<false>(Position&, SearchStack*, Value, Value, Value, Depth, Move, int, MovePicker*, int);
+template Value ThreadsManager::split<true>(Position&, SearchStack*, Value, Value, Value, Depth, Move, int, MovePicker*, int);