ThreadsManager Threads; // Global object definition
-namespace {
+namespace { extern "C" {
- // init_thread() is the function which is called when a new thread is
- // launched. It simply calls the idle_loop() function with the supplied
- // threadID. There are two versions of this function; one for POSIX
- // threads and one for Windows threads.
+ // start_routine() is the C function which is called when a new thread
+ // is launched. It simply calls idle_loop() with the supplied threadID.
+ // There are two versions of this function; one for POSIX threads and
+ // one for Windows threads.
-#if !defined(_MSC_VER)
+#if defined(_MSC_VER)
- void* init_thread(void* threadID) {
+ DWORD WINAPI start_routine(LPVOID threadID) {
Threads.idle_loop(*(int*)threadID, NULL);
- return NULL;
+ return 0;
}
#else
- DWORD WINAPI init_thread(LPVOID threadID) {
+ void* start_routine(void* threadID) {
Threads.idle_loop(*(int*)threadID, NULL);
- return 0;
+ return NULL;
}
#endif
-}
+} }
// wake_up() wakes up the thread, normally at the beginning of the search or,
}
-// init_threads() is called during startup. Initializes locks and condition
-// variables and launches all threads sending them immediately to sleep.
+// init() is called during startup. Initializes locks and condition variables
+// and launches all threads sending them immediately to sleep.
void ThreadsManager::init() {
- int arg[MAX_THREADS];
+ int threadID[MAX_THREADS];
// This flag is needed to properly end the threads when program exits
allThreadsShouldExit = false;
// Allocate pawn and material hash tables for main thread
init_hash_tables();
- lock_init(&mpLock);
+ lock_init(&threadsLock);
// Initialize thread and split point locks
for (int i = 0; i < MAX_THREADS; i++)
for (int i = 1; i < MAX_THREADS; i++)
{
threads[i].state = Thread::INITIALIZING;
- arg[i] = i;
+ threadID[i] = i;
-#if !defined(_MSC_VER)
- pthread_t pthread[1];
- bool ok = (pthread_create(pthread, NULL, init_thread, (void*)(&arg[i])) == 0);
- pthread_detach(pthread[0]);
+#if defined(_MSC_VER)
+ bool ok = (CreateThread(NULL, 0, start_routine, (LPVOID)&threadID[i], 0, NULL) != NULL);
#else
- bool ok = (CreateThread(NULL, 0, init_thread, (LPVOID)(&arg[i]), 0, NULL) != NULL);
+ pthread_t pthreadID;
+ bool ok = (pthread_create(&pthreadID, NULL, start_routine, (void*)&threadID[i]) == 0);
+ pthread_detach(pthreadID);
#endif
if (!ok)
{
}
-// exit_threads() is called when the program exits. It makes all the
-// helper threads exit cleanly.
+// exit() is called to cleanly exit the threads when the program finishes
void ThreadsManager::exit() {
lock_destroy(&(threads[i].splitPoints[j].lock));
}
- lock_destroy(&mpLock);
+ lock_destroy(&threadsLock);
}
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, bool pvNode) {
+ int moveCount, MovePicker* mp, int nodeType) {
assert(pos.is_ok());
assert(*bestValue >= -VALUE_INFINITE);
assert(*bestValue <= *alpha);
int i, master = pos.thread();
Thread& masterThread = threads[master];
- lock_grab(&mpLock);
-
- // If no other thread is available to help us, or if we have too many
- // active split points, don't split.
- if ( !available_slave_exists(master)
- || masterThread.activeSplitPoints >= MAX_ACTIVE_SPLIT_POINTS)
- {
- lock_release(&mpLock);
+ // If we already have too many active split points, don't split
+ if (masterThread.activeSplitPoints >= MAX_ACTIVE_SPLIT_POINTS)
return;
- }
// Pick the next available split point object from the split point stack
- SplitPoint& splitPoint = masterThread.splitPoints[masterThread.activeSplitPoints++];
+ SplitPoint& splitPoint = masterThread.splitPoints[masterThread.activeSplitPoints];
// Initialize the split point object
splitPoint.parent = masterThread.splitPoint;
splitPoint.threatMove = threatMove;
splitPoint.alpha = *alpha;
splitPoint.beta = beta;
- splitPoint.pvNode = pvNode;
+ splitPoint.nodeType = nodeType;
splitPoint.bestValue = *bestValue;
splitPoint.mp = mp;
splitPoint.moveCount = moveCount;
for (i = 0; i < activeThreads; i++)
splitPoint.is_slave[i] = false;
- masterThread.splitPoint = &splitPoint;
-
// If we are here it means we are not available
- assert(masterThread.state != Thread::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.
+ lock_grab(&threadsLock);
- // Allocate available threads setting state to THREAD_BOOKED
- for (i = 0; !Fake && i < activeThreads && workersCnt < maxThreadsPerSplitPoint; i++)
+ for (i = 0; !Fake && i < activeThreads && booked < maxThreadsPerSplitPoint; i++)
if (i != master && threads[i].is_available_to(master))
{
threads[i].state = Thread::BOOKED;
threads[i].splitPoint = &splitPoint;
splitPoint.is_slave[i] = true;
- workersCnt++;
+ booked++;
}
- assert(Fake || workersCnt > 1);
+ lock_release(&threadsLock);
- // We can release the lock because slave threads are already booked and master is not available
- lock_release(&mpLock);
+ // We failed to allocate even one slave, return
+ if (!Fake && !booked)
+ return;
+
+ masterThread.activeSplitPoints++;
+ masterThread.splitPoint = &splitPoint;
// Tell the threads that they have work to do. This will make them leave
// their idle loop.
{
assert(i == master || threads[i].state == Thread::BOOKED);
- threads[i].state = Thread::WORKISWAITING; // This makes the slave to exit from idle_loop()
+ // This makes the slave to exit from idle_loop()
+ threads[i].state = Thread::WORKISWAITING;
if (useSleepingThreads && i != master)
threads[i].wake_up();
idle_loop(master, &splitPoint);
// We have returned from the idle loop, which means that all threads are
- // finished. Update alpha and bestValue, and return.
- lock_grab(&mpLock);
+ // 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().
+ lock_grab(&threadsLock);
- *alpha = splitPoint.alpha;
- *bestValue = splitPoint.bestValue;
+ masterThread.state = Thread::SEARCHING;
masterThread.activeSplitPoints--;
masterThread.splitPoint = splitPoint.parent;
- pos.set_nodes_searched(pos.nodes_searched() + splitPoint.nodes);
- lock_release(&mpLock);
+ lock_release(&threadsLock);
+
+ *alpha = splitPoint.alpha;
+ *bestValue = splitPoint.bestValue;
+ pos.set_nodes_searched(pos.nodes_searched() + splitPoint.nodes);
}
// Explicit template instantiations
-template void ThreadsManager::split<false>(Position&, SearchStack*, Value*, const Value, Value*, Depth, Move, int, MovePicker*, bool);
-template void ThreadsManager::split<true>(Position&, SearchStack*, Value*, const Value, Value*, Depth, Move, int, MovePicker*, bool);
+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);
projects / stockfish / blobdiff