// 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 localActiveSplitPoints = activeSplitPoints;
+ int sp_count = activeSplitPoints;
// 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.
- if ( !localActiveSplitPoints
- || splitPoints[localActiveSplitPoints - 1].is_slave[master])
- return true;
-
- return false;
+ return !sp_count || (splitPoints[sp_count - 1].slavesMask & (1ULL << master));
}
void ThreadsManager::init() {
- // Initialize sleep condition and lock used by thread manager
cond_init(sleepCond);
- lock_init(threadsLock);
+ lock_init(splitLock);
- // Initialize thread's sleep conditions and split point locks
for (int i = 0; i <= MAX_THREADS; i++)
{
lock_init(threads[i].sleepLock);
void ThreadsManager::exit() {
+ assert(threads[0].is_searching == false);
+
for (int i = 0; i <= MAX_THREADS; i++)
{
- threads[i].do_terminate = true; // Search must be already finished
+ threads[i].do_exit = true; // Search must be already finished
threads[i].wake_up();
thread_join(threads[i].handle); // Wait for thread termination
- // Now we can safely destroy associated locks and wait conditions
lock_destroy(threads[i].sleepLock);
cond_destroy(threads[i].sleepCond);
lock_destroy(threads[i].splitPoints[j].lock);
}
- lock_destroy(threadsLock);
+ lock_destroy(splitLock);
cond_destroy(sleepCond);
}
}
-// split_point_finished() checks if all the slave threads of a given split
-// point have finished searching.
-
-bool ThreadsManager::split_point_finished(SplitPoint* sp) const {
-
- for (int i = 0; i < activeThreads; i++)
- if (sp->is_slave[i])
- return false;
-
- return true;
-}
-
-
// 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, or because we have no unused split
assert(pos.thread() >= 0 && pos.thread() < activeThreads);
assert(activeThreads > 1);
- int i, master = pos.thread();
+ int master = pos.thread();
Thread& masterThread = threads[master];
- // If we already have too many active split points, don't split
if (masterThread.activeSplitPoints >= MAX_ACTIVE_SPLIT_POINTS)
return bestValue;
// Pick the next available split point from the split point stack
SplitPoint* sp = &masterThread.splitPoints[masterThread.activeSplitPoints];
- // Initialize the split point
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->nodes = 0;
sp->ss = ss;
- for (i = 0; i < activeThreads; i++)
- sp->is_slave[i] = false;
-
- // If we are here it means we are not available
assert(masterThread.is_searching);
- int workersCnt = 1; // At least the master is included
+ 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(threadsLock);
+ lock_grab(sp->lock);
+ lock_grab(splitLock);
- for (i = 0; !Fake && i < activeThreads && workersCnt < maxThreadsPerSplitPoint; i++)
+ for (int i = 0; i < activeThreads && !Fake; i++)
if (threads[i].is_available_to(master))
{
- workersCnt++;
- sp->is_slave[i] = true;
+ sp->slavesMask |= 1ULL << i;
threads[i].splitPoint = sp;
-
- // This makes the slave to exit from idle_loop()
- threads[i].is_searching = true;
+ threads[i].is_searching = true; // Slave leaves idle_loop()
if (useSleepingThreads)
threads[i].wake_up();
- }
-
- lock_release(threadsLock);
- // We failed to allocate even one slave, return
- if (!Fake && workersCnt == 1)
- return bestValue;
+ if (++slavesCnt + 1 >= maxThreadsPerSplitPoint) // Master is always included
+ break;
+ }
masterThread.splitPoint = sp;
masterThread.activeSplitPoints++;
+ lock_release(splitLock);
+ lock_release(sp->lock);
+
// 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
// their work at this split point.
- masterThread.idle_loop(sp);
-
- // 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(!masterThread.is_searching);
+ if (slavesCnt || Fake)
+ masterThread.idle_loop(sp);
// We have returned from the idle loop, which means that all threads are
- // 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);
+ // finished. Note that setting is_searching and decreasing activeSplitPoints 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);
masterThread.is_searching = true;
masterThread.activeSplitPoints--;
-
- lock_release(threadsLock);
-
masterThread.splitPoint = sp->parent;
pos.set_nodes_searched(pos.nodes_searched() + sp->nodes);
+ lock_release(splitLock);
+ lock_release(sp->lock);
+
return sp->bestValue;
}
void Thread::timer_loop() {
- while (!do_terminate)
+ while (!do_exit)
{
lock_grab(sleepLock);
timed_wait(sleepCond, sleepLock, maxPly ? maxPly : INT_MAX);
do_sleep = true; // Always return to sleep after a search
is_searching = false;
- while (do_sleep && !do_terminate)
+ while (do_sleep && !do_exit)
{
cond_signal(Threads.sleepCond); // Wake up UI thread if needed
cond_wait(sleepCond, sleepLock);
lock_release(sleepLock);
- if (do_terminate)
+ if (do_exit)
return;
Search::think();
projects / stockfish / blobdiff