No functional change.
// Step 19. Check for splitting the search
if ( !SpNode
&& depth >= Threads.minimumSplitDepth
- && Threads.available_slave_exists(thisThread))
+ && Threads.slave_available(thisThread))
{
assert(bestValue < beta);
void Thread::idle_loop() {
- // Pointer 'sp_master', if non-NULL, points to the active SplitPoint
- // object for which the thread is the master.
- const SplitPoint* sp_master = splitPointsCnt ? curSplitPoint : NULL;
+ // Pointer 'this_sp' is not null only if we are called from split(), and not
+ // at the thread creation. So it means we are the split point's master.
+ const SplitPoint* this_sp = splitPointsSize ? activeSplitPoint : NULL;
- assert(!sp_master || (sp_master->master == this && searching));
+ assert(!this_sp || (this_sp->master == this && searching));
- // If this thread is the master of a split point and all slaves have
- // finished their work at this split point, return from the idle loop.
- while (!sp_master || sp_master->slavesMask)
+ // If this thread is the master of a split point and all slaves have finished
+ // their work at this split point, return from the idle loop.
+ while (!this_sp || this_sp->slavesMask)
{
- // If we are not searching, wait for a condition to be signaled
- // instead of wasting CPU time polling for work.
+ // If we are not searching, wait for a condition to be signaled instead of
+ // wasting CPU time polling for work.
while ((!searching && Threads.sleepWhileIdle) || exit)
{
if (exit)
{
- assert(!sp_master);
+ assert(!this_sp);
return;
}
- // Grab the lock to avoid races with Thread::wake_up()
+ // Grab the lock to avoid races with Thread::notify_one()
mutex.lock();
- // If we are master and all slaves have finished don't go to sleep
- if (sp_master && !sp_master->slavesMask)
+ // If we are master and all slaves have finished then exit idle_loop
+ if (this_sp && !this_sp->slavesMask)
{
mutex.unlock();
break;
// Do sleep after retesting sleep conditions under lock protection, in
// particular we need to avoid a deadlock in case a master thread has,
- // in the meanwhile, allocated us and sent the wake_up() call before we
- // had the chance to grab the lock.
+ // in the meanwhile, allocated us and sent the notify_one() call before
+ // we had the chance to grab the lock.
if (!searching && !exit)
sleepCondition.wait(mutex);
Threads.mutex.lock();
assert(searching);
- SplitPoint* sp = curSplitPoint;
+ SplitPoint* sp = activeSplitPoint;
Threads.mutex.unlock();
sp->mutex.lock();
- assert(sp->activePositions[idx] == NULL);
+ assert(sp->slavesPositions[idx] == NULL);
- sp->activePositions[idx] = &pos;
+ sp->slavesPositions[idx] = &pos;
- if (sp->nodeType == Root)
+ switch (sp->nodeType) {
+ case Root:
search<SplitPointRoot>(pos, ss+1, sp->alpha, sp->beta, sp->depth);
- else if (sp->nodeType == PV)
+ break;
+ case PV:
search<SplitPointPV>(pos, ss+1, sp->alpha, sp->beta, sp->depth);
- else if (sp->nodeType == NonPV)
+ break;
+ case NonPV:
search<SplitPointNonPV>(pos, ss+1, sp->alpha, sp->beta, sp->depth);
- else
+ break;
+ default:
assert(false);
+ }
assert(searching);
searching = false;
- sp->activePositions[idx] = NULL;
+ sp->slavesPositions[idx] = NULL;
sp->slavesMask &= ~(1ULL << idx);
sp->nodes += pos.nodes_searched();
- // Wake up master thread so to allow it to return from the idle loop in
- // case we are the last slave of the split point.
+ // Wake up master thread so to allow it to return from the idle loop
+ // in case we are the last slave of the split point.
if ( Threads.sleepWhileIdle
&& this != sp->master
&& !sp->slavesMask)
// Loop across all split points and sum accumulated SplitPoint nodes plus
// all the currently active slaves positions.
for (size_t i = 0; i < Threads.size(); i++)
- for (int j = 0; j < Threads[i].splitPointsCnt; j++)
+ for (int j = 0; j < Threads[i].splitPointsSize; j++)
{
SplitPoint& sp = Threads[i].splitPoints[j];
Bitboard sm = sp.slavesMask;
while (sm)
{
- Position* pos = sp.activePositions[pop_lsb(&sm)];
+ Position* pos = sp.slavesPositions[pop_lsb(&sm)];
nodes += pos ? pos->nodes_searched() : 0;
}
Thread::Thread() : splitPoints() {
searching = exit = false;
- maxPly = splitPointsCnt = 0;
- curSplitPoint = NULL;
+ maxPly = splitPointsSize = 0;
+ activeSplitPoint = NULL;
idx = Threads.size();
if (!thread_create(handle, start_routine, this))
bool Thread::cutoff_occurred() const {
- for (SplitPoint* sp = curSplitPoint; sp; sp = sp->parent)
+ for (SplitPoint* sp = activeSplitPoint; sp; sp = sp->parent)
if (sp->cutoff)
return true;
// Thread::is_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 active split point, it is only available as a slave to the
-// slaves which are busy searching the split point at the top of slaves split
-// point stack (the "helpful master concept" in YBWC terminology).
+// 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 slaves split point
+// stack (the "helpful master concept" in YBWC terminology).
bool Thread::is_available_to(Thread* master) const {
// 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 spCnt = splitPointsCnt;
+ int size = splitPointsSize;
- // No active split points means that the thread is available as a slave for any
+ // 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 !spCnt || (splitPoints[spCnt - 1].slavesMask & (1ULL << master->idx));
+ return !size || (splitPoints[size - 1].slavesMask & (1ULL << master->idx));
}
}
-// available_slave_exists() tries to find an idle thread which is available as
-// a slave for the thread 'master'.
+// slave_available() tries to find an idle thread which is available as a slave
+// for the thread 'master'.
-bool ThreadPool::available_slave_exists(Thread* master) const {
+bool ThreadPool::slave_available(Thread* master) const {
for (size_t i = 0; i < threads.size(); i++)
if (threads[i]->is_available_to(master))
Thread* master = pos.this_thread();
- if (master->splitPointsCnt >= MAX_SPLITPOINTS_PER_THREAD)
+ if (master->splitPointsSize >= MAX_SPLITPOINTS_PER_THREAD)
return bestValue;
// Pick the next available split point from the split point stack
- SplitPoint& sp = master->splitPoints[master->splitPointsCnt];
+ SplitPoint& sp = master->splitPoints[master->splitPointsSize];
- sp.parent = master->curSplitPoint;
sp.master = master;
- sp.cutoff = false;
+ sp.parent = master->activeSplitPoint;
sp.slavesMask = 1ULL << master->idx;
sp.depth = depth;
sp.bestMove = *bestMove;
sp.moveCount = moveCount;
sp.pos = &pos;
sp.nodes = 0;
+ sp.cutoff = false;
sp.ss = ss;
- assert(master->searching);
-
- master->curSplitPoint = &sp;
+ master->activeSplitPoint = &sp;
int slavesCnt = 0;
+ assert(master->searching);
+
// 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
+ // 'searching' flag. This must be done under lock protection to avoid concurrent
// allocation of the same slave by another master.
mutex.lock();
sp.mutex.lock();
if (threads[i]->is_available_to(master))
{
sp.slavesMask |= 1ULL << i;
- threads[i]->curSplitPoint = &sp;
+ threads[i]->activeSplitPoint = &sp;
threads[i]->searching = true; // Slave leaves idle_loop()
threads[i]->notify_one(); // Could be sleeping
- if (++slavesCnt + 1 >= maxThreadsPerSplitPoint) // Master is always included
+ if (++slavesCnt + 1 >= maxThreadsPerSplitPoint) // Include master
break;
}
- master->splitPointsCnt++;
+ master->splitPointsSize++;
sp.mutex.unlock();
mutex.unlock();
// 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.
+ // 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.
if (slavesCnt || Fake)
}
// We have returned from the idle loop, which means that all threads are
- // finished. Note that setting is_searching and decreasing splitPointsCnt is
+ // finished. Note that setting 'searching' and decreasing splitPointsSize is
// done under lock protection to avoid a race with Thread::is_available_to().
mutex.lock();
sp.mutex.lock();
master->searching = true;
- master->splitPointsCnt--;
- master->curSplitPoint = sp.parent;
+ master->splitPointsSize--;
+ master->activeSplitPoint = sp.parent;
pos.set_nodes_searched(pos.nodes_searched() + sp.nodes);
*bestMove = sp.bestMove;
// Const data after split point has been setup
const Position* pos;
const Search::Stack* ss;
+ Thread* master;
Depth depth;
Value beta;
int nodeType;
- Thread* master;
Move threatMove;
// Const pointers to shared data
// Shared data
Mutex mutex;
- Position* activePositions[MAX_THREADS];
+ Position* slavesPositions[MAX_THREADS];
volatile uint64_t slavesMask;
volatile int64_t nodes;
volatile Value alpha;
Mutex mutex;
ConditionVariable sleepCondition;
NativeHandle handle;
- SplitPoint* volatile curSplitPoint;
- volatile int splitPointsCnt;
+ SplitPoint* volatile activeSplitPoint;
+ volatile int splitPointsSize;
volatile bool searching;
volatile bool exit;
};
-/// MainThread and TimerThread are sublassed from Thread to charaterize the two
+/// MainThread and TimerThread are sublassed from Thread to characterize the two
/// special threads: the main one and the recurring timer.
struct MainThread : public Thread {
TimerThread* timer_thread() { return timer; }
void read_uci_options();
- bool available_slave_exists(Thread* master) const;
+ bool slave_available(Thread* master) const;
void wait_for_think_finished();
void start_thinking(const Position&, const Search::LimitsType&,
const std::vector<Move>&, Search::StateStackPtr&);
bool sleepWhileIdle;
Depth minimumSplitDepth;
+ Mutex mutex;
+ ConditionVariable sleepCondition;
private:
- friend struct Thread;
- friend struct MainThread;
- friend void check_time();
-
std::vector<Thread*> threads;
TimerThread* timer;
- Mutex mutex;
- ConditionVariable sleepCondition;
int maxThreadsPerSplitPoint;
};
projects / stockfish / commitdiff