// instead of wasting CPU time polling for work.
while ( do_sleep
|| do_terminate
- || (Threads.use_sleeping_threads() && state == Thread::AVAILABLE))
+ || (Threads.use_sleeping_threads() && !is_searching))
{
assert((!sp && threadID) || Threads.use_sleeping_threads());
// 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.
- if (do_sleep || state == Thread::AVAILABLE)
+ if (do_sleep || !is_searching)
cond_wait(&sleepCond, &sleepLock);
lock_release(&sleepLock);
}
// If this thread has been assigned work, launch a search
- if (state == Thread::SEARCHING)
+ if (is_searching)
{
assert(!do_terminate);
else
assert(false);
- assert(state == Thread::SEARCHING);
+ assert(is_searching);
- state = Thread::AVAILABLE;
+ is_searching = false;
// 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.use_sleeping_threads()
&& threadID != tsp->master
- && Threads[tsp->master].state == Thread::AVAILABLE)
+ && !Threads[tsp->master].is_searching)
Threads[tsp->master].wake_up();
}
bool Thread::is_available_to(int master) const {
- if (state != AVAILABLE)
+ if (is_searching)
return false;
// Make a local copy to be sure doesn't become zero under our feet while
}
// Initialize main thread's associated data
- threads[0].state = Thread::SEARCHING;
+ threads[0].is_searching = true;
threads[0].threadID = 0;
set_size(1); // This makes all the threads but the main to go to sleep
// threads will go immediately to sleep.
for (int i = 1; i < MAX_THREADS; i++)
{
- threads[i].state = Thread::AVAILABLE;
+ threads[i].is_searching = false;
threads[i].threadID = i;
#if defined(_MSC_VER)
sp->is_slave[i] = false;
// If we are here it means we are not available
- assert(masterThread.state == Thread::SEARCHING);
+ assert(masterThread.is_searching);
int workersCnt = 1; // At least the master is included
threads[i].splitPoint = sp;
// This makes the slave to exit from idle_loop()
- threads[i].state = Thread::SEARCHING;
+ threads[i].is_searching = true;
if (useSleepingThreads)
threads[i].wake_up();
masterThread.splitPoint = sp;
masterThread.activeSplitPoints++;
- // 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
- // loop when all threads have finished their work at this split point.
+ // 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, and
// because here is all finished is not possible master is booked.
- assert(masterThread.state == Thread::AVAILABLE);
+ assert(!masterThread.is_searching);
// 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);
- masterThread.state = Thread::SEARCHING;
+ masterThread.is_searching = true;
masterThread.activeSplitPoints--;
lock_release(&threadsLock);
struct Thread {
- enum ThreadState
- {
- AVAILABLE, // Thread is waiting for work
- SEARCHING // Thread is performing work
- };
-
void wake_up();
bool cutoff_occurred() const;
bool is_available_to(int master) const;
int maxPly;
Lock sleepLock;
WaitCondition sleepCond;
- volatile ThreadState state;
SplitPoint* volatile splitPoint;
volatile int activeSplitPoints;
+ volatile bool is_searching;
volatile bool do_sleep;
volatile bool do_terminate;