along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
+#include <algorithm> // For std::count
#include <cassert>
#include <iostream>
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->parentSplitPoint)
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));
}
-// init() is called at startup. Initializes lock and condition variable and
-// launches requested threads sending them immediately to sleep. We cannot use
+// init() is called at startup to create and launch requested threads, that will
+// go immediately to sleep due to 'sleepWhileIdle' set to true. We cannot use
// a c'tor becuase Threads is a static object and we need a fully initialized
-// engine at this point due to allocation of endgames in Thread c'tor.
+// engine at this point due to allocation of Endgames in Thread c'tor.
void ThreadPool::init() {
}
-// exit() cleanly terminates the threads before the program exits.
+// exit() cleanly terminates the threads before the program exits
void ThreadPool::exit() {
- delete timer; // As first becuase check_time() accesses threads data
+ delete timer; // As first because check_time() accesses threads data
for (size_t i = 0; i < threads.size(); i++)
delete threads[i];
}
-// 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))
// 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
-// point objects), the function immediately returns. If splitting is possible, a
-// SplitPoint object is initialized with all the data that must be copied to the
-// helper threads and then helper threads are told that they have been assigned
-// work. This will cause them to instantly leave their idle loops and call
-// search(). When all threads have returned from search() then split() returns.
+// (because no idle threads are available), the function immediately returns.
+// If splitting is possible, a SplitPoint object is initialized with all the
+// data that must be copied to the helper threads and then helper threads are
+// told that they have been assigned work. This will cause them to instantly
+// leave their idle loops and call search(). When all threads have returned from
+// search() then split() returns.
template <bool Fake>
Value ThreadPool::split(Position& pos, Stack* ss, Value alpha, Value beta,
int moveCount, MovePicker& mp, int nodeType) {
assert(pos.pos_is_ok());
+ assert(bestValue <= alpha && alpha < beta && beta <= VALUE_INFINITE);
assert(bestValue > -VALUE_INFINITE);
- assert(bestValue <= alpha);
- assert(alpha < beta);
- assert(beta <= VALUE_INFINITE);
- assert(depth > DEPTH_ZERO);
+ assert(depth >= Threads.minimumSplitDepth);
- Thread* master = pos.this_thread();
+ Thread* thisThread = pos.this_thread();
- if (master->splitPointsCnt >= MAX_SPLITPOINTS_PER_THREAD)
- return bestValue;
+ assert(thisThread->searching);
+ assert(thisThread->splitPointsSize < MAX_SPLITPOINTS_PER_THREAD);
// Pick the next available split point from the split point stack
- SplitPoint& sp = master->splitPoints[master->splitPointsCnt];
+ SplitPoint& sp = thisThread->splitPoints[thisThread->splitPointsSize];
- sp.parent = master->curSplitPoint;
- sp.master = master;
- sp.cutoff = false;
- sp.slavesMask = 1ULL << master->idx;
+ sp.masterThread = thisThread;
+ sp.parentSplitPoint = thisThread->activeSplitPoint;
+ sp.slavesMask = 1ULL << thisThread->idx;
sp.depth = depth;
sp.bestMove = *bestMove;
sp.threatMove = threatMove;
sp.beta = beta;
sp.nodeType = nodeType;
sp.bestValue = bestValue;
- sp.mp = ∓
+ sp.movePicker = ∓
sp.moveCount = moveCount;
sp.pos = &pos;
sp.nodes = 0;
+ sp.cutoff = false;
sp.ss = ss;
- assert(master->searching);
-
- master->curSplitPoint = &sp;
- 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
+ // '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();
+ thisThread->splitPointsSize++;
+ thisThread->activeSplitPoint = &sp;
+
+ size_t slavesCnt = 1; // Master is always included
+
for (size_t i = 0; i < threads.size() && !Fake; ++i)
- if (threads[i]->is_available_to(master))
+ if (threads[i]->is_available_to(thisThread) && ++slavesCnt <= maxThreadsPerSplitPoint)
{
- sp.slavesMask |= 1ULL << i;
- threads[i]->curSplitPoint = &sp;
+ sp.slavesMask |= 1ULL << threads[i]->idx;
+ 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
- break;
}
- master->splitPointsCnt++;
-
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)
+ if (slavesCnt > 1 || Fake)
{
- master->Thread::idle_loop(); // Force a call to base class idle_loop()
+ thisThread->Thread::idle_loop(); // Force a call to base class idle_loop()
// 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(!master->searching);
+ assert(!thisThread->searching);
}
// 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;
+ thisThread->searching = true;
+ thisThread->splitPointsSize--;
+ thisThread->activeSplitPoint = sp.parentSplitPoint;
pos.set_nodes_searched(pos.nodes_searched() + sp.nodes);
*bestMove = sp.bestMove;
}
-// start_thinking() wakes up the main thread sleeping in main_loop() so to start
-// a new search, then returns immediately.
+// start_thinking() wakes up the main thread sleeping in MainThread::idle_loop()
+// so to start a new search, then returns immediately.
void ThreadPool::start_thinking(const Position& pos, const LimitsType& limits,
const std::vector<Move>& searchMoves, StateStackPtr& states) {
RootMoves.clear();
for (MoveList<LEGAL> ml(pos); !ml.end(); ++ml)
- if (searchMoves.empty() || count(searchMoves.begin(), searchMoves.end(), ml.move()))
+ if ( searchMoves.empty()
+ || std::count(searchMoves.begin(), searchMoves.end(), ml.move()))
RootMoves.push_back(RootMove(ml.move()));
main_thread()->thinking = true;
projects / stockfish / blobdiff