along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
+#include <algorithm> // For std::count
#include <cassert>
#include <iostream>
using namespace Search;
-ThreadsManager Threads; // Global object
+ThreadPool Threads; // Global object
namespace { extern "C" {
// start_routine() is the C function which is called when a new thread
- // is launched. It is a wrapper to member function pointed by start_fn.
+ // is launched. It is a wrapper to the virtual function idle_loop().
- long start_routine(Thread* th) {
-
- Threads.set_this_thread(th); // Save pointer into thread local storage
- (th->*(th->start_fn))();
- return 0;
- }
+ long start_routine(Thread* th) { th->idle_loop(); return 0; }
} }
+
// Thread c'tor starts a newly-created thread of execution that will call
-// the idle loop function pointed by start_fn going immediately to sleep.
+// the the virtual function idle_loop(), going immediately to sleep.
-Thread::Thread(Fn fn) {
+Thread::Thread() : splitPoints() {
- is_searching = do_exit = false;
- maxPly = splitPointsCnt = 0;
- curSplitPoint = NULL;
- start_fn = fn;
+ searching = exit = false;
+ maxPly = splitPointsSize = 0;
+ activeSplitPoint = NULL;
idx = Threads.size();
- do_sleep = (fn != &Thread::main_loop); // Avoid a race with start_searching()
-
- lock_init(sleepLock);
- cond_init(sleepCond);
-
- for (int j = 0; j < MAX_SPLITPOINTS_PER_THREAD; j++)
- lock_init(splitPoints[j].lock);
-
if (!thread_create(handle, start_routine, this))
{
std::cerr << "Failed to create thread number " << idx << std::endl;
}
-// Thread d'tor waits for thread termination before to return.
+// Thread d'tor waits for thread termination before to return
Thread::~Thread() {
- assert(do_sleep);
-
- do_exit = true; // Search must be already finished
- wake_up();
-
+ exit = true; // Search must be already finished
+ notify_one();
thread_join(handle); // Wait for thread termination
-
- lock_destroy(sleepLock);
- cond_destroy(sleepCond);
-
- for (int j = 0; j < MAX_SPLITPOINTS_PER_THREAD; j++)
- lock_destroy(splitPoints[j].lock);
}
-// Thread::timer_loop() is where the timer thread waits maxPly milliseconds and
-// then calls check_time(). If maxPly is 0 thread sleeps until is woken up.
+// TimerThread::idle_loop() is where the timer thread waits msec milliseconds
+// and then calls check_time(). If msec is 0 thread sleeps until is woken up.
extern void check_time();
-void Thread::timer_loop() {
+void TimerThread::idle_loop() {
- while (!do_exit)
+ while (!exit)
{
- lock_grab(sleepLock);
- timed_wait(sleepCond, sleepLock, maxPly ? maxPly : INT_MAX);
- lock_release(sleepLock);
- check_time();
+ mutex.lock();
+
+ if (!exit)
+ sleepCondition.wait_for(mutex, msec ? msec : INT_MAX);
+
+ mutex.unlock();
+
+ if (msec)
+ check_time();
}
}
-// Thread::main_loop() is where the main thread is parked waiting to be started
+// MainThread::idle_loop() is where the main thread is parked waiting to be started
// when there is a new search. Main thread will launch all the slave threads.
-void Thread::main_loop() {
+void MainThread::idle_loop() {
while (true)
{
- lock_grab(sleepLock);
+ mutex.lock();
- do_sleep = true; // Always return to sleep after a search
- is_searching = false;
+ thinking = false;
- while (do_sleep && !do_exit)
+ while (!thinking && !exit)
{
- cond_signal(Threads.sleepCond); // Wake up UI thread if needed
- cond_wait(sleepCond, sleepLock);
+ Threads.sleepCondition.notify_one(); // Wake up UI thread if needed
+ sleepCondition.wait(mutex);
}
- lock_release(sleepLock);
+ mutex.unlock();
- if (do_exit)
+ if (exit)
return;
- is_searching = true;
+ searching = true;
Search::think();
+
+ assert(searching);
+
+ searching = false;
}
}
-// Thread::wake_up() wakes up the thread, normally at the beginning of the search
-// or, if "sleeping threads" is used at split time.
+// Thread::notify_one() wakes up the thread when there is some search to do
-void Thread::wake_up() {
+void Thread::notify_one() {
- lock_grab(sleepLock);
- cond_signal(sleepCond);
- lock_release(sleepLock);
+ mutex.lock();
+ sleepCondition.notify_one();
+ mutex.unlock();
}
-// Thread::wait_for_stop_or_ponderhit() is called when the maximum depth is
-// reached while the program is pondering. The point is to work around a wrinkle
-// in the UCI protocol: When pondering, the engine is not allowed to give a
-// "bestmove" before the GUI sends it a "stop" or "ponderhit" command. We simply
-// wait here until one of these commands (that raise StopRequest) is sent and
-// then return, after which the bestmove and pondermove will be printed.
+// Thread::wait_for() set the thread to sleep until condition 'b' turns true
-void Thread::wait_for_stop_or_ponderhit() {
+void Thread::wait_for(volatile const bool& b) {
- Signals.stopOnPonderhit = true;
-
- lock_grab(sleepLock);
- while (!Signals.stop) cond_wait(sleepCond, sleepLock);
- lock_release(sleepLock);
+ mutex.lock();
+ while (!b) sleepCondition.wait(mutex);
+ mutex.unlock();
}
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(const Thread& master) const {
+bool Thread::is_available_to(Thread* master) const {
- if (is_searching)
+ if (searching)
return false;
// 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 ThreadsManager::init() {
+void ThreadPool::init() {
- tls_init(tlsKey);
- cond_init(sleepCond);
- lock_init(splitLock);
- timer = new Thread(&Thread::timer_loop);
- threads.push_back(new Thread(&Thread::main_loop));
+ sleepWhileIdle = true;
+ timer = new TimerThread();
+ push_back(new MainThread());
read_uci_options();
}
-// d'tor cleanly terminates the threads when the program exits.
+// exit() cleanly terminates the threads before the program exits
-ThreadsManager::~ThreadsManager() {
+void ThreadPool::exit() {
- for (int i = 0; i < size(); i++)
- delete threads[i];
+ delete timer; // As first because check_time() accesses threads data
- delete timer;
- lock_destroy(splitLock);
- cond_destroy(sleepCond);
- tls_destroy(tlsKey);
+ for (iterator it = begin(); it != end(); ++it)
+ delete *it;
}
// objects are dynamically allocated to avoid creating in advance all possible
// threads, with included pawns and material tables, if only few are used.
-void ThreadsManager::read_uci_options() {
+void ThreadPool::read_uci_options() {
maxThreadsPerSplitPoint = Options["Max Threads per Split Point"];
minimumSplitDepth = Options["Min Split Depth"] * ONE_PLY;
- useSleepingThreads = Options["Use Sleeping Threads"];
- int requested = Options["Threads"];
+ size_t requested = Options["Threads"];
assert(requested > 0);
while (size() < requested)
- threads.push_back(new Thread(&Thread::idle_loop));
+ push_back(new Thread());
while (size() > requested)
{
- delete threads.back();
- threads.pop_back();
- }
-}
-
-
-// wake_up() is called before a new search to start the threads that are waiting
-// on the sleep condition and to reset maxPly. When useSleepingThreads is set
-// threads will be woken up at split time.
-
-void ThreadsManager::wake_up() const {
-
- for (int i = 0; i < size(); i++)
- {
- threads[i]->maxPly = 0;
- threads[i]->do_sleep = false;
-
- if (!useSleepingThreads)
- threads[i]->wake_up();
+ delete back();
+ pop_back();
}
}
-// sleep() is called after the search finishes to ask all the threads but the
-// main one to go waiting on a sleep condition.
-
-void ThreadsManager::sleep() const {
-
- for (int i = 1; i < size(); i++) // Main thread will go to sleep by itself
- threads[i]->do_sleep = true; // to avoid a race with start_searching()
-}
-
-
-// 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 ThreadsManager::available_slave_exists(const Thread& master) const {
+bool ThreadPool::slave_available(Thread* master) const {
- for (int i = 0; i < size(); i++)
- if (threads[i]->is_available_to(master))
+ for (const_iterator it = begin(); it != end(); ++it)
+ if ((*it)->is_available_to(master))
return true;
return false;
// 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 ThreadsManager::split(Position& pos, Stack* ss, Value alpha, Value beta,
- Value bestValue, Move* bestMove, Depth depth,
- Move threatMove, int moveCount, MovePicker* mp, int nodeType) {
- assert(pos.pos_is_ok());
- assert(bestValue > -VALUE_INFINITE);
- assert(bestValue <= alpha);
- assert(alpha < beta);
- assert(beta <= VALUE_INFINITE);
- assert(depth > DEPTH_ZERO);
-
- Thread& master = pos.this_thread();
+void Thread::split(Position& pos, Stack* ss, Value alpha, Value beta, Value* bestValue,
+ Move* bestMove, Depth depth, Move threatMove, int moveCount,
+ MovePicker* movePicker, int nodeType) {
- if (master.splitPointsCnt >= MAX_SPLITPOINTS_PER_THREAD)
- return bestValue;
+ assert(pos.pos_is_ok());
+ assert(*bestValue <= alpha && alpha < beta && beta <= VALUE_INFINITE);
+ assert(*bestValue > -VALUE_INFINITE);
+ assert(depth >= Threads.minimumSplitDepth);
+ assert(searching);
+ assert(splitPointsSize < MAX_SPLITPOINTS_PER_THREAD);
// Pick the next available split point from the split point stack
- SplitPoint* sp = &master.splitPoints[master.splitPointsCnt++];
-
- sp->parent = master.curSplitPoint;
- sp->master = &master;
- sp->cutoff = false;
- sp->slavesMask = 1ULL << master.idx;
- sp->depth = depth;
- sp->bestMove = *bestMove;
- sp->threatMove = threatMove;
- sp->alpha = alpha;
- sp->beta = beta;
- sp->nodeType = nodeType;
- sp->bestValue = bestValue;
- sp->mp = mp;
- sp->moveCount = moveCount;
- sp->pos = &pos;
- sp->nodes = 0;
- sp->ss = ss;
-
- assert(master.is_searching);
-
- master.curSplitPoint = sp;
- int slavesCnt = 0;
+ SplitPoint& sp = splitPoints[splitPointsSize];
+
+ sp.masterThread = this;
+ sp.parentSplitPoint = activeSplitPoint;
+ sp.slavesMask = 1ULL << idx;
+ sp.depth = depth;
+ sp.bestValue = *bestValue;
+ sp.bestMove = *bestMove;
+ sp.threatMove = threatMove;
+ sp.alpha = alpha;
+ sp.beta = beta;
+ sp.nodeType = nodeType;
+ sp.movePicker = movePicker;
+ sp.moveCount = moveCount;
+ sp.pos = &pos;
+ sp.nodes = 0;
+ sp.cutoff = false;
+ sp.ss = ss;
// 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.
- lock_grab(sp->lock);
- lock_grab(splitLock);
+ Threads.mutex.lock();
+ sp.mutex.lock();
- for (int i = 0; i < size() && !Fake; ++i)
- if (threads[i]->is_available_to(master))
- {
- sp->slavesMask |= 1ULL << i;
- threads[i]->curSplitPoint = sp;
- threads[i]->is_searching = true; // Slave leaves idle_loop()
+ splitPointsSize++;
+ activeSplitPoint = &sp;
+
+ size_t slavesCnt = 1; // This thread is always included
- if (useSleepingThreads)
- threads[i]->wake_up();
+ for (ThreadPool::iterator it = Threads.begin(); it != Threads.end() && !Fake; ++it)
+ {
+ Thread* slave = *it;
- if (++slavesCnt + 1 >= maxThreadsPerSplitPoint) // Master is always included
- break;
+ if (slave->is_available_to(this) && ++slavesCnt <= Threads.maxThreadsPerSplitPoint)
+ {
+ sp.slavesMask |= 1ULL << slave->idx;
+ slave->activeSplitPoint = &sp;
+ slave->searching = true; // Slave leaves idle_loop()
+ slave->notify_one(); // Could be sleeping
}
+ }
- lock_release(splitLock);
- lock_release(sp->lock);
+ sp.mutex.unlock();
+ Threads.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.
- // 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
+ // 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.idle_loop(sp);
+ 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.is_searching);
+ assert(!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().
- lock_grab(sp->lock); // To protect sp->nodes
- lock_grab(splitLock);
-
- master.is_searching = true;
- master.splitPointsCnt--;
- master.curSplitPoint = sp->parent;
- pos.set_nodes_searched(pos.nodes_searched() + sp->nodes);
- *bestMove = sp->bestMove;
-
- lock_release(splitLock);
- lock_release(sp->lock);
-
- return sp->bestValue;
+ Threads.mutex.lock();
+ sp.mutex.lock();
+
+ searching = true;
+ splitPointsSize--;
+ activeSplitPoint = sp.parentSplitPoint;
+ pos.set_nodes_searched(pos.nodes_searched() + sp.nodes);
+ *bestMove = sp.bestMove;
+ *bestValue = sp.bestValue;
+
+ sp.mutex.unlock();
+ Threads.mutex.unlock();
}
// Explicit template instantiations
-template Value ThreadsManager::split<false>(Position&, Stack*, Value, Value, Value, Move*, Depth, Move, int, MovePicker*, int);
-template Value ThreadsManager::split<true>(Position&, Stack*, Value, Value, Value, Move*, Depth, Move, int, MovePicker*, int);
-
-
-// ThreadsManager::set_timer() is used to set the timer to trigger after msec
-// milliseconds. If msec is 0 then timer is stopped.
-
-void ThreadsManager::set_timer(int msec) {
-
- lock_grab(timer->sleepLock);
- timer->maxPly = msec;
- cond_signal(timer->sleepCond); // Wake up and restart the timer
- lock_release(timer->sleepLock);
-}
+template void Thread::split<false>(Position&, Stack*, Value, Value, Value*, Move*, Depth, Move, int, MovePicker*, int);
+template void Thread::split< true>(Position&, Stack*, Value, Value, Value*, Move*, Depth, Move, int, MovePicker*, int);
-// ThreadsManager::wait_for_search_finished() waits for main thread to go to
-// sleep, this means search is finished. Then returns.
+// wait_for_think_finished() waits for main thread to go to sleep then returns
-void ThreadsManager::wait_for_search_finished() {
+void ThreadPool::wait_for_think_finished() {
- Thread* t = main_thread();
- lock_grab(t->sleepLock);
- cond_signal(t->sleepCond); // In case is waiting for stop or ponderhit
- while (!t->do_sleep) cond_wait(sleepCond, t->sleepLock);
- lock_release(t->sleepLock);
+ MainThread* t = main_thread();
+ t->mutex.lock();
+ while (t->thinking) sleepCondition.wait(t->mutex);
+ t->mutex.unlock();
}
-// ThreadsManager::start_searching() 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 ThreadsManager::start_searching(const Position& pos, const LimitsType& limits,
- const std::vector<Move>& searchMoves) {
- wait_for_search_finished();
+void ThreadPool::start_thinking(const Position& pos, const LimitsType& limits,
+ const std::vector<Move>& searchMoves, StateStackPtr& states) {
+ wait_for_think_finished();
- SearchTime.restart(); // As early as possible
+ SearchTime = Time::now(); // As early as possible
Signals.stopOnPonderhit = Signals.firstRootMove = false;
Signals.stop = Signals.failedLowAtRoot = false;
- RootPosition.copy(pos, main_thread());
+ RootPos = pos;
Limits = limits;
+ SetupStates = states; // Ownership transfer here
RootMoves.clear();
- for (MoveList<MV_LEGAL> ml(pos); !ml.end(); ++ml)
- if (searchMoves.empty() || count(searchMoves.begin(), searchMoves.end(), ml.move()))
+ for (MoveList<LEGAL> ml(pos); !ml.end(); ++ml)
+ if ( searchMoves.empty()
+ || std::count(searchMoves.begin(), searchMoves.end(), ml.move()))
RootMoves.push_back(RootMove(ml.move()));
- main_thread()->do_sleep = false;
- main_thread()->wake_up();
+ main_thread()->thinking = true;
+ main_thread()->notify_one(); // Starts main thread
}
projects / stockfish / blobdiff