X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fthread.cpp;h=9aa0b55ef0deaafac39f430bbab900a754ba855f;hp=65d01d9100a874e19db9addea3772bafa735dd69;hb=6950d07bf421b122ccb5a15a2ed4fa3a993d9609;hpb=3aa471f2a9cb1cccd37c27906dd386b9724e32ab

diff --git a/src/thread.cpp b/src/thread.cpp
index 65d01d91..9aa0b55e 100644
--- a/src/thread.cpp
+++ b/src/thread.cpp
@@ -27,136 +27,117 @@
 
 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) { (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;
-  threadID = 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);
+  searching = exit = false;
+  maxPly = splitPointsSize = 0;
+  activeSplitPoint = NULL;
+  idx = Threads.size();
 
   if (!thread_create(handle, start_routine, this))
   {
-      std::cerr << "Failed to create thread number " << threadID << std::endl;
+      std::cerr << "Failed to create thread number " << idx << std::endl;
       ::exit(EXIT_FAILURE);
   }
 }
 
 
-// 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);
-  do_sleep = false;
-  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.
-
-void Thread::wait_for_stop_or_ponderhit() {
+// Thread::wait_for() set the thread to sleep until condition 'b' turns true
 
-  Signals.stopOnPonderhit = true;
+void Thread::wait_for(volatile const bool& b) {
 
-  lock_grab(sleepLock);
-  while (!Signals.stop) cond_wait(sleepCond, sleepLock);
-  lock_release(sleepLock);
+  mutex.lock();
+  while (!b) sleepCondition.wait(mutex);
+  mutex.unlock();
 }
 
 
@@ -165,7 +146,7 @@ void Thread::wait_for_stop_or_ponderhit() {
 
 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;
 
@@ -174,52 +155,49 @@ bool Thread::cutoff_occurred() const {
 
 
 // Thread::is_available_to() checks whether the thread is available to help the
-// thread with threadID "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 threads which are busy searching the split point at the top of
-// "slave"'s split point stack (the "helpful master concept" in YBWC terminology).
+// 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 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(int 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));
+  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() {
 
-  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();
+  threads.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);
+  for (size_t i = 0; i < threads.size(); i++)
+      delete threads[i];
 }
 
 
@@ -228,19 +206,18 @@ ThreadsManager::~ThreadsManager() {
 // 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));
+  while (threads.size() < requested)
+      threads.push_back(new Thread());
 
-  while (size() > requested)
+  while (threads.size() > requested)
   {
       delete threads.back();
       threads.pop_back();
@@ -248,40 +225,12 @@ void ThreadsManager::read_uci_options() {
 }
 
 
-// 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;
-
-      if (!useSleepingThreads)
-          threads[i]->wake_up();
-  }
-}
-
-
-// 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 with threadID 'master'.
-
-bool ThreadsManager::available_slave_exists(int master) const {
+// slave_available() tries to find an idle thread which is available as a slave
+// for the thread 'master'.
 
-  assert(master >= 0 && master < size());
+bool ThreadPool::slave_available(Thread* master) const {
 
-  for (int i = 0; i < size(); i++)
+  for (size_t i = 0; i < threads.size(); i++)
       if (threads[i]->is_available_to(master))
           return true;
 
@@ -291,161 +240,139 @@ bool ThreadsManager::available_slave_exists(int master) const {
 
 // 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) {
+Value ThreadPool::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 <= 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);
 
-  int master = pos.thread();
-  Thread& masterThread = *threads[master];
+  Thread* master = pos.this_thread();
 
-  if (masterThread.splitPointsCnt >= MAX_SPLITPOINTS_PER_THREAD)
-      return bestValue;
+  assert(master->searching);
+  assert(master->splitPointsSize < MAX_SPLITPOINTS_PER_THREAD);
 
   // Pick the next available split point from the split point stack
-  SplitPoint* sp = &masterThread.splitPoints[masterThread.splitPointsCnt++];
-
-  sp->parent = masterThread.curSplitPoint;
-  sp->master = master;
-  sp->cutoff = false;
-  sp->slavesMask = 1ULL << master;
-  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(masterThread.is_searching);
-
-  masterThread.curSplitPoint = sp;
-  int slavesCnt = 0;
+  SplitPoint& sp = master->splitPoints[master->splitPointsSize];
+
+  sp.master = master;
+  sp.parent = master->activeSplitPoint;
+  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.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);
+  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()
+  master->splitPointsSize++;
+  master->activeSplitPoint = &sp;
 
-          if (useSleepingThreads)
-              threads[i]->wake_up();
+  size_t slavesCnt = 1; // Master is always included
 
-          if (++slavesCnt + 1 >= maxThreadsPerSplitPoint) // Master is always included
-              break;
+  for (size_t i = 0; i < threads.size() && !Fake; ++i)
+      if (threads[i]->is_available_to(master) && ++slavesCnt <= maxThreadsPerSplitPoint)
+      {
+          sp.slavesMask |= 1ULL << i;
+          threads[i]->activeSplitPoint = &sp;
+          threads[i]->searching = true; // Slave leaves idle_loop()
+          threads[i]->notify_one(); // Could be sleeping
       }
 
-  lock_release(splitLock);
-  lock_release(sp->lock);
+  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.
-  // 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)
   {
-      masterThread.idle_loop(sp);
+      master->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(!masterThread.is_searching);
+      assert(!master->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);
+  mutex.lock();
+  sp.mutex.lock();
 
-  masterThread.is_searching = true;
-  masterThread.splitPointsCnt--;
-  masterThread.curSplitPoint = sp->parent;
-  pos.set_nodes_searched(pos.nodes_searched() + sp->nodes);
-  *bestMove = sp->bestMove;
+  master->searching = true;
+  master->splitPointsSize--;
+  master->activeSplitPoint = sp.parent;
+  pos.set_nodes_searched(pos.nodes_searched() + sp.nodes);
+  *bestMove = sp.bestMove;
 
-  lock_release(splitLock);
-  lock_release(sp->lock);
+  sp.mutex.unlock();
+  mutex.unlock();
 
-  return sp->bestValue;
+  return sp.bestValue;
 }
 
 // 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);
+template Value ThreadPool::split<false>(Position&, Stack*, Value, Value, Value, Move*, Depth, Move, int, MovePicker&, int);
+template Value ThreadPool::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.
+// wait_for_think_finished() waits for main thread to go to sleep then returns
 
-void ThreadsManager::set_timer(int msec) {
+void ThreadPool::wait_for_think_finished() {
 
-  lock_grab(timer->sleepLock);
-  timer->maxPly = msec;
-  cond_signal(timer->sleepCond); // Wake up and restart the timer
-  lock_release(timer->sleepLock);
+  MainThread* t = main_thread();
+  t->mutex.lock();
+  while (t->thinking) sleepCondition.wait(t->mutex);
+  t->mutex.unlock();
 }
 
 
-// ThreadsManager::wait_for_search_finished() waits for main thread to go to
-// sleep, this means search is finished. Then returns.
+// start_thinking() wakes up the main thread sleeping in  main_loop() so to start
+// a new search, then returns immediately.
 
-void ThreadsManager::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();
 
-  Thread* main = threads[0];
-  lock_grab(main->sleepLock);
-  while (!main->do_sleep) cond_wait(sleepCond, main->sleepLock);
-  lock_release(main->sleepLock);
-}
-
-
-// ThreadsManager::start_searching() is used by UI thread to wake up the main
-// thread parked in main_loop() and starting a new search. If async is true
-// then function returns immediately, otherwise caller is blocked waiting for
-// the search to finish.
-
-void ThreadsManager::start_searching(const Position& pos, const LimitsType& limits,
-                                     const std::set<Move>& searchMoves, bool async) {
-  wait_for_search_finished();
+  SearchTime = Time::now(); // As early as possible
 
   Signals.stopOnPonderhit = Signals.firstRootMove = false;
   Signals.stop = Signals.failedLowAtRoot = false;
 
-  RootPosition.copy(pos, 0);
+  RootPos = pos;
   Limits = limits;
+  SetupStates = states; // Ownership transfer here
   RootMoves.clear();
 
-  for (MoveList<MV_LEGAL> ml(pos); !ml.end(); ++ml)
-      if (searchMoves.empty() || searchMoves.count(ml.move()))
+  for (MoveList<LEGAL> ml(pos); !ml.end(); ++ml)
+      if (searchMoves.empty() || count(searchMoves.begin(), searchMoves.end(), ml.move()))
           RootMoves.push_back(RootMove(ml.move()));
 
-  threads[0]->wake_up(); // Start main thread
-
-  if (!async)
-      wait_for_search_finished();
+  main_thread()->thinking = true;
+  main_thread()->notify_one(); // Starts main thread
 }