X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fthread.cpp;h=1336ce077cdeac25abb6fc2811221db3aee1dc38;hp=8a8e7199d43e00c42b3c5405ea95ace53af93d40;hb=588670e8d2ed5735300c5549ef754ceb09f1f461;hpb=51e8efdab5f62ebc23e4f7adaea96f619cbca194

diff --git a/src/thread.cpp b/src/thread.cpp
index 8a8e7199..1336ce07 100644
--- a/src/thread.cpp
+++ b/src/thread.cpp
@@ -27,193 +27,211 @@
 
 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 simply calls idle_loop() of the supplied thread. The first
- // and last thread are special. First one is the main search thread while the
- // last one mimics a timer, they run in main_loop() and timer_loop().
+ // is launched. It is a wrapper to the virtual function idle_loop().
 
-#if defined(_WIN32) || defined(_WIN64)
-  DWORD WINAPI start_routine(LPVOID thread) {
-#else
-  void* start_routine(void* thread) {
-#endif
+ long start_routine(Thread* th) { th->idle_loop(); return 0; }
 
-    Thread* th = (Thread*)thread;
+} }
 
-    if (th->threadID == 0)
-        th->main_loop();
 
-    else if (th->threadID == MAX_THREADS)
-        th->timer_loop();
+// Thread c'tor starts a newly-created thread of execution that will call
+// the the virtual function idle_loop(), going immediately to sleep.
 
-    else
-        th->idle_loop(NULL);
+Thread::Thread() : splitPoints() {
 
-    return 0;
-  }
+  searching = exit = false;
+  maxPly = splitPointsCnt = 0;
+  curSplitPoint = NULL;
+  idx = Threads.size();
 
-} }
+  if (!thread_create(handle, start_routine, this))
+  {
+      std::cerr << "Failed to create thread number " << idx << std::endl;
+      ::exit(EXIT_FAILURE);
+  }
+}
 
 
-// wake_up() wakes up the thread, normally at the beginning of the search or,
-// if "sleeping threads" is used, when there is some work to do.
+// Thread d'tor waits for thread termination before to return
 
-void Thread::wake_up() {
+Thread::~Thread() {
 
-  lock_grab(sleepLock);
-  cond_signal(sleepCond);
-  lock_release(sleepLock);
+  exit = true; // Search must be already finished
+  notify_one();
+  thread_join(handle); // Wait for thread termination
 }
 
 
-// cutoff_occurred() checks whether a beta cutoff has occurred in the current
-// active split point, or in some ancestor of the split point.
+// 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();
 
-bool Thread::cutoff_occurred() const {
+void TimerThread::idle_loop() {
 
-  for (SplitPoint* sp = splitPoint; sp; sp = sp->parent)
-      if (sp->is_betaCutoff)
-          return true;
+  while (!exit)
+  {
+      mutex.lock();
 
-  return false;
+      if (!exit)
+          sleepCondition.wait_for(mutex, msec ? msec : INT_MAX);
+
+      mutex.unlock();
+
+      if (msec)
+          check_time();
+  }
 }
 
 
-// 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 by itself 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).
+// 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.
 
-bool Thread::is_available_to(int master) const {
+void MainThread::idle_loop() {
 
-  if (is_searching)
-      return false;
+  while (true)
+  {
+      mutex.lock();
 
-  // 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 sp_count = activeSplitPoints;
+      thinking = false;
 
-  // No active split points means that the thread is available as a slave for any
-  // other thread otherwise apply the "helpful master" concept if possible.
-  return !sp_count || (splitPoints[sp_count - 1].slavesMask & (1ULL << master));
-}
+      while (!thinking && !exit)
+      {
+          Threads.sleepCondition.notify_one(); // Wake up UI thread if needed
+          sleepCondition.wait(mutex);
+      }
 
+      mutex.unlock();
 
-// read_uci_options() updates number of active threads and other parameters
-// according to the UCI options values. It is called before to start a new search.
+      if (exit)
+          return;
 
-void ThreadsManager::read_uci_options() {
+      searching = true;
 
-  maxThreadsPerSplitPoint = Options["Max Threads per Split Point"];
-  minimumSplitDepth       = Options["Min Split Depth"] * ONE_PLY;
-  useSleepingThreads      = Options["Use Sleeping Threads"];
+      Search::think();
+
+      assert(searching);
 
-  set_size(Options["Threads"]);
+      searching = false;
+  }
 }
 
 
-// set_size() changes the number of active threads and raises do_sleep flag for
-// all the unused threads that will go immediately to sleep.
+// Thread::notify_one() wakes up the thread when there is some search to do
 
-void ThreadsManager::set_size(int cnt) {
+void Thread::notify_one() {
 
-  assert(cnt > 0 && cnt <= MAX_THREADS);
+  mutex.lock();
+  sleepCondition.notify_one();
+  mutex.unlock();
+}
 
-  activeThreads = cnt;
 
-  for (int i = 1; i < MAX_THREADS; i++) // Ignore main thread
-      if (i < activeThreads)
-      {
-          // Dynamically allocate pawn and material hash tables according to the
-          // number of active threads. This avoids preallocating memory for all
-          // possible threads if only few are used.
-          threads[i].pawnTable.init();
-          threads[i].materialTable.init();
+// Thread::wait_for() set the thread to sleep until condition 'b' turns true
 
-          threads[i].do_sleep = false;
-      }
-      else
-          threads[i].do_sleep = true;
+void Thread::wait_for(volatile const bool& b) {
+
+  mutex.lock();
+  while (!b) sleepCondition.wait(mutex);
+  mutex.unlock();
 }
 
 
-// init() is called during startup. Initializes locks and condition variables
-// and launches all threads sending them immediately to sleep.
+// Thread::cutoff_occurred() checks whether a beta cutoff has occurred in the
+// current active split point, or in some ancestor of the split point.
 
-void ThreadsManager::init() {
+bool Thread::cutoff_occurred() const {
 
-  cond_init(sleepCond);
-  lock_init(splitLock);
+  for (SplitPoint* sp = curSplitPoint; sp; sp = sp->parent)
+      if (sp->cutoff)
+          return true;
 
-  for (int i = 0; i <= MAX_THREADS; i++)
-  {
-      lock_init(threads[i].sleepLock);
-      cond_init(threads[i].sleepCond);
+  return false;
+}
 
-      for (int j = 0; j < MAX_ACTIVE_SPLIT_POINTS; j++)
-          lock_init(threads[i].splitPoints[j].lock);
-  }
 
-  // Allocate main thread tables to call evaluate() also when not searching
-  threads[0].pawnTable.init();
-  threads[0].materialTable.init();
+// 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).
 
-  // Create and launch all the threads, threads will go immediately to sleep
-  for (int i = 0; i <= MAX_THREADS; i++)
-  {
-      threads[i].is_searching = false;
-      threads[i].do_sleep = (i != 0); // Avoid a race with start_thinking()
-      threads[i].threadID = i;
+bool Thread::is_available_to(Thread* master) const {
 
-      if (!thread_create(threads[i].handle, start_routine, threads[i]))
-      {
-          std::cerr << "Failed to create thread number " << i << std::endl;
-          ::exit(EXIT_FAILURE);
-      }
-  }
+  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;
+
+  // No active 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));
 }
 
 
-// exit() is called to cleanly terminate the threads when the program finishes
+// init() is called at startup. Initializes lock and condition variable and
+// launches requested threads sending them immediately to sleep. 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.
 
-void ThreadsManager::exit() {
+void ThreadPool::init() {
 
-  assert(threads[0].is_searching == false);
+  sleepWhileIdle = true;
+  timer = new TimerThread();
+  threads.push_back(new MainThread());
+  read_uci_options();
+}
 
-  for (int i = 0; i <= MAX_THREADS; i++)
-  {
-      threads[i].do_exit = true; // Search must be already finished
-      threads[i].wake_up();
 
-      thread_join(threads[i].handle); // Wait for thread termination
+// exit() cleanly terminates the threads before the program exits.
 
-      lock_destroy(threads[i].sleepLock);
-      cond_destroy(threads[i].sleepCond);
+void ThreadPool::exit() {
 
-      for (int j = 0; j < MAX_ACTIVE_SPLIT_POINTS; j++)
-          lock_destroy(threads[i].splitPoints[j].lock);
-  }
+  delete timer; // As first becuase check_time() accesses threads data
 
-  lock_destroy(splitLock);
-  cond_destroy(sleepCond);
+  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 with threadID 'master'.
+// read_uci_options() updates internal threads parameters from the corresponding
+// UCI options and creates/destroys threads to match the requested number. Thread
+// objects are dynamically allocated to avoid creating in advance all possible
+// threads, with included pawns and material tables, if only few are used.
+
+void ThreadPool::read_uci_options() {
+
+  maxThreadsPerSplitPoint = Options["Max Threads per Split Point"];
+  minimumSplitDepth       = Options["Min Split Depth"] * ONE_PLY;
+  size_t requested        = Options["Threads"];
+
+  assert(requested > 0);
+
+  while (threads.size() < requested)
+      threads.push_back(new Thread());
+
+  while (threads.size() > requested)
+  {
+      delete threads.back();
+      threads.pop_back();
+  }
+}
 
-bool ThreadsManager::available_slave_exists(int master) const {
 
-  assert(master >= 0 && master < activeThreads);
+// available_slave_exists() tries to find an idle thread which is available as
+// a slave for the thread 'master'.
+
+bool ThreadPool::available_slave_exists(Thread* master) const {
 
-  for (int i = 0; i < activeThreads; i++)
-      if (threads[i].is_available_to(master))
+  for (size_t i = 0; i < threads.size(); i++)
+      if (threads[i]->is_available_to(master))
           return true;
 
   return false;
@@ -230,242 +248,138 @@ bool ThreadsManager::available_slave_exists(int master) const {
 // 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, 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 > -VALUE_INFINITE);
   assert(bestValue <= alpha);
   assert(alpha < beta);
   assert(beta <= VALUE_INFINITE);
   assert(depth > DEPTH_ZERO);
-  assert(pos.thread() >= 0 && pos.thread() < activeThreads);
-  assert(activeThreads > 1);
 
-  int master = pos.thread();
-  Thread& masterThread = threads[master];
+  Thread* master = pos.this_thread();
 
-  if (masterThread.activeSplitPoints >= MAX_ACTIVE_SPLIT_POINTS)
+  if (master->splitPointsCnt >= MAX_SPLITPOINTS_PER_THREAD)
       return bestValue;
 
   // Pick the next available split point from the split point stack
-  SplitPoint* sp = &masterThread.splitPoints[masterThread.activeSplitPoints];
-
-  sp->parent = masterThread.splitPoint;
-  sp->master = master;
-  sp->is_betaCutoff = false;
-  sp->slavesMask = 1ULL << master;
-  sp->depth = depth;
-  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);
-
+  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->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
   // allocation of the same slave by another master.
-  lock_grab(splitLock);
-  lock_grab(sp->lock); // To protect sp->slaves_mask
+  mutex.lock();
+  sp.mutex.lock();
 
-  for (int i = 0; i < activeThreads && !Fake; i++)
-      if (threads[i].is_available_to(master))
+  for (size_t i = 0; i < threads.size() && !Fake; ++i)
+      if (threads[i]->is_available_to(master))
       {
-          sp->slavesMask |= 1ULL << i;
-          threads[i].splitPoint = sp;
-          threads[i].is_searching = true; // Slave leaves idle_loop()
-
-          if (useSleepingThreads)
-              threads[i].wake_up();
+          sp.slavesMask |= 1ULL << i;
+          threads[i]->curSplitPoint = &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;
       }
 
-  masterThread.splitPoint = sp;
-  masterThread.activeSplitPoints++;
+  master->splitPointsCnt++;
 
-  lock_release(sp->lock);
-  lock_release(splitLock);
+  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
+  // The thread will return from the idle loop when all slaves have finished
   // their work at this split point.
   if (slavesCnt || 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(!master->searching);
+  }
 
   // We have returned from the idle loop, which means that all threads are
-  // finished. Note that setting is_searching and decreasing activeSplitPoints is
+  // finished. Note that setting is_searching and decreasing splitPointsCnt is
   // done under lock protection to avoid a race with Thread::is_available_to().
-  lock_grab(splitLock);
-  lock_grab(sp->lock); // To protect sp->nodes
+  mutex.lock();
+  sp.mutex.lock();
 
-  masterThread.is_searching = true;
-  masterThread.activeSplitPoints--;
-  masterThread.splitPoint = sp->parent;
-  pos.set_nodes_searched(pos.nodes_searched() + sp->nodes);
+  master->searching = true;
+  master->splitPointsCnt--;
+  master->curSplitPoint = sp.parent;
+  pos.set_nodes_searched(pos.nodes_searched() + sp.nodes);
+  *bestMove = sp.bestMove;
 
-  lock_release(sp->lock);
-  lock_release(splitLock);
+  sp.mutex.unlock();
+  mutex.unlock();
 
-  return sp->bestValue;
+  return sp.bestValue;
 }
 
 // Explicit template instantiations
-template Value ThreadsManager::split<false>(Position&, Stack*, Value, Value, Value, Depth, Move, int, MovePicker*, int);
-template Value ThreadsManager::split<true>(Position&, Stack*, Value, Value, Value, 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);
 
 
-// Thread::timer_loop() is where the timer thread waits maxPly milliseconds and
-// then calls do_timer_event(). If maxPly is 0 thread sleeps until is woken up.
-extern void check_time();
+// wait_for_think_finished() waits for main thread to go to sleep then returns
 
-void Thread::timer_loop() {
+void ThreadPool::wait_for_think_finished() {
 
-  while (!do_exit)
-  {
-      lock_grab(sleepLock);
-      timed_wait(sleepCond, sleepLock, maxPly ? maxPly : INT_MAX);
-      lock_release(sleepLock);
-      check_time();
-  }
+  MainThread* t = main_thread();
+  t->mutex.lock();
+  while (t->thinking) sleepCondition.wait(t->mutex);
+  t->mutex.unlock();
 }
 
 
-// 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) {
+// start_thinking() wakes up the main thread sleeping in  main_loop() so to start
+// a new search, then returns immediately.
 
-  Thread& timer = threads[MAX_THREADS];
-
-  lock_grab(timer.sleepLock);
-  timer.maxPly = msec;
-  cond_signal(timer.sleepCond); // Wake up and restart the timer
-  lock_release(timer.sleepLock);
-}
+void ThreadPool::start_thinking(const Position& pos, const LimitsType& limits,
+                                const std::vector<Move>& searchMoves, StateStackPtr& states) {
+  wait_for_think_finished();
 
+  SearchTime = Time::now(); // As early as possible
 
-// Thread::main_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() {
-
-  while (true)
-  {
-      lock_grab(sleepLock);
-
-      do_sleep = true; // Always return to sleep after a search
-      is_searching = false;
-
-      while (do_sleep && !do_exit)
-      {
-          cond_signal(Threads.sleepCond); // Wake up UI thread if needed
-          cond_wait(sleepCond, sleepLock);
-      }
-
-      is_searching = true;
-
-      lock_release(sleepLock);
-
-      if (do_exit)
-          return;
-
-      Search::think();
-  }
-}
-
-
-// ThreadsManager::start_thinking() is used by UI thread to wake up the main
-// thread parked in main_loop() and starting a new search. If asyncMode is true
-// then function returns immediately, otherwise caller is blocked waiting for
-// the search to finish.
-
-void ThreadsManager::start_thinking(const Position& pos, const LimitsType& limits,
-                                    const std::set<Move>& searchMoves, bool async) {
-  Thread& main = threads[0];
-
-  lock_grab(main.sleepLock);
-
-  // Wait main thread has finished before to launch a new search
-  while (!main.do_sleep)
-      cond_wait(sleepCond, main.sleepLock);
+  Signals.stopOnPonderhit = Signals.firstRootMove = false;
+  Signals.stop = Signals.failedLowAtRoot = false;
 
-  // Copy input arguments to initialize the search
-  RootPosition.copy(pos, 0);
+  RootPos = pos;
   Limits = limits;
+  SetupStates = states; // Ownership transfer here
   RootMoves.clear();
 
-  // Populate RootMoves with all the legal moves (default) or, if a searchMoves
-  // set is given, with the subset of legal moves to search.
-  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()));
 
-  // Reset signals before to start the new search
-  Signals.stopOnPonderhit = Signals.firstRootMove = false;
-  Signals.stop = Signals.failedLowAtRoot = false;
-
-  main.do_sleep = false;
-  cond_signal(main.sleepCond); // Wake up main thread and start searching
-
-  if (!async)
-      while (!main.do_sleep)
-          cond_wait(sleepCond, main.sleepLock);
-
-  lock_release(main.sleepLock);
-}
-
-
-// ThreadsManager::stop_thinking() is used by UI thread to raise a stop request
-// and to wait for the main thread finishing the search. Needed to wait exiting
-// and terminate the threads after a 'quit' command.
-
-void ThreadsManager::stop_thinking() {
-
-  Thread& main = threads[0];
-
-  Search::Signals.stop = true;
-
-  lock_grab(main.sleepLock);
-
-  cond_signal(main.sleepCond); // In case is waiting for stop or ponderhit
-
-  while (!main.do_sleep)
-      cond_wait(sleepCond, main.sleepLock);
-
-  lock_release(main.sleepLock);
-}
-
-
-// ThreadsManager::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 ThreadsManager::wait_for_stop_or_ponderhit() {
-
-  Signals.stopOnPonderhit = true;
-
-  Thread& main = threads[0];
-
-  lock_grab(main.sleepLock);
-
-  while (!Signals.stop)
-      cond_wait(main.sleepCond, main.sleepLock);
-
-  lock_release(main.sleepLock);
+  main_thread()->thinking = true;
+  main_thread()->notify_one(); // Starts main thread
 }