X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fthread.cpp;h=b11447dfc175f41180fc3d2a265c215ad79b8372;hp=0d11a2d5330d1b3a720bd67faf56e58689e46130;hb=81cd7d787ef2b9d914c9c09ddbed59dffb78ec77;hpb=553655eb073cdd59c726dd77fcf368d499029467

diff --git a/src/thread.cpp b/src/thread.cpp
index 0d11a2d5..b11447df 100644
--- a/src/thread.cpp
+++ b/src/thread.cpp
@@ -27,82 +27,62 @@
 
 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 member function pointed by start_fn.
 
-  long start_routine(Thread* th) {
-
-    if (th->threadID == 0)
-        th->main_loop();
-
-    else if (th->threadID == MAX_THREADS)
-        th->timer_loop();
-
-    else
-        th->idle_loop(NULL);
-
-    return 0;
-  }
+ long start_routine(Thread* th) { (th->*(th->start_fn))(); return 0; }
 
 } }
 
 
-Thread::Thread(int id) {
+// 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.
+
+Thread::Thread(Fn fn) : splitPoints() {
 
-  threadID = id;
-  do_sleep = (id != 0); // Avoid a race with start_thinking()
   is_searching = do_exit = false;
   maxPly = splitPointsCnt = 0;
   curSplitPoint = NULL;
+  start_fn = fn;
+  idx = Threads.size();
 
-  lock_init(sleepLock);
-  cond_init(sleepCond);
-
-  for (int j = 0; j < MAX_SPLITPOINTS_PER_THREAD; j++)
-      lock_init(splitPoints[j].lock);
+  do_sleep = (fn != &Thread::main_loop); // Avoid a race with start_searching()
 
   if (!thread_create(handle, start_routine, this))
   {
-      std::cerr << "Failed to create thread number " << id << 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::~Thread() {
 
   assert(do_sleep);
 
   do_exit = true; // Search must be already finished
-  wake_up();
-
+  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 do_timer_event(). If maxPly is 0 thread sleeps until is woken up.
+// then calls check_time(). If maxPly is 0 thread sleeps until is woken up.
 extern void check_time();
 
 void Thread::timer_loop() {
 
   while (!do_exit)
   {
-      lock_grab(sleepLock);
-      timed_wait(sleepCond, sleepLock, maxPly ? maxPly : INT_MAX);
-      lock_release(sleepLock);
+      mutex.lock();
+      sleepCondition.wait_for(mutex, maxPly ? maxPly : INT_MAX);
+      mutex.unlock();
       check_time();
   }
 }
@@ -115,18 +95,18 @@ void Thread::main_loop() {
 
   while (true)
   {
-      lock_grab(sleepLock);
+      mutex.lock();
 
       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);
+          Threads.sleepCondition.notify_one(); // Wake up UI thread if needed
+          sleepCondition.wait(mutex);
       }
 
-      lock_release(sleepLock);
+      mutex.unlock();
 
       if (do_exit)
           return;
@@ -134,43 +114,40 @@ void Thread::main_loop() {
       is_searching = true;
 
       Search::think();
+
+      assert(is_searching);
   }
 }
 
 
-// Thread::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::notify_one() wakes up the thread, normally at the beginning of the
+// search or, if "sleeping threads" is used at split time.
 
-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
+// Thread::wait_for_stop() 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 Signals.stop) is sent and
 // then return, after which the bestmove and pondermove will be printed.
 
-void Thread::wait_for_stop_or_ponderhit() {
-
-  Signals.stopOnPonderhit = true;
+void Thread::wait_for_stop() {
 
-  lock_grab(sleepLock);
-
-  while (!Signals.stop)
-      cond_wait(sleepCond, sleepLock);
-
-  lock_release(sleepLock);
+  mutex.lock();
+  while (!Signals.stop) sleepCondition.wait(mutex);
+  mutex.unlock();
 }
 
 
-// cutoff_occurred() checks whether a beta cutoff has occurred in the current
-// active split point, or in some ancestor of the split point.
+// Thread::cutoff_occurred() checks whether a beta cutoff has occurred in the
+// current active split point, or in some ancestor of the split point.
 
 bool Thread::cutoff_occurred() const {
 
@@ -182,14 +159,14 @@ bool Thread::cutoff_occurred() const {
 }
 
 
-// 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
+// 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).
 
-bool Thread::is_available_to(int master) const {
+bool Thread::is_available_to(Thread* master) const {
 
   if (is_searching)
       return false;
@@ -200,85 +177,93 @@ bool Thread::is_available_to(int master) const {
 
   // 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));
+  return !spCnt || (splitPoints[spCnt - 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
+// 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 ThreadPool::init() {
+
+  timer = new Thread(&Thread::timer_loop);
+  threads.push_back(new Thread(&Thread::main_loop));
+  read_uci_options();
+}
+
+
+// exit() cleanly terminates the threads before the program exits.
+
+void ThreadPool::exit() {
+
+  delete timer; // As first becuase check_time() accesses threads data
+
+  for (size_t i = 0; i < threads.size(); i++)
+      delete threads[i];
 }
 
 
 // read_uci_options() updates internal threads parameters from the corresponding
-// UCI options. It is called before to start a new search.
+// 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 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"];
-  activeThreads           = Options["Threads"];
-
-  // Dynamically allocate Thread object according to the number of
-  // active threads. This avoids preallocating memory for all possible
-  // threads if only few are used.
-  for (int i = 0; i < MAX_THREADS; i++)
-      if (i < activeThreads && !threads[i])
-          threads[i] = new Thread(i);
-      else if (i >= activeThreads && threads[i])
-      {
-          delete threads[i];
-          threads[i] = NULL;
-      }
-}
+  size_t requested        = Options["Threads"];
 
+  assert(requested > 0);
 
-void ThreadsManager::wake_up() {
+  while (threads.size() < requested)
+      threads.push_back(new Thread(&Thread::idle_loop));
 
-  for (int i = 0; i < activeThreads; i++)
+  while (threads.size() > requested)
   {
-      threads[i]->do_sleep = false;
-      threads[i]->wake_up();
+      delete threads.back();
+      threads.pop_back();
   }
 }
 
 
-void ThreadsManager::sleep() {
-
-  for (int i = 0; i < activeThreads; i++)
-      threads[i]->do_sleep = true;
-}
-
+// 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.
 
-// init() is called during startup. Initializes locks and condition variables
-// and launches all threads sending them immediately to sleep.
+void ThreadPool::wake_up() const {
 
-void ThreadsManager::init() {
+  for (size_t i = 0; i < threads.size(); i++)
+  {
+      threads[i]->maxPly = 0;
+      threads[i]->do_sleep = false;
 
-    cond_init(sleepCond);
-    lock_init(splitLock);
-    timer = new Thread(MAX_THREADS);
-    read_uci_options(); // Creates at least main thread
+      if (!useSleepingThreads)
+          threads[i]->notify_one();
+  }
 }
 
 
-// exit() is called to cleanly terminate the threads when the program finishes
-
-void ThreadsManager::exit() {
+// sleep() is called after the search finishes to ask all the threads but the
+// main one to go waiting on a sleep condition.
 
-  for (int i = 0; i < MAX_THREADS; i++)
-      if (threads[i])
-          delete threads[i];
+void ThreadPool::sleep() const {
 
-  delete timer;
-  lock_destroy(splitLock);
-  cond_destroy(sleepCond);
+  // Main thread will go to sleep by itself to avoid a race with start_searching()
+  for (size_t i = 1; i < threads.size(); i++)
+      threads[i]->do_sleep = true;
 }
 
 
 // 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 {
+// a slave for the thread 'master'.
 
-  assert(master >= 0 && master < activeThreads);
+bool ThreadPool::available_slave_exists(Thread* master) const {
 
-  for (int i = 0; i < activeThreads; i++)
+  for (size_t i = 0; i < threads.size(); i++)
       if (threads[i]->is_available_to(master))
           return true;
 
@@ -286,6 +271,16 @@ bool ThreadsManager::available_slave_exists(int master) const {
 }
 
 
+// set_timer() is used to set the timer to trigger after msec milliseconds.
+// If msec is 0 then timer is stopped.
+
+void ThreadPool::set_timer(int msec) {
+
+  timer->maxPly = msec;
+  timer->notify_one(); // Wake up and restart the timer
+}
+
+
 // 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
@@ -296,178 +291,141 @@ 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, 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 > -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.splitPointsCnt >= MAX_SPLITPOINTS_PER_THREAD)
+  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.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;
+  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;
 
   // 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(sp->lock);
-  lock_grab(splitLock);
+  mutex.lock();
+  sp.mutex.lock();
 
-  for (int i = 0; i < activeThreads && !Fake; i++)
+  for (size_t i = 0; i < threads.size() && !Fake; ++i)
       if (threads[i]->is_available_to(master))
       {
-          sp->slavesMask |= 1ULL << i;
-          threads[i]->curSplitPoint = sp;
+          sp.slavesMask |= 1ULL << i;
+          threads[i]->curSplitPoint = &sp;
           threads[i]->is_searching = true; // Slave leaves idle_loop()
 
           if (useSleepingThreads)
-              threads[i]->wake_up();
+              threads[i]->notify_one();
 
           if (++slavesCnt + 1 >= maxThreadsPerSplitPoint) // Master is always included
               break;
       }
 
-  lock_release(splitLock);
-  lock_release(sp->lock);
+  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.
-  // 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->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->is_searching);
   }
 
   // We have returned from the idle loop, which means that all threads are
   // 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(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->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);
+  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_search_finished() waits for main thread to go to sleep, this means
+// search is finished. Then returns.
 
-void ThreadsManager::set_timer(int msec) {
+void ThreadPool::wait_for_search_finished() {
 
-  lock_grab(timer->sleepLock);
-  timer->maxPly = msec;
-  cond_signal(timer->sleepCond); // Wake up and restart the timer
-  lock_release(timer->sleepLock);
+  Thread* t = main_thread();
+  t->mutex.lock();
+  while (!t->do_sleep) sleepCondition.wait(t->mutex);
+  t->mutex.unlock();
 }
 
 
-// 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.
+// start_searching() wakes up the main thread sleeping in  main_loop() so to start
+// a new search, then returns immediately.
 
-void ThreadsManager::start_thinking(const Position& pos, const LimitsType& limits,
-                                    const std::set<Move>& searchMoves, bool async) {
-  Thread& main = *threads[0];
+void ThreadPool::start_searching(const Position& pos, const LimitsType& limits,
+                                 const std::vector<Move>& searchMoves, StateStackPtr& states) {
+  wait_for_search_finished();
 
-  lock_grab(main.sleepLock);
+  SearchTime = Time::now(); // As early as possible
 
-  // 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);
+  main_thread()->do_sleep = false;
+  main_thread()->notify_one();
 }