X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fthread.cpp;h=457a92780ced8cb17348516c2d8fc69e6b5b6334;hp=3b7a10eeed31a2dc33415d2f5cbd6fe7037cc7c8;hb=b46bf2950f76696fb965c79c5c95ffd7177268ac;hpb=7fb6fd2f558c9e2967fb393238d1dbe063f2d277

diff --git a/src/thread.cpp b/src/thread.cpp
index 3b7a10ee..457a9278 100644
--- a/src/thread.cpp
+++ b/src/thread.cpp
@@ -59,8 +59,54 @@ namespace { extern "C" {
 } }
 
 
-// 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::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();
+
+void Thread::timer_loop() {
+
+  while (!do_exit)
+  {
+      lock_grab(sleepLock);
+      timed_wait(sleepCond, sleepLock, maxPly ? maxPly : INT_MAX);
+      lock_release(sleepLock);
+      check_time();
+  }
+}
+
+
+// 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);
+      }
+
+      lock_release(sleepLock);
+
+      if (do_exit)
+          return;
+
+      is_searching = true;
+
+      Search::think();
+  }
+}
+
+
+// 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.
 
 void Thread::wake_up() {
 
@@ -70,13 +116,33 @@ void Thread::wake_up() {
 }
 
 
+// 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() {
+
+  Signals.stopOnPonderhit = true;
+
+  lock_grab(sleepLock);
+
+  while (!Signals.stop)
+      cond_wait(sleepCond, sleepLock);
+
+  lock_release(sleepLock);
+}
+
+
 // 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 {
 
   for (SplitPoint* sp = splitPoint; sp; sp = sp->parent)
-      if (sp->is_betaCutoff)
+      if (sp->cutoff)
           return true;
 
   return false;
@@ -101,10 +167,7 @@ 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.
-  if (!sp_count || (splitPoints[sp_count - 1].slavesMask & (1ULL << master)))
-      return true;
-
-  return false;
+  return !sp_count || (splitPoints[sp_count - 1].slavesMask & (1ULL << master));
 }
 
 
@@ -151,11 +214,9 @@ void ThreadsManager::set_size(int cnt) {
 
 void ThreadsManager::init() {
 
-  // Initialize sleep condition and lock used by thread manager
   cond_init(sleepCond);
-  lock_init(threadsLock);
+  lock_init(splitLock);
 
-  // Initialize thread's sleep conditions and split point locks
   for (int i = 0; i <= MAX_THREADS; i++)
   {
       lock_init(threads[i].sleepLock);
@@ -189,16 +250,15 @@ void ThreadsManager::init() {
 
 void ThreadsManager::exit() {
 
-  assert(threads[0].is_searching == false);
-
   for (int i = 0; i <= MAX_THREADS; i++)
   {
+      assert(threads[i].do_sleep);
+
       threads[i].do_exit = true; // Search must be already finished
       threads[i].wake_up();
 
       thread_join(threads[i].handle); // Wait for thread termination
 
-      // Now we can safely destroy associated locks and wait conditions
       lock_destroy(threads[i].sleepLock);
       cond_destroy(threads[i].sleepCond);
 
@@ -206,7 +266,7 @@ void ThreadsManager::exit() {
           lock_destroy(threads[i].splitPoints[j].lock);
   }
 
-  lock_destroy(threadsLock);
+  lock_destroy(splitLock);
   cond_destroy(sleepCond);
 }
 
@@ -248,21 +308,19 @@ Value ThreadsManager::split(Position& pos, Stack* ss, Value alpha, Value beta,
   assert(pos.thread() >= 0 && pos.thread() < activeThreads);
   assert(activeThreads > 1);
 
-  int i, master = pos.thread();
+  int master = pos.thread();
   Thread& masterThread = threads[master];
 
-  // If we already have too many active split points, don't split
   if (masterThread.activeSplitPoints >= MAX_ACTIVE_SPLIT_POINTS)
       return bestValue;
 
   // Pick the next available split point from the split point stack
   SplitPoint* sp = &masterThread.splitPoints[masterThread.activeSplitPoints];
 
-  // Initialize the split point
   sp->parent = masterThread.splitPoint;
   sp->master = master;
-  sp->is_betaCutoff = false;
-  sp->slavesMask = (1ULL << master);
+  sp->cutoff = false;
+  sp->slavesMask = 1ULL << master;
   sp->depth = depth;
   sp->threatMove = threatMove;
   sp->alpha = alpha;
@@ -275,68 +333,57 @@ Value ThreadsManager::split(Position& pos, Stack* ss, Value alpha, Value beta,
   sp->nodes = 0;
   sp->ss = ss;
 
-  // If we are here it means we are not available
   assert(masterThread.is_searching);
 
-  int workersCnt = 1; // At least the master is included
+  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(threadsLock);
-  lock_grab(sp->lock); // To protect sp->slaves_mask
+  lock_grab(sp->lock);
+  lock_grab(splitLock);
 
-  for (i = 0; !Fake && i < activeThreads; i++)
+  for (int i = 0; i < activeThreads && !Fake; i++)
       if (threads[i].is_available_to(master))
       {
-          sp->slavesMask |= (1ULL << i);
+          sp->slavesMask |= 1ULL << i;
           threads[i].splitPoint = sp;
-
-          // Allocate the slave and make it exit from idle_loop()
-          threads[i].is_searching = true;
+          threads[i].is_searching = true; // Slave leaves idle_loop()
 
           if (useSleepingThreads)
               threads[i].wake_up();
 
-          if (++workersCnt >= maxThreadsPerSplitPoint)
+          if (++slavesCnt + 1 >= maxThreadsPerSplitPoint) // Master is always included
               break;
       }
 
-  lock_release(sp->lock);
-  lock_release(threadsLock);
-
-  // We failed to allocate even one slave, return
-  if (!Fake && workersCnt == 1)
-      return bestValue;
-
   masterThread.splitPoint = sp;
   masterThread.activeSplitPoints++;
 
+  lock_release(splitLock);
+  lock_release(sp->lock);
+
   // 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
   // their work at this split point.
-  masterThread.idle_loop(sp);
-
-  // 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);
+  if (slavesCnt || Fake)
+      masterThread.idle_loop(sp);
 
   // We have returned from the idle loop, which means that all threads are
-  // finished. Note that changing state and decreasing activeSplitPoints is done
-  // under lock protection to avoid a race with Thread::is_available_to().
-  lock_grab(threadsLock);
+  // finished. Note that setting is_searching and decreasing activeSplitPoints 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);
 
   masterThread.is_searching = true;
   masterThread.activeSplitPoints--;
   masterThread.splitPoint = sp->parent;
   pos.set_nodes_searched(pos.nodes_searched() + sp->nodes);
 
+  lock_release(splitLock);
   lock_release(sp->lock);
-  lock_release(threadsLock);
 
   return sp->bestValue;
 }
@@ -346,22 +393,6 @@ template Value ThreadsManager::split<false>(Position&, Stack*, Value, Value, Val
 template Value ThreadsManager::split<true>(Position&, Stack*, Value, Value, Value, 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();
-
-void Thread::timer_loop() {
-
-  while (!do_exit)
-  {
-      lock_grab(sleepLock);
-      timed_wait(sleepCond, sleepLock, maxPly ? maxPly : INT_MAX);
-      lock_release(sleepLock);
-      check_time();
-  }
-}
-
-
 // ThreadsManager::set_timer() is used to set the timer to trigger after msec
 // milliseconds. If msec is 0 then timer is stopped.
 
@@ -376,36 +407,6 @@ void ThreadsManager::set_timer(int msec) {
 }
 
 
-// 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
@@ -466,25 +467,3 @@ void ThreadsManager::stop_thinking() {
 
   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);
-}