Reformat and simplify previous patch

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index fbe6b2c052fa3fee50e7f98bcf37639134e438a1..1d40f8a070bfbe9f64ccd85355985aa54a769916 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -984,8 +984,10 @@ moves_loop: // When in check and at SpNode search starts from here
 
       // Step 19. Check for splitting the search
       if (   !SpNode
+          &&  Threads.size() >= 2
           &&  depth >= Threads.minimumSplitDepth
-          &&  Threads.available_slave(thisThread)
+          &&  (   !thisThread->activeSplitPoint
+               || !thisThread->activeSplitPoint->allSlavesSearching)
           &&  thisThread->splitPointsSize < MAX_SPLITPOINTS_PER_THREAD)
       {
           assert(bestValue > -VALUE_INFINITE && bestValue < beta);
@@ -1530,6 +1532,7 @@ void Thread::idle_loop() {
           searching = false;
           activePosition = NULL;
           sp->slavesMask.reset(idx);
+          sp->allSlavesSearching = false;
           sp->nodes += pos.nodes_searched();
 
           // Wake up the master thread so to allow it to return from the idle
@@ -1547,6 +1550,37 @@ void Thread::idle_loop() {
           // the sp master. Also accessing other Thread objects is unsafe because
           // if we are exiting there is a chance that they are already freed.
           sp->mutex.unlock();
+
+          // Try to late join to another split point if none of its slaves has
+          // already finished.
+          if (Threads.size() > 2)
+              for (size_t i = 0; i < Threads.size(); ++i)
+              {
+                  int size = Threads[i]->splitPointsSize; // Local copy
+                  sp = size ? &Threads[i]->splitPoints[size - 1] : NULL;
+
+                  if (   sp
+                      && sp->allSlavesSearching
+                      && available_to(Threads[i]))
+                  {
+                      // Recheck the conditions under lock protection
+                      Threads.mutex.lock();
+                      sp->mutex.lock();
+
+                      if (   sp->allSlavesSearching
+                          && available_to(Threads[i]))
+                      {
+                           sp->slavesMask.set(idx);
+                           activeSplitPoint = sp;
+                           searching = true;
+                      }
+
+                      sp->mutex.unlock();
+                      Threads.mutex.unlock();
+
+                      break; // Just a single attempt
+                  }
+              }
       }
 
       // If this thread is the master of a split point and all slaves have finished