Use acquire() and release() for spinlocks

It is more idiomatick than lock() and unlock()

No functional change.

diff --git a/src/movepick.cpp b/src/movepick.cpp
index d6a40d70af4c7d2d37305fe1f60dde62d6f51791..b82e68b66a8019160998e7c0880c71ef58bbac2a 100644 (file)
--- a/src/movepick.cpp
+++ b/src/movepick.cpp
@@ -162,9 +162,9 @@ void MovePicker::score<CAPTURES>() {
 
 template<>
 void MovePicker::score<QUIETS>() {
 
 template<>
 void MovePicker::score<QUIETS>() {

-  Square prevMoveSq = to_sq((ss-1)->currentMove);
-  Piece prevMovePiece = pos.piece_on(prevMoveSq);
-  const HistoryStats &cmh = counterMovesHistory[prevMovePiece][prevMoveSq];
+
+  Square prevSq = to_sq((ss-1)->currentMove);
+  const HistoryStats& cmh = counterMovesHistory[pos.piece_on(prevSq)][prevSq];

 
   for (auto& m : *this)
       m.value =  history[pos.moved_piece(m)][to_sq(m)]
 
   for (auto& m : *this)
       m.value =  history[pos.moved_piece(m)][to_sq(m)]

diff --git a/src/search.cpp b/src/search.cpp
index 374f6e6fe836bce8e689144f9dea32caf96c2576..948f526cce836613e4e88fa80db9533ab9613c8e 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -826,7 +826,7 @@ moves_loop: // When in check and at SpNode search starts from here
               continue;
 
           moveCount = ++splitPoint->moveCount;
               continue;
 
           moveCount = ++splitPoint->moveCount;

-          splitPoint->mutex.unlock();
+          splitPoint->spinlock.release();

       }
       else
           ++moveCount;
       }
       else
           ++moveCount;


@@ -895,7 +895,7 @@ moves_loop: // When in check and at SpNode search starts from here
               && moveCount >= FutilityMoveCounts[improving][depth])
           {
               if (SpNode)
               && moveCount >= FutilityMoveCounts[improving][depth])
           {
               if (SpNode)

-                  splitPoint->mutex.lock();
+                  splitPoint->spinlock.acquire();

 
               continue;
           }
 
               continue;
           }


@@ -914,7 +914,7 @@ moves_loop: // When in check and at SpNode search starts from here
 
                   if (SpNode)
                   {
 
                   if (SpNode)
                   {

-                      splitPoint->mutex.lock();
+                      splitPoint->spinlock.acquire();

                       if (bestValue > splitPoint->bestValue)
                           splitPoint->bestValue = bestValue;
                   }
                       if (bestValue > splitPoint->bestValue)
                           splitPoint->bestValue = bestValue;
                   }


@@ -926,7 +926,7 @@ moves_loop: // When in check and at SpNode search starts from here
           if (predictedDepth < 4 * ONE_PLY && pos.see_sign(move) < VALUE_ZERO)
           {
               if (SpNode)
           if (predictedDepth < 4 * ONE_PLY && pos.see_sign(move) < VALUE_ZERO)
           {
               if (SpNode)

-                  splitPoint->mutex.lock();
+                  splitPoint->spinlock.acquire();

 
               continue;
           }
 
               continue;
           }


@@ -1026,7 +1026,7 @@ moves_loop: // When in check and at SpNode search starts from here
       // Step 18. Check for new best move
       if (SpNode)
       {
       // Step 18. Check for new best move
       if (SpNode)
       {

-          splitPoint->mutex.lock();
+          splitPoint->spinlock.acquire();

           bestValue = splitPoint->bestValue;
           alpha = splitPoint->alpha;
       }
           bestValue = splitPoint->bestValue;
           alpha = splitPoint->alpha;
       }


@@ -1630,7 +1630,7 @@ void Thread::idle_loop() {
           std::memcpy(ss-2, sp->ss-2, 5 * sizeof(Stack));
           ss->splitPoint = sp;
 
           std::memcpy(ss-2, sp->ss-2, 5 * sizeof(Stack));
           ss->splitPoint = sp;
 

-          sp->mutex.lock();
+          sp->spinlock.acquire();

 
           assert(activePosition == nullptr);
 
 
           assert(activePosition == nullptr);
 


@@ -1659,7 +1659,7 @@ void Thread::idle_loop() {
           // After releasing the lock we can't access any SplitPoint related data
           // in a safe way because it could have been released under our feet by
           // the sp master.
           // After releasing the lock we can't access any SplitPoint related data
           // in a safe way because it could have been released under our feet by
           // the sp master.

-          sp->mutex.unlock();
+          sp->spinlock.release();

 
           // Try to late join to another split point if none of its slaves has
           // already finished.
 
           // Try to late join to another split point if none of its slaves has
           // already finished.


@@ -1699,12 +1699,12 @@ void Thread::idle_loop() {
               sp = bestSp;
 
               // Recheck the conditions under lock protection
               sp = bestSp;
 
               // Recheck the conditions under lock protection

-              sp->mutex.lock();
+              sp->spinlock.acquire();

 
               if (   sp->allSlavesSearching
                   && sp->slavesMask.count() < MAX_SLAVES_PER_SPLITPOINT)
               {
 
               if (   sp->allSlavesSearching
                   && sp->slavesMask.count() < MAX_SLAVES_PER_SPLITPOINT)
               {

-                  allocMutex.lock();
+                  spinlock.acquire();

 
                   if (can_join(sp))
                   {
 
                   if (can_join(sp))
                   {


@@ -1713,10 +1713,10 @@ void Thread::idle_loop() {
                       searching = true;
                   }
 
                       searching = true;
                   }
 

-                  allocMutex.unlock();
+                  spinlock.release();

               }
 
               }
 

-              sp->mutex.unlock();
+              sp->spinlock.release();

           }
       }
   }
           }
       }
   }


@@ -1767,7 +1767,7 @@ void check_time() {
           {
               SplitPoint& sp = th->splitPoints[i];
 
           {
               SplitPoint& sp = th->splitPoints[i];
 

-              sp.mutex.lock();
+              sp.spinlock.acquire();

 
               nodes += sp.nodes;
 
 
               nodes += sp.nodes;
 


@@ -1775,7 +1775,7 @@ void check_time() {
                   if (sp.slavesMask.test(idx) && Threads[idx]->activePosition)
                       nodes += Threads[idx]->activePosition->nodes_searched();
 
                   if (sp.slavesMask.test(idx) && Threads[idx]->activePosition)
                       nodes += Threads[idx]->activePosition->nodes_searched();
 

-              sp.mutex.unlock();
+              sp.spinlock.release();

           }
 
       if (nodes >= Limits.nodes)
           }
 
       if (nodes >= Limits.nodes)

diff --git a/src/thread.cpp b/src/thread.cpp
index 71bf08d2da67e238590a93b8c23182f047d4e4a4..4b5d845bd83577992601f1306a881bdacb812d19 100644 (file)
--- a/src/thread.cpp
+++ b/src/thread.cpp
@@ -144,7 +144,7 @@ void Thread::split(Position& pos, Stack* ss, Value alpha, Value beta, Value* bes
   // Pick and init the next available split point
   SplitPoint& sp = splitPoints[splitPointsSize];
 
   // Pick and init the next available split point
   SplitPoint& sp = splitPoints[splitPointsSize];
 

-  sp.mutex.lock(); // No contention here until we don't increment splitPointsSize
+  sp.spinlock.acquire(); // No contention here until we don't increment splitPointsSize

 
   sp.master = this;
   sp.parentSplitPoint = activeSplitPoint;
 
   sp.master = this;
   sp.parentSplitPoint = activeSplitPoint;


@@ -174,7 +174,7 @@ void Thread::split(Position& pos, Stack* ss, Value alpha, Value beta, Value* bes
   while (    sp.slavesMask.count() < MAX_SLAVES_PER_SPLITPOINT
          && (slave = Threads.available_slave(&sp)) != nullptr)
   {
   while (    sp.slavesMask.count() < MAX_SLAVES_PER_SPLITPOINT
          && (slave = Threads.available_slave(&sp)) != nullptr)
   {

-     slave->allocMutex.lock();
+     slave->spinlock.acquire();

 
       if (slave->can_join(activeSplitPoint))
       {
 
       if (slave->can_join(activeSplitPoint))
       {


@@ -183,14 +183,14 @@ void Thread::split(Position& pos, Stack* ss, Value alpha, Value beta, Value* bes
           slave->searching = true;
       }
 
           slave->searching = true;
       }
 

-      slave->allocMutex.unlock();
+      slave->spinlock.release();

   }
 
   // Everything is set up. The master thread enters the idle loop, from which
   // 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.
   }
 
   // Everything is set up. The master thread enters the idle loop, from which
   // 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.

-  sp.mutex.unlock();
+  sp.spinlock.release();

 
   Thread::idle_loop(); // Force a call to base class idle_loop()
 
 
   Thread::idle_loop(); // Force a call to base class idle_loop()
 


@@ -205,7 +205,7 @@ void Thread::split(Position& pos, Stack* ss, Value alpha, Value beta, Value* bes
   // We have returned from the idle loop, which means that all threads are
   // finished. Note that decreasing splitPointsSize must be done under lock
   // protection to avoid a race with Thread::can_join().
   // We have returned from the idle loop, which means that all threads are
   // finished. Note that decreasing splitPointsSize must be done under lock
   // protection to avoid a race with Thread::can_join().

-  sp.mutex.lock();
+  sp.spinlock.acquire();

 
   --splitPointsSize;
   activeSplitPoint = sp.parentSplitPoint;
 
   --splitPointsSize;
   activeSplitPoint = sp.parentSplitPoint;


@@ -214,7 +214,7 @@ void Thread::split(Position& pos, Stack* ss, Value alpha, Value beta, Value* bes
   *bestMove = sp.bestMove;
   *bestValue = sp.bestValue;
 
   *bestMove = sp.bestMove;
   *bestValue = sp.bestValue;
 

-  sp.mutex.unlock();
+  sp.spinlock.release();

 }
 
 
 }
 
 

diff --git a/src/thread.h b/src/thread.h
index 8f930149f333e764d3525fc9d93fd8f4dba3798b..7932ad45f6b0e967229b6557f69858a3abd94fcf 100644 (file)
--- a/src/thread.h
+++ b/src/thread.h
@@ -41,16 +41,17 @@ const size_t MAX_SPLITPOINTS_PER_THREAD = 8;
 const size_t MAX_SLAVES_PER_SPLITPOINT = 4;
 
 class Spinlock {
 const size_t MAX_SLAVES_PER_SPLITPOINT = 4;
 
 class Spinlock {

-  std::atomic_int _lock;
+
+  std::atomic_int lock;

 
 public:
 
 public:

-  Spinlock() { _lock = 1; } // Init here to workaround a bug with MSVC 2013
-  void lock() {
-      while (_lock.fetch_sub(1, std::memory_order_acquire) != 1)
-          for (int cnt = 0; _lock.load(std::memory_order_relaxed) <= 0; ++cnt)
+  Spinlock() { lock = 1; } // Init here to workaround a bug with MSVC 2013
+  void acquire() {
+      while (lock.fetch_sub(1, std::memory_order_acquire) != 1)
+          for (int cnt = 0; lock.load(std::memory_order_relaxed) <= 0; ++cnt)

               if (cnt >= 10000) std::this_thread::yield(); // Be nice to hyperthreading
   }
               if (cnt >= 10000) std::this_thread::yield(); // Be nice to hyperthreading
   }

-  void unlock() { _lock.store(1, std::memory_order_release); }
+  void release() { lock.store(1, std::memory_order_release); }

 };
 
 
 };
 
 


@@ -73,7 +74,7 @@ struct SplitPoint {
   SplitPoint* parentSplitPoint;
 
   // Shared variable data
   SplitPoint* parentSplitPoint;
 
   // Shared variable data

-  Spinlock mutex;
+  Spinlock spinlock;

   std::bitset<MAX_THREADS> slavesMask;
   volatile bool allSlavesSearching;
   volatile uint64_t nodes;
   std::bitset<MAX_THREADS> slavesMask;
   volatile bool allSlavesSearching;
   volatile uint64_t nodes;


@@ -97,6 +98,7 @@ struct ThreadBase {
 
   std::thread nativeThread;
   Mutex mutex;
 
   std::thread nativeThread;
   Mutex mutex;

+  Spinlock spinlock;

   ConditionVariable sleepCondition;
   volatile bool exit = false;
 };
   ConditionVariable sleepCondition;
   volatile bool exit = false;
 };


@@ -127,7 +129,6 @@ struct Thread : public ThreadBase {
   SplitPoint* volatile activeSplitPoint;
   volatile size_t splitPointsSize;
   volatile bool searching;
   SplitPoint* volatile activeSplitPoint;
   volatile size_t splitPointsSize;
   volatile bool searching;

-  Spinlock allocMutex;

 };
 
 
 };