X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fthread.h;h=34307297dead0fa04a8c21b30f3045d588076f5c;hp=166ea80f65a8af4ec6dca96ada543142873e71c4;hb=cb2111f0b62afec5fd977e1dd4ca5843bd006956;hpb=775f8239d3bec75c8deaf951ab24d3a030b671ee

diff --git a/src/thread.h b/src/thread.h
index 166ea80f..34307297 100644
--- a/src/thread.h
+++ b/src/thread.h
@@ -39,6 +39,35 @@ const size_t MAX_THREADS = 128;
 const size_t MAX_SPLITPOINTS_PER_THREAD = 8;
 const size_t MAX_SLAVES_PER_SPLITPOINT = 4;
 
+#if 0
+/// Spinlock class wraps low level atomic operations to provide a spin lock
+
+class Spinlock {
+
+  std::atomic_int lock;
+
+public:
+  Spinlock() { lock = 1; } // Init here to workaround a bug with MSVC 2013
+  void acquire() {
+    while (lock.fetch_sub(1, std::memory_order_acquire) != 1)
+        while (lock.load(std::memory_order_relaxed) <= 0) {}
+  }
+  void release() { lock.store(1, std::memory_order_release); }
+};
+
+#else
+
+class Spinlock {
+
+  std::mutex mutex;
+
+public:
+  void acquire() { mutex.lock(); }
+  void release() { mutex.unlock(); }
+};
+
+#endif
+
 /// SplitPoint struct stores information shared by the threads searching in
 /// parallel below the same split point. It is populated at splitting time.
 
@@ -58,7 +87,7 @@ struct SplitPoint {
   SplitPoint* parentSplitPoint;
 
   // Shared variable data
-  std::mutex mutex;
+  Spinlock spinlock;
   std::bitset<MAX_THREADS> slavesMask;
   volatile bool allSlavesSearching;
   volatile uint64_t nodes;
@@ -70,19 +99,6 @@ struct SplitPoint {
 };
 
 
-/// Spinlock class wraps low level atomic operations to provide spin lock functionality
-
-class Spinlock {
-
-  std::atomic_flag lock;
-
-public:
-  Spinlock() { std::atomic_flag_clear(&lock); }
-  void acquire() { while (lock.test_and_set(std::memory_order_acquire)) {} }
-  void release() { lock.clear(std::memory_order_release); }
-};
-
-
 /// ThreadBase struct is the base of the hierarchy from where we derive all the
 /// specialized thread classes.
 
@@ -110,7 +126,7 @@ struct Thread : public ThreadBase {
   Thread();
   virtual void idle_loop();
   bool cutoff_occurred() const;
-  bool available_to(const Thread* master) const;
+  bool can_join(const SplitPoint* sp) const;
 
   void split(Position& pos, Search::Stack* ss, Value alpha, Value beta, Value* bestValue, Move* bestMove,
              Depth depth, int moveCount, MovePicker* movePicker, int nodeType, bool cutNode);
@@ -157,12 +173,12 @@ struct ThreadPool : public std::vector<Thread*> {
 
   MainThread* main() { return static_cast<MainThread*>(at(0)); }
   void read_uci_options();
-  Thread* available_slave(const Thread* master) const;
+  Thread* available_slave(const SplitPoint* sp) const;
   void wait_for_think_finished();
   void start_thinking(const Position&, const Search::LimitsType&, Search::StateStackPtr&);
 
   Depth minimumSplitDepth;
-  std::mutex mutex;
+  Spinlock spinlock;
   std::condition_variable sleepCondition;
   TimerThread* timer;
 };