X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fthread.h;h=b6809f4e37221dcca2329b62980f07a7e42c5238;hp=b18170dfcccfa9b29b1bf4f011747142e48e3166;hb=a590d1d52deb22dfe42d5e59740ef07853320bb7;hpb=bf706c4a4ff06e91edf8c24685d24130146f88d4

diff --git a/src/thread.h b/src/thread.h
index b18170df..b6809f4e 100644
--- a/src/thread.h
+++ b/src/thread.h
@@ -1,7 +1,7 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
   Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
-  Copyright (C) 2008-2012 Marco Costalba, Joona Kiiski, Tord Romstad
+  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -17,9 +17,14 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-#if !defined(THREAD_H_INCLUDED)
+#ifndef THREAD_H_INCLUDED
 #define THREAD_H_INCLUDED
 
+#include <atomic>
+#include <bitset>
+#include <condition_variable>
+#include <mutex>
+#include <thread>
 #include <vector>
 
 #include "material.h"
@@ -28,56 +33,52 @@
 #include "position.h"
 #include "search.h"
 
-const int MAX_THREADS = 64; // Because SplitPoint::slavesMask is a uint64_t
-const int MAX_SPLITPOINTS_PER_THREAD = 8;
-
-struct Mutex {
-  Mutex() { lock_init(l); }
- ~Mutex() { lock_destroy(l); }
+struct Thread;
 
-  void lock() { lock_grab(l); }
-  void unlock() { lock_release(l); }
+const size_t MAX_THREADS = 128;
+const size_t MAX_SPLITPOINTS_PER_THREAD = 8;
+const size_t MAX_SLAVES_PER_SPLITPOINT = 4;
 
-private:
-  friend struct ConditionVariable;
 
-  Lock l;
-};
+/// Spinlock class wraps low level atomic operations to provide a spin lock
 
-struct ConditionVariable {
-  ConditionVariable() { cond_init(c); }
- ~ConditionVariable() { cond_destroy(c); }
+class Spinlock {
 
-  void wait(Mutex& m) { cond_wait(c, m.l); }
-  void wait_for(Mutex& m, int ms) { timed_wait(c, m.l, ms); }
-  void notify_one() { cond_signal(c); }
+  std::atomic_int lock;
 
-private:
-  WaitCondition c;
+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); }
 };
 
-struct Thread;
+
+/// SplitPoint struct stores information shared by the threads searching in
+/// parallel below the same split point. It is populated at splitting time.
 
 struct SplitPoint {
 
   // Const data after split point has been setup
   const Position* pos;
-  const Search::Stack* ss;
-  Thread* masterThread;
+  Search::Stack* ss;
+  Thread* master;
   Depth depth;
   Value beta;
   int nodeType;
-  Move threatMove;
+  bool cutNode;
 
   // Const pointers to shared data
   MovePicker* movePicker;
   SplitPoint* parentSplitPoint;
 
-  // Shared data
-  Mutex mutex;
-  Position* slavesPositions[MAX_THREADS];
-  volatile uint64_t slavesMask;
-  volatile int64_t nodes;
+  // Shared variable data
+  Spinlock spinlock;
+  std::bitset<MAX_THREADS> slavesMask;
+  volatile bool allSlavesSearching;
+  volatile uint64_t nodes;
   volatile Value alpha;
   volatile Value bestValue;
   volatile Move bestMove;
@@ -86,82 +87,90 @@ struct SplitPoint {
 };
 
 
+/// ThreadBase struct is the base of the hierarchy from where we derive all the
+/// specialized thread classes.
+
+struct ThreadBase {
+
+  virtual ~ThreadBase() = default;
+  virtual void idle_loop() = 0;
+  void notify_one();
+  void wait_for(volatile const bool& b);
+
+  std::thread nativeThread;
+  std::mutex mutex;
+  std::condition_variable sleepCondition;
+  volatile bool exit = false;
+};
+
+
 /// Thread struct keeps together all the thread related stuff like locks, state
 /// and especially split points. We also use per-thread pawn and material hash
 /// tables so that once we get a pointer to an entry its life time is unlimited
 /// and we don't have to care about someone changing the entry under our feet.
 
-struct Thread {
+struct Thread : public ThreadBase {
 
   Thread();
-  virtual ~Thread();
-
   virtual void idle_loop();
-  void notify_one();
   bool cutoff_occurred() const;
-  bool is_available_to(Thread* master) const;
-  void wait_for(volatile const bool& b);
+  bool can_join(const SplitPoint* sp) const;
 
-  template <bool Fake>
   void split(Position& pos, Search::Stack* ss, Value alpha, Value beta, Value* bestValue, Move* bestMove,
-             Depth depth, Move threatMove, int moveCount, MovePicker* movePicker, int nodeType);
+             Depth depth, int moveCount, MovePicker* movePicker, int nodeType, bool cutNode);
 
   SplitPoint splitPoints[MAX_SPLITPOINTS_PER_THREAD];
+  Pawns::Table pawnsTable;
   Material::Table materialTable;
   Endgames endgames;
-  Pawns::Table pawnsTable;
+  Position* activePosition;
   size_t idx;
   int maxPly;
-  Mutex mutex;
-  ConditionVariable sleepCondition;
-  NativeHandle handle;
   SplitPoint* volatile activeSplitPoint;
-  volatile int splitPointsSize;
+  volatile size_t splitPointsSize;
   volatile bool searching;
-  volatile bool exit;
 };
 
 
-/// MainThread and TimerThread are sublassed from Thread to characterize the two
+/// MainThread and TimerThread are derived classes used to characterize the two
 /// special threads: the main one and the recurring timer.
 
 struct MainThread : public Thread {
-  MainThread() : thinking(true) {} // Avoid a race with start_thinking()
   virtual void idle_loop();
-  volatile bool thinking;
+  volatile bool thinking = true; // Avoid a race with start_thinking()
 };
 
-struct TimerThread : public Thread {
-  TimerThread() : msec(0) {}
+struct TimerThread : public ThreadBase {
+
+  static const int Resolution = 5; // Millisec between two check_time() calls
+
   virtual void idle_loop();
-  int msec;
+
+  bool run = false;
 };
 
 
 /// ThreadPool struct handles all the threads related stuff like init, starting,
-/// parking and, the most important, launching a slave thread at a split point.
+/// parking and, most importantly, launching a slave thread at a split point.
 /// All the access to shared thread data is done through this class.
 
 struct ThreadPool : public std::vector<Thread*> {
 
-  void init(); // No c'tor and d'tor, threads rely on globals that should
-  void exit(); // be initialized and valid during the whole thread lifetime.
+  void init(); // No c'tor and d'tor, threads rely on globals that should be
+  void exit(); // initialized and are valid during the whole thread lifetime.
 
-  MainThread* main_thread() { return static_cast<MainThread*>((*this)[0]); }
+  MainThread* main() { return static_cast<MainThread*>(at(0)); }
   void read_uci_options();
-  bool slave_available(Thread* master) const;
+  Thread* available_slave(const SplitPoint* sp) const;
   void wait_for_think_finished();
-  void start_thinking(const Position&, const Search::LimitsType&,
-                      const std::vector<Move>&, Search::StateStackPtr&);
+  void start_thinking(const Position&, const Search::LimitsType&, Search::StateStackPtr&);
 
-  bool sleepWhileIdle;
   Depth minimumSplitDepth;
-  size_t maxThreadsPerSplitPoint;
-  Mutex mutex;
-  ConditionVariable sleepCondition;
+  Spinlock spinlock;
+  std::condition_variable sleepCondition;
   TimerThread* timer;
 };
 
 extern ThreadPool Threads;
 
-#endif // !defined(THREAD_H_INCLUDED)
+#endif // #ifndef THREAD_H_INCLUDED