X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fthread.h;h=e6a4cf95744ca0260f2ae11fd7c58aa7a1dae169;hp=d97a25a693831b047a547ba539d51fc01e7fec06;hb=63a5fc2366ba215365f8ab246f4a910fcf31c38e;hpb=8da2153ee89dd6874cdf35bacedcc73ea8d13d2c

diff --git a/src/thread.h b/src/thread.h
index d97a25a6..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 Marco Costalba
+  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
@@ -17,63 +17,160 @@
   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>
 
-////
-//// Includes
-////
-
-#include "lock.h"
+#include "material.h"
 #include "movepick.h"
+#include "pawns.h"
 #include "position.h"
 #include "search.h"
 
+struct Thread;
+
+const size_t MAX_THREADS = 128;
+const size_t MAX_SPLITPOINTS_PER_THREAD = 8;
+const size_t MAX_SLAVES_PER_SPLITPOINT = 4;
 
-////
-//// Constants and variables
-////
 
-const int THREAD_MAX = 8;
+/// Spinlock class wraps low level atomic operations to provide a spin lock
 
+class Spinlock {
 
-////
-//// Types
-////
+  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); }
+};
+
+
+/// SplitPoint struct stores information shared by the threads searching in
+/// parallel below the same split point. It is populated at splitting time.
 
 struct SplitPoint {
-  SplitPoint *parent;
-  Position pos;
-  SearchStack sstack[THREAD_MAX][PLY_MAX];
-  SearchStack *parentSstack;
-  int ply;
+
+  // Const data after split point has been setup
+  const Position* pos;
+  Search::Stack* ss;
+  Thread* master;
   Depth depth;
-  volatile Value alpha, beta, bestValue;
-  bool pvNode;
-  Bitboard dcCandidates;
-  int master, slaves[THREAD_MAX];
-  Lock lock;
-  MovePicker *mp;
-  volatile int moves;
-  volatile int cpus;
-  bool finished;
+  Value beta;
+  int nodeType;
+  bool cutNode;
+
+  // Const pointers to shared data
+  MovePicker* movePicker;
+  SplitPoint* parentSplitPoint;
+
+  // 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;
+  volatile int moveCount;
+  volatile bool cutoff;
+};
+
+
+/// 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 : public ThreadBase {
+
+  Thread();
+  virtual void idle_loop();
+  bool cutoff_occurred() 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);
+
+  SplitPoint splitPoints[MAX_SPLITPOINTS_PER_THREAD];
+  Pawns::Table pawnsTable;
+  Material::Table materialTable;
+  Endgames endgames;
+  Position* activePosition;
+  size_t idx;
+  int maxPly;
+  SplitPoint* volatile activeSplitPoint;
+  volatile size_t splitPointsSize;
+  volatile bool searching;
 };
 
 
-struct Thread {
-  SplitPoint *splitPoint;
-  int activeSplitPoints;
-  uint64_t nodes;
-  bool failHighPly1;
-  volatile bool stop;
-  volatile bool running;
-  volatile bool idle;
-  volatile bool workIsWaiting;
-  volatile bool printCurrentLine;
-  unsigned char pad[64];
+/// MainThread and TimerThread are derived classes used to characterize the two
+/// special threads: the main one and the recurring timer.
+
+struct MainThread : public Thread {
+  virtual void idle_loop();
+  volatile bool thinking = true; // Avoid a race with start_thinking()
+};
+
+struct TimerThread : public ThreadBase {
+
+  static const int Resolution = 5; // Millisec between two check_time() calls
+
+  virtual void idle_loop();
+
+  bool run = false;
+};
+
+
+/// ThreadPool struct handles all the threads related stuff like init, starting,
+/// 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 be
+  void exit(); // initialized and are valid during the whole thread lifetime.
+
+  MainThread* main() { return static_cast<MainThread*>(at(0)); }
+  void read_uci_options();
+  Thread* available_slave(const SplitPoint* sp) const;
+  void wait_for_think_finished();
+  void start_thinking(const Position&, const Search::LimitsType&, Search::StateStackPtr&);
+
+  Depth minimumSplitDepth;
+  Spinlock spinlock;
+  std::condition_variable sleepCondition;
+  TimerThread* timer;
 };
 
+extern ThreadPool Threads;
 
-#endif // !defined(THREAD_H_INCLUDED)
+#endif // #ifndef THREAD_H_INCLUDED