Thread code reformat

Simplify out low level sync stuff (mutex
and friends) and avoid to use them directly
in many functions.

Also some renaming and better comment while
there.

No functional change.

src/thread.h

@@ -35,20 +35,21 @@
 #include "thread_win32.h"
 
 
-/// Thread struct keeps together all the thread-related stuff. 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.
+/// Thread class keeps together all the thread-related stuff. We 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.
 
 class Thread {
 
-  std::thread nativeThread;
   Mutex mutex;
-  ConditionVariable sleepCondition;
-  bool exit, searching;
+  ConditionVariable cv;
+  size_t idx;
+  bool exit = false, searching = true; // Set before starting std::thread
+  std::thread stdThread;
 
 public:
-  Thread();
+  explicit Thread(size_t);
   virtual ~Thread();
   virtual void search();
   void idle_loop();
@@ -58,52 +59,62 @@ public:
   Pawns::Table pawnsTable;
   Material::Table materialTable;
   Endgames endgames;
-  size_t idx, PVIdx;
+  size_t PVIdx;
   int selDepth;
   std::atomic<uint64_t> nodes, tbHits;
 
   Position rootPos;
   Search::RootMoves rootMoves;
-  Depth rootDepth;
-  Depth completedDepth;
+  Depth rootDepth, completedDepth;
   CounterMoveHistory counterMoves;
   ButterflyHistory mainHistory;
   ContinuationHistory contHistory;
 };
 
 
-/// MainThread is a derived class with a specific overload for the main thread
+/// MainThread is a derived class specific for main thread
 
 struct MainThread : public Thread {
+
+  using Thread::Thread;
+
   virtual void search();
   void check_time();
 
   bool easyMovePlayed, failedLow;
   double bestMoveChanges;
   Value previousScore;
-  int callsCnt = 0;
+  int callsCnt;
 };
 
 
 /// ThreadPool struct handles all the threads-related stuff like init, starting,
 /// parking and, most importantly, launching a thread. All the access to threads
-/// data is done through this class.
+/// is done through this class.
 
 struct ThreadPool : public std::vector<Thread*> {
 
-  void init(); // No constructor and destructor, threads rely on globals that should
-  void exit(); // be initialized and valid during the whole thread lifetime.
-
-  MainThread* main() { return static_cast<MainThread*>(at(0)); }
+  void init(size_t); // No constructor and destructor, threads rely on globals that should
+  void exit();       // be initialized and valid during the whole thread lifetime.
   void start_thinking(Position&, StateListPtr&, const Search::LimitsType&, bool = false);
-  void read_uci_options();
-  uint64_t nodes_searched() const;
-  uint64_t tb_hits() const;
+  void set(size_t);
+
+  MainThread* main()        const { return static_cast<MainThread*>(front()); }
+  uint64_t nodes_searched() const { return accumulate(&Thread::nodes); }
+  uint64_t tb_hits()        const { return accumulate(&Thread::tbHits); }
 
   std::atomic_bool stop, ponder, stopOnPonderhit;
 
 private:
   StateListPtr setupStates;
+
+  uint64_t accumulate(std::atomic<uint64_t> Thread::* member) const {
+
+    uint64_t sum = 0;
+    for (Thread* th : *this)
+        sum += (th->*member).load(std::memory_order_relaxed);
+    return sum;
+  }
 };
 
 extern ThreadPool Threads;