Move ThreadsManager::exit() to d'tor

And add final touches to this long patch series.

All the series has been verified against regression with
20K games at fast TC.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>

src/main.cpp

@@ -55,6 +55,4 @@ int main(int argc, char* argv[]) {
       cerr << "\nUsage: stockfish bench [hash size = 128] [threads = 1] "
            << "[limit = 12] [fen positions file = default] "
            << "[limited by depth, time, nodes or perft = depth]" << endl;
-
-  Threads.exit();
 }

src/thread.cpp

@@ -32,7 +32,7 @@ ThreadsManager Threads; // Global object
 namespace { extern "C" {
 
  // start_routine() is the C function which is called when a new thread
- // is launched. It is a wrapper to member function pointed by start_fn
+ // is launched. It is a wrapper to member function pointed by start_fn.
 
  long start_routine(Thread* th) { (th->*(th->start_fn))(); return 0; }
 
@@ -49,7 +49,8 @@ Thread::Thread(Fn fn) {
   curSplitPoint = NULL;
   start_fn = fn;
   threadID = Threads.size();
-  do_sleep = (threadID != 0); // Avoid a race with start_thinking()
+
+  do_sleep = (fn != &Thread::main_loop); // Avoid a race with start_thinking()
 
   lock_init(sleepLock);
   cond_init(sleepCond);
@@ -65,7 +66,7 @@ Thread::Thread(Fn fn) {
 }
 
 
-// Thread d'tor will wait for thread termination before to return.
+// Thread d'tor waits for thread termination before to return.
 
 Thread::~Thread() {
 
@@ -85,7 +86,7 @@ Thread::~Thread() {
 
 
 // Thread::timer_loop() is where the timer thread waits maxPly milliseconds and
-// then calls do_timer_event(). If maxPly is 0 thread sleeps until is woken up.
+// then calls check_time(). If maxPly is 0 thread sleeps until is woken up.
 extern void check_time();
 
 void Thread::timer_loop() {
@@ -131,7 +132,7 @@ void Thread::main_loop() {
 
 
 // Thread::wake_up() wakes up the thread, normally at the beginning of the search
-// or, if "sleeping threads" is used, when there is some work to do.
+// or, if "sleeping threads" is used at split time.
 
 void Thread::wake_up() {
 
@@ -161,8 +162,8 @@ void Thread::wait_for_stop_or_ponderhit() {
 }
 
 
-// cutoff_occurred() checks whether a beta cutoff has occurred in the current
-// active split point, or in some ancestor of the split point.
+// Thread::cutoff_occurred() checks whether a beta cutoff has occurred in the
+// current active split point, or in some ancestor of the split point.
 
 bool Thread::cutoff_occurred() const {
 
@@ -174,12 +175,12 @@ bool Thread::cutoff_occurred() const {
 }
 
 
-// is_available_to() checks whether the thread is available to help the thread with
-// threadID "master" at a split point. An obvious requirement is that thread must be
-// idle. With more than two threads, this is not by itself sufficient: If the thread
-// is the master of some active split point, it is only available as a slave to the
-// threads which are busy searching the split point at the top of "slave"'s split
-// point stack (the "helpful master concept" in YBWC terminology).
+// Thread::is_available_to() checks whether the thread is available to help the
+// thread with threadID "master" at a split point. An obvious requirement is that
+// thread must be idle. With more than two threads, this is not sufficient: If
+// the thread is the master of some active split point, it is only available as a
+// slave to the threads which are busy searching the split point at the top of
+// "slave"'s split point stack (the "helpful master concept" in YBWC terminology).
 
 bool Thread::is_available_to(int master) const {
 
@@ -196,6 +197,34 @@ bool Thread::is_available_to(int master) const {
 }
 
 
+// init() is called at startup. Initializes lock and condition variable and
+// launches requested threads sending them immediately to sleep. We cannot use
+// a c'tor becuase Threads is a static object and we need a fully initialized
+// engine at this point due to allocation of endgames in Thread c'tor.
+
+void ThreadsManager::init() {
+
+  cond_init(sleepCond);
+  lock_init(splitLock);
+  timer = new Thread(&Thread::timer_loop);
+  threads.push_back(new Thread(&Thread::main_loop));
+  read_uci_options();
+}
+
+
+// d'tor cleanly terminates the threads when the program exits.
+
+ThreadsManager::~ThreadsManager() {
+
+  for (int i = 0; i < size(); i++)
+      delete threads[i];
+
+  delete timer;
+  lock_destroy(splitLock);
+  cond_destroy(sleepCond);
+}
+
+
 // read_uci_options() updates internal threads parameters from the corresponding
 // UCI options and creates/destroys threads to match the requested number. Thread
 // objects are dynamically allocated to avoid creating in advance all possible
@@ -222,10 +251,10 @@ void ThreadsManager::read_uci_options() {
 
 
 // wake_up() is called before a new search to start the threads that are waiting
-// on the sleep condition. If useSleepingThreads is set threads will be woken up
-// at split time.
+// on the sleep condition and to reset maxPly. When useSleepingThreads is set
+// threads will be woken up at split time.
 
-void ThreadsManager::wake_up() {
+void ThreadsManager::wake_up() const {
 
   for (int i = 0; i < size(); i++)
   {
@@ -238,42 +267,16 @@ void ThreadsManager::wake_up() {
 }
 
 
-// sleep() is called after the search to ask all the threads but the main to go
-// waiting on a sleep condition.
+// sleep() is called after the search finishes to ask all the threads but the
+// main one to go waiting on a sleep condition.
 
-void ThreadsManager::sleep() {
+void ThreadsManager::sleep() const {
 
   for (int i = 1; i < size(); i++) // Main thread will go to sleep by itself
       threads[i]->do_sleep = true; // to avoid a race with start_thinking()
 }
 
 
-// init() is called during startup. Initializes locks and condition variables
-// and launches all threads sending them immediately to sleep.
-
-void ThreadsManager::init() {
-
-    cond_init(sleepCond);
-    lock_init(splitLock);
-    timer = new Thread(&Thread::timer_loop);
-    threads.push_back(new Thread(&Thread::main_loop));
-    read_uci_options();
-}
-
-
-// exit() is called to cleanly terminate the threads before the program finishes
-
-void ThreadsManager::exit() {
-
-  for (int i = 0; i < size(); i++)
-      delete threads[i];
-
-  delete timer;
-  lock_destroy(splitLock);
-  cond_destroy(sleepCond);
-}
-
-
 // available_slave_exists() tries to find an idle thread which is available as
 // a slave for the thread with threadID 'master'.
 
@@ -413,7 +416,7 @@ void ThreadsManager::set_timer(int msec) {
 
 
 // ThreadsManager::start_thinking() is used by UI thread to wake up the main
-// thread parked in main_loop() and starting a new search. If asyncMode is true
+// thread parked in main_loop() and starting a new search. If async is true
 // then function returns immediately, otherwise caller is blocked waiting for
 // the search to finish.
 
@@ -423,25 +426,20 @@ void ThreadsManager::start_thinking(const Position& pos, const LimitsType& limit
 
   lock_grab(main.sleepLock);
 
-  // Wait main thread has finished before to launch a new search
   while (!main.do_sleep)
-      cond_wait(sleepCond, main.sleepLock);
+      cond_wait(sleepCond, main.sleepLock); // Wait main thread has finished
+
+  Signals.stopOnPonderhit = Signals.firstRootMove = false;
+  Signals.stop = Signals.failedLowAtRoot = false;
 
-  // Copy input arguments to initialize the search
   RootPosition.copy(pos, 0);
   Limits = limits;
   RootMoves.clear();
 
-  // Populate RootMoves with all the legal moves (default) or, if a searchMoves
-  // set is given, with the subset of legal moves to search.
   for (MoveList<MV_LEGAL> ml(pos); !ml.end(); ++ml)
       if (searchMoves.empty() || searchMoves.count(ml.move()))
           RootMoves.push_back(RootMove(ml.move()));
 
-  // Reset signals before to start the new search
-  Signals.stopOnPonderhit = Signals.firstRootMove = false;
-  Signals.stop = Signals.failedLowAtRoot = false;
-
   main.do_sleep = false;
   cond_signal(main.sleepCond); // Wake up main thread and start searching
 
@@ -454,8 +452,8 @@ void ThreadsManager::start_thinking(const Position& pos, const LimitsType& limit
 
 
 // ThreadsManager::stop_thinking() is used by UI thread to raise a stop request
-// and to wait for the main thread finishing the search. Needed to wait exiting
-// and terminate the threads after a 'quit' command.
+// and to wait for the main thread finishing the search. We cannot return before
+// main has finished to avoid a crash in case of a 'quit' command.
 
 void ThreadsManager::stop_thinking() {
 

src/thread.h

@@ -112,16 +112,16 @@ class ThreadsManager {
      static storage duration are automatically set to zero before enter main()
   */
 public:
-  void init();
-  void exit();
+  void init(); // No c'tor becuase Threads is static and we need stuff initialized
+  ~ThreadsManager();
 
   Thread& operator[](int id) { return *threads[id]; }
   bool use_sleeping_threads() const { return useSleepingThreads; }
   int min_split_depth() const { return minimumSplitDepth; }
   int size() const { return (int)threads.size(); }
 
-  void wake_up();
-  void sleep();
+  void wake_up() const;
+  void sleep() const;
   void read_uci_options();
   bool available_slave_exists(int master) const;
   void set_timer(int msec);

src/tt.h

@@ -139,7 +139,7 @@ inline void TranspositionTable::refresh(const TTEntry* tte) const {
 
 /// A simple fixed size hash table used to store pawns and material
 /// configurations. It is basically just an array of Entry objects.
-/// Without cluster concept or overwrite policy.
+/// Without cluster concept, overwrite policy nor resizing.
 
 template<class Entry, int HashSize>
 struct SimpleHash {
@@ -153,7 +153,7 @@ struct SimpleHash {
     {
         std::cerr << "Failed to allocate " << HashSize * sizeof(Entry)
                   << " bytes for hash table." << std::endl;
-        exit(EXIT_FAILURE);
+        ::exit(EXIT_FAILURE);
     }
     memset(entries, 0, HashSize * sizeof(Entry));
   }