Futher renaming in thread.cpp

No functional change.

src/search.cpp

@@ -1008,7 +1008,7 @@ split_point_start: // At split points actual search starts from here
       // Step 19. Check for splitting the search
       if (   !SpNode
           &&  depth >= Threads.minimumSplitDepth
-          &&  Threads.available_slave_exists(thisThread))
+          &&  Threads.slave_available(thisThread))
       {
           assert(bestValue < beta);
 
@@ -1554,31 +1554,31 @@ void RootMove::insert_pv_in_tt(Position& pos) {
 
 void Thread::idle_loop() {
 
-  // Pointer 'sp_master', if non-NULL, points to the active SplitPoint
+  // Pointer 'this_sp' is not null only if we are called from split(), and not
-  // object for which the thread is the master.
+  // at the thread creation. So it means we are the split point's master.
-  const SplitPoint* sp_master = splitPointsCnt ? curSplitPoint : NULL;
+  const SplitPoint* this_sp = splitPointsSize ? activeSplitPoint : NULL;
 
-  assert(!sp_master || (sp_master->master == this && searching));
+  assert(!this_sp || (this_sp->master == this && searching));
 
-  // If this thread is the master of a split point and all slaves have
+  // If this thread is the master of a split point and all slaves have finished
-  // finished their work at this split point, return from the idle loop.
+  // their work at this split point, return from the idle loop.
-  while (!sp_master || sp_master->slavesMask)
+  while (!this_sp || this_sp->slavesMask)
   {
-      // If we are not searching, wait for a condition to be signaled
+      // If we are not searching, wait for a condition to be signaled instead of
-      // instead of wasting CPU time polling for work.
+      // wasting CPU time polling for work.
       while ((!searching && Threads.sleepWhileIdle) || exit)
       {
           if (exit)
           {
-              assert(!sp_master);
+              assert(!this_sp);
               return;
           }
 
-          // Grab the lock to avoid races with Thread::wake_up()
+          // Grab the lock to avoid races with Thread::notify_one()
           mutex.lock();
 
-          // If we are master and all slaves have finished don't go to sleep
+          // If we are master and all slaves have finished then exit idle_loop
-          if (sp_master && !sp_master->slavesMask)
+          if (this_sp && !this_sp->slavesMask)
           {
               mutex.unlock();
               break;
@@ -1586,8 +1586,8 @@ void Thread::idle_loop() {
 
           // Do sleep after retesting sleep conditions under lock protection, in
           // particular we need to avoid a deadlock in case a master thread has,
-          // in the meanwhile, allocated us and sent the wake_up() call before we
+          // in the meanwhile, allocated us and sent the notify_one() call before
-          // had the chance to grab the lock.
+          // we had the chance to grab the lock.
           if (!searching && !exit)
               sleepCondition.wait(mutex);
 
@@ -1602,7 +1602,7 @@ void Thread::idle_loop() {
           Threads.mutex.lock();
 
           assert(searching);
-          SplitPoint* sp = curSplitPoint;
+          SplitPoint* sp = activeSplitPoint;
 
           Threads.mutex.unlock();
 
@@ -1614,28 +1614,33 @@ void Thread::idle_loop() {
 
           sp->mutex.lock();
 
-          assert(sp->activePositions[idx] == NULL);
+          assert(sp->slavesPositions[idx] == NULL);
 
-          sp->activePositions[idx] = &pos;
+          sp->slavesPositions[idx] = &pos;
 
-          if (sp->nodeType == Root)
+          switch (sp->nodeType) {
+          case Root:
               search<SplitPointRoot>(pos, ss+1, sp->alpha, sp->beta, sp->depth);
-          else if (sp->nodeType == PV)
+              break;
+          case PV:
               search<SplitPointPV>(pos, ss+1, sp->alpha, sp->beta, sp->depth);
-          else if (sp->nodeType == NonPV)
+              break;
+          case NonPV:
               search<SplitPointNonPV>(pos, ss+1, sp->alpha, sp->beta, sp->depth);
-          else
+              break;
+          default:
               assert(false);
+          }
 
           assert(searching);
 
           searching = false;
-          sp->activePositions[idx] = NULL;
+          sp->slavesPositions[idx] = NULL;
           sp->slavesMask &= ~(1ULL << idx);
           sp->nodes += pos.nodes_searched();
 
-          // Wake up master thread so to allow it to return from the idle loop in
+          // Wake up master thread so to allow it to return from the idle loop
-          // case we are the last slave of the split point.
+          // in case we are the last slave of the split point.
           if (    Threads.sleepWhileIdle
               &&  this != sp->master
               && !sp->slavesMask)
@@ -1681,7 +1686,7 @@ void check_time() {
       // Loop across all split points and sum accumulated SplitPoint nodes plus
       // all the currently active slaves positions.
       for (size_t i = 0; i < Threads.size(); i++)
-          for (int j = 0; j < Threads[i].splitPointsCnt; j++)
+          for (int j = 0; j < Threads[i].splitPointsSize; j++)
           {
               SplitPoint& sp = Threads[i].splitPoints[j];
 
@@ -1691,7 +1696,7 @@ void check_time() {
               Bitboard sm = sp.slavesMask;
               while (sm)
               {
-                  Position* pos = sp.activePositions[pop_lsb(&sm)];
+                  Position* pos = sp.slavesPositions[pop_lsb(&sm)];
                   nodes += pos ? pos->nodes_searched() : 0;
               }
 

src/thread.cpp

@@ -45,8 +45,8 @@ namespace { extern "C" {
 Thread::Thread() : splitPoints() {
 
   searching = exit = false;
-  maxPly = splitPointsCnt = 0;
+  maxPly = splitPointsSize = 0;
-  curSplitPoint = NULL;
+  activeSplitPoint = NULL;
   idx = Threads.size();
 
   if (!thread_create(handle, start_routine, this))
@@ -146,7 +146,7 @@ void Thread::wait_for(volatile const bool& b) {
 
 bool Thread::cutoff_occurred() const {
 
-  for (SplitPoint* sp = curSplitPoint; sp; sp = sp->parent)
+  for (SplitPoint* sp = activeSplitPoint; sp; sp = sp->parent)
       if (sp->cutoff)
           return true;
 
@@ -157,9 +157,9 @@ bool Thread::cutoff_occurred() const {
 // Thread::is_available_to() checks whether the thread is available to help the
 // thread '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
+// the master of some split point, it is only available as a slave to the slaves
-// slaves which are busy searching the split point at the top of slaves split
+// which are busy searching the split point at the top of slaves split point
-// point stack (the "helpful master concept" in YBWC terminology).
+// stack (the "helpful master concept" in YBWC terminology).
 
 bool Thread::is_available_to(Thread* master) const {
 
@@ -168,11 +168,11 @@ bool Thread::is_available_to(Thread* master) const {
 
   // Make a local copy to be sure doesn't become zero under our feet while
   // testing next condition and so leading to an out of bound access.
-  int spCnt = splitPointsCnt;
+  int size = splitPointsSize;
 
-  // No active split points means that the thread is available as a slave for any
+  // No split points means that the thread is available as a slave for any
   // other thread otherwise apply the "helpful master" concept if possible.
-  return !spCnt || (splitPoints[spCnt - 1].slavesMask & (1ULL << master->idx));
+  return !size || (splitPoints[size - 1].slavesMask & (1ULL << master->idx));
 }
 
 
@@ -225,10 +225,10 @@ void ThreadPool::read_uci_options() {
 }
 
 
-// available_slave_exists() tries to find an idle thread which is available as
+// slave_available() tries to find an idle thread which is available as a slave
-// a slave for the thread 'master'.
+// for the thread 'master'.
 
-bool ThreadPool::available_slave_exists(Thread* master) const {
+bool ThreadPool::slave_available(Thread* master) const {
 
   for (size_t i = 0; i < threads.size(); i++)
       if (threads[i]->is_available_to(master))
@@ -261,15 +261,14 @@ Value ThreadPool::split(Position& pos, Stack* ss, Value alpha, Value beta,
 
   Thread* master = pos.this_thread();
 
-  if (master->splitPointsCnt >= MAX_SPLITPOINTS_PER_THREAD)
+  if (master->splitPointsSize >= MAX_SPLITPOINTS_PER_THREAD)
       return bestValue;
 
   // Pick the next available split point from the split point stack
-  SplitPoint& sp = master->splitPoints[master->splitPointsCnt];
+  SplitPoint& sp = master->splitPoints[master->splitPointsSize];
 
-  sp.parent = master->curSplitPoint;
   sp.master = master;
-  sp.cutoff = false;
+  sp.parent = master->activeSplitPoint;
   sp.slavesMask = 1ULL << master->idx;
   sp.depth = depth;
   sp.bestMove = *bestMove;
@@ -282,15 +281,16 @@ Value ThreadPool::split(Position& pos, Stack* ss, Value alpha, Value beta,
   sp.moveCount = moveCount;
   sp.pos = &pos;
   sp.nodes = 0;
+  sp.cutoff = false;
   sp.ss = ss;
 
+  master->activeSplitPoint = &sp;
+  int slavesCnt = 0;
+
   assert(master->searching);
 
-  master->curSplitPoint = &sp;
-  int slavesCnt = 0;
-
   // Try to allocate available threads and ask them to start searching setting
-  // is_searching flag. This must be done under lock protection to avoid concurrent
+  // 'searching' flag. This must be done under lock protection to avoid concurrent
   // allocation of the same slave by another master.
   mutex.lock();
   sp.mutex.lock();
@@ -299,21 +299,21 @@ Value ThreadPool::split(Position& pos, Stack* ss, Value alpha, Value beta,
       if (threads[i]->is_available_to(master))
       {
           sp.slavesMask |= 1ULL << i;
-          threads[i]->curSplitPoint = &sp;
+          threads[i]->activeSplitPoint = &sp;
           threads[i]->searching = true; // Slave leaves idle_loop()
           threads[i]->notify_one(); // Could be sleeping
 
-          if (++slavesCnt + 1 >= maxThreadsPerSplitPoint) // Master is always included
+          if (++slavesCnt + 1 >= maxThreadsPerSplitPoint) // Include master
               break;
       }
 
-  master->splitPointsCnt++;
+  master->splitPointsSize++;
 
   sp.mutex.unlock();
   mutex.unlock();
 
   // Everything is set up. The master thread enters the idle loop, from which
-  // it will instantly launch a search, because its is_searching flag is set.
+  // it will instantly launch a search, because its 'searching' flag is set.
   // The thread will return from the idle loop when all slaves have finished
   // their work at this split point.
   if (slavesCnt || Fake)
@@ -326,14 +326,14 @@ Value ThreadPool::split(Position& pos, Stack* ss, Value alpha, Value beta,
   }
 
   // We have returned from the idle loop, which means that all threads are
-  // finished. Note that setting is_searching and decreasing splitPointsCnt is
+  // finished. Note that setting 'searching' and decreasing splitPointsSize is
   // done under lock protection to avoid a race with Thread::is_available_to().
   mutex.lock();
   sp.mutex.lock();
 
   master->searching = true;
-  master->splitPointsCnt--;
+  master->splitPointsSize--;
-  master->curSplitPoint = sp.parent;
+  master->activeSplitPoint = sp.parent;
   pos.set_nodes_searched(pos.nodes_searched() + sp.nodes);
   *bestMove = sp.bestMove;
 

src/thread.h

@@ -63,10 +63,10 @@ struct SplitPoint {
   // Const data after split point has been setup
   const Position* pos;
   const Search::Stack* ss;
+  Thread* master;
   Depth depth;
   Value beta;
   int nodeType;
-  Thread* master;
   Move threatMove;
 
   // Const pointers to shared data
@@ -75,7 +75,7 @@ struct SplitPoint {
 
   // Shared data
   Mutex mutex;
-  Position* activePositions[MAX_THREADS];
+  Position* slavesPositions[MAX_THREADS];
   volatile uint64_t slavesMask;
   volatile int64_t nodes;
   volatile Value alpha;
@@ -111,14 +111,14 @@ struct Thread {
   Mutex mutex;
   ConditionVariable sleepCondition;
   NativeHandle handle;
-  SplitPoint* volatile curSplitPoint;
+  SplitPoint* volatile activeSplitPoint;
-  volatile int splitPointsCnt;
+  volatile int splitPointsSize;
   volatile bool searching;
   volatile bool exit;
 };
 
 
-/// MainThread and TimerThread are sublassed from Thread to charaterize the two
+/// MainThread and TimerThread are sublassed from Thread to characterize the two
 /// special threads: the main one and the recurring timer.
 
 struct MainThread : public Thread {
@@ -150,7 +150,7 @@ public:
   TimerThread* timer_thread() { return timer; }
 
   void read_uci_options();
-  bool available_slave_exists(Thread* master) const;
+  bool slave_available(Thread* master) const;
   void wait_for_think_finished();
   void start_thinking(const Position&, const Search::LimitsType&,
                        const std::vector<Move>&, Search::StateStackPtr&);
@@ -161,16 +161,12 @@ public:
 
   bool sleepWhileIdle;
   Depth minimumSplitDepth;
-
-private:
-  friend struct Thread;
-  friend struct MainThread;
-  friend void check_time();
-
-  std::vector<Thread*> threads;
-  TimerThread* timer;
   Mutex mutex;
   ConditionVariable sleepCondition;
+
+private:
+  std::vector<Thread*> threads;
+  TimerThread* timer;
   int maxThreadsPerSplitPoint;
 };