X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fthread.cpp;h=7d85db8618ca982059b96466d963e29d3b1b5ba7;hp=229c6beb365154b9c0ec8bc8eb5ebcc1f64c8ebe;hb=c65d67feb53895a34423cc2043edc69741f2ba92;hpb=62b32a47378fa84108bb8aee2192ba66c87c3280

diff --git a/src/thread.cpp b/src/thread.cpp
index 229c6beb..7d85db86 100644
--- a/src/thread.cpp
+++ b/src/thread.cpp
@@ -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) 2008-2013 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
@@ -17,8 +17,8 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
+#include <algorithm> // For std::count
 #include <cassert>
-#include <iostream>
 
 #include "movegen.h"
 #include "search.h"
@@ -29,41 +29,64 @@ using namespace Search;
 
 ThreadPool Threads; // Global object
 
-namespace { extern "C" {
+namespace {
 
  // start_routine() is the C function which is called when a new thread
  // is launched. It is a wrapper to the virtual function idle_loop().
 
- long start_routine(Thread* th) { th->idle_loop(); return 0; }
+ extern "C" { long start_routine(ThreadBase* th) { th->idle_loop(); return 0; } }
 
-} }
 
+ // Helpers to launch a thread after creation and joining before delete. Must be
+ // outside Thread c'tor and d'tor because object shall be fully initialized
+ // when start_routine (and hence virtual idle_loop) is called and when joining.
 
-// Thread c'tor starts a newly-created thread of execution that will call
-// the the virtual function idle_loop(), going immediately to sleep.
+ template<typename T> T* new_thread() {
+   T* th = new T();
+   thread_create(th->handle, start_routine, th); // Will go to sleep
+   return th;
+ }
 
-Thread::Thread() : splitPoints() {
+ void delete_thread(ThreadBase* th) {
+   th->exit = true; // Search must be already finished
+   th->notify_one();
+   thread_join(th->handle); // Wait for thread termination
+   delete th;
+ }
 
-  searching = exit = false;
-  maxPly = splitPointsSize = 0;
-  activeSplitPoint = NULL;
-  idx = Threads.size();
+}
 
-  if (!thread_create(handle, start_routine, this))
-  {
-      std::cerr << "Failed to create thread number " << idx << std::endl;
-      ::exit(EXIT_FAILURE);
-  }
+
+// ThreadBase::notify_one() wakes up the thread when there is some work to do
+
+void ThreadBase::notify_one() {
+
+  mutex.lock();
+  sleepCondition.notify_one();
+  mutex.unlock();
+}
+
+
+// ThreadBase::wait_for() set the thread to sleep until condition 'b' turns true
+
+void ThreadBase::wait_for(volatile const bool& b) {
+
+  mutex.lock();
+  while (!b) sleepCondition.wait(mutex);
+  mutex.unlock();
 }
 
 
-// Thread d'tor waits for thread termination before to return
+// Thread c'tor just inits data but does not launch any thread of execution that
+// instead will be started only upon c'tor returns.
 
-Thread::~Thread() {
+Thread::Thread() /* : splitPoints() */ { // Value-initialization bug in MSVC
 
-  exit = true; // Search must be already finished
-  notify_one();
-  thread_join(handle); // Wait for thread termination
+  searching = false;
+  maxPly = splitPointsSize = 0;
+  activeSplitPoint = NULL;
+  activePosition = NULL;
+  idx = Threads.size();
 }
 
 
@@ -121,32 +144,12 @@ void MainThread::idle_loop() {
 }
 
 
-// Thread::notify_one() wakes up the thread when there is some search to do
-
-void Thread::notify_one() {
-
-  mutex.lock();
-  sleepCondition.notify_one();
-  mutex.unlock();
-}
-
-
-// Thread::wait_for() set the thread to sleep until condition 'b' turns true
-
-void Thread::wait_for(volatile const bool& b) {
-
-  mutex.lock();
-  while (!b) sleepCondition.wait(mutex);
-  mutex.unlock();
-}
-
-
 // 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 {
 
-  for (SplitPoint* sp = activeSplitPoint; sp; sp = sp->parent)
+  for (SplitPoint* sp = activeSplitPoint; sp; sp = sp->parentSplitPoint)
       if (sp->cutoff)
           return true;
 
@@ -161,7 +164,7 @@ bool Thread::cutoff_occurred() const {
 // which are busy searching the split point at the top of slaves split point
 // stack (the "helpful master concept" in YBWC terminology).
 
-bool Thread::is_available_to(Thread* master) const {
+bool Thread::is_available_to(const Thread* master) const {
 
   if (searching)
       return false;
@@ -176,28 +179,28 @@ bool Thread::is_available_to(Thread* master) const {
 }
 
 
-// init() is called at startup. Initializes lock and condition variable and
-// launches requested threads sending them immediately to sleep. We cannot use
+// init() is called at startup to create and launch requested threads, that will
+// go immediately to sleep due to 'sleepWhileIdle' set to true. 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.
+// engine at this point due to allocation of Endgames in Thread c'tor.
 
 void ThreadPool::init() {
 
   sleepWhileIdle = true;
-  timer = new TimerThread();
-  threads.push_back(new MainThread());
+  timer = new_thread<TimerThread>();
+  push_back(new_thread<MainThread>());
   read_uci_options();
 }
 
 
-// exit() cleanly terminates the threads before the program exits.
+// exit() cleanly terminates the threads before the program exits
 
 void ThreadPool::exit() {
 
-  delete timer; // As first becuase check_time() accesses threads data
+  delete_thread(timer); // As first because check_time() accesses threads data
 
-  for (size_t i = 0; i < threads.size(); i++)
-      delete threads[i];
+  for (iterator it = begin(); it != end(); ++it)
+      delete_thread(*it);
 }
 
 
@@ -214,13 +217,20 @@ void ThreadPool::read_uci_options() {
 
   assert(requested > 0);
 
-  while (threads.size() < requested)
-      threads.push_back(new Thread());
+  // Value 0 has a special meaning: We determine the optimal minimum split depth
+  // automatically. Anyhow the minimumSplitDepth should never be under 4 plies.
+  if (!minimumSplitDepth)
+      minimumSplitDepth = (requested < 8 ? 4 : 7) * ONE_PLY;
+  else
+      minimumSplitDepth = std::max(4 * ONE_PLY, minimumSplitDepth);
+
+  while (size() < requested)
+      push_back(new_thread<Thread>());
 
-  while (threads.size() > requested)
+  while (size() > requested)
   {
-      delete threads.back();
-      threads.pop_back();
+      delete_thread(back());
+      pop_back();
   }
 }
 
@@ -228,139 +238,133 @@ void ThreadPool::read_uci_options() {
 // slave_available() tries to find an idle thread which is available as a slave
 // for the thread 'master'.
 
-bool ThreadPool::slave_available(Thread* master) const {
+Thread* ThreadPool::available_slave(const Thread* master) const {
 
-  for (size_t i = 0; i < threads.size(); i++)
-      if (threads[i]->is_available_to(master))
-          return true;
+  for (const_iterator it = begin(); it != end(); ++it)
+      if ((*it)->is_available_to(master))
+          return *it;
 
-  return false;
+  return NULL;
 }
 
 
 // split() does the actual work of distributing the work at a node between
 // several available threads. If it does not succeed in splitting the node
-// (because no idle threads are available, or because we have no unused split
-// point objects), the function immediately returns. If splitting is possible, a
-// SplitPoint object is initialized with all the data that must be copied to the
-// helper threads and then helper threads are told that they have been assigned
-// work. This will cause them to instantly leave their idle loops and call
-// search(). When all threads have returned from search() then split() returns.
+// (because no idle threads are available), the function immediately returns.
+// If splitting is possible, a SplitPoint object is initialized with all the
+// data that must be copied to the helper threads and then helper threads are
+// told that they have been assigned work. This will cause them to instantly
+// leave their idle loops and call search(). When all threads have returned from
+// search() then split() returns.
 
 template <bool Fake>
-Value ThreadPool::split(Position& pos, Stack* ss, Value alpha, Value beta,
-                        Value bestValue, Move* bestMove, Depth depth, Move threatMove,
-                        int moveCount, MovePicker& mp, int nodeType) {
+void Thread::split(Position& pos, const Stack* ss, Value alpha, Value beta, Value* bestValue,
+                   Move* bestMove, Depth depth, Move threatMove, int moveCount,
+                   MovePicker* movePicker, int nodeType, bool cutNode) {
 
   assert(pos.pos_is_ok());
-  assert(bestValue > -VALUE_INFINITE);
-  assert(bestValue <= alpha);
-  assert(alpha < beta);
-  assert(beta <= VALUE_INFINITE);
-  assert(depth > DEPTH_ZERO);
-
-  Thread* master = pos.this_thread();
-
-  if (master->splitPointsSize >= MAX_SPLITPOINTS_PER_THREAD)
-      return bestValue;
+  assert(*bestValue <= alpha && alpha < beta && beta <= VALUE_INFINITE);
+  assert(*bestValue > -VALUE_INFINITE);
+  assert(depth >= Threads.minimumSplitDepth);
+  assert(searching);
+  assert(splitPointsSize < MAX_SPLITPOINTS_PER_THREAD);
 
   // Pick the next available split point from the split point stack
-  SplitPoint& sp = master->splitPoints[master->splitPointsSize];
+  SplitPoint& sp = splitPoints[splitPointsSize];
 
-  sp.master = master;
-  sp.parent = master->activeSplitPoint;
-  sp.slavesMask = 1ULL << master->idx;
+  sp.masterThread = this;
+  sp.parentSplitPoint = activeSplitPoint;
+  sp.slavesMask = 1ULL << idx;
   sp.depth = depth;
+  sp.bestValue = *bestValue;
   sp.bestMove = *bestMove;
   sp.threatMove = threatMove;
   sp.alpha = alpha;
   sp.beta = beta;
   sp.nodeType = nodeType;
-  sp.bestValue = bestValue;
-  sp.mp = &mp;
+  sp.cutNode = cutNode;
+  sp.movePicker = movePicker;
   sp.moveCount = moveCount;
   sp.pos = &pos;
   sp.nodes = 0;
   sp.cutoff = false;
   sp.ss = ss;
 
-  master->activeSplitPoint = &sp;
-  int slavesCnt = 0;
-
-  assert(master->searching);
-
   // Try to allocate available threads and ask them to start searching setting
   // 'searching' flag. This must be done under lock protection to avoid concurrent
   // allocation of the same slave by another master.
-  mutex.lock();
+  Threads.mutex.lock();
   sp.mutex.lock();
 
-  for (size_t i = 0; i < threads.size() && !Fake; ++i)
-      if (threads[i]->is_available_to(master))
-      {
-          sp.slavesMask |= 1ULL << i;
-          threads[i]->activeSplitPoint = &sp;
-          threads[i]->searching = true; // Slave leaves idle_loop()
-          threads[i]->notify_one(); // Could be sleeping
-
-          if (++slavesCnt + 1 >= maxThreadsPerSplitPoint) // Include master
-              break;
-      }
+  splitPointsSize++;
+  activeSplitPoint = &sp;
+  activePosition = NULL;
 
-  master->splitPointsSize++;
+  size_t slavesCnt = 1; // This thread is always included
+  Thread* slave;
 
-  sp.mutex.unlock();
-  mutex.unlock();
+  while (    (slave = Threads.available_slave(this)) != NULL
+         && ++slavesCnt <= Threads.maxThreadsPerSplitPoint && !Fake)
+  {
+      sp.slavesMask |= 1ULL << slave->idx;
+      slave->activeSplitPoint = &sp;
+      slave->searching = true; // Slave leaves idle_loop()
+      slave->notify_one(); // Could be sleeping
+  }
 
   // Everything is set up. The master thread enters the idle loop, from which
   // 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)
+  if (slavesCnt > 1 || Fake)
   {
-      master->Thread::idle_loop(); // Force a call to base class idle_loop()
+      sp.mutex.unlock();
+      Threads.mutex.unlock();
+
+      Thread::idle_loop(); // Force a call to base class idle_loop()
 
       // In helpful master concept a master can help only a sub-tree of its split
       // point, and because here is all finished is not possible master is booked.
-      assert(!master->searching);
+      assert(!searching);
+      assert(!activePosition);
+
+      // We have returned from the idle loop, which means that all threads are
+      // finished. Note that setting 'searching' and decreasing splitPointsSize is
+      // done under lock protection to avoid a race with Thread::is_available_to().
+      Threads.mutex.lock();
+      sp.mutex.lock();
   }
 
-  // We have returned from the idle loop, which means that all threads are
-  // 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->splitPointsSize--;
-  master->activeSplitPoint = sp.parent;
+  searching = true;
+  splitPointsSize--;
+  activeSplitPoint = sp.parentSplitPoint;
+  activePosition = &pos;
   pos.set_nodes_searched(pos.nodes_searched() + sp.nodes);
   *bestMove = sp.bestMove;
+  *bestValue = sp.bestValue;
 
   sp.mutex.unlock();
-  mutex.unlock();
-
-  return sp.bestValue;
+  Threads.mutex.unlock();
 }
 
 // Explicit template instantiations
-template Value ThreadPool::split<false>(Position&, Stack*, Value, Value, Value, Move*, Depth, Move, int, MovePicker&, int);
-template Value ThreadPool::split<true>(Position&, Stack*, Value, Value, Value, Move*, Depth, Move, int, MovePicker&, int);
+template void Thread::split<false>(Position&, const Stack*, Value, Value, Value*, Move*, Depth, Move, int, MovePicker*, int, bool);
+template void Thread::split< true>(Position&, const Stack*, Value, Value, Value*, Move*, Depth, Move, int, MovePicker*, int, bool);
 
 
 // wait_for_think_finished() waits for main thread to go to sleep then returns
 
 void ThreadPool::wait_for_think_finished() {
 
-  MainThread* t = main_thread();
+  MainThread* t = main();
   t->mutex.lock();
   while (t->thinking) sleepCondition.wait(t->mutex);
   t->mutex.unlock();
 }
 
 
-// start_thinking() wakes up the main thread sleeping in  main_loop() so to start
-// a new search, then returns immediately.
+// start_thinking() wakes up the main thread sleeping in MainThread::idle_loop()
+// so to start a new search, then returns immediately.
 
 void ThreadPool::start_thinking(const Position& pos, const LimitsType& limits,
                                 const std::vector<Move>& searchMoves, StateStackPtr& states) {
@@ -371,15 +375,20 @@ void ThreadPool::start_thinking(const Position& pos, const LimitsType& limits,
   Signals.stopOnPonderhit = Signals.firstRootMove = false;
   Signals.stop = Signals.failedLowAtRoot = false;
 
+  RootMoves.clear();
   RootPos = pos;
   Limits = limits;
-  SetupStates = states; // Ownership transfer here
-  RootMoves.clear();
+  if (states.get()) // If we don't set a new position, preserve current state
+  {
+      SetupStates = states; // Ownership transfer here
+      assert(!states.get());
+  }
 
-  for (MoveList<LEGAL> ml(pos); !ml.end(); ++ml)
-      if (searchMoves.empty() || count(searchMoves.begin(), searchMoves.end(), ml.move()))
-          RootMoves.push_back(RootMove(ml.move()));
+  for (MoveList<LEGAL> it(pos); *it; ++it)
+      if (   searchMoves.empty()
+          || std::count(searchMoves.begin(), searchMoves.end(), *it))
+          RootMoves.push_back(RootMove(*it));
 
-  main_thread()->thinking = true;
-  main_thread()->notify_one(); // Starts main thread
+  main()->thinking = true;
+  main()->notify_one(); // Starts main thread
 }