X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fthread.cpp;h=1217e3ab020656787c9dd1b8a5886fecdadcaa1a;hp=4fc0953eac6ec7145ba8ade4e16b228db6d70e0f;hb=38112060dc2da351c6dde8f12d0ee5cfaeac5084;hpb=4739037f967ac3c818907e89cc88c7b97021d027

diff --git a/src/thread.cpp b/src/thread.cpp
index 4fc0953e..1217e3ab 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) 2008-2014 Marco Costalba, Joona Kiiski, Tord Romstad
+  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
@@ -33,66 +33,63 @@ extern void check_time();
 
 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().
-
- 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 the object will be fully initialized
+ // outside Thread c'tor and d'tor because the object must be fully initialized
  // when start_routine (and hence virtual idle_loop) is called and when joining.
 
  template<typename T> T* new_thread() {
    T* th = new T();
-   thread_create(th->handle, start_routine, th); // Will go to sleep
+   th->nativeThread = std::thread(&ThreadBase::idle_loop, th); // Will go to sleep
    return th;
  }
 
  void delete_thread(ThreadBase* th) {
+
+   th->mutex.lock();
    th->exit = true; // Search must be already finished
+   th->mutex.unlock();
+
    th->notify_one();
-   thread_join(th->handle); // Wait for thread termination
+   th->nativeThread.join(); // Wait for thread termination
    delete th;
  }
 
 }
 
 
-// notify_one() wakes up the thread when there is some work to do
+// ThreadBase::notify_one() wakes up the thread when there is some work to do
 
 void ThreadBase::notify_one() {
 
-  mutex.lock();
+  std::unique_lock<std::mutex>(this->mutex);
   sleepCondition.notify_one();
-  mutex.unlock();
 }
 
 
-// wait_for() set the thread to sleep until condition 'b' turns true
+// ThreadBase::wait_for() set the thread to sleep until 'condition' turns true
 
-void ThreadBase::wait_for(volatile const bool& b) {
+void ThreadBase::wait_for(volatile const bool& condition) {
 
-  mutex.lock();
-  while (!b) sleepCondition.wait(mutex);
-  mutex.unlock();
+  std::unique_lock<std::mutex> lk(mutex);
+  sleepCondition.wait(lk, [&]{ return condition; });
 }
 
 
-// Thread c'tor just inits data and does not launch any execution thread.
-// Such a thread will only be started when c'tor returns.
+// Thread c'tor makes some init but does not launch any execution thread that
+// will be started only when c'tor returns.
 
-Thread::Thread() /* : splitPoints() */ { // Value-initialization bug in MSVC
+Thread::Thread() /* : splitPoints() */ { // Initialization of non POD broken in MSVC
 
   searching = false;
-  maxPly = splitPointsSize = 0;
-  activeSplitPoint = NULL;
-  activePosition = NULL;
+  maxPly = 0;
+  splitPointsSize = 0;
+  activeSplitPoint = nullptr;
+  activePosition = nullptr;
   idx = Threads.size(); // Starts from 0
 }
 
 
-// cutoff_occurred() checks whether a beta cutoff has occurred in the
+// 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 {
@@ -119,7 +116,7 @@ bool Thread::available_to(const Thread* master) const {
 
   // Make a local copy to be sure it doesn't become zero under our feet while
   // testing next condition and so leading to an out of bounds access.
-  const int size = splitPointsSize;
+  const size_t size = splitPointsSize;
 
   // No split points means that the thread is available as a slave for any
   // other thread otherwise apply the "helpful master" concept if possible.
@@ -127,19 +124,113 @@ bool Thread::available_to(const Thread* master) const {
 }
 
 
-// TimerThread::idle_loop() is where the timer thread waits msec milliseconds
-// and then calls check_time(). If msec is 0 thread sleeps until it's woken up.
+// Thread::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), 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
+// informed 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.
+
+void Thread::split(Position& pos, Stack* ss, Value alpha, Value beta, Value* bestValue,
+                   Move* bestMove, Depth depth, int moveCount,
+                   MovePicker* movePicker, int nodeType, bool cutNode) {
+
+  assert(searching);
+  assert(-VALUE_INFINITE < *bestValue && *bestValue <= alpha && alpha < beta && beta <= VALUE_INFINITE);
+  assert(depth >= Threads.minimumSplitDepth);
+  assert(splitPointsSize < MAX_SPLITPOINTS_PER_THREAD);
+
+  // Pick and init the next available split point
+  SplitPoint& sp = splitPoints[splitPointsSize];
+
+  sp.master = this;
+  sp.parentSplitPoint = activeSplitPoint;
+  sp.slavesMask = 0, sp.slavesMask.set(idx);
+  sp.depth = depth;
+  sp.bestValue = *bestValue;
+  sp.bestMove = *bestMove;
+  sp.alpha = alpha;
+  sp.beta = beta;
+  sp.nodeType = nodeType;
+  sp.cutNode = cutNode;
+  sp.movePicker = movePicker;
+  sp.moveCount = moveCount;
+  sp.pos = &pos;
+  sp.nodes = 0;
+  sp.cutoff = false;
+  sp.ss = ss;
+
+  // 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.
+  Threads.spinlock.acquire();
+  sp.spinlock.acquire();
+
+  sp.allSlavesSearching = true; // Must be set under lock protection
+  ++splitPointsSize;
+  activeSplitPoint = &sp;
+  activePosition = nullptr;
+
+  Thread* slave;
+
+  while (    sp.slavesMask.count() < MAX_SLAVES_PER_SPLITPOINT
+         && (slave = Threads.available_slave(this)) != nullptr)
+  {
+      sp.slavesMask.set(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.
+  sp.spinlock.release();
+  Threads.spinlock.release();
+
+  Thread::idle_loop(); // Force a call to base class idle_loop()
+
+  // In the helpful master concept, a master can help only a sub-tree of its
+  // split point and because everything is finished here, it's not possible
+  // for the master to be booked.
+  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 must
+  // be done under lock protection to avoid a race with Thread::available_to().
+  Threads.spinlock.acquire();
+  sp.spinlock.acquire();
+
+  searching = true;
+  --splitPointsSize;
+  activeSplitPoint = sp.parentSplitPoint;
+  activePosition = &pos;
+  pos.set_nodes_searched(pos.nodes_searched() + sp.nodes);
+  *bestMove = sp.bestMove;
+  *bestValue = sp.bestValue;
+
+  sp.spinlock.release();
+  Threads.spinlock.release();
+}
+
+
+// TimerThread::idle_loop() is where the timer thread waits Resolution milliseconds
+// and then calls check_time(). When not searching, thread sleeps until it's woken up.
 
 void TimerThread::idle_loop() {
 
   while (!exit)
   {
-      mutex.lock();
+      std::unique_lock<std::mutex> lk(mutex);
 
       if (!exit)
-          sleepCondition.wait_for(mutex, run ? Resolution : INT_MAX);
+          sleepCondition.wait_for(lk, std::chrono::milliseconds(run ? Resolution : INT_MAX));
 
-      mutex.unlock();
+      lk.unlock();
 
       if (run)
           check_time();
@@ -152,38 +243,38 @@ void TimerThread::idle_loop() {
 
 void MainThread::idle_loop() {
 
-  while (true)
+  while (!exit)
   {
-      mutex.lock();
+      std::unique_lock<std::mutex> lk(mutex);
 
       thinking = false;
 
       while (!thinking && !exit)
       {
           Threads.sleepCondition.notify_one(); // Wake up the UI thread if needed
-          sleepCondition.wait(mutex);
+          sleepCondition.wait(lk);
       }
 
-      mutex.unlock();
-
-      if (exit)
-          return;
+      lk.unlock();
 
-      searching = true;
+      if (!exit)
+      {
+          searching = true;
 
-      Search::think();
+          Search::think();
 
-      assert(searching);
+          assert(searching);
 
-      searching = false;
+          searching = false;
+      }
   }
 }
 
 
-// init() is called at startup to create and launch requested threads, that will
-// go immediately to sleep. We cannot use a c'tor because Threads is a static
-// object and we need a fully initialized engine at this point due to allocation
-// of Endgames in Thread c'tor.
+// ThreadPool::init() is called at startup to create and launch requested threads,
+// that will go immediately to sleep. We cannot use a c'tor because 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 ThreadPool::init() {
 
@@ -193,23 +284,23 @@ void ThreadPool::init() {
 }
 
 
-// exit() cleanly terminates the threads before the program exits. Cannot be done in
-// d'tor because we have to terminate the threads before to free ThreadPool object.
+// ThreadPool::exit() terminates the threads before the program exits. Cannot be
+// done in d'tor because threads must be terminated before freeing us.
 
 void ThreadPool::exit() {
 
   delete_thread(timer); // As first because check_time() accesses threads data
 
-  for (iterator it = begin(); it != end(); ++it)
-      delete_thread(*it);
+  for (Thread* th : *this)
+      delete_thread(th);
 }
 
 
-// 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 all possible threads
-// in advance (which include pawns and material tables), even if only a few
-// are to be used.
+// ThreadPool::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 all possible
+// threads in advance (which include pawns and material tables), even if only a
+// few are to be used.
 
 void ThreadPool::read_uci_options() {
 
@@ -233,126 +324,33 @@ void ThreadPool::read_uci_options() {
 }
 
 
-// available_slave() tries to find an idle thread which is available as a slave
-// for the thread 'master'.
+// ThreadPool::available_slave() tries to find an idle thread which is available
+// as a slave for the thread 'master'.
 
 Thread* ThreadPool::available_slave(const Thread* master) const {
 
-  for (const_iterator it = begin(); it != end(); ++it)
-      if ((*it)->available_to(master))
-          return *it;
+  for (Thread* th : *this)
+      if (th->available_to(master))
+          return th;
 
-  return NULL;
+  return nullptr;
 }
 
 
-// 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), 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.
-
-void Thread::split(Position& pos, Stack* ss, Value alpha, Value beta, Value* bestValue,
-                   Move* bestMove, Depth depth, int moveCount,
-                   MovePicker* movePicker, int nodeType, bool cutNode) {
-
-  assert(pos.pos_is_ok());
-  assert(-VALUE_INFINITE < *bestValue && *bestValue <= alpha && alpha < beta && beta <= 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 = splitPoints[splitPointsSize];
-
-  sp.masterThread = this;
-  sp.parentSplitPoint = activeSplitPoint;
-  sp.slavesMask = 0, sp.slavesMask.set(idx);
-  sp.depth = depth;
-  sp.bestValue = *bestValue;
-  sp.bestMove = *bestMove;
-  sp.alpha = alpha;
-  sp.beta = beta;
-  sp.nodeType = nodeType;
-  sp.cutNode = cutNode;
-  sp.movePicker = movePicker;
-  sp.moveCount = moveCount;
-  sp.pos = &pos;
-  sp.nodes = 0;
-  sp.cutoff = false;
-  sp.ss = ss;
-
-  // 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.
-  Threads.mutex.lock();
-  sp.mutex.lock();
-
-  sp.allSlavesSearching = true; // Must be set under lock protection
-  ++splitPointsSize;
-  activeSplitPoint = &sp;
-  activePosition = NULL;
-
-  for (Thread* slave; (slave = Threads.available_slave(this)) != NULL; )
-  {
-      sp.slavesMask.set(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.
-  sp.mutex.unlock();
-  Threads.mutex.unlock();
-
-  Thread::idle_loop(); // Force a call to base class idle_loop()
-
-  // In the helpful master concept, a master can help only a sub-tree of its
-  // split point and because everything is finished here, it's not possible
-  // for the master to be booked.
-  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::available_to().
-  Threads.mutex.lock();
-  sp.mutex.lock();
-
-  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();
-  Threads.mutex.unlock();
-}
-
-// wait_for_think_finished() waits for main thread to go to sleep then returns
+// ThreadPool::wait_for_think_finished() waits for main thread to finish the search
 
 void ThreadPool::wait_for_think_finished() {
 
-  MainThread* t = main();
-  t->mutex.lock();
-  while (t->thinking) sleepCondition.wait(t->mutex);
-  t->mutex.unlock();
+  std::unique_lock<std::mutex> lk(main()->mutex);
+  sleepCondition.wait(lk, [&]{ return !main()->thinking; });
 }
 
 
-// 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, StateStackPtr& states) {
+// ThreadPool::start_thinking() wakes up the main thread sleeping in
+// MainThread::idle_loop() and starts a new search, then returns immediately.
 
+void ThreadPool::start_thinking(const Position& pos, const LimitsType& limits,
+                                StateStackPtr& states) {
   wait_for_think_finished();
 
   SearchTime = Time::now(); // As early as possible
@@ -365,14 +363,14 @@ void ThreadPool::start_thinking(const Position& pos, const LimitsType& limits, S
   Limits = limits;
   if (states.get()) // If we don't set a new position, preserve current state
   {
-      SetupStates = states; // Ownership transfer here
+      SetupStates = std::move(states); // Ownership transfer here
       assert(!states.get());
   }
 
-  for (MoveList<LEGAL> it(pos); *it; ++it)
+  for (const auto& m : MoveList<LEGAL>(pos))
       if (   limits.searchmoves.empty()
-          || std::count(limits.searchmoves.begin(), limits.searchmoves.end(), *it))
-          RootMoves.push_back(RootMove(*it));
+          || std::count(limits.searchmoves.begin(), limits.searchmoves.end(), m))
+          RootMoves.push_back(RootMove(m));
 
   main()->thinking = true;
   main()->notify_one(); // Starts main thread