X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fthread.cpp;h=4dc7d9e9b02aa565a56dd626155c706baf5893ad;hp=2fd3c7aa9e37fbfc24b579ddd2f89d33dbb6d983;hb=e082112cfeb6a40ca592a15983cdedb0210daf3a;hpb=5d1b92e8f9836e1d403bcf60653dcf6b059c8720

diff --git a/src/thread.cpp b/src/thread.cpp
index 2fd3c7aa..4dc7d9e9 100644
--- a/src/thread.cpp
+++ b/src/thread.cpp
@@ -2,6 +2,7 @@
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
   Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
   Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
+  Copyright (C) 2015-2016 Marco Costalba, Joona Kiiski, Gary Linscott, 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
@@ -25,354 +26,181 @@
 #include "thread.h"
 #include "uci.h"
 
-using namespace Search;
-
 ThreadPool Threads; // Global object
 
-extern void check_time();
-
-namespace {
-
- // Helpers to launch a thread after creation and joining before delete. Must be
- // 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() {
-   std::thread* th = new T;
-   *th = std::thread(&T::idle_loop, (T*)th); // Will go to sleep
-   return (T*)th;
- }
-
- void delete_thread(ThreadBase* th) {
+/// Thread constructor launches the thread and then waits until it goes to sleep
+/// in idle_loop().
 
-   th->mutex.lock();
-   th->exit = true; // Search must be already finished
-   th->mutex.unlock();
+Thread::Thread() {
 
-   th->notify_one();
-   th->join(); // Wait for thread termination
-   delete th;
- }
+  resetCalls = exit = false;
+  maxPly = callsCnt = 0;
+  history.clear();
+  counterMoves.clear();
+  idx = Threads.size(); // Start from 0
 
+  std::unique_lock<Mutex> lk(mutex);
+  searching = true;
+  nativeThread = std::thread(&Thread::idle_loop, this);
+  sleepCondition.wait(lk, [&]{ return !searching; });
 }
 
 
-// ThreadBase::notify_one() wakes up the thread when there is some work to do
+/// Thread destructor waits for thread termination before returning
 
-void ThreadBase::notify_one() {
+Thread::~Thread() {
 
-  std::unique_lock<Mutex> lk(mutex);
+  mutex.lock();
+  exit = true;
   sleepCondition.notify_one();
+  mutex.unlock();
+  nativeThread.join();
 }
 
 
-// ThreadBase::wait_for() set the thread to sleep until 'condition' turns true
+/// Thread::wait_for_search_finished() waits on sleep condition
+/// until not searching
 
-void ThreadBase::wait_for(volatile const bool& condition) {
+void Thread::wait_for_search_finished() {
 
   std::unique_lock<Mutex> lk(mutex);
-  sleepCondition.wait(lk, [&]{ return condition; });
-}
-
-
-// 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() */ { // Initialization of non POD broken in MSVC
-
-  searching = false;
-  maxPly = 0;
-  splitPointsSize = 0;
-  activeSplitPoint = nullptr;
-  activePosition = nullptr;
-  idx = Threads.size(); // Starts from 0
-}
-
-
-// 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->parentSplitPoint)
-      if (sp->cutoff)
-          return true;
-
-  return false;
+  sleepCondition.wait(lk, [&]{ return !searching; });
 }
 
 
-// Thread::can_join() checks whether the thread is available to join the split
-// point 'sp'. 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 split
-// point, it is only available as a slave for the split points below his active
-// one (the "helpful master" concept in YBWC terminology).
-
-bool Thread::can_join(const SplitPoint* sp) const {
-
-  if (searching)
-      return false;
-
-  // 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 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.
-  return !size || splitPoints[size - 1].slavesMask.test(sp->master->idx);
-}
-
-
-// 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.spinlock.acquire(); // No contention here until we don't increment 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;
-  sp.allSlavesSearching = true; // Must be set under lock protection
-
-  ++splitPointsSize;
-  activeSplitPoint = &sp;
-  activePosition = nullptr;
-
-  // Try to allocate available threads
-  Thread* slave;
-
-  while (    sp.slavesMask.count() < MAX_SLAVES_PER_SPLITPOINT
-         && (slave = Threads.available_slave(&sp)) != nullptr)
-  {
-     slave->spinlock.acquire();
-
-      if (slave->can_join(activeSplitPoint))
-      {
-          activeSplitPoint->slavesMask.set(slave->idx);
-          slave->activeSplitPoint = activeSplitPoint;
-          slave->searching = true;
-      }
-
-      slave->spinlock.release();
-  }
-
-  // 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();
-
-  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);
-
-  searching = true;
-
-  // We have returned from the idle loop, which means that all threads are
-  // finished. Note that decreasing splitPointsSize must be done under lock
-  // protection to avoid a race with Thread::can_join().
-  sp.spinlock.acquire();
+/// Thread::wait() waits on sleep condition until condition is true
 
-  --splitPointsSize;
-  activeSplitPoint = sp.parentSplitPoint;
-  activePosition = &pos;
-  pos.set_nodes_searched(pos.nodes_searched() + sp.nodes);
-  *bestMove = sp.bestMove;
-  *bestValue = sp.bestValue;
+void Thread::wait(std::atomic_bool& condition) {
 
-  sp.spinlock.release();
+  std::unique_lock<Mutex> lk(mutex);
+  sleepCondition.wait(lk, [&]{ return bool(condition); });
 }
 
 
-// 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() {
+/// Thread::start_searching() wakes up the thread that will start the search
 
-  while (!exit)
-  {
-      std::unique_lock<Mutex> lk(mutex);
+void Thread::start_searching(bool resume) {
 
-      if (!exit)
-          sleepCondition.wait_for(lk, std::chrono::milliseconds(run ? Resolution : INT_MAX));
+  std::unique_lock<Mutex> lk(mutex);
 
-      lk.unlock();
+  if (!resume)
+      searching = true;
 
-      if (run)
-          check_time();
-  }
+  sleepCondition.notify_one();
 }
 
 
-// MainThread::idle_loop() is where the main thread is parked waiting to be started
-// when there is a new search. The main thread will launch all the slave threads.
+/// Thread::idle_loop() is where the thread is parked when it has no work to do
 
-void MainThread::idle_loop() {
+void Thread::idle_loop() {
 
   while (!exit)
   {
       std::unique_lock<Mutex> lk(mutex);
 
-      thinking = false;
+      searching = false;
 
-      while (!thinking && !exit)
+      while (!searching && !exit)
       {
-          sleepCondition.notify_one(); // Wake up the UI thread if needed
+          sleepCondition.notify_one(); // Wake up any waiting thread
           sleepCondition.wait(lk);
       }
 
       lk.unlock();
 
       if (!exit)
-      {
-          searching = true;
-
-          Search::think();
-
-          assert(searching);
-
-          searching = false;
-      }
+          search();
   }
 }
 
 
-// MainThread::join() waits for main thread to finish the search
-
-void MainThread::join() {
-
-  std::unique_lock<Mutex> lk(mutex);
-  sleepCondition.wait(lk, [&]{ return !thinking; });
-}
-
-
-// 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.
+/// ThreadPool::init() creates and launches requested threads that will go
+/// immediately to sleep. We cannot use a constructor because Threads is a
+/// static object and we need a fully initialized engine at this point due to
+/// allocation of Endgames in the Thread constructor.
 
 void ThreadPool::init() {
 
-  timer = new_thread<TimerThread>();
-  push_back(new_thread<MainThread>());
+  push_back(new MainThread);
   read_uci_options();
 }
 
 
-// ThreadPool::exit() terminates the threads before the program exits. Cannot be
-// done in d'tor because threads must be terminated before freeing us.
+/// ThreadPool::exit() terminates threads before the program exits. Cannot be
+/// done in destructor because threads must be terminated before deleting any
+/// static objects while still in main().
 
 void ThreadPool::exit() {
 
-  delete_thread(timer); // As first because check_time() accesses threads data
-  timer = nullptr;
-
-  for (Thread* th : *this)
-      delete_thread(th);
-
-  clear(); // Get rid of stale pointers
+  while (size())
+      delete back(), pop_back();
 }
 
 
-// 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.
+/// ThreadPool::read_uci_options() updates internal threads parameters from the
+/// corresponding UCI options and creates/destroys threads to match requested
+/// number. Thread objects are dynamically allocated.
 
 void ThreadPool::read_uci_options() {
 
-  minimumSplitDepth = Options["Min Split Depth"] * ONE_PLY;
-  size_t requested  = Options["Threads"];
+  size_t requested = Options["Threads"];
 
   assert(requested > 0);
 
-  // If zero (default) then set best minimum split depth automatically
-  if (!minimumSplitDepth)
-      minimumSplitDepth = requested < 8 ? 4 * ONE_PLY : 7 * ONE_PLY;
-
   while (size() < requested)
-      push_back(new_thread<Thread>());
+      push_back(new Thread);
 
   while (size() > requested)
-  {
-      delete_thread(back());
-      pop_back();
-  }
+      delete back(), pop_back();
 }
 
 
-// ThreadPool::available_slave() tries to find an idle thread which is available
-// to join SplitPoint 'sp'.
+/// ThreadPool::nodes_searched() returns the number of nodes searched
 
-Thread* ThreadPool::available_slave(const SplitPoint* sp) const {
+int64_t ThreadPool::nodes_searched() {
 
+  int64_t nodes = 0;
   for (Thread* th : *this)
-      if (th->can_join(sp))
-          return th;
-
-  return nullptr;
+      nodes += th->rootPos.nodes_searched();
+  return nodes;
 }
 
 
-// ThreadPool::start_thinking() wakes up the main thread sleeping in
-// MainThread::idle_loop() and starts a new search, then returns immediately.
+/// ThreadPool::start_thinking() wakes up the main thread sleeping in idle_loop()
+/// and starts a new search, then returns immediately.
 
-void ThreadPool::start_thinking(const Position& pos, const LimitsType& limits,
-                                StateStackPtr& states) {
-  main()->join();
+void ThreadPool::start_thinking(const Position& pos, StateListPtr& states,
+                                const Search::LimitsType& limits) {
 
-  Signals.stopOnPonderhit = Signals.firstRootMove = false;
-  Signals.stop = Signals.failedLowAtRoot = false;
+  main()->wait_for_search_finished();
 
-  RootMoves.clear();
-  RootPos = pos;
-  Limits = limits;
-  if (states.get()) // If we don't set a new position, preserve current state
-  {
-      SetupStates = std::move(states); // Ownership transfer here
-      assert(!states.get());
-  }
+  Search::Signals.stopOnPonderhit = Search::Signals.stop = false;
+  Search::Limits = limits;
+  Search::RootMoves rootMoves;
 
   for (const auto& m : MoveList<LEGAL>(pos))
       if (   limits.searchmoves.empty()
           || std::count(limits.searchmoves.begin(), limits.searchmoves.end(), m))
-          RootMoves.push_back(RootMove(m));
+          rootMoves.push_back(Search::RootMove(m));
+
+  // After ownership transfer 'states' becomes empty, so if we stop the search
+  // and call 'go' again without setting a new position states.get() == NULL.
+  assert(states.get() || setupStates.get());
+
+  if (states.get())
+      setupStates = std::move(states); // Ownership transfer, states is now empty
+
+  StateInfo tmp = setupStates->back();
+
+  for (Thread* th : Threads)
+  {
+      th->maxPly = 0;
+      th->rootDepth = DEPTH_ZERO;
+      th->rootMoves = rootMoves;
+      th->rootPos.set(pos.fen(), pos.is_chess960(), &setupStates->back(), th);
+  }
+
+  setupStates->back() = tmp; // Restore st->previous, cleared by Position::set()
 
-  main()->thinking = true;
-  main()->notify_one(); // Wake up main thread: 'thinking' must be already set
+  main()->start_searching();
 }