X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fthread.cpp;h=a8e26b9f85c43a69a3f0260db1313285ca3ccee2;hb=00d9e9fd283b31e63389af091b158dbc3fedfc0e;hp=4ef145781511aacbf61930844dcf5153b8942ba4;hpb=ffa150bec3af540fbaff57fdbb657940225e69e6;p=stockfish

diff --git a/src/thread.cpp b/src/thread.cpp
index 4ef14578..eb64f7ee 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) 2008-2010 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
@@ -17,329 +17,244 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-#include <iostream>
+#include <algorithm> // For std::count
+#include <cassert>
 
+#include "movegen.h"
+#include "search.h"
 #include "thread.h"
-#include "ucioption.h"
+#include "uci.h"
 
-ThreadsManager Threads; // Global object definition
+using namespace Search;
 
-namespace { extern "C" {
+ThreadPool Threads; // Global object
 
- // start_routine() is the C function which is called when a new thread
- // is launched. It simply calls idle_loop() with the supplied threadID.
- // There are two versions of this function; one for POSIX threads and
- // one for Windows threads.
+extern void check_time();
 
-#if defined(_MSC_VER)
+namespace {
 
-  DWORD WINAPI start_routine(LPVOID threadID) {
+ // 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.
 
-    Threads.idle_loop(*(int*)threadID, NULL);
-    return 0;
-  }
-
-#else
+ 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* start_routine(void* threadID) {
+ void delete_thread(ThreadBase* th) {
 
-    Threads.idle_loop(*(int*)threadID, NULL);
-    return NULL;
-  }
+   th->mutex.lock();
+   th->exit = true; // Search must be already finished
+   th->mutex.unlock();
 
-#endif
+   th->notify_one();
+   th->join(); // Wait for thread termination
+   delete th;
+ }
 
-} }
+}
 
 
-// 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.
+// ThreadBase::notify_one() wakes up the thread when there is some work to do
 
-void Thread::wake_up() {
+void ThreadBase::notify_one() {
 
-  lock_grab(&sleepLock);
-  cond_signal(&sleepCond);
-  lock_release(&sleepLock);
+  std::unique_lock<Mutex> lk(mutex);
+  sleepCondition.notify_one();
 }
 
 
-// cutoff_occurred() checks whether a beta cutoff has occurred in
-// the thread's currently active split point, or in some ancestor of
-// the current split point.
+// ThreadBase::wait() set the thread to sleep until 'condition' turns true
 
-bool Thread::cutoff_occurred() const {
+void ThreadBase::wait(std::atomic<bool>& condition) {
 
-  for (SplitPoint* sp = splitPoint; sp; sp = sp->parent)
-      if (sp->is_betaCutoff)
-          return true;
-  return false;
+  std::unique_lock<Mutex> lk(mutex);
+  sleepCondition.wait(lk, [&]{ return bool(condition); });
 }
 
 
-// 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).
+// ThreadBase::wait_while() set the thread to sleep until 'condition' turns false
+void ThreadBase::wait_while(std::atomic<bool>& condition) {
 
-bool Thread::is_available_to(int master) const {
+  std::unique_lock<Mutex> lk(mutex);
+  sleepCondition.wait(lk, [&]{ return !condition; });
+}
 
-  if (state != AVAILABLE)
-      return false;
 
-  // 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 localActiveSplitPoints = activeSplitPoints;
+// Thread c'tor makes some init but does not launch any execution thread that
+// will be started only when c'tor returns.
 
-  // No active split points means that the thread is available as a slave for any
-  // other thread otherwise apply the "helpful master" concept if possible.
-  if (   !localActiveSplitPoints
-      || splitPoints[localActiveSplitPoints - 1].is_slave[master])
-      return true;
+Thread::Thread() {
 
-  return false;
+  searching = false;
+  maxPly = 0;
+  history.clear();
+  counterMoves.clear();
+  idx = Threads.size(); // Starts from 0
 }
 
 
-// read_uci_options() updates number of active threads and other internal
-// parameters according to the UCI options values. It is called before
-// to start a new search.
+// 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 ThreadsManager::read_uci_options() {
+void TimerThread::idle_loop() {
 
-  maxThreadsPerSplitPoint = Options["Maximum Number of Threads per Split Point"].value<int>();
-  minimumSplitDepth       = Options["Minimum Split Depth"].value<int>() * ONE_PLY;
-  useSleepingThreads      = Options["Use Sleeping Threads"].value<bool>();
-  activeThreads           = Options["Threads"].value<int>();
-}
-
-
-// init() is called during startup. Initializes locks and condition variables
-// and launches all threads sending them immediately to sleep.
+  while (!exit)
+  {
+      std::unique_lock<Mutex> lk(mutex);
 
-void ThreadsManager::init() {
+      if (!exit)
+          sleepCondition.wait_for(lk, std::chrono::milliseconds(run ? Resolution : INT_MAX));
 
-  int threadID[MAX_THREADS];
+      lk.unlock();
 
-  // This flag is needed to properly end the threads when program exits
-  allThreadsShouldExit = false;
+      if (!exit && run)
+          check_time();
+  }
+}
 
-  // Threads will sent to sleep as soon as created, only main thread is kept alive
-  activeThreads = 1;
-  threads[0].state = Thread::SEARCHING;
 
-  // Allocate pawn and material hash tables for main thread
-  init_hash_tables();
+// Thread::idle_loop() is where the thread is parked when it has no work to do
 
-  lock_init(&mpLock);
+void Thread::idle_loop() {
 
-  // Initialize thread and split point locks
-  for (int i = 0; i < MAX_THREADS; i++)
+  while (!exit)
   {
-      lock_init(&threads[i].sleepLock);
-      cond_init(&threads[i].sleepCond);
+      std::unique_lock<Mutex> lk(mutex);
 
-      for (int j = 0; j < MAX_ACTIVE_SPLIT_POINTS; j++)
-          lock_init(&(threads[i].splitPoints[j].lock));
-  }
+      while (!searching && !exit)
+          sleepCondition.wait(lk);
 
-  // Create and startup all the threads but the main that is already running
-  for (int i = 1; i < MAX_THREADS; i++)
-  {
-      threads[i].state = Thread::INITIALIZING;
-      threadID[i] = i;
-
-#if defined(_MSC_VER)
-      bool ok = (CreateThread(NULL, 0, start_routine, (LPVOID)&threadID[i], 0, NULL) != NULL);
-#else
-      pthread_t pthreadID;
-      bool ok = (pthread_create(&pthreadID, NULL, start_routine, (void*)&threadID[i]) == 0);
-      pthread_detach(pthreadID);
-#endif
-      if (!ok)
-      {
-          std::cout << "Failed to create thread number " << i << std::endl;
-          ::exit(EXIT_FAILURE);
-      }
+      lk.unlock();
 
-      // Wait until the thread has finished launching and is gone to sleep
-      while (threads[i].state == Thread::INITIALIZING) {}
+      if (!exit && searching)
+          search();
   }
 }
 
 
-// exit() is called to cleanly exit the threads when the program finishes
+// 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.
 
-void ThreadsManager::exit() {
+void MainThread::idle_loop() {
 
-  // Force the woken up threads to exit idle_loop() and hence terminate
-  allThreadsShouldExit = true;
-
-  for (int i = 0; i < MAX_THREADS; i++)
+  while (!exit)
   {
-      // Wake up all the threads and waits for termination
-      if (i != 0)
+      std::unique_lock<Mutex> lk(mutex);
+
+      thinking = false;
+
+      while (!thinking && !exit)
       {
-          threads[i].wake_up();
-          while (threads[i].state != Thread::TERMINATED) {}
+          sleepCondition.notify_one(); // Wake up the UI thread if needed
+          sleepCondition.wait(lk);
       }
 
-      // Now we can safely destroy the locks and wait conditions
-      lock_destroy(&threads[i].sleepLock);
-      cond_destroy(&threads[i].sleepCond);
+      lk.unlock();
 
-      for (int j = 0; j < MAX_ACTIVE_SPLIT_POINTS; j++)
-          lock_destroy(&(threads[i].splitPoints[j].lock));
+      if (!exit)
+          think();
   }
+}
+
 
-  lock_destroy(&mpLock);
+// MainThread::join() waits for main thread to finish thinking
+
+void MainThread::join() {
+
+  std::unique_lock<Mutex> lk(mutex);
+  sleepCondition.wait(lk, [&]{ return !thinking; });
 }
 
 
-// init_hash_tables() dynamically allocates pawn and material hash tables
-// according to the number of active threads. This avoids preallocating
-// memory for all possible threads if only few are used as, for instance,
-// on mobile devices where memory is scarce and allocating for MAX_THREADS
-// threads could even result in a crash.
+// 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 ThreadsManager::init_hash_tables() {
+void ThreadPool::init() {
 
-  for (int i = 0; i < activeThreads; i++)
-  {
-      threads[i].pawnTable.init();
-      threads[i].materialTable.init();
-  }
+  timer = new_thread<TimerThread>();
+  push_back(new_thread<MainThread>());
+  read_uci_options();
 }
 
 
-// available_slave_exists() tries to find an idle thread which is available as
-// a slave for the thread with threadID "master".
+// ThreadPool::exit() terminates the threads before the program exits. Cannot be
+// done in d'tor because threads must be terminated before freeing us.
 
-bool ThreadsManager::available_slave_exists(int master) const {
+void ThreadPool::exit() {
 
-  assert(master >= 0 && master < activeThreads);
+  delete_thread(timer); // As first because check_time() accesses threads data
+  timer = nullptr;
 
-  for (int i = 0; i < activeThreads; i++)
-      if (i != master && threads[i].is_available_to(master))
-          return true;
+  for (Thread* th : *this)
+      delete_thread(th);
 
-  return false;
+  clear(); // Get rid of stale pointers
 }
 
 
-// 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 we tell our helper threads 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>
-void ThreadsManager::split(Position& pos, SearchStack* ss, Value* alpha, const Value beta,
-                           Value* bestValue, Depth depth, Move threatMove,
-                           int moveCount, MovePicker* mp, int nodeType) {
-  assert(pos.is_ok());
-  assert(*bestValue >= -VALUE_INFINITE);
-  assert(*bestValue <= *alpha);
-  assert(*alpha < beta);
-  assert(beta <= VALUE_INFINITE);
-  assert(depth > DEPTH_ZERO);
-  assert(pos.thread() >= 0 && pos.thread() < activeThreads);
-  assert(activeThreads > 1);
-
-  int i, master = pos.thread();
-  Thread& masterThread = threads[master];
-
-  lock_grab(&mpLock);
-
-  // If no other thread is available to help us, or if we have too many
-  // active split points, don't split.
-  if (   !available_slave_exists(master)
-      || masterThread.activeSplitPoints >= MAX_ACTIVE_SPLIT_POINTS)
+// 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() {
+
+  size_t requested  = Options["Threads"];
+
+  assert(requested > 0);
+
+  while (size() < requested)
+      push_back(new_thread<Thread>());
+
+  while (size() > requested)
   {
-      lock_release(&mpLock);
-      return;
+      delete_thread(back());
+      pop_back();
   }
+}
 
-  // Pick the next available split point object from the split point stack
-  SplitPoint& splitPoint = masterThread.splitPoints[masterThread.activeSplitPoints++];
-
-  // Initialize the split point object
-  splitPoint.parent = masterThread.splitPoint;
-  splitPoint.master = master;
-  splitPoint.is_betaCutoff = false;
-  splitPoint.depth = depth;
-  splitPoint.threatMove = threatMove;
-  splitPoint.alpha = *alpha;
-  splitPoint.beta = beta;
-  splitPoint.nodeType = nodeType;
-  splitPoint.bestValue = *bestValue;
-  splitPoint.mp = mp;
-  splitPoint.moveCount = moveCount;
-  splitPoint.pos = &pos;
-  splitPoint.nodes = 0;
-  splitPoint.ss = ss;
-  for (i = 0; i < activeThreads; i++)
-      splitPoint.is_slave[i] = false;
-
-  masterThread.splitPoint = &splitPoint;
-
-  // If we are here it means we are not available
-  assert(masterThread.state != Thread::AVAILABLE);
-
-  int workersCnt = 1; // At least the master is included
-
-  // Allocate available threads setting state to THREAD_BOOKED
-  for (i = 0; !Fake && i < activeThreads && workersCnt < maxThreadsPerSplitPoint; i++)
-      if (i != master && threads[i].is_available_to(master))
-      {
-          threads[i].state = Thread::BOOKED;
-          threads[i].splitPoint = &splitPoint;
-          splitPoint.is_slave[i] = true;
-          workersCnt++;
-      }
 
-  assert(Fake || workersCnt > 1);
+// ThreadPool::nodes_searched() returns the number of nodes searched
 
-  // We can release the lock because slave threads are already booked and master is not available
-  lock_release(&mpLock);
+int64_t ThreadPool::nodes_searched() {
 
-  // Tell the threads that they have work to do. This will make them leave
-  // their idle loop.
-  for (i = 0; i < activeThreads; i++)
-      if (i == master || splitPoint.is_slave[i])
-      {
-          assert(i == master || threads[i].state == Thread::BOOKED);
+  int64_t nodes = 0;
+  for (Thread *th : *this)
+      nodes += th->rootPos.nodes_searched();
+  return nodes;
+}
 
-          threads[i].state = Thread::WORKISWAITING; // This makes the slave to exit from idle_loop()
 
-          if (useSleepingThreads && i != master)
-              threads[i].wake_up();
-      }
+// ThreadPool::start_thinking() wakes up the main thread sleeping in
+// MainThread::idle_loop() and starts a new search, then returns immediately.
 
-  // Everything is set up. The master thread enters the idle loop, from
-  // which it will instantly launch a search, because its state is
-  // THREAD_WORKISWAITING.  We send the split point as a second parameter to the
-  // idle loop, which means that the main thread will return from the idle
-  // loop when all threads have finished their work at this split point.
-  idle_loop(master, &splitPoint);
+void ThreadPool::start_thinking(const Position& pos, const LimitsType& limits,
+                                StateStackPtr& states) {
+  main()->join();
 
-  // We have returned from the idle loop, which means that all threads are
-  // finished. Update alpha and bestValue, and return.
-  lock_grab(&mpLock);
+  Signals.stopOnPonderhit = Signals.firstRootMove = false;
+  Signals.stop = Signals.failedLowAtRoot = false;
 
-  *alpha = splitPoint.alpha;
-  *bestValue = splitPoint.bestValue;
-  masterThread.activeSplitPoints--;
-  masterThread.splitPoint = splitPoint.parent;
-  pos.set_nodes_searched(pos.nodes_searched() + splitPoint.nodes);
+  main()->rootMoves.clear();
+  main()->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());
+  }
 
-  lock_release(&mpLock);
-}
+  for (const auto& m : MoveList<LEGAL>(pos))
+      if (   limits.searchmoves.empty()
+          || std::count(limits.searchmoves.begin(), limits.searchmoves.end(), m))
+          main()->rootMoves.push_back(RootMove(m));
 
-// Explicit template instantiations
-template void ThreadsManager::split<false>(Position&, SearchStack*, Value*, const Value, Value*, Depth, Move, int, MovePicker*, int);
-template void ThreadsManager::split<true>(Position&, SearchStack*, Value*, const Value, Value*, Depth, Move, int, MovePicker*, int);
+  main()->thinking = true;
+  main()->notify_one(); // Wake up main thread: 'thinking' must be already set
+}