X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fthread.cpp;h=3b87a72415ddd0fd3fc57ba345a55c3af78fbc97;hp=8269dcf3d50029d2e4e355a8da8c345b48ddee80;hb=b1768c115cf2bbe7ed6f89dc53a8db85b4442353;hpb=d156e7a20b4ea15c2cbb4bcfa2dca5f1e96ece3b

diff --git a/src/thread.cpp b/src/thread.cpp
index 8269dcf3..3b87a724 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) 2008-2012 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
@@ -17,49 +17,122 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
+#include <cassert>
 #include <iostream>
 
+#include "movegen.h"
+#include "search.h"
 #include "thread.h"
 #include "ucioption.h"
 
-ThreadsManager Threads; // Global object definition
+using namespace Search;
+
+ThreadsManager Threads; // Global object
 
 namespace { extern "C" {
 
  // start_routine() is the C function which is called when a new thread
- // is launched. It simply calls idle_loop() of the supplied thread.
- // There are two versions of this function; one for POSIX threads and
- // one for Windows threads.
-
-#if defined(_MSC_VER)
+ // is launched. It simply calls idle_loop() of the supplied thread. The first
+ // and last thread are special. First one is the main search thread while the
+ // last one mimics a timer, they run in main_loop() and timer_loop().
 
+#if defined(_WIN32) || defined(_WIN64)
   DWORD WINAPI start_routine(LPVOID thread) {
+#else
+  void* start_routine(void* thread) {
+#endif
+
+    Thread* th = (Thread*)thread;
+
+    if (th->threadID == 0)
+        th->main_loop();
+
+    else if (th->threadID == MAX_THREADS)
+        th->timer_loop();
+
+    else
+        th->idle_loop(NULL);
 
-    ((Thread*)thread)->idle_loop(NULL);
     return 0;
   }
 
-#else
+} }
 
-  void* start_routine(void* thread) {
 
-    ((Thread*)thread)->idle_loop(NULL);
-    return NULL;
+// Thread::timer_loop() is where the timer thread waits maxPly milliseconds and
+// then calls do_timer_event(). If maxPly is 0 thread sleeps until is woken up.
+extern void check_time();
+
+void Thread::timer_loop() {
+
+  while (!do_exit)
+  {
+      lock_grab(sleepLock);
+      timed_wait(sleepCond, sleepLock, maxPly ? maxPly : INT_MAX);
+      lock_release(sleepLock);
+      check_time();
   }
+}
 
-#endif
 
-} }
+// Thread::main_loop() is where the main thread is parked waiting to be started
+// when there is a new search. Main thread will launch all the slave threads.
 
+void Thread::main_loop() {
+
+  while (true)
+  {
+      lock_grab(sleepLock);
+
+      do_sleep = true; // Always return to sleep after a search
+      is_searching = false;
+
+      while (do_sleep && !do_exit)
+      {
+          cond_signal(Threads.sleepCond); // Wake up UI thread if needed
+          cond_wait(sleepCond, sleepLock);
+      }
 
-// 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.
+      lock_release(sleepLock);
+
+      if (do_exit)
+          return;
+
+      is_searching = true;
+
+      Search::think();
+  }
+}
+
+
+// Thread::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.
 
 void Thread::wake_up() {
 
-  lock_grab(&sleepLock);
-  cond_signal(&sleepCond);
-  lock_release(&sleepLock);
+  lock_grab(sleepLock);
+  cond_signal(sleepCond);
+  lock_release(sleepLock);
+}
+
+
+// Thread::wait_for_stop_or_ponderhit() is called when the maximum depth is
+// reached while the program is pondering. The point is to work around a wrinkle
+// in the UCI protocol: When pondering, the engine is not allowed to give a
+// "bestmove" before the GUI sends it a "stop" or "ponderhit" command. We simply
+// wait here until one of these commands (that raise StopRequest) is sent and
+// then return, after which the bestmove and pondermove will be printed.
+
+void Thread::wait_for_stop_or_ponderhit() {
+
+  Signals.stopOnPonderhit = true;
+
+  lock_grab(sleepLock);
+
+  while (!Signals.stop)
+      cond_wait(sleepCond, sleepLock);
+
+  lock_release(sleepLock);
 }
 
 
@@ -69,8 +142,9 @@ void Thread::wake_up() {
 bool Thread::cutoff_occurred() const {
 
   for (SplitPoint* sp = splitPoint; sp; sp = sp->parent)
-      if (sp->is_betaCutoff)
+      if (sp->cutoff)
           return true;
+
   return false;
 }
 
@@ -89,29 +163,22 @@ bool Thread::is_available_to(int 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 localActiveSplitPoints = activeSplitPoints;
+  int sp_count = activeSplitPoints;
 
   // 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;
-
-  return false;
+  return !sp_count || (splitPoints[sp_count - 1].slavesMask & (1ULL << master));
 }
 
 
-// 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.
+// read_uci_options() updates internal threads parameters from the corresponding
+// UCI options. It is called before to start a new search.
 
 void ThreadsManager::read_uci_options() {
 
-  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>();
-
-  set_size(Options["Threads"].value<int>());
+  maxThreadsPerSplitPoint = Options["Max Threads per Split Point"];
+  minimumSplitDepth       = Options["Min Split Depth"] * ONE_PLY;
+  useSleepingThreads      = Options["Use Sleeping Threads"];
 }
 
 
@@ -120,7 +187,7 @@ void ThreadsManager::read_uci_options() {
 
 void ThreadsManager::set_size(int cnt) {
 
-  assert(cnt > 0 && cnt <= MAX_THREADS);
+  assert(cnt > 0 && cnt < MAX_THREADS);
 
   activeThreads = cnt;
 
@@ -129,13 +196,15 @@ void ThreadsManager::set_size(int cnt) {
       {
           // Dynamically allocate 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 could
-          // even result in a crash.
+          // possible threads if only few are used.
           threads[i].pawnTable.init();
           threads[i].materialTable.init();
+          threads[i].maxPly = 0;
 
           threads[i].do_sleep = false;
+
+          if (!useSleepingThreads)
+              threads[i].wake_up();
       }
       else
           threads[i].do_sleep = true;
@@ -147,39 +216,30 @@ void ThreadsManager::set_size(int cnt) {
 
 void ThreadsManager::init() {
 
-  // Initialize threads lock, used when allocating slaves during splitting
-  lock_init(&threadsLock);
+  cond_init(sleepCond);
+  lock_init(splitLock);
 
-  // Initialize sleep and split point locks
-  for (int i = 0; i < MAX_THREADS; i++)
+  for (int i = 0; i <= MAX_THREADS; i++)
   {
-      lock_init(&threads[i].sleepLock);
-      cond_init(&threads[i].sleepCond);
+      lock_init(threads[i].sleepLock);
+      cond_init(threads[i].sleepCond);
 
       for (int j = 0; j < MAX_ACTIVE_SPLIT_POINTS; j++)
-          lock_init(&(threads[i].splitPoints[j].lock));
+          lock_init(threads[i].splitPoints[j].lock);
   }
 
-  // Initialize main thread's associated data
-  threads[0].is_searching = true;
-  threads[0].threadID = 0;
-  set_size(1); // This makes all the threads but the main to go to sleep
+  // Allocate main thread tables to call evaluate() also when not searching
+  threads[0].pawnTable.init();
+  threads[0].materialTable.init();
 
-  // Create and launch all the threads but the main that is already running,
-  // threads will go immediately to sleep.
-  for (int i = 1; i < MAX_THREADS; i++)
+  // Create and launch all the threads, threads will go immediately to sleep
+  for (int i = 0; i <= MAX_THREADS; i++)
   {
       threads[i].is_searching = false;
+      threads[i].do_sleep = (i != 0); // Avoid a race with start_thinking()
       threads[i].threadID = i;
 
-#if defined(_MSC_VER)
-      threads[i].handle = CreateThread(NULL, 0, start_routine, (LPVOID)&threads[i], 0, NULL);
-      bool ok = (threads[i].handle != NULL);
-#else
-      bool ok = (pthread_create(&threads[i].handle, NULL, start_routine, (void*)&threads[i]) == 0);
-#endif
-
-      if (!ok)
+      if (!thread_create(threads[i].handle, start_routine, threads[i]))
       {
           std::cerr << "Failed to create thread number " << i << std::endl;
           ::exit(EXIT_FAILURE);
@@ -192,43 +252,36 @@ void ThreadsManager::init() {
 
 void ThreadsManager::exit() {
 
-  for (int i = 0; i < MAX_THREADS; i++)
+  for (int i = 0; i <= MAX_THREADS; i++)
   {
-      // Wake up all the slave threads and wait for termination
-      if (i != 0)
-      {
-          threads[i].do_terminate = true;
-          threads[i].wake_up();
+      assert(threads[i].do_sleep);
 
-#if defined(_MSC_VER)
-          WaitForSingleObject(threads[i].handle, 0);
-          CloseHandle(threads[i].handle);
-#else
-          pthread_join(threads[i].handle, NULL);
-#endif
-      }
+      threads[i].do_exit = true; // Search must be already finished
+      threads[i].wake_up();
+
+      thread_join(threads[i].handle); // Wait for thread termination
 
-      // Now we can safely destroy locks and wait conditions
-      lock_destroy(&threads[i].sleepLock);
-      cond_destroy(&threads[i].sleepCond);
+      lock_destroy(threads[i].sleepLock);
+      cond_destroy(threads[i].sleepCond);
 
       for (int j = 0; j < MAX_ACTIVE_SPLIT_POINTS; j++)
-          lock_destroy(&(threads[i].splitPoints[j].lock));
+          lock_destroy(threads[i].splitPoints[j].lock);
   }
 
-  lock_destroy(&threadsLock);
+  lock_destroy(splitLock);
+  cond_destroy(sleepCond);
 }
 
 
 // available_slave_exists() tries to find an idle thread which is available as
-// a slave for the thread with threadID "master".
+// a slave for the thread with threadID 'master'.
 
 bool ThreadsManager::available_slave_exists(int master) const {
 
   assert(master >= 0 && master < activeThreads);
 
   for (int i = 0; i < activeThreads; i++)
-      if (i != master && threads[i].is_available_to(master))
+      if (threads[i].is_available_to(master))
           return true;
 
   return false;
@@ -236,20 +289,20 @@ bool ThreadsManager::available_slave_exists(int master) const {
 
 
 // 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.
+// 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.
 
 template <bool Fake>
-Value ThreadsManager::split(Position& pos, SearchStack* ss, Value alpha, Value beta,
+Value ThreadsManager::split(Position& pos, Stack* ss, Value alpha, Value beta,
                             Value bestValue, Depth depth, Move threatMove,
                             int moveCount, MovePicker* mp, int nodeType) {
-  assert(pos.is_ok());
-  assert(bestValue >= -VALUE_INFINITE);
+  assert(pos.pos_is_ok());
+  assert(bestValue > -VALUE_INFINITE);
   assert(bestValue <= alpha);
   assert(alpha < beta);
   assert(beta <= VALUE_INFINITE);
@@ -257,20 +310,19 @@ Value ThreadsManager::split(Position& pos, SearchStack* ss, Value alpha, Value b
   assert(pos.thread() >= 0 && pos.thread() < activeThreads);
   assert(activeThreads > 1);
 
-  int i, master = pos.thread();
+  int master = pos.thread();
   Thread& masterThread = threads[master];
 
-  // If we already have too many active split points, don't split
   if (masterThread.activeSplitPoints >= MAX_ACTIVE_SPLIT_POINTS)
       return bestValue;
 
-  // Pick the next available split point object from the split point stack
-  SplitPoint* sp = masterThread.splitPoints + masterThread.activeSplitPoints;
+  // Pick the next available split point from the split point stack
+  SplitPoint* sp = &masterThread.splitPoints[masterThread.activeSplitPoints];
 
-  // Initialize the split point object
   sp->parent = masterThread.splitPoint;
   sp->master = master;
-  sp->is_betaCutoff = false;
+  sp->cutoff = false;
+  sp->slavesMask = 1ULL << master;
   sp->depth = depth;
   sp->threatMove = threatMove;
   sp->alpha = alpha;
@@ -282,69 +334,138 @@ Value ThreadsManager::split(Position& pos, SearchStack* ss, Value alpha, Value b
   sp->pos = &pos;
   sp->nodes = 0;
   sp->ss = ss;
-  for (i = 0; i < activeThreads; i++)
-      sp->is_slave[i] = false;
 
-  // If we are here it means we are not available
   assert(masterThread.is_searching);
 
-  int workersCnt = 1; // At least the master is included
+  int slavesCnt = 0;
 
   // Try to allocate available threads and ask them to start searching setting
-  // the state to Thread::WORKISWAITING, this must be done under lock protection
-  // to avoid concurrent allocation of the same slave by another master.
-  lock_grab(&threadsLock);
+  // is_searching flag. This must be done under lock protection to avoid concurrent
+  // allocation of the same slave by another master.
+  lock_grab(sp->lock);
+  lock_grab(splitLock);
 
-  for (i = 0; !Fake && i < activeThreads && workersCnt < maxThreadsPerSplitPoint; i++)
-      if (i != master && threads[i].is_available_to(master))
+  for (int i = 0; i < activeThreads && !Fake; i++)
+      if (threads[i].is_available_to(master))
       {
-          workersCnt++;
-          sp->is_slave[i] = true;
+          sp->slavesMask |= 1ULL << i;
           threads[i].splitPoint = sp;
-
-          // This makes the slave to exit from idle_loop()
-          threads[i].is_searching = true;
+          threads[i].is_searching = true; // Slave leaves idle_loop()
 
           if (useSleepingThreads)
               threads[i].wake_up();
-      }
-
-  lock_release(&threadsLock);
 
-  // We failed to allocate even one slave, return
-  if (!Fake && workersCnt == 1)
-      return bestValue;
+          if (++slavesCnt + 1 >= maxThreadsPerSplitPoint) // Master is always included
+              break;
+      }
 
   masterThread.splitPoint = sp;
   masterThread.activeSplitPoints++;
 
+  lock_release(splitLock);
+  lock_release(sp->lock);
+
   // 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.
   // We pass the split point as a parameter to the idle loop, which means that
   // the thread will return from the idle loop when all slaves have finished
   // their work at this split point.
-  masterThread.idle_loop(sp);
-
-  // In helpful master concept a master can help only a sub-tree, and
-  // because here is all finished is not possible master is booked.
-  assert(!masterThread.is_searching);
+  if (slavesCnt || Fake)
+      masterThread.idle_loop(sp);
 
   // We have returned from the idle loop, which means that all threads are
-  // finished. Note that changing state and decreasing activeSplitPoints is done
-  // under lock protection to avoid a race with Thread::is_available_to().
-  lock_grab(&threadsLock);
+  // finished. Note that setting is_searching and decreasing activeSplitPoints is
+  // done under lock protection to avoid a race with Thread::is_available_to().
+  lock_grab(sp->lock); // To protect sp->nodes
+  lock_grab(splitLock);
 
   masterThread.is_searching = true;
   masterThread.activeSplitPoints--;
-
-  lock_release(&threadsLock);
-
   masterThread.splitPoint = sp->parent;
   pos.set_nodes_searched(pos.nodes_searched() + sp->nodes);
 
+  lock_release(splitLock);
+  lock_release(sp->lock);
+
   return sp->bestValue;
 }
 
 // Explicit template instantiations
-template Value ThreadsManager::split<false>(Position&, SearchStack*, Value, Value, Value, Depth, Move, int, MovePicker*, int);
-template Value ThreadsManager::split<true>(Position&, SearchStack*, Value, Value, Value, Depth, Move, int, MovePicker*, int);
+template Value ThreadsManager::split<false>(Position&, Stack*, Value, Value, Value, Depth, Move, int, MovePicker*, int);
+template Value ThreadsManager::split<true>(Position&, Stack*, Value, Value, Value, Depth, Move, int, MovePicker*, int);
+
+
+// ThreadsManager::set_timer() is used to set the timer to trigger after msec
+// milliseconds. If msec is 0 then timer is stopped.
+
+void ThreadsManager::set_timer(int msec) {
+
+  Thread& timer = threads[MAX_THREADS];
+
+  lock_grab(timer.sleepLock);
+  timer.maxPly = msec;
+  cond_signal(timer.sleepCond); // Wake up and restart the timer
+  lock_release(timer.sleepLock);
+}
+
+
+// ThreadsManager::start_thinking() is used by UI thread to wake up the main
+// thread parked in main_loop() and starting a new search. If asyncMode is true
+// then function returns immediately, otherwise caller is blocked waiting for
+// the search to finish.
+
+void ThreadsManager::start_thinking(const Position& pos, const LimitsType& limits,
+                                    const std::set<Move>& searchMoves, bool async) {
+  Thread& main = threads[0];
+
+  lock_grab(main.sleepLock);
+
+  // Wait main thread has finished before to launch a new search
+  while (!main.do_sleep)
+      cond_wait(sleepCond, main.sleepLock);
+
+  // Copy input arguments to initialize the search
+  RootPosition.copy(pos, 0);
+  Limits = limits;
+  RootMoves.clear();
+
+  // Populate RootMoves with all the legal moves (default) or, if a searchMoves
+  // set is given, with the subset of legal moves to search.
+  for (MoveList<MV_LEGAL> ml(pos); !ml.end(); ++ml)
+      if (searchMoves.empty() || searchMoves.count(ml.move()))
+          RootMoves.push_back(RootMove(ml.move()));
+
+  // Reset signals before to start the new search
+  Signals.stopOnPonderhit = Signals.firstRootMove = false;
+  Signals.stop = Signals.failedLowAtRoot = false;
+
+  main.do_sleep = false;
+  cond_signal(main.sleepCond); // Wake up main thread and start searching
+
+  if (!async)
+      while (!main.do_sleep)
+          cond_wait(sleepCond, main.sleepLock);
+
+  lock_release(main.sleepLock);
+}
+
+
+// ThreadsManager::stop_thinking() is used by UI thread to raise a stop request
+// and to wait for the main thread finishing the search. Needed to wait exiting
+// and terminate the threads after a 'quit' command.
+
+void ThreadsManager::stop_thinking() {
+
+  Thread& main = threads[0];
+
+  Search::Signals.stop = true;
+
+  lock_grab(main.sleepLock);
+
+  cond_signal(main.sleepCond); // In case is waiting for stop or ponderhit
+
+  while (!main.do_sleep)
+      cond_wait(sleepCond, main.sleepLock);
+
+  lock_release(main.sleepLock);
+}