Moved DroidFish project to trunk/

DroidFish/jni/stockfish/thread.cpp

@@ -0,0 +1,345 @@
+/*
+  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
+
+  Stockfish is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  Stockfish is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <iostream>
+
+#include "thread.h"
+#include "ucioption.h"
+
+ThreadsManager Threads; // Global object definition
+
+namespace { extern "C" {
+
+ // 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.
+
+#if defined(_MSC_VER)
+
+  DWORD WINAPI start_routine(LPVOID threadID) {
+
+    Threads.idle_loop(*(int*)threadID, NULL);
+    return 0;
+  }
+
+#else
+
+  void* start_routine(void* threadID) {
+
+    Threads.idle_loop(*(int*)threadID, NULL);
+    return NULL;
+  }
+
+#endif
+
+} }
+
+
+// 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);
+}
+
+
+// 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.
+
+bool Thread::cutoff_occurred() const {
+
+  for (SplitPoint* sp = splitPoint; sp; sp = sp->parent)
+      if (sp->is_betaCutoff)
+          return true;
+  return false;
+}
+
+
+// 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).
+
+bool Thread::is_available_to(int master) const {
+
+  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;
+
+  // 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;
+}
+
+
+// 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.
+
+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>();
+  activeThreads           = Options["Threads"].value<int>();
+}
+
+
+// init() is called during startup. Initializes locks and condition variables
+// and launches all threads sending them immediately to sleep.
+
+void ThreadsManager::init() {
+
+  int threadID[MAX_THREADS];
+
+  // This flag is needed to properly end the threads when program exits
+  allThreadsShouldExit = false;
+
+  // 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();
+
+  lock_init(&mpLock);
+
+  // Initialize thread and split point locks
+  for (int i = 0; i < MAX_THREADS; i++)
+  {
+      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));
+  }
+
+  // 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);
+      }
+
+      // Wait until the thread has finished launching and is gone to sleep
+      while (threads[i].state == Thread::INITIALIZING) {}
+  }
+}
+
+
+// exit() is called to cleanly exit the threads when the program finishes
+
+void ThreadsManager::exit() {
+
+  // Force the woken up threads to exit idle_loop() and hence terminate
+  allThreadsShouldExit = true;
+
+  for (int i = 0; i < MAX_THREADS; i++)
+  {
+      // Wake up all the threads and waits for termination
+      if (i != 0)
+      {
+          threads[i].wake_up();
+          while (threads[i].state != Thread::TERMINATED) {}
+      }
+
+      // Now we can safely destroy the locks and wait conditions
+      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(&mpLock);
+}
+
+
+// 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.
+
+void ThreadsManager::init_hash_tables() {
+
+  for (int i = 0; i < activeThreads; i++)
+  {
+      threads[i].pawnTable.init();
+      threads[i].materialTable.init();
+  }
+}
+
+
+// available_slave_exists() tries to find an idle thread which is available as
+// 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))
+          return true;
+
+  return false;
+}
+
+
+// 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, bool pvNode) {
+  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)
+  {
+      lock_release(&mpLock);
+      return;
+  }
+
+  // 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.pvNode = pvNode;
+  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);
+
+  // We can release the lock because slave threads are already booked and master is not available
+  lock_release(&mpLock);
+
+  // 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);
+
+          threads[i].state = Thread::WORKISWAITING; // This makes the slave to exit from idle_loop()
+
+          if (useSleepingThreads && i != master)
+              threads[i].wake_up();
+      }
+
+  // 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);
+
+  // We have returned from the idle loop, which means that all threads are
+  // finished. Update alpha and bestValue, and return.
+  lock_grab(&mpLock);
+
+  *alpha = splitPoint.alpha;
+  *bestValue = splitPoint.bestValue;
+  masterThread.activeSplitPoints--;
+  masterThread.splitPoint = splitPoint.parent;
+  pos.set_nodes_searched(pos.nodes_searched() + splitPoint.nodes);
+
+  lock_release(&mpLock);
+}
+
+// Explicit template instantiations
+template void ThreadsManager::split<false>(Position&, SearchStack*, Value*, const Value, Value*, Depth, Move, int, MovePicker*, bool);
+template void ThreadsManager::split<true>(Position&, SearchStack*, Value*, const Value, Value*, Depth, Move, int, MovePicker*, bool);