/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2012 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2008-2013 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
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
+#include <algorithm> // For std::count
#include <cassert>
#include <iostream>
using namespace Search;
-ThreadsManager Threads; // Global object
+ThreadPool 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. 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().
+ // is launched. It is a wrapper to the virtual function idle_loop().
- long start_routine(Thread* th) {
+ long start_routine(Thread* th) { th->idle_loop(); return 0; }
- if (th->threadID == 0)
- th->main_loop();
+} }
+
+
+// Thread c'tor starts a newly-created thread of execution that will call
+// the the virtual function idle_loop(), going immediately to sleep.
- else if (th->threadID == MAX_THREADS)
- th->timer_loop();
+Thread::Thread() /* : splitPoints() */ { // Value-initialization bug in MSVC
- else
- th->idle_loop(NULL);
+ searching = exit = false;
+ maxPly = splitPointsSize = 0;
+ activeSplitPoint = NULL;
+ activePosition = NULL;
+ idx = Threads.size();
- return 0;
+ if (!thread_create(handle, start_routine, this))
+ {
+ std::cerr << "Failed to create thread number " << idx << std::endl;
+ ::exit(EXIT_FAILURE);
}
+}
-} }
+// Thread d'tor waits for thread termination before to return
-// 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.
+Thread::~Thread() {
+
+ exit = true; // Search must be already finished
+ notify_one();
+ thread_join(handle); // Wait for thread termination
+}
+
+
+// TimerThread::idle_loop() is where the timer thread waits msec milliseconds
+// and then calls check_time(). If msec is 0 thread sleeps until is woken up.
extern void check_time();
-void Thread::timer_loop() {
+void TimerThread::idle_loop() {
- while (!do_exit)
+ while (!exit)
{
- lock_grab(sleepLock);
- timed_wait(sleepCond, sleepLock, maxPly ? maxPly : INT_MAX);
- lock_release(sleepLock);
- check_time();
+ mutex.lock();
+
+ if (!exit)
+ sleepCondition.wait_for(mutex, msec ? msec : INT_MAX);
+
+ mutex.unlock();
+
+ if (msec)
+ check_time();
}
}
-// Thread::main_loop() is where the main thread is parked waiting to be started
+// MainThread::idle_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() {
+void MainThread::idle_loop() {
while (true)
{
- lock_grab(sleepLock);
+ mutex.lock();
- do_sleep = true; // Always return to sleep after a search
- is_searching = false;
+ thinking = false;
- while (do_sleep && !do_exit)
+ while (!thinking && !exit)
{
- cond_signal(Threads.sleepCond); // Wake up UI thread if needed
- cond_wait(sleepCond, sleepLock);
+ Threads.sleepCondition.notify_one(); // Wake up UI thread if needed
+ sleepCondition.wait(mutex);
}
- lock_release(sleepLock);
+ mutex.unlock();
- if (do_exit)
+ if (exit)
return;
- is_searching = true;
+ searching = true;
Search::think();
+
+ assert(searching);
+
+ searching = false;
}
}
-// 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.
+// Thread::notify_one() wakes up the thread when there is some search to do
-void Thread::wake_up() {
+void Thread::notify_one() {
- lock_grab(sleepLock);
- cond_signal(sleepCond);
- lock_release(sleepLock);
+ mutex.lock();
+ sleepCondition.notify_one();
+ mutex.unlock();
}
-// 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() {
+// Thread::wait_for() set the thread to sleep until condition 'b' turns true
- Signals.stopOnPonderhit = true;
+void Thread::wait_for(volatile const bool& b) {
- lock_grab(sleepLock);
-
- while (!Signals.stop)
- cond_wait(sleepCond, sleepLock);
-
- lock_release(sleepLock);
+ mutex.lock();
+ while (!b) sleepCondition.wait(mutex);
+ mutex.unlock();
}
-// cutoff_occurred() checks whether a beta cutoff has occurred in the current
-// active split point, or in some ancestor of the split point.
+// 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 = curSplitPoint; sp; sp = sp->parent)
+ for (SplitPoint* sp = activeSplitPoint; sp; sp = sp->parentSplitPoint)
if (sp->cutoff)
return true;
}
-// 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).
+// Thread::is_available_to() checks whether the thread is available to help the
+// thread 'master' at a split point. 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 to the slaves
+// which are busy searching the split point at the top of slaves split point
+// stack (the "helpful master concept" in YBWC terminology).
-bool Thread::is_available_to(int master) const {
+bool Thread::is_available_to(Thread* master) const {
- if (is_searching)
+ if (searching)
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 spCnt = splitPointsCnt;
+ int size = splitPointsSize;
- // No active split points means that the thread is available as a slave for any
+ // 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 !spCnt || (splitPoints[spCnt - 1].slavesMask & (1ULL << master));
+ return !size || (splitPoints[size - 1].slavesMask & (1ULL << master->idx));
}
-// read_uci_options() updates internal threads parameters from the corresponding
-// UCI options. It is called before to start a new search.
+// init() is called at startup to create and launch requested threads, that will
+// go immediately to sleep due to 'sleepWhileIdle' set to true. We cannot use
+// a c'tor becuase 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::read_uci_options() {
+void ThreadPool::init() {
- maxThreadsPerSplitPoint = Options["Max Threads per Split Point"];
- minimumSplitDepth = Options["Min Split Depth"] * ONE_PLY;
- useSleepingThreads = Options["Use Sleeping Threads"];
- activeThreads = Options["Threads"];
-
- // 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.
- for (int i = 0; i < MAX_THREADS; i++)
- if (i < activeThreads)
- {
- threads[i].pawnTable.init();
- threads[i].materialTable.init();
- threads[i].maxPly = 0;
- }
+ sleepWhileIdle = true;
+ timer = new TimerThread();
+ push_back(new MainThread());
+ read_uci_options();
}
-void ThreadsManager::wake_up() {
-
- for (int i = 0; i < activeThreads; i++)
- {
- threads[i].do_sleep = false;
- threads[i].wake_up();
- }
-}
+// exit() cleanly terminates the threads before the program exits
+void ThreadPool::exit() {
-void ThreadsManager::sleep() {
+ delete timer; // As first because check_time() accesses threads data
- for (int i = 0; i < activeThreads; i++)
- threads[i].do_sleep = true;
+ for (iterator it = begin(); it != end(); ++it)
+ delete *it;
}
-// init() is called during startup. Initializes locks and condition variables
-// and launches all threads sending them immediately to sleep.
-
-void ThreadsManager::init() {
-
- read_uci_options();
-
- cond_init(sleepCond);
- lock_init(splitLock);
-
- // 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, 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;
-
- lock_init(threads[i].sleepLock);
- cond_init(threads[i].sleepCond);
+// 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 in advance all possible
+// threads, with included pawns and material tables, if only few are used.
- for (int j = 0; j < MAX_SPLITPOINTS_PER_THREAD; j++)
- lock_init(threads[i].splitPoints[j].lock);
-
- if (!thread_create(threads[i].handle, start_routine, threads[i]))
- {
- std::cerr << "Failed to create thread number " << i << std::endl;
- ::exit(EXIT_FAILURE);
- }
- }
-}
+void ThreadPool::read_uci_options() {
+ maxThreadsPerSplitPoint = Options["Max Threads per Split Point"];
+ minimumSplitDepth = Options["Min Split Depth"] * ONE_PLY;
+ size_t requested = Options["Threads"];
-// exit() is called to cleanly terminate the threads when the program finishes
+ assert(requested > 0);
-void ThreadsManager::exit() {
+ while (size() < requested)
+ push_back(new Thread());
- for (int i = 0; i <= MAX_THREADS; i++)
+ while (size() > requested)
{
- assert(threads[i].do_sleep);
-
- threads[i].do_exit = true; // Search must be already finished
- threads[i].wake_up();
-
- thread_join(threads[i].handle); // Wait for thread termination
-
- lock_destroy(threads[i].sleepLock);
- cond_destroy(threads[i].sleepCond);
-
- for (int j = 0; j < MAX_SPLITPOINTS_PER_THREAD; j++)
- lock_destroy(threads[i].splitPoints[j].lock);
+ delete back();
+ pop_back();
}
-
- 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'.
+// slave_available() tries to find an idle thread which is available as a slave
+// for the thread 'master'.
-bool ThreadsManager::available_slave_exists(int master) const {
+Thread* ThreadPool::available_slave(Thread* master) const {
- assert(master >= 0 && master < activeThreads);
-
- for (int i = 0; i < activeThreads; i++)
- if (threads[i].is_available_to(master))
- return true;
+ for (const_iterator it = begin(); it != end(); ++it)
+ if ((*it)->is_available_to(master))
+ return *it;
- return false;
+ return NULL;
}
// 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 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.
+// (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.
template <bool Fake>
-Value ThreadsManager::split(Position& pos, Stack* ss, Value alpha, Value beta,
- Value bestValue, Move* bestMove, Depth depth,
- Move threatMove, int moveCount, MovePicker* mp, int nodeType) {
- assert(pos.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 master = pos.thread();
- Thread& masterThread = threads[master];
+void Thread::split(Position& pos, Stack* ss, Value alpha, Value beta, Value* bestValue,
+ Move* bestMove, Depth depth, Move threatMove, int moveCount,
+ MovePicker* movePicker, int nodeType) {
- if (masterThread.splitPointsCnt >= MAX_SPLITPOINTS_PER_THREAD)
- return bestValue;
+ assert(pos.pos_is_ok());
+ assert(*bestValue <= alpha && alpha < beta && beta <= VALUE_INFINITE);
+ assert(*bestValue > -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 = &masterThread.splitPoints[masterThread.splitPointsCnt++];
-
- sp->parent = masterThread.curSplitPoint;
- sp->master = master;
- sp->cutoff = false;
- sp->slavesMask = 1ULL << master;
- sp->depth = depth;
- sp->bestMove = *bestMove;
- sp->threatMove = threatMove;
- sp->alpha = alpha;
- sp->beta = beta;
- sp->nodeType = nodeType;
- sp->bestValue = bestValue;
- sp->mp = mp;
- sp->moveCount = moveCount;
- sp->pos = &pos;
- sp->nodes = 0;
- sp->ss = ss;
-
- assert(masterThread.is_searching);
-
- masterThread.curSplitPoint = sp;
- int slavesCnt = 0;
+ SplitPoint& sp = splitPoints[splitPointsSize];
+
+ sp.masterThread = this;
+ sp.parentSplitPoint = activeSplitPoint;
+ sp.slavesMask = 1ULL << idx;
+ sp.depth = depth;
+ sp.bestValue = *bestValue;
+ sp.bestMove = *bestMove;
+ sp.threatMove = threatMove;
+ sp.alpha = alpha;
+ sp.beta = beta;
+ sp.nodeType = nodeType;
+ 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
- // is_searching flag. This must be done under lock protection to avoid concurrent
+ // '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 (int i = 0; i < activeThreads && !Fake; i++)
- if (threads[i].is_available_to(master))
- {
- sp->slavesMask |= 1ULL << i;
- threads[i].curSplitPoint = sp;
- threads[i].is_searching = true; // Slave leaves idle_loop()
+ Threads.mutex.lock();
+ sp.mutex.lock();
- if (useSleepingThreads)
- threads[i].wake_up();
+ splitPointsSize++;
+ activeSplitPoint = &sp;
+ activePosition = NULL;
- if (++slavesCnt + 1 >= maxThreadsPerSplitPoint) // Master is always included
- break;
- }
+ size_t slavesCnt = 1; // This thread is always included
+ Thread* slave;
- lock_release(splitLock);
- lock_release(sp->lock);
+ while ( (slave = Threads.available_slave(this)) != NULL
+ && ++slavesCnt <= Threads.maxThreadsPerSplitPoint && !Fake)
+ {
+ sp.slavesMask |= 1ULL << 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 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
+ // 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.
- if (slavesCnt || Fake)
+ if (slavesCnt > 1 || Fake)
{
- masterThread.idle_loop(sp);
+ sp.mutex.unlock();
+ Threads.mutex.unlock();
+
+ Thread::idle_loop(); // Force a call to base class idle_loop()
// In helpful master concept a master can help only a sub-tree of its split
// point, and because here is all finished is not possible master is booked.
- assert(!masterThread.is_searching);
+ 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::is_available_to().
+ Threads.mutex.lock();
+ sp.mutex.lock();
}
- // We have returned from the idle loop, which means that all threads are
- // finished. Note that setting is_searching and decreasing splitPointsCnt 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);
+ searching = true;
+ splitPointsSize--;
+ activeSplitPoint = sp.parentSplitPoint;
+ activePosition = &pos;
+ pos.set_nodes_searched(pos.nodes_searched() + sp.nodes);
+ *bestMove = sp.bestMove;
+ *bestValue = sp.bestValue;
- masterThread.is_searching = true;
- masterThread.splitPointsCnt--;
- masterThread.curSplitPoint = sp->parent;
- pos.set_nodes_searched(pos.nodes_searched() + sp->nodes);
- *bestMove = sp->bestMove;
-
- lock_release(splitLock);
- lock_release(sp->lock);
-
- return sp->bestValue;
+ sp.mutex.unlock();
+ Threads.mutex.unlock();
}
// Explicit template instantiations
-template Value ThreadsManager::split<false>(Position&, Stack*, Value, Value, Value, Move*, Depth, Move, int, MovePicker*, int);
-template Value ThreadsManager::split<true>(Position&, Stack*, Value, Value, Value, Move*, Depth, Move, int, MovePicker*, int);
-
+template void Thread::split<false>(Position&, Stack*, Value, Value, Value*, Move*, Depth, Move, int, MovePicker*, int);
+template void Thread::split< true>(Position&, Stack*, Value, Value, Value*, Move*, 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) {
+// wait_for_think_finished() waits for main thread to go to sleep then returns
- Thread& timer = threads[MAX_THREADS];
+void ThreadPool::wait_for_think_finished() {
- lock_grab(timer.sleepLock);
- timer.maxPly = msec;
- cond_signal(timer.sleepCond); // Wake up and restart the timer
- lock_release(timer.sleepLock);
+ MainThread* t = main_thread();
+ t->mutex.lock();
+ while (t->thinking) sleepCondition.wait(t->mutex);
+ t->mutex.unlock();
}
-// 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);
+// start_thinking() wakes up the main thread sleeping in MainThread::idle_loop()
+// so to start a new search, then returns immediately.
- // Wait main thread has finished before to launch a new search
- while (!main.do_sleep)
- cond_wait(sleepCond, main.sleepLock);
+void ThreadPool::start_thinking(const Position& pos, const LimitsType& limits,
+ const std::vector<Move>& searchMoves, StateStackPtr& states) {
+ wait_for_think_finished();
- // 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()));
+ SearchTime = Time::now(); // As early as possible
- // 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
+ RootPos = pos;
+ Limits = limits;
+ SetupStates = states; // Ownership transfer here
+ RootMoves.clear();
- while (!main.do_sleep)
- cond_wait(sleepCond, main.sleepLock);
+ for (MoveList<LEGAL> it(pos); !it.end(); ++it)
+ if ( searchMoves.empty()
+ || std::count(searchMoves.begin(), searchMoves.end(), *it))
+ RootMoves.push_back(RootMove(*it));
- lock_release(main.sleepLock);
+ main_thread()->thinking = true;
+ main_thread()->notify_one(); // Starts main thread
}
projects / stockfish / blobdiff