/*
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>
#include "movegen.h"
#include "search.h"
ThreadPool Threads; // Global object
-namespace { extern "C" {
+namespace {
// start_routine() is the C function which is called when a new thread
- // is launched. It is a wrapper to member function pointed by start_fn.
+ // is launched. It is a wrapper to the virtual function idle_loop().
- long start_routine(Thread* th) { (th->*(th->start_fn))(); return 0; }
+ extern "C" { long start_routine(ThreadBase* th) { th->idle_loop(); return 0; } }
-} }
+ // Helpers to launch a thread after creation and joining before delete. Must be
+ // outside Thread c'tor and d'tor because object shall be fully initialized
+ // when start_routine (and hence virtual idle_loop) is called and when joining.
-// Thread c'tor starts a newly-created thread of execution that will call
-// the idle loop function pointed by start_fn going immediately to sleep.
+ template<typename T> T* new_thread() {
+ T* th = new T();
+ thread_create(th->handle, start_routine, th); // Will go to sleep
+ return th;
+ }
-Thread::Thread(Fn fn) : splitPoints() {
+ void delete_thread(ThreadBase* th) {
+ th->exit = true; // Search must be already finished
+ th->notify_one();
+ thread_join(th->handle); // Wait for thread termination
+ delete th;
+ }
- is_searching = do_exit = false;
- maxPly = splitPointsCnt = 0;
- curSplitPoint = NULL;
- start_fn = fn;
- idx = Threads.size();
+}
- do_sleep = (fn != &Thread::main_loop); // Avoid a race with start_searching()
- if (!thread_create(handle, start_routine, this))
- {
- std::cerr << "Failed to create thread number " << idx << std::endl;
- ::exit(EXIT_FAILURE);
- }
+// ThreadBase::notify_one() wakes up the thread when there is some work to do
+
+void ThreadBase::notify_one() {
+
+ mutex.lock();
+ sleepCondition.notify_one();
+ mutex.unlock();
}
-// Thread d'tor waits for thread termination before to return.
+// ThreadBase::wait_for() set the thread to sleep until condition 'b' turns true
-Thread::~Thread() {
+void ThreadBase::wait_for(volatile const bool& b) {
- assert(do_sleep);
+ mutex.lock();
+ while (!b) sleepCondition.wait(mutex);
+ mutex.unlock();
+}
- do_exit = true; // Search must be already finished
- notify_one();
- thread_join(handle); // Wait for thread termination
+
+// Thread c'tor just inits data but does not launch any thread of execution that
+// instead will be started only upon c'tor returns.
+
+Thread::Thread() /* : splitPoints() */ { // Value-initialization bug in MSVC
+
+ searching = false;
+ maxPly = splitPointsSize = 0;
+ activeSplitPoint = NULL;
+ activePosition = NULL;
+ idx = Threads.size();
}
-// Thread::timer_loop() is where the timer thread waits maxPly milliseconds and
-// then calls check_time(). If maxPly is 0 thread sleeps until is woken up.
+// 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)
{
mutex.lock();
- while (!maxPly && !do_exit)
- sleepCondition.wait_for(mutex, maxPly ? maxPly : INT_MAX);
+
+ if (!exit)
+ sleepCondition.wait_for(mutex, msec ? msec : INT_MAX);
+
mutex.unlock();
- check_time();
+
+ 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)
{
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)
{
Threads.sleepCondition.notify_one(); // Wake up UI thread if needed
sleepCondition.wait(mutex);
mutex.unlock();
- if (do_exit)
+ if (exit)
return;
- is_searching = true;
+ searching = true;
Search::think();
- assert(is_searching);
- }
-}
-
-
-// Thread::notify_one() wakes up the thread, normally at the beginning of the
-// search or, if "sleeping threads" is used at split time.
-
-void Thread::notify_one() {
-
- mutex.lock();
- sleepCondition.notify_one();
- mutex.unlock();
-}
-
-
-// Thread::wait_for() set the thread to sleep until condition 'b' turns true
-
-void Thread::wait_for(volatile const bool& b) {
+ assert(searching);
- mutex.lock();
- while (!b) sleepCondition.wait(mutex);
- mutex.unlock();
+ searching = false;
+ }
}
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;
// 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 active 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).
+// 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(Thread* master) const {
+bool Thread::is_available_to(const 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->idx));
+ return !size || (splitPoints[size - 1].slavesMask & (1ULL << master->idx));
}
-// init() is called at startup. Initializes lock and condition variable and
-// launches requested threads sending them immediately to sleep. We cannot use
+// 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.
+// engine at this point due to allocation of Endgames in Thread c'tor.
void ThreadPool::init() {
- timer = new Thread(&Thread::timer_loop);
- threads.push_back(new Thread(&Thread::main_loop));
+ sleepWhileIdle = true;
+ timer = new_thread<TimerThread>();
+ push_back(new_thread<MainThread>());
read_uci_options();
}
-// exit() cleanly terminates the threads before the program exits.
+// exit() cleanly terminates the threads before the program exits
void ThreadPool::exit() {
- delete timer; // As first becuase check_time() accesses threads data
+ delete_thread(timer); // As first because check_time() accesses threads data
- for (size_t i = 0; i < threads.size(); i++)
- delete threads[i];
+ for (iterator it = begin(); it != end(); ++it)
+ delete_thread(*it);
}
maxThreadsPerSplitPoint = Options["Max Threads per Split Point"];
minimumSplitDepth = Options["Min Split Depth"] * ONE_PLY;
- useSleepingThreads = Options["Use Sleeping Threads"];
size_t requested = Options["Threads"];
assert(requested > 0);
- while (threads.size() < requested)
- threads.push_back(new Thread(&Thread::idle_loop));
+ // Value 0 has a special meaning: We determine the optimal minimum split depth
+ // automatically. Anyhow the minimumSplitDepth should never be under 4 plies.
+ if (!minimumSplitDepth)
+ minimumSplitDepth = (requested < 8 ? 4 : 7) * ONE_PLY;
+ else
+ minimumSplitDepth = std::max(4 * ONE_PLY, minimumSplitDepth);
- while (threads.size() > requested)
+ while (size() < requested)
+ push_back(new_thread<Thread>());
+
+ while (size() > requested)
{
- delete threads.back();
- threads.pop_back();
+ delete_thread(back());
+ pop_back();
}
}
-// available_slave_exists() tries to find an idle thread which is available as
-// a slave for the thread 'master'.
+// slave_available() tries to find an idle thread which is available as a slave
+// for the thread 'master'.
-bool ThreadPool::available_slave_exists(Thread* master) const {
+Thread* ThreadPool::available_slave(const Thread* master) const {
- for (size_t i = 0; i < threads.size(); 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 ThreadPool::split(Position& pos, Stack* ss, Value alpha, Value beta,
- Value bestValue, Move* bestMove, Depth depth, Move threatMove,
- int moveCount, MovePicker& mp, int nodeType) {
+void Thread::split(Position& pos, const Stack* ss, Value alpha, Value beta, Value* bestValue,
+ Move* bestMove, Depth depth, Move threatMove, int moveCount,
+ MovePicker* movePicker, int nodeType, bool cutNode) {
assert(pos.pos_is_ok());
- assert(bestValue > -VALUE_INFINITE);
- assert(bestValue <= alpha);
- assert(alpha < beta);
- assert(beta <= VALUE_INFINITE);
- assert(depth > DEPTH_ZERO);
-
- Thread* master = pos.this_thread();
-
- if (master->splitPointsCnt >= MAX_SPLITPOINTS_PER_THREAD)
- return bestValue;
+ 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 = master->splitPoints[master->splitPointsCnt];
+ SplitPoint& sp = splitPoints[splitPointsSize];
- sp.parent = master->curSplitPoint;
- sp.master = master;
- sp.cutoff = false;
- sp.slavesMask = 1ULL << master->idx;
+ 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.bestValue = bestValue;
- sp.mp = ∓
+ sp.cutNode = cutNode;
+ sp.movePicker = movePicker;
sp.moveCount = moveCount;
sp.pos = &pos;
sp.nodes = 0;
+ sp.cutoff = false;
sp.ss = ss;
- assert(master->is_searching);
-
- master->curSplitPoint = &sp;
- int slavesCnt = 0;
-
// 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.
- mutex.lock();
+ Threads.mutex.lock();
sp.mutex.lock();
- for (size_t i = 0; i < threads.size() && !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()
-
- if (useSleepingThreads)
- threads[i]->notify_one();
+ splitPointsSize++;
+ activeSplitPoint = &sp;
+ activePosition = NULL;
- if (++slavesCnt + 1 >= maxThreadsPerSplitPoint) // Master is always included
- break;
- }
-
- master->splitPointsCnt++;
+ size_t slavesCnt = 1; // This thread is always included
+ Thread* slave;
- sp.mutex.unlock();
- mutex.unlock();
+ 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.
+ // 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)
{
- master->idle_loop();
+ 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(!master->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().
- mutex.lock();
- sp.mutex.lock();
-
- master->is_searching = true;
- master->splitPointsCnt--;
- master->curSplitPoint = sp.parent;
+ searching = true;
+ splitPointsSize--;
+ activeSplitPoint = sp.parentSplitPoint;
+ activePosition = &pos;
pos.set_nodes_searched(pos.nodes_searched() + sp.nodes);
*bestMove = sp.bestMove;
+ *bestValue = sp.bestValue;
sp.mutex.unlock();
- mutex.unlock();
-
- return sp.bestValue;
+ Threads.mutex.unlock();
}
// Explicit template instantiations
-template Value ThreadPool::split<false>(Position&, Stack*, Value, Value, Value, Move*, Depth, Move, int, MovePicker&, int);
-template Value ThreadPool::split<true>(Position&, Stack*, Value, Value, Value, Move*, Depth, Move, int, MovePicker&, int);
+template void Thread::split<false>(Position&, const Stack*, Value, Value, Value*, Move*, Depth, Move, int, MovePicker*, int, bool);
+template void Thread::split< true>(Position&, const Stack*, Value, Value, Value*, Move*, Depth, Move, int, MovePicker*, int, bool);
-// wait_for_search_finished() waits for main thread to go to sleep, this means
-// search is finished. Then returns.
+// wait_for_think_finished() waits for main thread to go to sleep then returns
-void ThreadPool::wait_for_search_finished() {
+void ThreadPool::wait_for_think_finished() {
- Thread* t = main_thread();
+ MainThread* t = main();
t->mutex.lock();
- while (!t->do_sleep) sleepCondition.wait(t->mutex);
+ while (t->thinking) sleepCondition.wait(t->mutex);
t->mutex.unlock();
}
-// start_searching() wakes up the main thread sleeping in main_loop() so to start
-// a new search, then returns immediately.
+// start_thinking() wakes up the main thread sleeping in MainThread::idle_loop()
+// so to start a new search, then returns immediately.
-void ThreadPool::start_searching(const Position& pos, const LimitsType& limits,
- const std::vector<Move>& searchMoves, StateStackPtr& states) {
- wait_for_search_finished();
+void ThreadPool::start_thinking(const Position& pos, const LimitsType& limits,
+ const std::vector<Move>& searchMoves, StateStackPtr& states) {
+ wait_for_think_finished();
SearchTime = Time::now(); // As early as possible
Signals.stopOnPonderhit = Signals.firstRootMove = false;
Signals.stop = Signals.failedLowAtRoot = false;
+ RootMoves.clear();
RootPos = pos;
Limits = limits;
- SetupStates = states; // Ownership transfer here
- RootMoves.clear();
+ if (states.get()) // If we don't set a new position, preserve current state
+ {
+ SetupStates = states; // Ownership transfer here
+ assert(!states.get());
+ }
- for (MoveList<LEGAL> ml(pos); !ml.end(); ++ml)
- if (searchMoves.empty() || count(searchMoves.begin(), searchMoves.end(), ml.move()))
- RootMoves.push_back(RootMove(ml.move()));
+ for (MoveList<LEGAL> it(pos); *it; ++it)
+ if ( searchMoves.empty()
+ || std::count(searchMoves.begin(), searchMoves.end(), *it))
+ RootMoves.push_back(RootMove(*it));
- main_thread()->do_sleep = false;
- main_thread()->notify_one();
+ main()->thinking = true;
+ main()->notify_one(); // Starts main thread
}
projects / stockfish / blobdiff