/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2013 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
#include "movegen.h"
#include "search.h"
#include "thread.h"
-#include "ucioption.h"
+#include "uci.h"
using namespace Search;
ThreadPool Threads; // Global object
-namespace {
-
- // start_routine() is the C function which is called when a new thread
- // is launched. It is a wrapper to the virtual function idle_loop().
-
- extern "C" { long start_routine(ThreadBase* th) { th->idle_loop(); return 0; } }
+extern void check_time();
+namespace {
// Helpers to launch a thread after creation and joining before delete. Must be
- // outside Thread c'tor and d'tor because the object will be fully initialized
+ // 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.
template<typename T> T* new_thread() {
- T* th = new T();
- thread_create(th->handle, start_routine, th); // Will go to sleep
- return th;
+ std::thread* th = new T;
+ *th = std::thread(&T::idle_loop, (T*)th); // Will go to sleep
+ return (T*)th;
}
void delete_thread(ThreadBase* th) {
+
+ th->mutex.lock();
th->exit = true; // Search must be already finished
+ th->mutex.unlock();
+
th->notify_one();
- thread_join(th->handle); // Wait for thread termination
+ th->join(); // Wait for thread termination
delete th;
}
void ThreadBase::notify_one() {
- mutex.lock();
+ std::unique_lock<Mutex> lk(mutex);
sleepCondition.notify_one();
- mutex.unlock();
}
-// ThreadBase::wait_for() set the thread to sleep until condition 'b' turns true
+// ThreadBase::wait_for() set the thread to sleep until 'condition' turns true
-void ThreadBase::wait_for(volatile const bool& b) {
+void ThreadBase::wait_for(volatile const bool& condition) {
- mutex.lock();
- while (!b) sleepCondition.wait(mutex);
- mutex.unlock();
+ std::unique_lock<Mutex> lk(mutex);
+ sleepCondition.wait(lk, [&]{ return condition; });
}
-// Thread c'tor just inits data and does not launch any execution thread.
-// Such a thread will only be started when c'tor returns.
+// Thread c'tor makes some init but does not launch any execution thread that
+// will be started only when c'tor returns.
-Thread::Thread() /* : splitPoints() */ { // Value-initialization bug in MSVC
+Thread::Thread() /* : splitPoints() */ { // Initialization of non POD broken in MSVC
searching = false;
- maxPly = splitPointsSize = 0;
- activeSplitPoint = NULL;
- activePosition = NULL;
- idx = Threads.size();
-}
-
-
-// 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 TimerThread::idle_loop() {
-
- while (!exit)
- {
- mutex.lock();
-
- if (!exit)
- sleepCondition.wait_for(mutex, run ? Resolution : INT_MAX);
-
- mutex.unlock();
-
- if (run)
- check_time();
- }
-}
-
-
-// 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 MainThread::idle_loop() {
-
- while (true)
- {
- mutex.lock();
-
- thinking = false;
-
- while (!thinking && !exit)
- {
- Threads.sleepCondition.notify_one(); // Wake up the UI thread if needed
- sleepCondition.wait(mutex);
- }
-
- mutex.unlock();
-
- if (exit)
- return;
-
- searching = true;
-
- Search::think();
-
- assert(searching);
-
- searching = false;
- }
+ maxPly = 0;
+ splitPointsSize = 0;
+ activeSplitPoint = nullptr;
+ activePosition = nullptr;
+ idx = Threads.size(); // Starts from 0
}
}
-// Thread::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 slave's split point
-// stack (the "helpful master concept" in YBWC terminology).
+// Thread::can_join() checks whether the thread is available to join the split
+// point 'sp'. 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 for the split points below his active
+// one (the "helpful master" concept in YBWC terminology).
-bool Thread::available_to(const Thread* master) const {
+bool Thread::can_join(const SplitPoint* sp) const {
if (searching)
return false;
- // Make a local copy to be sure doesn't become zero under our feet while
+ // Make a local copy to be sure it doesn't become zero under our feet while
// testing next condition and so leading to an out of bounds access.
- int size = splitPointsSize;
+ const size_t size = splitPointsSize;
// 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 !size || (splitPoints[size - 1].slavesMask & (1ULL << master->idx));
-}
-
-
-// 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 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 ThreadPool::init() {
-
- sleepWhileIdle = true;
- timer = new_thread<TimerThread>();
- push_back(new_thread<MainThread>());
- read_uci_options();
-}
-
-
-// exit() cleanly terminates the threads before the program exits
-
-void ThreadPool::exit() {
-
- delete_thread(timer); // As first because check_time() accesses threads data
-
- for (iterator it = begin(); it != end(); ++it)
- delete_thread(*it);
-}
-
-
-// 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() {
-
- maxThreadsPerSplitPoint = Options["Max Threads per Split Point"];
- minimumSplitDepth = Options["Min Split Depth"] * ONE_PLY;
- size_t requested = Options["Threads"];
-
- assert(requested > 0);
-
- // 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 (size() < requested)
- push_back(new_thread<Thread>());
-
- while (size() > requested)
- {
- delete_thread(back());
- pop_back();
- }
+ return !size || splitPoints[size - 1].slavesMask.test(sp->master->idx);
}
-// slave_available() tries to find an idle thread which is available as a slave
-// for the thread 'master'.
-
-Thread* ThreadPool::available_slave(const Thread* master) const {
-
- for (const_iterator it = begin(); it != end(); ++it)
- if ((*it)->available_to(master))
- return *it;
-
- return NULL;
-}
-
-
-// split() does the actual work of distributing the work at a node between
+// Thread::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), 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
+// informed 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 Thread::split(Position& pos, const Stack* ss, Value alpha, Value beta, Value* bestValue,
- Move* bestMove, Depth depth, Move threatMove, int moveCount,
+void Thread::split(Position& pos, Stack* ss, Value alpha, Value beta, Value* bestValue,
+ Move* bestMove, Depth depth, int moveCount,
MovePicker* movePicker, int nodeType, bool cutNode) {
- assert(pos.pos_is_ok());
- assert(*bestValue <= alpha && alpha < beta && beta <= VALUE_INFINITE);
- assert(*bestValue > -VALUE_INFINITE);
- assert(depth >= Threads.minimumSplitDepth);
assert(searching);
+ assert(-VALUE_INFINITE < *bestValue && *bestValue <= alpha && alpha < beta && beta <= VALUE_INFINITE);
+ assert(depth >= Threads.minimumSplitDepth);
assert(splitPointsSize < MAX_SPLITPOINTS_PER_THREAD);
- // Pick the next available split point from the split point stack
+ // Pick and init the next available split point
SplitPoint& sp = splitPoints[splitPointsSize];
- sp.masterThread = this;
+ sp.spinlock.acquire(); // No contention here until we don't increment splitPointsSize
+
+ sp.master = this;
sp.parentSplitPoint = activeSplitPoint;
- sp.slavesMask = 1ULL << idx;
+ sp.slavesMask = 0, sp.slavesMask.set(idx);
sp.depth = depth;
sp.bestValue = *bestValue;
sp.bestMove = *bestMove;
- sp.threatMove = threatMove;
sp.alpha = alpha;
sp.beta = beta;
sp.nodeType = nodeType;
sp.nodes = 0;
sp.cutoff = false;
sp.ss = ss;
-
- // Try to allocate available threads and ask them to start searching setting
- // 'searching' flag. This must be done under lock protection to avoid concurrent
- // allocation of the same slave by another master.
- Threads.mutex.lock();
- sp.mutex.lock();
+ sp.allSlavesSearching = true; // Must be set under lock protection
++splitPointsSize;
activeSplitPoint = &sp;
- activePosition = NULL;
+ activePosition = nullptr;
- size_t slavesCnt = 1; // This thread is always included
+ // Try to allocate available threads
Thread* slave;
- while ( (slave = Threads.available_slave(this)) != NULL
- && ++slavesCnt <= Threads.maxThreadsPerSplitPoint && !Fake)
+ while ( sp.slavesMask.count() < MAX_SLAVES_PER_SPLITPOINT
+ && (slave = Threads.available_slave(&sp)) != nullptr)
{
- sp.slavesMask |= 1ULL << slave->idx;
- slave->activeSplitPoint = &sp;
- slave->searching = true; // Slave leaves idle_loop()
- slave->notify_one(); // Could be sleeping
+ slave->spinlock.acquire();
+
+ if (slave->can_join(activeSplitPoint))
+ {
+ activeSplitPoint->slavesMask.set(slave->idx);
+ slave->activeSplitPoint = activeSplitPoint;
+ slave->searching = true;
+ }
+
+ slave->spinlock.release();
}
// Everything is set up. The master thread enters the idle loop, from which
// 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 > 1 || Fake)
- {
- sp.mutex.unlock();
- Threads.mutex.unlock();
-
- Thread::idle_loop(); // Force a call to base class idle_loop()
-
- // In the helpful master concept, a master can help only a sub-tree of its
- // split point and because everything is finished here, it's not possible
- // for the master to be booked.
- 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::available_to().
- Threads.mutex.lock();
- sp.mutex.lock();
- }
+ sp.spinlock.release();
+
+ Thread::idle_loop(); // Force a call to base class idle_loop()
+
+ // In the helpful master concept, a master can help only a sub-tree of its
+ // split point and because everything is finished here, it's not possible
+ // for the master to be booked.
+ assert(!searching);
+ assert(!activePosition);
searching = true;
+
+ // We have returned from the idle loop, which means that all threads are
+ // finished. Note that decreasing splitPointsSize must be done under lock
+ // protection to avoid a race with Thread::can_join().
+ sp.spinlock.acquire();
+
--splitPointsSize;
activeSplitPoint = sp.parentSplitPoint;
activePosition = &pos;
*bestMove = sp.bestMove;
*bestValue = sp.bestValue;
- sp.mutex.unlock();
- Threads.mutex.unlock();
+ sp.spinlock.release();
}
-// Explicit template instantiations
-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);
+// 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.
-// wait_for_think_finished() waits for main thread to go to sleep then returns
+void TimerThread::idle_loop() {
-void ThreadPool::wait_for_think_finished() {
+ while (!exit)
+ {
+ std::unique_lock<Mutex> lk(mutex);
- MainThread* t = main();
- t->mutex.lock();
- while (t->thinking) sleepCondition.wait(t->mutex);
- t->mutex.unlock();
+ if (!exit)
+ sleepCondition.wait_for(lk, std::chrono::milliseconds(run ? Resolution : INT_MAX));
+
+ lk.unlock();
+
+ if (run)
+ check_time();
+ }
}
-// start_thinking() wakes up the main thread sleeping in MainThread::idle_loop()
-// so to start a new search, then returns immediately.
+// 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 ThreadPool::start_thinking(const Position& pos, const LimitsType& limits,
- const std::vector<Move>& searchMoves, StateStackPtr& states) {
- wait_for_think_finished();
+void MainThread::idle_loop() {
+
+ while (!exit)
+ {
+ std::unique_lock<Mutex> lk(mutex);
+
+ thinking = false;
+
+ while (!thinking && !exit)
+ {
+ sleepCondition.notify_one(); // Wake up the UI thread if needed
+ sleepCondition.wait(lk);
+ }
+
+ lk.unlock();
+
+ if (!exit)
+ {
+ searching = true;
+
+ Search::think();
+
+ assert(searching);
+
+ searching = false;
+ }
+ }
+}
+
+
+// MainThread::join() waits for main thread to finish the search
+
+void MainThread::join() {
+
+ std::unique_lock<Mutex> lk(mutex);
+ sleepCondition.wait(lk, [&]{ return !thinking; });
+}
- SearchTime = Time::now(); // As early as possible
+
+// 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 ThreadPool::init() {
+
+ timer = new_thread<TimerThread>();
+ push_back(new_thread<MainThread>());
+ read_uci_options();
+}
+
+
+// ThreadPool::exit() terminates the threads before the program exits. Cannot be
+// done in d'tor because threads must be terminated before freeing us.
+
+void ThreadPool::exit() {
+
+ delete_thread(timer); // As first because check_time() accesses threads data
+ timer = nullptr;
+
+ for (Thread* th : *this)
+ delete_thread(th);
+
+ clear(); // Get rid of stale pointers
+}
+
+
+// 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() {
+
+ minimumSplitDepth = Options["Min Split Depth"] * ONE_PLY;
+ size_t requested = Options["Threads"];
+
+ assert(requested > 0);
+
+ // If zero (default) then set best minimum split depth automatically
+ if (!minimumSplitDepth)
+ minimumSplitDepth = 5 * ONE_PLY ;
+
+ while (size() < requested)
+ push_back(new_thread<Thread>());
+
+ while (size() > requested)
+ {
+ delete_thread(back());
+ pop_back();
+ }
+}
+
+
+// ThreadPool::available_slave() tries to find an idle thread which is available
+// to join SplitPoint 'sp'.
+
+Thread* ThreadPool::available_slave(const SplitPoint* sp) const {
+
+ for (Thread* th : *this)
+ if (th->can_join(sp))
+ return th;
+
+ return nullptr;
+}
+
+
+// ThreadPool::start_thinking() wakes up the main thread sleeping in
+// MainThread::idle_loop() and starts a new search, then returns immediately.
+
+void ThreadPool::start_thinking(const Position& pos, const LimitsType& limits,
+ StateStackPtr& states) {
+ main()->join();
Signals.stopOnPonderhit = Signals.firstRootMove = false;
Signals.stop = Signals.failedLowAtRoot = false;
Limits = limits;
if (states.get()) // If we don't set a new position, preserve current state
{
- SetupStates = states; // Ownership transfer here
+ SetupStates = std::move(states); // Ownership transfer here
assert(!states.get());
}
- for (MoveList<LEGAL> it(pos); *it; ++it)
- if ( searchMoves.empty()
- || std::count(searchMoves.begin(), searchMoves.end(), *it))
- RootMoves.push_back(RootMove(*it));
+ for (const auto& m : MoveList<LEGAL>(pos))
+ if ( limits.searchmoves.empty()
+ || std::count(limits.searchmoves.begin(), limits.searchmoves.end(), m))
+ RootMoves.push_back(RootMove(m));
main()->thinking = true;
- main()->notify_one(); // Starts main thread
+ main()->notify_one(); // Wake up main thread: 'thinking' must be already set
}
projects / stockfish / blobdiff