/*
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) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2015-2016 Marco Costalba, Joona Kiiski, Gary Linscott, 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"
#include "thread.h"
-#include "ucioption.h"
-
-using namespace Search;
+#include "uci.h"
+#include "syzygy/tbprobe.h"
ThreadPool Threads; // Global object
-namespace { extern "C" {
-
- // 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.
-
- long start_routine(Thread* th) { (th->*(th->start_fn))(); return 0; }
-
-} }
-
+/// Thread constructor launches the thread and then waits until it goes to sleep
+/// in idle_loop().
-// 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.
+Thread::Thread() {
-Thread::Thread(Fn fn) {
+ resetCalls = exit = false;
+ maxPly = callsCnt = 0;
+ history.clear();
+ counterMoves.clear();
+ idx = Threads.size(); // Start from 0
- 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()
-
- lock_init(sleepLock);
- cond_init(sleepCond);
-
- for (size_t j = 0; j < MAX_SPLITPOINTS_PER_THREAD; j++)
- lock_init(splitPoints[j].lock);
-
- if (!thread_create(handle, start_routine, this))
- {
- std::cerr << "Failed to create thread number " << idx << std::endl;
- ::exit(EXIT_FAILURE);
- }
+ std::unique_lock<Mutex> lk(mutex);
+ searching = true;
+ nativeThread = std::thread(&Thread::idle_loop, this);
+ sleepCondition.wait(lk, [&]{ return !searching; });
}
-// Thread d'tor waits for thread termination before to return.
+/// Thread destructor waits for thread termination before returning
Thread::~Thread() {
- assert(do_sleep);
-
- do_exit = true; // Search must be already finished
- wake_up();
-
- thread_join(handle); // Wait for thread termination
-
- lock_destroy(sleepLock);
- cond_destroy(sleepCond);
-
- for (int j = 0; j < MAX_SPLITPOINTS_PER_THREAD; j++)
- lock_destroy(splitPoints[j].lock);
+ mutex.lock();
+ exit = true;
+ sleepCondition.notify_one();
+ mutex.unlock();
+ nativeThread.join();
}
-// 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.
-extern void check_time();
+/// Thread::wait_for_search_finished() waits on sleep condition
+/// until not searching
-void Thread::timer_loop() {
+void Thread::wait_for_search_finished() {
- while (!do_exit)
- {
- lock_grab(sleepLock);
- timed_wait(sleepCond, sleepLock, maxPly ? maxPly : INT_MAX);
- lock_release(sleepLock);
- check_time();
- }
+ std::unique_lock<Mutex> lk(mutex);
+ sleepCondition.wait(lk, [&]{ return !searching; });
}
-// 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);
+/// Thread::wait() waits on sleep condition until condition is true
- do_sleep = true; // Always return to sleep after a search
- is_searching = false;
+void Thread::wait(std::atomic_bool& condition) {
- while (do_sleep && !do_exit)
- {
- cond_signal(Threads.sleepCond); // Wake up UI thread if needed
- cond_wait(sleepCond, sleepLock);
- }
-
- lock_release(sleepLock);
-
- if (do_exit)
- return;
-
- is_searching = true;
-
- Search::think();
- }
+ std::unique_lock<Mutex> lk(mutex);
+ sleepCondition.wait(lk, [&]{ return bool(condition); });
}
-// Thread::wake_up() wakes up the thread, normally at the beginning of the search
-// or, if "sleeping threads" is used at split time.
-
-void Thread::wake_up() {
-
- lock_grab(sleepLock);
- cond_signal(sleepCond);
- lock_release(sleepLock);
-}
+/// Thread::start_searching() wakes up the thread that will start the search
+void Thread::start_searching(bool resume) {
-// 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.
+ std::unique_lock<Mutex> lk(mutex);
-void Thread::wait_for_stop_or_ponderhit() {
+ if (!resume)
+ searching = true;
- Signals.stopOnPonderhit = true;
-
- lock_grab(sleepLock);
- while (!Signals.stop) cond_wait(sleepCond, sleepLock);
- lock_release(sleepLock);
+ sleepCondition.notify_one();
}
-// 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)
- if (sp->cutoff)
- return true;
-
- return false;
-}
+/// Thread::idle_loop() is where the thread is parked when it has no work to do
+void Thread::idle_loop() {
-// 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).
+ while (!exit)
+ {
+ std::unique_lock<Mutex> lk(mutex);
-bool Thread::is_available_to(Thread* master) const {
+ searching = false;
- if (is_searching)
- return false;
+ while (!searching && !exit)
+ {
+ sleepCondition.notify_one(); // Wake up any waiting thread
+ sleepCondition.wait(lk);
+ }
- // 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;
+ lk.unlock();
- // 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.
- return !spCnt || (splitPoints[spCnt - 1].slavesMask & (1ULL << master->idx));
+ if (!exit)
+ search();
+ }
}
-// init() is called at startup. Initializes lock and condition variable and
-// launches requested threads sending them immediately to sleep. 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.
+/// ThreadPool::init() creates and launches requested threads that will go
+/// immediately to sleep. We cannot use a constructor because Threads is a
+/// static object and we need a fully initialized engine at this point due to
+/// allocation of Endgames in the Thread constructor.
void ThreadPool::init() {
- cond_init(sleepCond);
- lock_init(splitLock);
- timer = new Thread(&Thread::timer_loop);
- threads.push_back(new Thread(&Thread::main_loop));
+ push_back(new MainThread);
read_uci_options();
}
-// d'tor cleanly terminates the threads when the program exits.
+/// ThreadPool::exit() terminates threads before the program exits. Cannot be
+/// done in destructor because threads must be terminated before deleting any
+/// static objects while still in main().
-ThreadPool::~ThreadPool() {
+void ThreadPool::exit() {
- for (size_t i = 0; i < size(); i++)
- delete threads[i];
-
- delete timer;
- lock_destroy(splitLock);
- cond_destroy(sleepCond);
+ while (size())
+ delete back(), pop_back();
}
-// 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.
+/// ThreadPool::read_uci_options() updates internal threads parameters from the
+/// corresponding UCI options and creates/destroys threads to match requested
+/// number. Thread objects are dynamically allocated.
void ThreadPool::read_uci_options() {
- maxThreadsPerSplitPoint = Options["Max Threads per Split Point"];
- minimumSplitDepth = Options["Min Split Depth"] * ONE_PLY;
- useSleepingThreads = Options["Use Sleeping Threads"];
- size_t requested = Options["Threads"];
+ size_t requested = Options["Threads"];
assert(requested > 0);
while (size() < requested)
- threads.push_back(new Thread(&Thread::idle_loop));
+ push_back(new Thread);
while (size() > requested)
- {
- delete threads.back();
- threads.pop_back();
- }
+ delete back(), pop_back();
}
-// wake_up() is called before a new search to start the threads that are waiting
-// on the sleep condition and to reset maxPly. When useSleepingThreads is set
-// threads will be woken up at split time.
+/// ThreadPool::nodes_searched() returns the number of nodes searched
-void ThreadPool::wake_up() const {
-
- for (size_t i = 0; i < size(); i++)
- {
- threads[i]->maxPly = 0;
- threads[i]->do_sleep = false;
+int64_t ThreadPool::nodes_searched() {
- if (!useSleepingThreads)
- threads[i]->wake_up();
- }
+ int64_t nodes = 0;
+ for (Thread* th : *this)
+ nodes += th->rootPos.nodes_searched();
+ return nodes;
}
-// sleep() is called after the search finishes to ask all the threads but the
-// main one to go waiting on a sleep condition.
+/// ThreadPool::start_thinking() wakes up the main thread sleeping in idle_loop()
+/// and starts a new search, then returns immediately.
-void ThreadPool::sleep() const {
+void ThreadPool::start_thinking(Position& pos, StateListPtr& states,
+ const Search::LimitsType& limits) {
- for (size_t i = 1; i < size(); i++) // Main thread will go to sleep by itself
- threads[i]->do_sleep = true; // to avoid a race with start_searching()
-}
+ main()->wait_for_search_finished();
+ Search::Signals.stopOnPonderhit = Search::Signals.stop = false;
+ Search::Limits = limits;
+ Search::RootMoves rootMoves;
-// available_slave_exists() tries to find an idle thread which is available as
-// a slave for the thread 'master'.
+ for (const auto& m : MoveList<LEGAL>(pos))
+ if ( limits.searchmoves.empty()
+ || std::count(limits.searchmoves.begin(), limits.searchmoves.end(), m))
+ rootMoves.push_back(Search::RootMove(m));
-bool ThreadPool::available_slave_exists(Thread* master) const {
+ Tablebases::filter_root_moves(pos, rootMoves);
- for (size_t i = 0; i < size(); i++)
- if (threads[i]->is_available_to(master))
- return true;
+ // After ownership transfer 'states' becomes empty, so if we stop the search
+ // and call 'go' again without setting a new position states.get() == NULL.
+ assert(states.get() || setupStates.get());
- return false;
-}
+ if (states.get())
+ setupStates = std::move(states); // Ownership transfer, states is now empty
+ StateInfo tmp = setupStates->back();
-// 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.
-
-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) {
-
- 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;
-
- // Pick the next available split point from the split point stack
- SplitPoint* sp = &master->splitPoints[master->splitPointsCnt];
-
- sp->parent = master->curSplitPoint;
- sp->master = master;
- sp->cutoff = false;
- sp->slavesMask = 1ULL << master->idx;
- 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(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
- // allocation of the same slave by another master.
- lock_grab(sp->lock);
- lock_grab(splitLock);
-
- for (size_t i = 0; i < 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]->wake_up();
-
- if (++slavesCnt + 1 >= maxThreadsPerSplitPoint) // Master is always included
- break;
- }
-
- master->splitPointsCnt++;
-
- 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.
- if (slavesCnt || Fake)
+ for (Thread* th : Threads)
{
- master->idle_loop(sp);
-
- // 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);
+ th->maxPly = 0;
+ th->rootDepth = DEPTH_ZERO;
+ th->rootMoves = rootMoves;
+ th->rootPos.set(pos.fen(), pos.is_chess960(), &setupStates->back(), th);
}
- // 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);
-
- master->is_searching = true;
- master->splitPointsCnt--;
- master->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;
-}
-
-// 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);
-
-
-// set_timer() is used to set the timer to trigger after msec milliseconds.
-// If msec is 0 then timer is stopped.
-
-void ThreadPool::set_timer(int msec) {
-
- lock_grab(timer->sleepLock);
- timer->maxPly = msec;
- cond_signal(timer->sleepCond); // Wake up and restart the timer
- lock_release(timer->sleepLock);
-}
-
-
-// wait_for_search_finished() waits for main thread to go to sleep, this means
-// search is finished. Then returns.
-
-void ThreadPool::wait_for_search_finished() {
-
- Thread* t = main_thread();
- lock_grab(t->sleepLock);
- cond_signal(t->sleepCond); // In case is waiting for stop or ponderhit
- while (!t->do_sleep) cond_wait(sleepCond, t->sleepLock);
- lock_release(t->sleepLock);
-}
-
-
-// start_searching() wakes up the main thread sleeping in main_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) {
- wait_for_search_finished();
-
- SearchTime.restart(); // As early as possible
-
- Signals.stopOnPonderhit = Signals.firstRootMove = false;
- Signals.stop = Signals.failedLowAtRoot = false;
-
- RootPosition = pos;
- Limits = limits;
- RootMoves.clear();
-
- for (MoveList<LEGAL> ml(pos); !ml.end(); ++ml)
- if (searchMoves.empty() || count(searchMoves.begin(), searchMoves.end(), ml.move()))
- RootMoves.push_back(RootMove(ml.move()));
+ setupStates->back() = tmp; // Restore st->previous, cleared by Position::set()
- main_thread()->do_sleep = false;
- main_thread()->wake_up();
+ main()->start_searching();
}
projects / stockfish / blobdiff