/*
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
+ 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
#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"
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 the virtual function idle_loop().
-
- long start_routine(Thread* th) { th->idle_loop(); 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 the virtual function idle_loop(), going immediately to sleep.
+Thread::Thread() {
-Thread::Thread() /* : splitPoints() */ { // Value-initialization bug in MSVC
+ resetCalls = exit = false;
+ maxPly = callsCnt = 0;
+ history.clear();
+ counterMoves.clear();
+ idx = Threads.size(); // Start from 0
- searching = exit = false;
- maxPly = splitPointsSize = 0;
- activeSplitPoint = NULL;
- activePosition = NULL;
- idx = Threads.size();
-
- 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() {
- exit = true; // Search must be already finished
- notify_one();
- thread_join(handle); // Wait for thread termination
+ mutex.lock();
+ exit = true;
+ sleepCondition.notify_one();
+ mutex.unlock();
+ nativeThread.join();
}
-// 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() {
+/// Thread::wait_for_search_finished() waits on sleep condition
+/// until not searching
- while (!exit)
- {
- mutex.lock();
+void Thread::wait_for_search_finished() {
- if (!exit)
- sleepCondition.wait_for(mutex, msec ? msec : INT_MAX);
-
- mutex.unlock();
-
- if (msec)
- check_time();
- }
+ std::unique_lock<Mutex> lk(mutex);
+ sleepCondition.wait(lk, [&]{ return !searching; });
}
-// 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.
+/// Thread::wait() waits on sleep condition until condition is true
-void MainThread::idle_loop() {
+void Thread::wait(std::atomic_bool& condition) {
- while (true)
- {
- mutex.lock();
+ std::unique_lock<Mutex> lk(mutex);
+ sleepCondition.wait(lk, [&]{ return bool(condition); });
+}
- thinking = false;
- while (!thinking && !exit)
- {
- Threads.sleepCondition.notify_one(); // Wake up UI thread if needed
- sleepCondition.wait(mutex);
- }
+/// Thread::start_searching() wakes up the thread that will start the search
- mutex.unlock();
+void Thread::start_searching(bool resume) {
- if (exit)
- return;
+ std::unique_lock<Mutex> lk(mutex);
+ if (!resume)
searching = true;
- Search::think();
-
- assert(searching);
-
- searching = false;
- }
-}
-
-
-// Thread::notify_one() wakes up the thread when there is some search to do
-
-void Thread::notify_one() {
-
- mutex.lock();
sleepCondition.notify_one();
- mutex.unlock();
}
-// Thread::wait_for() set the thread to sleep until condition 'b' turns true
+/// Thread::idle_loop() is where the thread is parked when it has no work to do
-void Thread::wait_for(volatile const bool& b) {
+void Thread::idle_loop() {
- mutex.lock();
- while (!b) sleepCondition.wait(mutex);
- mutex.unlock();
-}
-
-
-// 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 = activeSplitPoint; sp; sp = sp->parentSplitPoint)
- if (sp->cutoff)
- return true;
-
- return false;
-}
-
-
-// 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).
+ while (!exit)
+ {
+ std::unique_lock<Mutex> lk(mutex);
-bool Thread::is_available_to(Thread* master) const {
+ searching = false;
- if (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 size = splitPointsSize;
+ lk.unlock();
- // 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));
+ if (!exit)
+ 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.
+/// 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() {
- sleepWhileIdle = true;
- timer = new TimerThread();
- push_back(new MainThread());
+ push_back(new MainThread);
read_uci_options();
}
-// exit() cleanly terminates the threads before 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().
void ThreadPool::exit() {
- delete timer; // As first because check_time() accesses threads data
-
- for (iterator it = begin(); it != end(); ++it)
- delete *it;
+ 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;
- size_t requested = Options["Threads"];
+ size_t requested = Options["Threads"];
assert(requested > 0);
while (size() < requested)
- push_back(new Thread());
+ push_back(new Thread);
while (size() > requested)
- {
- delete back();
- pop_back();
- }
+ delete back(), pop_back();
}
-// slave_available() tries to find an idle thread which is available as a slave
-// for the thread 'master'.
+/// ThreadPool::nodes_searched() returns the number of nodes searched
-Thread* ThreadPool::available_slave(Thread* master) const {
+int64_t ThreadPool::nodes_searched() {
- for (const_iterator it = begin(); it != end(); ++it)
- if ((*it)->is_available_to(master))
- return *it;
-
- 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), 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>
-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) {
-
- 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 = 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
- // '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();
-
- splitPointsSize++;
- activeSplitPoint = &sp;
- activePosition = NULL;
-
- size_t slavesCnt = 1; // This thread is always included
- Thread* slave;
-
- 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
- }
-
- sp.mutex.unlock();
- Threads.mutex.unlock();
-
- // 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)
- {
- 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(!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();
-
- 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();
- Threads.mutex.unlock();
+ int64_t nodes = 0;
+ for (Thread* th : *this)
+ nodes += th->rootPos.nodes_searched();
+ return nodes;
}
-// Explicit template instantiations
-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);
+/// ThreadPool::start_thinking() wakes up the main thread sleeping in idle_loop()
+/// and starts a new search, then returns immediately.
-// wait_for_think_finished() waits for main thread to go to sleep then returns
+void ThreadPool::start_thinking(const Position& pos, StateListPtr& states,
+ const Search::LimitsType& limits) {
-void ThreadPool::wait_for_think_finished() {
-
- MainThread* t = main_thread();
- t->mutex.lock();
- while (t->thinking) sleepCondition.wait(t->mutex);
- t->mutex.unlock();
-}
+ main()->wait_for_search_finished();
+ Search::Signals.stopOnPonderhit = Search::Signals.stop = false;
+ Search::Limits = limits;
+ Search::RootMoves rootMoves;
-// start_thinking() wakes up the main thread sleeping in MainThread::idle_loop()
-// so to start a new search, then returns immediately.
+ 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));
-void ThreadPool::start_thinking(const Position& pos, const LimitsType& limits,
- const std::vector<Move>& searchMoves, StateStackPtr& states) {
- wait_for_think_finished();
+ // 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());
- SearchTime = Time::now(); // As early as possible
+ if (states.get())
+ setupStates = std::move(states); // Ownership transfer, states is now empty
- Signals.stopOnPonderhit = Signals.firstRootMove = false;
- Signals.stop = Signals.failedLowAtRoot = false;
+ StateInfo tmp = setupStates->back();
- RootPos = pos;
- Limits = limits;
- SetupStates = states; // Ownership transfer here
- RootMoves.clear();
+ for (Thread* th : Threads)
+ {
+ th->maxPly = 0;
+ th->rootDepth = DEPTH_ZERO;
+ th->rootMoves = rootMoves;
+ th->rootPos.set(pos.fen(), pos.is_chess960(), &setupStates->back(), th);
+ }
- for (MoveList<LEGAL> ml(pos); !ml.end(); ++ml)
- if ( searchMoves.empty()
- || std::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()->thinking = true;
- main_thread()->notify_one(); // Starts main thread
+ main()->start_searching();
}
projects / stockfish / blobdiff