X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fthread.cpp;h=4fc0953eac6ec7145ba8ade4e16b228db6d70e0f;hp=271890c6f008b85eedee8d2302f0ebe4f2353e57;hb=4739037f967ac3c818907e89cc88c7b97021d027;hpb=ed0fb0b05fa72ccc6333bf5331eb9abeb7c86457
diff --git a/src/thread.cpp b/src/thread.cpp
index 271890c6..4fc0953e 100644
--- a/src/thread.cpp
+++ b/src/thread.cpp
@@ -1,7 +1,7 @@
/*
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) 2008-2014 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
@@ -17,420 +17,363 @@
along with this program. If not, see .
*/
+#include // For std::count
#include
-#include
#include "movegen.h"
#include "search.h"
#include "thread.h"
-#include "ucioption.h"
+#include "uci.h"
using namespace Search;
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.
+extern void check_time();
- long start_routine(Thread* th) { (th->*(th->start_fn))(); return 0; }
+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; } }
-// 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(Fn fn) : splitPoints() {
+ // 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
+ // when start_routine (and hence virtual idle_loop) is called and when joining.
- is_searching = do_exit = false;
- maxPly = splitPointsCnt = 0;
- curSplitPoint = NULL;
- start_fn = fn;
- idx = Threads.size();
+ template T* new_thread() {
+ T* th = new T();
+ thread_create(th->handle, start_routine, th); // Will go to sleep
+ return th;
+ }
- do_sleep = (fn != &Thread::main_loop); // Avoid a race with start_searching()
+ 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;
+ }
- 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.
+// notify_one() wakes up the thread when there is some work to do
-Thread::~Thread() {
+void ThreadBase::notify_one() {
- assert(do_sleep);
-
- do_exit = true; // Search must be already finished
- wake_up();
- thread_join(handle); // Wait for thread termination
+ mutex.lock();
+ sleepCondition.notify_one();
+ mutex.unlock();
}
-// 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();
+// wait_for() set the thread to sleep until condition 'b' turns true
-void Thread::timer_loop() {
+void ThreadBase::wait_for(volatile const bool& b) {
- while (!do_exit)
- {
- mutex.lock();
- sleepCondition.wait_for(mutex, maxPly ? maxPly : INT_MAX);
- mutex.unlock();
- check_time();
- }
+ mutex.lock();
+ while (!b) sleepCondition.wait(mutex);
+ mutex.unlock();
}
-// 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.
+// Thread c'tor just inits data and does not launch any execution thread.
+// Such a thread will only be started when c'tor returns.
-void Thread::main_loop() {
+Thread::Thread() /* : splitPoints() */ { // Value-initialization bug in MSVC
- while (true)
- {
- mutex.lock();
+ searching = false;
+ maxPly = splitPointsSize = 0;
+ activeSplitPoint = NULL;
+ activePosition = NULL;
+ idx = Threads.size(); // Starts from 0
+}
- do_sleep = true; // Always return to sleep after a search
- is_searching = false;
- while (do_sleep && !do_exit)
- {
- Threads.sleepCondition.notify_one(); // Wake up UI thread if needed
- sleepCondition.wait(mutex);
- }
+// cutoff_occurred() checks whether a beta cutoff has occurred in the
+// current active split point, or in some ancestor of the split point.
- mutex.unlock();
+bool Thread::cutoff_occurred() const {
- if (do_exit)
- return;
+ for (SplitPoint* sp = activeSplitPoint; sp; sp = sp->parentSplitPoint)
+ if (sp->cutoff)
+ return true;
- is_searching = true;
+ return false;
+}
- Search::think();
- assert(is_searching);
- }
-}
+// 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).
+bool Thread::available_to(const Thread* master) const {
-// Thread::wake_up() wakes up the thread, normally at the beginning of the search
-// or, if "sleeping threads" is used at split time.
+ if (searching)
+ return false;
-void Thread::wake_up() {
+ // 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.
+ const int size = splitPointsSize;
- mutex.lock();
- sleepCondition.notify_one();
- mutex.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.test(master->idx);
}
-// 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.
+// TimerThread::idle_loop() is where the timer thread waits msec milliseconds
+// and then calls check_time(). If msec is 0 thread sleeps until it's woken up.
-void Thread::wait_for_stop_or_ponderhit() {
+void TimerThread::idle_loop() {
- Signals.stopOnPonderhit = true;
+ while (!exit)
+ {
+ mutex.lock();
- mutex.lock();
- while (!Signals.stop) sleepCondition.wait(mutex);;
- mutex.unlock();
+ if (!exit)
+ sleepCondition.wait_for(mutex, run ? Resolution : INT_MAX);
+
+ mutex.unlock();
+
+ if (run)
+ check_time();
+ }
}
-// Thread::cutoff_occurred() checks whether a beta cutoff has occurred in the
-// current active split point, or in some ancestor of the split point.
+// 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.
-bool Thread::cutoff_occurred() const {
+void MainThread::idle_loop() {
- for (SplitPoint* sp = curSplitPoint; sp; sp = sp->parent)
- if (sp->cutoff)
- return true;
+ while (true)
+ {
+ mutex.lock();
- return false;
-}
+ thinking = false;
+ while (!thinking && !exit)
+ {
+ Threads.sleepCondition.notify_one(); // Wake up the UI thread if needed
+ sleepCondition.wait(mutex);
+ }
-// 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).
+ mutex.unlock();
-bool Thread::is_available_to(Thread* master) const {
+ if (exit)
+ return;
- if (is_searching)
- return false;
+ searching = true;
- // 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;
+ Search::think();
- // 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));
+ assert(searching);
+
+ searching = false;
+ }
}
-// 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.
+// 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(&Thread::timer_loop);
- threads.push_back(new Thread(&Thread::main_loop));
+ timer = new_thread();
+ push_back(new_thread());
read_uci_options();
}
-// exit() cleanly terminates the threads before the program exits.
+// exit() cleanly terminates the threads before the program exits. Cannot be done in
+// d'tor because we have to terminate the threads before to free ThreadPool object.
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);
}
// 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.
+// 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;
- useSleepingThreads = Options["Use Sleeping Threads"];
- size_t requested = Options["Threads"];
+ minimumSplitDepth = Options["Min Split Depth"] * ONE_PLY;
+ size_t requested = Options["Threads"];
assert(requested > 0);
- while (threads.size() < requested)
- threads.push_back(new Thread(&Thread::idle_loop));
-
- while (threads.size() > requested)
- {
- delete threads.back();
- threads.pop_back();
- }
-}
-
+ // If zero (default) then set best minimum split depth automatically
+ if (!minimumSplitDepth)
+ minimumSplitDepth = requested < 8 ? 4 * ONE_PLY : 7 * ONE_PLY;
-// 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.
+ while (size() < requested)
+ push_back(new_thread());
-void ThreadPool::wake_up() const {
-
- for (size_t i = 0; i < threads.size(); i++)
+ while (size() > requested)
{
- threads[i]->maxPly = 0;
- threads[i]->do_sleep = false;
-
- if (!useSleepingThreads)
- threads[i]->wake_up();
+ delete_thread(back());
+ pop_back();
}
}
-// sleep() is called after the search finishes to ask all the threads but the
-// main one to go waiting on a sleep condition.
-
-void ThreadPool::sleep() const {
-
- // Main thread will go to sleep by itself to avoid a race with start_searching()
- for (size_t i = 1; i < threads.size(); i++)
- threads[i]->do_sleep = true;
-}
-
-
-// available_slave_exists() tries to find an idle thread which is available as
-// a slave for the thread 'master'.
+// available_slave() 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)->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.
-
-template
-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);
+// (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.
- Thread* master = pos.this_thread();
+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) {
- if (master->splitPointsCnt >= MAX_SPLITPOINTS_PER_THREAD)
- return bestValue;
+ assert(pos.pos_is_ok());
+ assert(-VALUE_INFINITE < *bestValue && *bestValue <= alpha && alpha < beta && beta <= 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 = 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.bestValue = bestValue;
- sp.mp = 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]->wake_up();
+ sp.allSlavesSearching = true; // Must be set under lock protection
+ ++splitPointsSize;
+ activeSplitPoint = &sp;
+ activePosition = NULL;
- if (++slavesCnt + 1 >= maxThreadsPerSplitPoint) // Master is always included
- break;
- }
-
- master->splitPointsCnt++;
-
- sp.mutex.unlock();
- mutex.unlock();
+ for (Thread* slave; (slave = Threads.available_slave(this)) != NULL; )
+ {
+ sp.slavesMask.set(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)
- {
- master->idle_loop();
+ sp.mutex.unlock();
+ Threads.mutex.unlock();
- // 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);
- }
+ 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 is_searching and decreasing splitPointsCnt is
- // done under lock protection to avoid a race with Thread::is_available_to().
- mutex.lock();
+ // 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();
- 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(Position&, Stack*, Value, Value, Value, Move*, Depth, Move, int, MovePicker*, int);
-template Value ThreadPool::split(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) {
-
- timer->mutex.lock();
- timer->maxPly = msec;
- timer->sleepCondition.notify_one(); // Wake up and restart the timer
- timer->mutex.unlock();
-}
+// wait_for_think_finished() waits for main thread to go to sleep then returns
+void ThreadPool::wait_for_think_finished() {
-// 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();
+ MainThread* t = main();
t->mutex.lock();
- t->sleepCondition.notify_one(); // In case is waiting for stop or ponderhit
- 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& searchMoves, StateStackPtr& states) {
- wait_for_search_finished();
+void ThreadPool::start_thinking(const Position& pos, const LimitsType& limits, StateStackPtr& states) {
+
+ wait_for_think_finished();
SearchTime = Time::now(); // As early as possible
Signals.stopOnPonderhit = Signals.firstRootMove = false;
Signals.stop = Signals.failedLowAtRoot = false;
- RootPosition = pos;
- Limits = limits;
- SetupStates = states; // Ownership transfer here
RootMoves.clear();
+ RootPos = pos;
+ Limits = limits;
+ if (states.get()) // If we don't set a new position, preserve current state
+ {
+ SetupStates = states; // Ownership transfer here
+ assert(!states.get());
+ }
- for (MoveList ml(pos); !ml.end(); ++ml)
- if (searchMoves.empty() || count(searchMoves.begin(), searchMoves.end(), ml.move()))
- RootMoves.push_back(RootMove(ml.move()));
+ for (MoveList it(pos); *it; ++it)
+ if ( limits.searchmoves.empty()
+ || std::count(limits.searchmoves.begin(), limits.searchmoves.end(), *it))
+ RootMoves.push_back(RootMove(*it));
- main_thread()->do_sleep = false;
- main_thread()->wake_up();
+ main()->thinking = true;
+ main()->notify_one(); // Starts main thread
}