/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2008-2012 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 <cassert>
#include <iostream>
+#include "movegen.h"
+#include "search.h"
#include "thread.h"
#include "ucioption.h"
-ThreadsManager Threads; // Global object definition
+using namespace Search;
+
+ThreadsManager Threads; // Global object
namespace { extern "C" {
// start_routine() is the C function which is called when a new thread
- // is launched. It simply calls idle_loop() with the supplied threadID.
- // There are two versions of this function; one for POSIX threads and
- // one for Windows threads.
+ // is launched. It simply calls idle_loop() of the supplied thread. The first
+ // and last thread are special. First one is the main search thread while the
+ // last one mimics a timer, they run in main_loop() and timer_loop().
-#if defined(_MSC_VER)
+#if defined(_WIN32) || defined(_WIN64)
+ DWORD WINAPI start_routine(LPVOID thread) {
+#else
+ void* start_routine(void* thread) {
+#endif
- DWORD WINAPI start_routine(LPVOID threadID) {
+ Thread* th = (Thread*)thread;
- Threads.idle_loop(*(int*)threadID, NULL);
- return 0;
- }
+ if (th->threadID == 0)
+ th->main_loop();
-#else
+ else if (th->threadID == MAX_THREADS)
+ th->timer_loop();
- void* start_routine(void* threadID) {
+ else
+ th->idle_loop(NULL);
- Threads.idle_loop(*(int*)threadID, NULL);
- return NULL;
+ return 0;
}
-#endif
-
} }
void Thread::wake_up() {
- lock_grab(&sleepLock);
- cond_signal(&sleepCond);
- lock_release(&sleepLock);
+ lock_grab(sleepLock);
+ cond_signal(sleepCond);
+ lock_release(sleepLock);
}
-// cutoff_occurred() checks whether a beta cutoff has occurred in
-// the thread's currently active split point, or in some ancestor of
-// the current split point.
+// 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 = splitPoint; sp; sp = sp->parent)
if (sp->is_betaCutoff)
return true;
+
return false;
}
bool Thread::is_available_to(int master) const {
- if (state != AVAILABLE)
+ if (is_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 localActiveSplitPoints = activeSplitPoints;
+ int sp_count = activeSplitPoints;
// 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.
- if ( !localActiveSplitPoints
- || splitPoints[localActiveSplitPoints - 1].is_slave[master])
+ if (!sp_count || (splitPoints[sp_count - 1].slavesMask & (1ULL << master)))
return true;
return false;
}
-// read_uci_options() updates number of active threads and other internal
-// parameters according to the UCI options values. It is called before
-// to start a new search.
+// read_uci_options() updates number of active threads and other parameters
+// according to the UCI options values. It is called before to start a new search.
void ThreadsManager::read_uci_options() {
- maxThreadsPerSplitPoint = Options["Maximum Number of Threads per Split Point"].value<int>();
- minimumSplitDepth = Options["Minimum Split Depth"].value<int>() * ONE_PLY;
- useSleepingThreads = Options["Use Sleeping Threads"].value<bool>();
- activeThreads = Options["Threads"].value<int>();
+ maxThreadsPerSplitPoint = Options["Max Threads per Split Point"];
+ minimumSplitDepth = Options["Min Split Depth"] * ONE_PLY;
+ useSleepingThreads = Options["Use Sleeping Threads"];
+
+ set_size(Options["Threads"]);
}
-// init() is called during startup. Initializes locks and condition variables
-// and launches all threads sending them immediately to sleep.
+// set_size() changes the number of active threads and raises do_sleep flag for
+// all the unused threads that will go immediately to sleep.
-void ThreadsManager::init() {
+void ThreadsManager::set_size(int cnt) {
- int threadID[MAX_THREADS];
+ assert(cnt > 0 && cnt <= MAX_THREADS);
- // This flag is needed to properly end the threads when program exits
- allThreadsShouldExit = false;
+ activeThreads = cnt;
- // Threads will sent to sleep as soon as created, only main thread is kept alive
- activeThreads = 1;
- threads[0].state = Thread::SEARCHING;
+ for (int i = 1; i < MAX_THREADS; i++) // Ignore main thread
+ if (i < activeThreads)
+ {
+ // Dynamically allocate pawn and material hash tables according to the
+ // number of active threads. This avoids preallocating memory for all
+ // possible threads if only few are used.
+ threads[i].pawnTable.init();
+ threads[i].materialTable.init();
+
+ threads[i].do_sleep = false;
+ }
+ else
+ threads[i].do_sleep = true;
+}
+
+
+// init() is called during startup. Initializes locks and condition variables
+// and launches all threads sending them immediately to sleep.
- // Allocate pawn and material hash tables for main thread
- init_hash_tables();
+void ThreadsManager::init() {
- lock_init(&mpLock);
+ // Initialize sleep condition and lock used by thread manager
+ cond_init(sleepCond);
+ lock_init(threadsLock);
- // Initialize thread and split point locks
- for (int i = 0; i < MAX_THREADS; i++)
+ // Initialize thread's sleep conditions and split point locks
+ for (int i = 0; i <= MAX_THREADS; i++)
{
- lock_init(&threads[i].sleepLock);
- cond_init(&threads[i].sleepCond);
+ lock_init(threads[i].sleepLock);
+ cond_init(threads[i].sleepCond);
for (int j = 0; j < MAX_ACTIVE_SPLIT_POINTS; j++)
- lock_init(&(threads[i].splitPoints[j].lock));
+ lock_init(threads[i].splitPoints[j].lock);
}
- // Create and startup all the threads but the main that is already running
- for (int i = 1; i < MAX_THREADS; i++)
+ // Allocate main thread tables to call evaluate() also when not searching
+ threads[0].pawnTable.init();
+ threads[0].materialTable.init();
+
+ // Create and launch all the threads, threads will go immediately to sleep
+ for (int i = 0; i <= MAX_THREADS; i++)
{
- threads[i].state = Thread::INITIALIZING;
- threadID[i] = i;
+ threads[i].is_searching = false;
+ threads[i].do_sleep = (i != 0); // Avoid a race with start_thinking()
+ threads[i].threadID = i;
-#if defined(_MSC_VER)
- bool ok = (CreateThread(NULL, 0, start_routine, (LPVOID)&threadID[i], 0, NULL) != NULL);
-#else
- pthread_t pthreadID;
- bool ok = (pthread_create(&pthreadID, NULL, start_routine, (void*)&threadID[i]) == 0);
- pthread_detach(pthreadID);
-#endif
- if (!ok)
+ if (!thread_create(threads[i].handle, start_routine, threads[i]))
{
- std::cout << "Failed to create thread number " << i << std::endl;
+ std::cerr << "Failed to create thread number " << i << std::endl;
::exit(EXIT_FAILURE);
}
-
- // Wait until the thread has finished launching and is gone to sleep
- while (threads[i].state == Thread::INITIALIZING) {}
}
}
-// exit() is called to cleanly exit the threads when the program finishes
+// exit() is called to cleanly terminate the threads when the program finishes
void ThreadsManager::exit() {
- // Force the woken up threads to exit idle_loop() and hence terminate
- allThreadsShouldExit = true;
+ assert(threads[0].is_searching == false);
- for (int i = 0; i < MAX_THREADS; i++)
+ for (int i = 0; i <= MAX_THREADS; i++)
{
- // Wake up all the threads and waits for termination
- if (i != 0)
- {
- threads[i].wake_up();
- while (threads[i].state != Thread::TERMINATED) {}
- }
+ threads[i].do_exit = true; // Search must be already finished
+ threads[i].wake_up();
+
+ thread_join(threads[i].handle); // Wait for thread termination
- // Now we can safely destroy the locks and wait conditions
- lock_destroy(&threads[i].sleepLock);
- cond_destroy(&threads[i].sleepCond);
+ // Now we can safely destroy associated locks and wait conditions
+ lock_destroy(threads[i].sleepLock);
+ cond_destroy(threads[i].sleepCond);
for (int j = 0; j < MAX_ACTIVE_SPLIT_POINTS; j++)
- lock_destroy(&(threads[i].splitPoints[j].lock));
+ lock_destroy(threads[i].splitPoints[j].lock);
}
- lock_destroy(&mpLock);
-}
-
-
-// init_hash_tables() dynamically allocates pawn and material hash tables
-// according to the number of active threads. This avoids preallocating
-// memory for all possible threads if only few are used as, for instance,
-// on mobile devices where memory is scarce and allocating for MAX_THREADS
-// threads could even result in a crash.
-
-void ThreadsManager::init_hash_tables() {
-
- for (int i = 0; i < activeThreads; i++)
- {
- threads[i].pawnTable.init();
- threads[i].materialTable.init();
- }
+ lock_destroy(threadsLock);
+ cond_destroy(sleepCond);
}
// available_slave_exists() tries to find an idle thread which is available as
-// a slave for the thread with threadID "master".
+// a slave for the thread with threadID 'master'.
bool ThreadsManager::available_slave_exists(int master) const {
assert(master >= 0 && master < activeThreads);
for (int i = 0; i < activeThreads; i++)
- if (i != master && threads[i].is_available_to(master))
+ if (threads[i].is_available_to(master))
return true;
return false;
// 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 we tell our helper threads 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.
+// 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>
-void ThreadsManager::split(Position& pos, SearchStack* ss, Value* alpha, const Value beta,
- Value* bestValue, Depth depth, Move threatMove,
- int moveCount, MovePicker* mp, bool pvNode) {
- assert(pos.is_ok());
- assert(*bestValue >= -VALUE_INFINITE);
- assert(*bestValue <= *alpha);
- assert(*alpha < beta);
+Value ThreadsManager::split(Position& pos, Stack* ss, Value alpha, Value beta,
+ Value bestValue, 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);
assert(pos.thread() >= 0 && pos.thread() < activeThreads);
int i, master = pos.thread();
Thread& masterThread = threads[master];
- lock_grab(&mpLock);
-
- // If no other thread is available to help us, or if we have too many
- // active split points, don't split.
- if ( !available_slave_exists(master)
- || masterThread.activeSplitPoints >= MAX_ACTIVE_SPLIT_POINTS)
- {
- lock_release(&mpLock);
- return;
- }
-
- // Pick the next available split point object from the split point stack
- SplitPoint& splitPoint = masterThread.splitPoints[masterThread.activeSplitPoints++];
-
- // Initialize the split point object
- splitPoint.parent = masterThread.splitPoint;
- splitPoint.master = master;
- splitPoint.is_betaCutoff = false;
- splitPoint.depth = depth;
- splitPoint.threatMove = threatMove;
- splitPoint.alpha = *alpha;
- splitPoint.beta = beta;
- splitPoint.pvNode = pvNode;
- splitPoint.bestValue = *bestValue;
- splitPoint.mp = mp;
- splitPoint.moveCount = moveCount;
- splitPoint.pos = &pos;
- splitPoint.nodes = 0;
- splitPoint.ss = ss;
- for (i = 0; i < activeThreads; i++)
- splitPoint.is_slave[i] = false;
-
- masterThread.splitPoint = &splitPoint;
+ // If we already have too many active split points, don't split
+ if (masterThread.activeSplitPoints >= MAX_ACTIVE_SPLIT_POINTS)
+ return bestValue;
+
+ // Pick the next available split point from the split point stack
+ SplitPoint* sp = &masterThread.splitPoints[masterThread.activeSplitPoints];
+
+ // Initialize the split point
+ sp->parent = masterThread.splitPoint;
+ sp->master = master;
+ sp->is_betaCutoff = false;
+ sp->slavesMask = (1ULL << master);
+ sp->depth = depth;
+ 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;
// If we are here it means we are not available
- assert(masterThread.state != Thread::AVAILABLE);
+ assert(masterThread.is_searching);
int workersCnt = 1; // At least the master is included
- // Allocate available threads setting state to THREAD_BOOKED
- for (i = 0; !Fake && i < activeThreads && workersCnt < maxThreadsPerSplitPoint; i++)
- if (i != master && threads[i].is_available_to(master))
- {
- threads[i].state = Thread::BOOKED;
- threads[i].splitPoint = &splitPoint;
- splitPoint.is_slave[i] = true;
- workersCnt++;
- }
-
- assert(Fake || workersCnt > 1);
-
- // We can release the lock because slave threads are already booked and master is not available
- lock_release(&mpLock);
+ // 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(threadsLock);
+ lock_grab(sp->lock); // To protect sp->slaves_mask
- // Tell the threads that they have work to do. This will make them leave
- // their idle loop.
- for (i = 0; i < activeThreads; i++)
- if (i == master || splitPoint.is_slave[i])
+ for (i = 0; !Fake && i < activeThreads; i++)
+ if (threads[i].is_available_to(master))
{
- assert(i == master || threads[i].state == Thread::BOOKED);
+ sp->slavesMask |= (1ULL << i);
+ threads[i].splitPoint = sp;
- threads[i].state = Thread::WORKISWAITING; // This makes the slave to exit from idle_loop()
+ // Allocate the slave and make it exit from idle_loop()
+ threads[i].is_searching = true;
- if (useSleepingThreads && i != master)
+ if (useSleepingThreads)
threads[i].wake_up();
+
+ if (++workersCnt >= maxThreadsPerSplitPoint)
+ break;
}
- // Everything is set up. The master thread enters the idle loop, from
- // which it will instantly launch a search, because its state is
- // THREAD_WORKISWAITING. We send the split point as a second parameter to the
- // idle loop, which means that the main thread will return from the idle
- // loop when all threads have finished their work at this split point.
- idle_loop(master, &splitPoint);
+ lock_release(sp->lock);
+ lock_release(threadsLock);
+
+ // We failed to allocate even one slave, return
+ if (!Fake && workersCnt == 1)
+ return bestValue;
+
+ masterThread.splitPoint = sp;
+ masterThread.activeSplitPoints++;
+
+ // 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.
+ masterThread.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(!masterThread.is_searching);
// We have returned from the idle loop, which means that all threads are
- // finished. Update alpha and bestValue, and return.
- lock_grab(&mpLock);
+ // finished. Note that changing state and decreasing activeSplitPoints is done
+ // under lock protection to avoid a race with Thread::is_available_to().
+ lock_grab(threadsLock);
+ lock_grab(sp->lock); // To protect sp->nodes
- *alpha = splitPoint.alpha;
- *bestValue = splitPoint.bestValue;
+
+ masterThread.is_searching = true;
masterThread.activeSplitPoints--;
- masterThread.splitPoint = splitPoint.parent;
- pos.set_nodes_searched(pos.nodes_searched() + splitPoint.nodes);
+ masterThread.splitPoint = sp->parent;
+ pos.set_nodes_searched(pos.nodes_searched() + sp->nodes);
+
+ lock_release(sp->lock);
+ lock_release(threadsLock);
- lock_release(&mpLock);
+ return sp->bestValue;
}
// Explicit template instantiations
-template void ThreadsManager::split<false>(Position&, SearchStack*, Value*, const Value, Value*, Depth, Move, int, MovePicker*, bool);
-template void ThreadsManager::split<true>(Position&, SearchStack*, Value*, const Value, Value*, Depth, Move, int, MovePicker*, bool);
+template Value ThreadsManager::split<false>(Position&, Stack*, Value, Value, Value, Depth, Move, int, MovePicker*, int);
+template Value ThreadsManager::split<true>(Position&, Stack*, Value, Value, Value, Depth, Move, int, MovePicker*, int);
+
+
+// Thread::timer_loop() is where the timer thread waits maxPly milliseconds and
+// then calls do_timer_event(). If maxPly is 0 thread sleeps until is woken up.
+extern void check_time();
+
+void Thread::timer_loop() {
+
+ while (!do_exit)
+ {
+ lock_grab(sleepLock);
+ timed_wait(sleepCond, sleepLock, maxPly ? maxPly : INT_MAX);
+ lock_release(sleepLock);
+ check_time();
+ }
+}
+
+
+// ThreadsManager::set_timer() is used to set the timer to trigger after msec
+// milliseconds. If msec is 0 then timer is stopped.
+
+void ThreadsManager::set_timer(int msec) {
+
+ Thread& timer = threads[MAX_THREADS];
+
+ lock_grab(timer.sleepLock);
+ timer.maxPly = msec;
+ cond_signal(timer.sleepCond); // Wake up and restart the timer
+ lock_release(timer.sleepLock);
+}
+
+
+// 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);
+
+ do_sleep = true; // Always return to sleep after a search
+ is_searching = false;
+
+ while (do_sleep && !do_exit)
+ {
+ cond_signal(Threads.sleepCond); // Wake up UI thread if needed
+ cond_wait(sleepCond, sleepLock);
+ }
+
+ is_searching = true;
+
+ lock_release(sleepLock);
+
+ if (do_exit)
+ return;
+
+ Search::think();
+ }
+}
+
+
+// ThreadsManager::start_thinking() is used by UI thread to wake up the main
+// thread parked in main_loop() and starting a new search. If asyncMode is true
+// then function returns immediately, otherwise caller is blocked waiting for
+// the search to finish.
+
+void ThreadsManager::start_thinking(const Position& pos, const LimitsType& limits,
+ const std::set<Move>& searchMoves, bool async) {
+ Thread& main = threads[0];
+
+ lock_grab(main.sleepLock);
+
+ // Wait main thread has finished before to launch a new search
+ while (!main.do_sleep)
+ cond_wait(sleepCond, main.sleepLock);
+
+ // Copy input arguments to initialize the search
+ RootPosition.copy(pos, 0);
+ Limits = limits;
+ RootMoves.clear();
+
+ // Populate RootMoves with all the legal moves (default) or, if a searchMoves
+ // set is given, with the subset of legal moves to search.
+ for (MoveList<MV_LEGAL> ml(pos); !ml.end(); ++ml)
+ if (searchMoves.empty() || searchMoves.count(ml.move()))
+ RootMoves.push_back(RootMove(ml.move()));
+
+ // Reset signals before to start the new search
+ Signals.stopOnPonderhit = Signals.firstRootMove = false;
+ Signals.stop = Signals.failedLowAtRoot = false;
+
+ main.do_sleep = false;
+ cond_signal(main.sleepCond); // Wake up main thread and start searching
+
+ if (!async)
+ while (!main.do_sleep)
+ cond_wait(sleepCond, main.sleepLock);
+
+ lock_release(main.sleepLock);
+}
+
+
+// ThreadsManager::stop_thinking() is used by UI thread to raise a stop request
+// and to wait for the main thread finishing the search. Needed to wait exiting
+// and terminate the threads after a 'quit' command.
+
+void ThreadsManager::stop_thinking() {
+
+ Thread& main = threads[0];
+
+ Search::Signals.stop = true;
+
+ lock_grab(main.sleepLock);
+
+ cond_signal(main.sleepCond); // In case is waiting for stop or ponderhit
+
+ while (!main.do_sleep)
+ cond_wait(sleepCond, main.sleepLock);
+
+ lock_release(main.sleepLock);
+}
+
+
+// ThreadsManager::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.
+
+void ThreadsManager::wait_for_stop_or_ponderhit() {
+
+ Signals.stopOnPonderhit = true;
+
+ Thread& main = threads[0];
+
+ lock_grab(main.sleepLock);
+
+ while (!Signals.stop)
+ cond_wait(main.sleepCond, main.sleepLock);
+
+ lock_release(main.sleepLock);
+}
projects / stockfish / blobdiff