/*
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
#include <iostream>
+#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)
+ 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
-
} }
}
-// 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
}
-// 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;
+}
- // Allocate pawn and material hash tables for main thread
- init_hash_tables();
- // Initialize threads lock, used when allocating slaves during splitting
+// init() is called during startup. Initializes locks and condition variables
+// and launches all threads sending them immediately to sleep.
+
+void ThreadsManager::init() {
+
+ // Initialize sleep condition and lock used by thread manager
+ cond_init(&sleepCond);
lock_init(&threadsLock);
- // Initialize sleep 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].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 = true;
+ threads[i].threadID = i;
#if defined(_MSC_VER)
- bool ok = (CreateThread(NULL, 0, start_routine, (LPVOID)&threadID[i], 0, NULL) != NULL);
+ threads[i].handle = CreateThread(NULL, 0, start_routine, &threads[i], 0, NULL);
+ bool ok = (threads[i].handle != NULL);
#else
- pthread_t pthreadID;
- bool ok = (pthread_create(&pthreadID, NULL, start_routine, (void*)&threadID[i]) == 0);
- pthread_detach(pthreadID);
+ bool ok = !pthread_create(&threads[i].handle, NULL, start_routine, &threads[i]);
#endif
+
if (!ok)
{
- 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) {}
}
}
void ThreadsManager::exit() {
- // Force the woken up threads to exit idle_loop() and hence terminate
- allThreadsShouldExit = true;
-
- for (int i = 0; i < MAX_THREADS; i++)
+ for (int i = 0; i <= MAX_THREADS; i++)
{
- // Wake up all the threads and wait for termination
- if (i != 0)
- {
- threads[i].wake_up();
- while (threads[i].state != Thread::TERMINATED) {}
- }
+ threads[i].do_terminate = true; // Search must be already finished
+ threads[i].wake_up();
- // Now we can safely destroy locks and wait conditions
+ // Wait for thread termination
+#if defined(_MSC_VER)
+ WaitForSingleObject(threads[i].handle, INFINITE);
+ CloseHandle(threads[i].handle);
+#else
+ pthread_join(threads[i].handle, NULL);
+#endif
+
+ // Now we can safely destroy associated locks and wait conditions
lock_destroy(&threads[i].sleepLock);
cond_destroy(&threads[i].sleepCond);
}
lock_destroy(&threadsLock);
-}
-
-
-// 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();
- }
+ 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_point_finished() checks if all the slave threads of a given split
+// point have finished searching.
+
+bool ThreadsManager::split_point_finished(SplitPoint* sp) const {
+
+ for (int i = 0; i < activeThreads; i++)
+ if (sp->is_slave[i])
+ return false;
+
+ return true;
+}
+
+
// 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>
-Value ThreadsManager::split(Position& pos, SearchStack* ss, Value alpha, Value 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.is_ok());
- assert(bestValue >= -VALUE_INFINITE);
+ assert(pos.pos_is_ok());
+ assert(bestValue > -VALUE_INFINITE);
assert(bestValue <= alpha);
assert(alpha < beta);
assert(beta <= VALUE_INFINITE);
if (masterThread.activeSplitPoints >= MAX_ACTIVE_SPLIT_POINTS)
return bestValue;
- // Pick the next available split point object from the split point stack
- SplitPoint* sp = masterThread.splitPoints + masterThread.activeSplitPoints;
+ // Pick the next available split point from the split point stack
+ SplitPoint* sp = &masterThread.splitPoints[masterThread.activeSplitPoints];
- // Initialize the split point object
+ // Initialize the split point
sp->parent = masterThread.splitPoint;
sp->master = master;
sp->is_betaCutoff = false;
sp->pos = &pos;
sp->nodes = 0;
sp->ss = ss;
+
for (i = 0; i < activeThreads; i++)
sp->is_slave[i] = false;
// If we are here it means we are not available
- assert(masterThread.state == Thread::SEARCHING);
+ assert(masterThread.is_searching);
int workersCnt = 1; // At least the master is included
// Try to allocate available threads and ask them to start searching setting
- // the state to Thread::WORKISWAITING, this must be done under lock protection
- // to avoid concurrent allocation of the same slave by another master.
+ // is_searching flag. This must be done under lock protection to avoid concurrent
+ // allocation of the same slave by another master.
lock_grab(&threadsLock);
for (i = 0; !Fake && i < activeThreads && workersCnt < maxThreadsPerSplitPoint; i++)
- if (i != master && threads[i].is_available_to(master))
+ if (threads[i].is_available_to(master))
{
workersCnt++;
sp->is_slave[i] = true;
threads[i].splitPoint = sp;
// This makes the slave to exit from idle_loop()
- threads[i].state = Thread::WORKISWAITING;
+ threads[i].is_searching = true;
if (useSleepingThreads)
threads[i].wake_up();
masterThread.splitPoint = sp;
masterThread.activeSplitPoints++;
- masterThread.state = Thread::WORKISWAITING;
- // 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, sp);
+ // 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, and
- // because here is all finished is not possible master is booked.
- assert(masterThread.state == Thread::AVAILABLE);
+ // 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. Note that changing state and decreasing activeSplitPoints is done
// under lock protection to avoid a race with Thread::is_available_to().
lock_grab(&threadsLock);
- masterThread.state = Thread::SEARCHING;
+ masterThread.is_searching = true;
masterThread.activeSplitPoints--;
lock_release(&threadsLock);
}
// Explicit template instantiations
-template Value ThreadsManager::split<false>(Position&, SearchStack*, Value, Value, Value, Depth, Move, int, MovePicker*, int);
-template Value ThreadsManager::split<true>(Position&, SearchStack*, Value, Value, Value, Depth, Move, int, MovePicker*, int);
+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 do_timer_event();
+
+void Thread::timer_loop() {
+
+ while (!do_terminate)
+ {
+ lock_grab(&sleepLock);
+ timed_wait(&sleepCond, &sleepLock, maxPly ? maxPly : INT_MAX);
+ lock_release(&sleepLock);
+ do_timer_event();
+ }
+}
+
+
+// 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_terminate)
+ {
+ cond_signal(&Threads.sleepCond); // Wake up UI thread if needed
+ cond_wait(&sleepCond, &sleepLock);
+ }
+
+ is_searching = true;
+
+ lock_release(&sleepLock);
+
+ if (do_terminate)
+ return;
+
+ think(); // This is the search entry point
+ }
+}
+
+
+// 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::vector<Move>& searchMoves, bool asyncMode) {
+ 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;
+ SearchMoves = searchMoves;
+
+ // Reset signals before to start the new search
+ memset((void*)&Signals, 0, sizeof(Signals));
+
+ main.do_sleep = false;
+ cond_signal(&main.sleepCond); // Wake up main thread and start searching
+
+ if (!asyncMode)
+ 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