#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() of the supplied thread. The
- // last two threads are dedicated to read input from GUI and to mimic a
- // timer, so they run in listener_loop() and timer_loop() respectively.
+ // 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) {
void* start_routine(void* thread) {
#endif
- if (((Thread*)thread)->threadID == MAX_THREADS)
- ((Thread*)thread)->listener_loop();
+ Thread* th = (Thread*)thread;
+
+ if (th->threadID == 0)
+ th->main_loop();
+
+ else if (th->threadID == MAX_THREADS)
+ th->timer_loop();
- else if (((Thread*)thread)->threadID == MAX_THREADS + 1)
- ((Thread*)thread)->timer_loop();
else
- ((Thread*)thread)->idle_loop(NULL);
+ th->idle_loop(NULL);
return 0;
}
for (SplitPoint* sp = splitPoint; sp; sp = sp->parent)
if (sp->is_betaCutoff)
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() {
activeThreads = cnt;
- for (int i = 0; i < MAX_THREADS; i++)
+ 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 as, for instance, on mobile
- // devices where memory is scarce and allocating for MAX_THREADS could
- // even result in a crash.
+ // possible threads if only few are used.
threads[i].pawnTable.init();
threads[i].materialTable.init();
void ThreadsManager::init() {
- // Initialize sleep condition used to block waiting for GUI input
+ // Initialize sleep condition and lock used by thread manager
cond_init(&sleepCond);
-
- // Initialize threads lock, used when allocating slaves during splitting
lock_init(&threadsLock);
- // Initialize sleep and split point locks
- for (int i = 0; i < MAX_THREADS + 2; 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));
}
- // Initialize main thread's associated data
- threads[0].is_searching = true;
- threads[0].threadID = 0;
- set_size(1); // This makes all the threads but the main to go to sleep
+ // 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 but the main that is already running,
- // threads will go immediately to sleep.
- for (int i = 1; i < MAX_THREADS + 2; i++)
+ // Create and launch all the threads, threads will go immediately to sleep
+ for (int i = 0; i <= MAX_THREADS; i++)
{
threads[i].is_searching = false;
+ threads[i].do_sleep = true;
threads[i].threadID = i;
#if defined(_MSC_VER)
threads[i].handle = CreateThread(NULL, 0, start_routine, (LPVOID)&threads[i], 0, NULL);
bool ok = (threads[i].handle != NULL);
#else
- bool ok = (pthread_create(&threads[i].handle, NULL, start_routine, (void*)&threads[i]) == 0);
+ bool ok = !pthread_create(&threads[i].handle, NULL, start_routine, (void*)&threads[i]);
#endif
if (!ok)
void ThreadsManager::exit() {
- for (int i = 0; i < MAX_THREADS + 2; i++)
+ for (int i = 0; i <= MAX_THREADS; i++)
{
- if (i != 0)
- {
- threads[i].do_terminate = true;
- threads[i].wake_up();
+ threads[i].do_terminate = true;
+ threads[i].wake_up();
- // Wait for slave termination
+ // Wait for thread termination
#if defined(_MSC_VER)
- WaitForSingleObject(threads[i].handle, 0);
- CloseHandle(threads[i].handle);
+ WaitForSingleObject(threads[i].handle, 0);
+ CloseHandle(threads[i].handle);
#else
- pthread_join(threads[i].handle, NULL);
+ pthread_join(threads[i].handle, NULL);
#endif
- }
- // Now we can safely destroy locks and wait conditions
+ // Now we can safely destroy associated locks and wait conditions
lock_destroy(&threads[i].sleepLock);
cond_destroy(&threads[i].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>
-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.pos_is_ok());
- assert(bestValue >= -VALUE_INFINITE);
+ 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;
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;
// 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.
+ // 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
}
// 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().
+// 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() {
void ThreadsManager::set_timer(int msec) {
- Thread& timer = threads[MAX_THREADS + 1];
+ Thread& timer = threads[MAX_THREADS];
lock_grab(&timer.sleepLock);
timer.maxPly = msec;
}
-// Thread::listener_loop() is where the listener thread, used for I/O, waits for
-// input. When is_searching is false then input is read in sync with main thread
-// (that blocks), otherwise the listener thread reads any input asynchronously
-// and processes the input line calling do_uci_async_cmd().
-
-void Thread::listener_loop() {
+// 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.
- std::string cmd;
+void Thread::main_loop() {
while (true)
{
lock_grab(&sleepLock);
- Threads.inputLine = cmd;
- do_sleep = !is_searching;
+ do_sleep = true; // Always return to sleep after a search
+ is_searching = false;
- // Here the thread is parked in sync mode after a line has been read
- while (do_sleep && !do_terminate) // Catches spurious wake ups
+ while (do_sleep && !do_terminate)
{
- cond_signal(&Threads.sleepCond); // Wake up main thread
- cond_wait(&sleepCond, &sleepLock); // Sleep here
+ cond_signal(&Threads.sleepCond); // Wake up UI thread if needed
+ cond_wait(&sleepCond, &sleepLock);
}
+ is_searching = true;
+
lock_release(&sleepLock);
if (do_terminate)
return;
- if (!std::getline(std::cin, cmd)) // Block waiting for input
- cmd = "quit";
-
- lock_grab(&sleepLock);
-
- // If we are in async mode then process the command now
- if (is_searching)
- {
- // Command "quit" is the last one received by the GUI, so park the
- // thread waiting for exiting. Also, after a "stop", for instance on a
- // ponder miss, GUI can immediately send the new position to search,
- // so return to in-sync mode to avoid discarding good data.
- if (cmd == "quit" || cmd == "stop")
- is_searching = false;
-
- do_uci_async_cmd(cmd);
- cmd = ""; // Input has been consumed
- }
-
- lock_release(&sleepLock);
+ think(); // This is the search entry point
}
}
-// ThreadsManager::getline() is used by main thread to block and wait for input,
-// the behaviour mimics std::getline().
+// 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::getline(std::string& cmd) {
+void ThreadsManager::start_thinking(const Position& pos, const LimitsType& limits,
+ const std::vector<Move>& searchMoves, bool asyncMode) {
+ Thread& main = threads[0];
- Thread& listener = threads[MAX_THREADS];
+ lock_grab(&main.sleepLock);
- lock_grab(&listener.sleepLock);
+ // Wait main thread has finished before to launch a new search
+ while (!main.do_sleep)
+ cond_wait(&sleepCond, &main.sleepLock);
- listener.is_searching = false; // Set sync mode
+ // Copy input arguments to initialize the search
+ RootPosition.copy(pos, 0);
+ Limits = limits;
+ SearchMoves = searchMoves;
- // If there is already some input to grab then skip without to wake up the
- // listener. This can happen if after we send the "bestmove", the GUI sends
- // a command that the listener buffers in inputLine before going to sleep.
- if (inputLine.empty())
- {
- listener.do_sleep = false;
- cond_signal(&listener.sleepCond); // Wake up listener thread
+ // Reset signals before to start the new search
+ memset((void*)&Signals, 0, sizeof(Signals));
- while (!listener.do_sleep)
- cond_wait(&sleepCond, &listener.sleepLock); // Wait for input
- }
+ main.do_sleep = false;
+ cond_signal(&main.sleepCond); // Wake up main thread and start searching
- cmd = inputLine;
- inputLine = ""; // Input has been consumed
+ if (!asyncMode)
+ cond_wait(&sleepCond, &main.sleepLock);
- lock_release(&listener.sleepLock);
+ lock_release(&main.sleepLock);
}
-// ThreadsManager::start_listener() is called at the beginning of the search to
-// swith from sync behaviour (default) to async and so be able to read from UCI
-// while other threads are searching. This avoids main thread polling for input.
-
-void ThreadsManager::start_listener() {
+// 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.
- Thread& listener = threads[MAX_THREADS];
-
- lock_grab(&listener.sleepLock);
- listener.is_searching = true;
- listener.do_sleep = false;
- cond_signal(&listener.sleepCond); // Wake up listener thread
- lock_release(&listener.sleepLock);
-}
+void ThreadsManager::wait_for_stop_or_ponderhit() {
+ Signals.stopOnPonderhit = true;
-// ThreadsManager::stop_listener() is called before to send "bestmove" to GUI to
-// return to in-sync behaviour. This is needed because while in async mode any
-// command is discarded without being processed (except for a very few ones).
+ Thread& main = threads[0];
-void ThreadsManager::stop_listener() {
+ lock_grab(&main.sleepLock);
- Thread& listener = threads[MAX_THREADS];
+ while (!Signals.stop)
+ cond_wait(&main.sleepCond, &main.sleepLock);
- lock_grab(&listener.sleepLock);
- listener.is_searching = false;
- lock_release(&listener.sleepLock);
+ lock_release(&main.sleepLock);
}