#include "thread.h"
#include "ucioption.h"
-ThreadsManager Threads; // Global object definition
+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 == 0)
- ((Thread*)thread)->main_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)
- ((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() {
{
// 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 end of searching
+ // 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
+ // Initialize thread's sleep conditions and split point locks
for (int i = 0; i <= MAX_THREADS; i++)
{
lock_init(&threads[i].sleepLock);
lock_init(&(threads[i].splitPoints[j].lock));
}
- // Initialize main thread's associated data
+ // Allocate main thread tables to call evaluate() also when not searching
threads[0].pawnTable.init();
threads[0].materialTable.init();
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)
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);
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,
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
template Value ThreadsManager::split<true>(Position&, SearchStack*, 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.
void Thread::timer_loop() {
lock_grab(&sleepLock);
do_sleep = true; // Always return to sleep after a search
-
is_searching = false;
while (do_sleep && !do_terminate)
if (do_terminate)
return;
- Search::think();
+ Search::think(); // This is the search entry point
}
}
while (!main.do_sleep)
cond_wait(&sleepCond, &main.sleepLock);
- // Copy input arguments to Search global variables
+ // Copy input arguments to initialize the search
Search::RootPosition.copy(pos, 0);
Search::Limits = limits;
Search::RootMoves = searchMoves;
- // Reset signals before to start the search
+ // Reset signals before to start the new search
memset((void*)&Search::Signals, 0, sizeof(Search::Signals));
main.do_sleep = false;
- cond_signal(&main.sleepCond); // Wake up main thread
+ cond_signal(&main.sleepCond); // Wake up main thread and start searching
if (!asyncMode)
cond_wait(&sleepCond, &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 return, after which the bestmove and pondermove will be printed.
+// "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() {
projects / stockfish / blobdiff