diff --git a/src/thread.cpp b/src/thread.cpp index ca87e1dd..9400b38d 100644 --- a/src/thread.cpp +++ b/src/thread.cpp @@ -40,7 +40,7 @@ namespace { // 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 + // outside Thread c'tor and d'tor because the object must be fully initialized // when start_routine (and hence virtual idle_loop) is called and when joining. template T* new_thread() { @@ -50,7 +50,11 @@ namespace { } void delete_thread(ThreadBase* th) { + + th->mutex.lock(); th->exit = true; // Search must be already finished + th->mutex.unlock(); + th->notify_one(); thread_join(th->handle); // Wait for thread termination delete th; @@ -59,7 +63,7 @@ namespace { } -// notify_one() wakes up the thread when there is some work to do +// ThreadBase::notify_one() wakes up the thread when there is some work to do void ThreadBase::notify_one() { @@ -69,7 +73,7 @@ void ThreadBase::notify_one() { } -// wait_for() set the thread to sleep until 'condition' turns true +// ThreadBase::wait_for() set the thread to sleep until 'condition' turns true void ThreadBase::wait_for(volatile const bool& condition) { @@ -79,8 +83,8 @@ void ThreadBase::wait_for(volatile const bool& condition) { } -// Thread c'tor just inits data and does not launch any execution thread. -// Such a thread will only be started when c'tor returns. +// Thread c'tor makes some init but does not launch any execution thread that +// will be started only when c'tor returns. Thread::Thread() /* : splitPoints() */ { // Value-initialization bug in MSVC @@ -92,7 +96,7 @@ Thread::Thread() /* : splitPoints() */ { // Value-initialization bug in MSVC } -// cutoff_occurred() checks whether a beta cutoff has occurred in the +// Thread::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 { @@ -127,131 +131,12 @@ bool Thread::available_to(const Thread* master) const { } -// 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 TimerThread::idle_loop() { - - while (!exit) - { - mutex.lock(); - - if (!exit) - sleepCondition.wait_for(mutex, run ? Resolution : INT_MAX); - - mutex.unlock(); - - if (run) - check_time(); - } -} - - -// 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. - -void MainThread::idle_loop() { - - while (true) - { - mutex.lock(); - - thinking = false; - - while (!thinking && !exit) - { - Threads.sleepCondition.notify_one(); // Wake up the UI thread if needed - sleepCondition.wait(mutex); - } - - mutex.unlock(); - - if (exit) - return; - - searching = true; - - Search::think(); - - assert(searching); - - searching = false; - } -} - - -// 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(); - push_back(new_thread()); - read_uci_options(); -} - - -// 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_thread(timer); // As first because check_time() accesses threads data - - 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 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() { - - minimumSplitDepth = Options["Min Split Depth"] * ONE_PLY; - size_t requested = Options["Threads"]; - - assert(requested > 0); - - // If zero (default) then set best minimum split depth automatically - if (!minimumSplitDepth) - minimumSplitDepth = requested < 8 ? 4 * ONE_PLY : 7 * ONE_PLY; - - while (size() < requested) - push_back(new_thread()); - - while (size() > requested) - { - delete_thread(back()); - pop_back(); - } -} - - -// available_slave() tries to find an idle thread which is available as a slave -// for the thread 'master'. - -Thread* ThreadPool::available_slave(const Thread* master) const { - - for (const_iterator it = begin(); it != end(); ++it) - if ((*it)->available_to(master)) - return *it; - - return NULL; -} - - -// split() does the actual work of distributing the work at a node between +// Thread::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), 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 +// informed 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. @@ -259,13 +144,12 @@ void Thread::split(Position& pos, Stack* ss, Value alpha, Value beta, Value* bes Move* bestMove, Depth depth, int moveCount, MovePicker* movePicker, int nodeType, bool cutNode) { - assert(pos.pos_is_ok()); + assert(searching); 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 + // Pick and init the next available split point SplitPoint& sp = splitPoints[splitPointsSize]; sp.masterThread = this; @@ -296,7 +180,9 @@ void Thread::split(Position& pos, Stack* ss, Value alpha, Value beta, Value* bes activeSplitPoint = &sp; activePosition = NULL; - for (Thread* slave; (slave = Threads.available_slave(this)) != NULL; ) + Thread* slave; + + while ((slave = Threads.available_slave(this)) != NULL) { sp.slavesMask.set(slave->idx); slave->activeSplitPoint = &sp; @@ -320,8 +206,8 @@ void Thread::split(Position& pos, Stack* ss, Value alpha, Value beta, Value* bes assert(!activePosition); // We have returned from the idle loop, which means that all threads are - // finished. Note that setting 'searching' and decreasing splitPointsSize is - // done under lock protection to avoid a race with Thread::available_to(). + // finished. Note that setting 'searching' and decreasing splitPointsSize must + // be done under lock protection to avoid a race with Thread::available_to(). Threads.mutex.lock(); sp.mutex.lock(); @@ -337,7 +223,127 @@ void Thread::split(Position& pos, Stack* ss, Value alpha, Value beta, Value* bes Threads.mutex.unlock(); } -// wait_for_think_finished() waits for main thread to go to sleep then returns + +// TimerThread::idle_loop() is where the timer thread waits Resolution milliseconds +// and then calls check_time(). When not searching, thread sleeps until it's woken up. + +void TimerThread::idle_loop() { + + while (!exit) + { + mutex.lock(); + + if (!exit) + sleepCondition.wait_for(mutex, run ? Resolution : INT_MAX); + + mutex.unlock(); + + if (run) + check_time(); + } +} + + +// 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. + +void MainThread::idle_loop() { + + while (!exit) + { + mutex.lock(); + + thinking = false; + + while (!thinking && !exit) + { + Threads.sleepCondition.notify_one(); // Wake up the UI thread if needed + sleepCondition.wait(mutex); + } + + mutex.unlock(); + + if (!exit) + { + searching = true; + + Search::think(); + + assert(searching); + + searching = false; + } + } +} + + +// ThreadPool::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(); + push_back(new_thread()); + read_uci_options(); +} + + +// ThreadPool::exit() terminates the threads before the program exits. Cannot be +// done in d'tor because threads must be terminated before freeing us. + +void ThreadPool::exit() { + + delete_thread(timer); // As first because check_time() accesses threads data + + for (iterator it = begin(); it != end(); ++it) + delete_thread(*it); +} + + +// ThreadPool::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 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() { + + minimumSplitDepth = Options["Min Split Depth"] * ONE_PLY; + size_t requested = Options["Threads"]; + + assert(requested > 0); + + // If zero (default) then set best minimum split depth automatically + if (!minimumSplitDepth) + minimumSplitDepth = requested < 8 ? 4 * ONE_PLY : 7 * ONE_PLY; + + while (size() < requested) + push_back(new_thread()); + + while (size() > requested) + { + delete_thread(back()); + pop_back(); + } +} + + +// ThreadPool::available_slave() tries to find an idle thread which is available +// as a slave for the thread 'master'. + +Thread* ThreadPool::available_slave(const Thread* master) const { + + for (const_iterator it = begin(); it != end(); ++it) + if ((*it)->available_to(master)) + return *it; + + return NULL; +} + + +// ThreadPool::wait_for_think_finished() waits for main thread to finish the search void ThreadPool::wait_for_think_finished() { @@ -348,11 +354,11 @@ void ThreadPool::wait_for_think_finished() { } -// start_thinking() wakes up the main thread sleeping in MainThread::idle_loop() -// so to start a new search, then returns immediately. - -void ThreadPool::start_thinking(const Position& pos, const LimitsType& limits, StateStackPtr& states) { +// ThreadPool::start_thinking() wakes up the main thread sleeping in +// MainThread::idle_loop() and starts a new search, then returns immediately. +void ThreadPool::start_thinking(const Position& pos, const LimitsType& limits, + StateStackPtr& states) { wait_for_think_finished(); SearchTime = Time::now(); // As early as possible