ThreadPool Threads; // Global object
-// Thread constructor makes some init and launches the thread that will go to
-// sleep in idle_loop().
+/// Thread constructor launch the thread and then wait until it goes to sleep
+/// in idle_loop().
Thread::Thread() {
- searching = true; // Avoid a race with start_thinking()
- exit = resetCalls = false;
+ resetCalls = exit = false;
maxPly = callsCnt = 0;
history.clear();
counterMoves.clear();
- idx = Threads.size(); // Starts from 0
- std::thread::operator=(std::thread(&Thread::idle_loop, this));
+ idx = Threads.size(); // Start from 0
+
+ std::unique_lock<Mutex> lk(mutex);
+ searching = true;
+ nativeThread = std::thread(&Thread::idle_loop, this);
+ sleepCondition.wait(lk, [&]{ return !searching; });
}
-// Thread destructor waits for thread termination before deleting
+/// Thread destructor wait for thread termination before returning
Thread::~Thread() {
mutex.lock();
- exit = true; // Search must be already finished
+ exit = true;
+ sleepCondition.notify_one();
mutex.unlock();
-
- notify_one();
- std::thread::join(); // Wait for thread termination
+ nativeThread.join();
}
-// Thread::join() waits for the thread to finish searching
-void Thread::join() {
+/// Thread::wait_for_search_finished() wait on sleep condition until not searching
+
+void Thread::wait_for_search_finished() {
std::unique_lock<Mutex> lk(mutex);
sleepCondition.wait(lk, [&]{ return !searching; });
}
-// Thread::notify_one() wakes up the thread when there is some work to do
+/// Thread::wait() wait on sleep condition until condition is true
-void Thread::notify_one() {
+void Thread::wait(std::atomic_bool& condition) {
std::unique_lock<Mutex> lk(mutex);
- sleepCondition.notify_one();
+ sleepCondition.wait(lk, [&]{ return bool(condition); });
}
-// Thread::wait() set the thread to sleep until 'condition' turns true
+/// Thread::start_searching() wake up the thread that will start the search
-void Thread::wait(std::atomic_bool& condition) {
+void Thread::start_searching(bool resume) {
std::unique_lock<Mutex> lk(mutex);
- sleepCondition.wait(lk, [&]{ return bool(condition); });
+
+ if (!resume)
+ searching = true;
+
+ sleepCondition.notify_one();
}
-// Thread::idle_loop() is where the thread is parked when it has no work to do
+/// Thread::idle_loop() is where the thread is parked when it has no work to do
void Thread::idle_loop() {
while (!searching && !exit)
{
- sleepCondition.notify_one(); // Wake up main thread if needed
+ sleepCondition.notify_one(); // Wake up any waiting thread
sleepCondition.wait(lk);
}
lk.unlock();
- if (!exit && searching)
+ if (!exit)
search();
}
}
-// ThreadPool::init() is called at startup to create and launch requested threads,
-// that will go immediately to sleep. We cannot use a constructor because Threads
-// is a static object and we need a fully initialized engine at this point due to
-// allocation of Endgames in the Thread constructor.
+/// ThreadPool::init() create and launch requested threads, that will go
+/// immediately to sleep. We cannot use a constructor because Threads is a
+/// static object and we need a fully initialized engine at this point due to
+/// allocation of Endgames in the Thread constructor.
void ThreadPool::init() {
}
-// ThreadPool::exit() terminates the threads before the program exits. Cannot be
-// done in destructor because threads must be terminated before freeing us.
+/// ThreadPool::exit() terminate threads before the program exits. Cannot be
+/// done in destructor because threads must be terminated before deleting any
+/// static objects, so while still in main().
void ThreadPool::exit() {
- for (Thread* th : *this)
- delete th;
-
- clear(); // Get rid of stale pointers
+ while (size())
+ delete back(), pop_back();
}
-// 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.
+/// ThreadPool::read_uci_options() updates internal threads parameters from the
+/// corresponding UCI options and creates/destroys threads to match requested
+/// number. Thread objects are dynamically allocated.
void ThreadPool::read_uci_options() {
- size_t requested = Options["Threads"];
+ size_t requested = Options["Threads"];
assert(requested > 0);
push_back(new Thread);
while (size() > requested)
- {
- delete back();
- pop_back();
- }
+ delete back(), pop_back();
}
-// ThreadPool::nodes_searched() returns the number of nodes searched
+/// ThreadPool::nodes_searched() return the number of nodes searched
int64_t ThreadPool::nodes_searched() {
int64_t nodes = 0;
- for (Thread *th : *this)
+ for (Thread* th : *this)
nodes += th->rootPos.nodes_searched();
return nodes;
}
-// ThreadPool::start_thinking() wakes up the main thread sleeping in
-// MainThread::idle_loop() and starts a new search, then returns immediately.
+/// ThreadPool::start_thinking() wake up the main thread sleeping in idle_loop()
+/// and start a new search, then return immediately.
void ThreadPool::start_thinking(const Position& pos, const LimitsType& limits,
StateStackPtr& states) {
- for (Thread* th : Threads)
- th->join();
+
+ main()->wait_for_search_finished();
Signals.stopOnPonderhit = Signals.firstRootMove = false;
Signals.stop = Signals.failedLowAtRoot = false;
|| std::count(limits.searchmoves.begin(), limits.searchmoves.end(), m))
main()->rootMoves.push_back(RootMove(m));
- main()->searching = true;
- main()->notify_one(); // Wake up main thread: 'searching' must be already set
+ main()->start_searching();
}
/// entry its life time is unlimited and we don't have to care about someone
/// changing the entry under our feet.
-struct Thread : public std::thread {
+class Thread {
+ std::thread nativeThread;
+ Mutex mutex;
+ ConditionVariable sleepCondition;
+ bool exit, searching;
+
+public:
Thread();
virtual ~Thread();
virtual void search();
void idle_loop();
- void join();
- void notify_one();
+ void start_searching(bool resume = false);
+ void wait_for_search_finished();
void wait(std::atomic_bool& b);
- std::atomic_bool exit, searching, resetCalls;
- Mutex mutex;
- ConditionVariable sleepCondition;
-
Pawns::Table pawnsTable;
Material::Table materialTable;
Endgames endgames;
HistoryStats history;
MovesStats counterMoves;
Depth completedDepth;
+ std::atomic_bool resetCalls;
};
-/// MainThread is a derived classes used to characterize the the main one
+/// MainThread is a derived class with a specific overload for the main thread
struct MainThread : public Thread {
virtual void search();
/// ThreadPool struct handles all the threads related stuff like init, starting,
-/// parking and, most importantly, launching a thread.
-/// All the access to shared thread data is done through this class.
+/// parking and, most importantly, launching a thread. All the access to threads
+/// data is done through this class.
struct ThreadPool : public std::vector<Thread*> {
void exit(); // be initialized and valid during the whole thread lifetime.
MainThread* main() { return static_cast<MainThread*>(at(0)); }
- void read_uci_options();
void start_thinking(const Position&, const Search::LimitsType&, Search::StateStackPtr&);
+ void read_uci_options();
int64_t nodes_searched();
};
projects / stockfish / commitdiff