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Polymorphic Thread hierarchy

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Subclass MainThread and TimerThread and declare
idle_loop() virtual. This allow us to cleanly
remove a good bunch of hacks, relying on C++
polymorphism to do the job.

No functional change.
This commit is contained in:
Marco Costalba
2013-01-14 00:32:30 +01:00
parent e70eae2c91
commit d1143794a0
3 changed files with 40 additions and 39 deletions
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42
src/thread.cpp
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@@ -32,26 +32,23 @@ ThreadPool Threads; // Global object
namespace { extern "C" {
// start_routine() is the C function which is called when a new thread
// is launched. It is a wrapper to member function pointed by start_fn.
// is launched. It is a wrapper to the virtual function idle_loop().
long start_routine(Thread* th) { (th->*(th->start_fn))(); return 0; }
long start_routine(Thread* th) { th->idle_loop(); return 0; }
} }
// Thread c'tor starts a newly-created thread of execution that will call
// the idle loop function pointed by start_fn going immediately to sleep.
// the the virtual function idle_loop(), going immediately to sleep.
Thread::Thread(Fn fn) : splitPoints() {
Thread::Thread() : splitPoints() {
is_searching = do_exit = false;
maxPly = splitPointsCnt = 0;
curSplitPoint = NULL;
start_fn = fn;
idx = Threads.size();
is_finished = (fn != &Thread::main_loop); // Avoid a race with start_searching()
if (!thread_create(handle, start_routine, this))
{
std::cerr << "Failed to create thread number " << idx << std::endl;
@@ -60,39 +57,37 @@ Thread::Thread(Fn fn) : splitPoints() {
}
// Thread d'tor waits for thread termination before to return.
// Thread d'tor waits for thread termination before to return
Thread::~Thread() {
assert(is_finished);
do_exit = true; // Search must be already finished
notify_one();
thread_join(handle); // Wait for thread termination
}
// Thread::timer_loop() is where the timer thread waits maxPly milliseconds and
// then calls check_time(). If maxPly is 0 thread sleeps until is woken up.
// TimerThread::idle_loop() is where the timer thread waits msec milliseconds
// and then calls check_time(). If msec is 0 thread sleeps until is woken up.
extern void check_time();
void Thread::timer_loop() {
void TimerThread::idle_loop() {
while (!do_exit)
{
mutex.lock();
while (!maxPly && !do_exit)
sleepCondition.wait_for(mutex, maxPly ? maxPly : INT_MAX);
while (!msec && !do_exit)
sleepCondition.wait_for(mutex, msec ? msec : INT_MAX);
mutex.unlock();
check_time();
}
}
// Thread::main_loop() is where the main thread is parked waiting to be started
// MainThread::idle_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() {
void MainThread::idle_loop() {
while (true)
{
@@ -121,8 +116,7 @@ void Thread::main_loop() {
}
// Thread::notify_one() wakes up the thread, normally at the beginning of the
// search or, if "sleeping threads" is used at split time.
// Thread::notify_one() wakes up the thread, normally at split time
void Thread::notify_one() {
@@ -184,9 +178,9 @@ bool Thread::is_available_to(Thread* master) const {
void ThreadPool::init() {
timer = new Thread(&Thread::timer_loop);
threads.push_back(new Thread(&Thread::main_loop));
sleepWhileIdle = true;
timer = new TimerThread();
threads.push_back(new MainThread());
read_uci_options();
}
@@ -216,7 +210,7 @@ void ThreadPool::read_uci_options() {
assert(requested > 0);
while (threads.size() < requested)
threads.push_back(new Thread(&Thread::idle_loop));
threads.push_back(new Thread());
while (threads.size() > requested)
{
@@ -319,7 +313,7 @@ Value ThreadPool::split(Position& pos, Stack* ss, Value alpha, Value beta,
// their work at this split point.
if (slavesCnt || Fake)
{
master->idle_loop();
master->Thread::idle_loop(); // Force a call to base class idle_loop()
// 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.
@@ -354,7 +348,7 @@ template Value ThreadPool::split<true>(Position&, Stack*, Value, Value, Value, M
void ThreadPool::wait_for_search_finished() {
Thread* t = main_thread();
MainThread* t = main_thread();
t->mutex.lock();
while (!t->is_finished) sleepCondition.wait(t->mutex);
t->mutex.unlock();