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Fix comments in thread.cpp

Browse source 
And reshuffle a bit the functions to place
them in a consistent order.

To be on the safe side, patch has been
validated for no regression/crashes with
a small 8K games test with 3 threads:

ELO: 3.98 +-4.4 (95%) LOS: 96.3%
Total: 8388 W: 1500 L: 1404 D: 5484

No functional change.
This commit is contained in:
Marco Costalba 2015-01-01 10:46:31 +01:00
parent 91cc82aa25
commit 62f531254e
1 changed files with 144 additions and 138 deletions
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282
src/thread.cpp
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@ -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<typename T> 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<TimerThread>();
push_back(new_thread<MainThread>());
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<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<TimerThread>();
push_back(new_thread<MainThread>());
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<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