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Code Issues Releases Wiki Activity

Tidy up comments in thread.cpp

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No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba 2011-11-28 15:54:40 +01:00
parent e870afa5d5
commit 0f7cbaca75
2 changed files with 57 additions and 58 deletions
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99
src/thread.cpp
View file

@ -23,14 +23,14 @@
#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) {
@ -38,13 +38,16 @@ namespace { extern "C" {
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;
}
@ -71,6 +74,7 @@ bool Thread::cutoff_occurred() const {
for (SplitPoint* sp = splitPoint; sp; sp = sp->parent)
if (sp->is_betaCutoff)
return true;
return false;
}
@ -101,9 +105,8 @@ bool Thread::is_available_to(int master) const {
}
// 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() {
@ -129,9 +132,7 @@ void ThreadsManager::set_size(int cnt) {
{
// 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();
@ -147,13 +148,11 @@ void ThreadsManager::set_size(int cnt) {
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);
@ -163,7 +162,7 @@ void ThreadsManager::init() {
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();
@ -178,7 +177,7 @@ void ThreadsManager::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)
@ -199,7 +198,7 @@ void ThreadsManager::exit() {
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);
@ -207,7 +206,7 @@ void ThreadsManager::exit() {
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);
@ -221,14 +220,14 @@ void ThreadsManager::exit() {
// 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;
@ -249,13 +248,13 @@ bool ThreadsManager::split_point_finished(SplitPoint* sp) const {
// 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,
@ -277,10 +276,10 @@ Value ThreadsManager::split(Position& pos, SearchStack* ss, Value alpha, Value b
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;
@ -295,6 +294,7 @@ Value ThreadsManager::split(Position& pos, SearchStack* ss, Value alpha, Value b
sp->pos = &pos;
sp->nodes = 0;
sp->ss = ss;
for (i = 0; i < activeThreads; i++)
sp->is_slave[i] = false;
@ -304,12 +304,12 @@ Value ThreadsManager::split(Position& pos, SearchStack* ss, Value alpha, Value b
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;
@ -338,8 +338,8 @@ Value ThreadsManager::split(Position& pos, SearchStack* ss, Value alpha, Value b
// 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
@ -363,8 +363,8 @@ template Value ThreadsManager::split<false>(Position&, SearchStack*, Value, Valu
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() {
@ -402,7 +402,6 @@ void Thread::main_loop() {
lock_grab(&sleepLock);
do_sleep = true; // Always return to sleep after a search
is_searching = false;
while (do_sleep && !do_terminate)
@ -418,7 +417,7 @@ void Thread::main_loop() {
if (do_terminate)
return;
Search::think();
Search::think(); // This is the search entry point
}
}
@ -438,16 +437,16 @@ void ThreadsManager::start_thinking(const Position& pos, const Search::LimitsTyp
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);
@ -459,9 +458,9 @@ void ThreadsManager::start_thinking(const Position& pos, const Search::LimitsTyp
// 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() {

16
src/thread.h
View file

@ -59,10 +59,10 @@ struct SplitPoint {
};
/// Thread struct is used to keep together all the thread related stuff like locks,
/// state and especially split points. We also use per-thread pawn and material hash
/// tables so that once we get a pointer to an entry its life time is unlimited and
/// we don't have to care about someone changing the entry under our feet.
/// Thread struct keeps together all the thread related stuff like locks, state
/// and especially split points. We also use per-thread pawn and material hash
/// tables so that once we get a pointer to an entry its life time is unlimited
/// and we don't have to care about someone changing the entry under our feet.
struct Thread {
@ -94,9 +94,9 @@ struct Thread {
};
/// ThreadsManager class is used to handle all the threads related stuff like init,
/// starting, parking and, the most important, launching a slave thread at a split
/// point. All the access to shared thread data is done through this class.
/// ThreadsManager class handles all the threads related stuff like init, starting,
/// parking and, the most important, launching a slave thread at a split point.
/// All the access to shared thread data is done through this class.
class ThreadsManager {
/* As long as the single ThreadsManager object is defined as a global we don't
@ -127,7 +127,7 @@ public:
private:
friend struct Thread;
Thread threads[MAX_THREADS + 2]; // Last 2 are the listener and the timer
Thread threads[MAX_THREADS + 1]; // Last one is used as a timer
Lock threadsLock;
Depth minimumSplitDepth;
int maxThreadsPerSplitPoint;