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Reformat threads code

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Apart from some renaming the biggest change
is the retire of split_point_finished()
replaced by slavesMask flags. As a side
effect we now take also split point lock
when allocation available threads.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba
2012-01-26 23:18:43 +01:00
parent a189a5f0c5
commit 7fb6fd2f55
3 changed files with 72 additions and 95 deletions
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52
src/thread.cpp
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@@ -97,12 +97,11 @@ bool Thread::is_available_to(int master) const {
// Make a local copy to be sure doesn't become zero under our feet while
// testing next condition and so leading to an out of bound access.
int localActiveSplitPoints = activeSplitPoints;
int sp_count = activeSplitPoints;
// No active split points means that the thread is available as a slave for any
// other thread otherwise apply the "helpful master" concept if possible.
if ( !localActiveSplitPoints
|| splitPoints[localActiveSplitPoints - 1].is_slave[master])
if (!sp_count || (splitPoints[sp_count - 1].slavesMask & (1ULL << master)))
return true;
return false;
@@ -190,9 +189,11 @@ void ThreadsManager::init() {
void ThreadsManager::exit() {
assert(threads[0].is_searching == false);
for (int i = 0; i <= MAX_THREADS; i++)
{
threads[i].do_terminate = true; // Search must be already finished
threads[i].do_exit = true; // Search must be already finished
threads[i].wake_up();
thread_join(threads[i].handle); // Wait for thread termination
@@ -225,19 +226,6 @@ bool ThreadsManager::available_slave_exists(int master) const {
}
// split_point_finished() checks if all the slave threads of a given split
// point have finished searching.
bool ThreadsManager::split_point_finished(SplitPoint* sp) const {
for (int i = 0; i < activeThreads; i++)
if (sp->is_slave[i])
return false;
return true;
}
// 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
@@ -274,6 +262,7 @@ Value ThreadsManager::split(Position& pos, Stack* ss, Value alpha, Value beta,
sp->parent = masterThread.splitPoint;
sp->master = master;
sp->is_betaCutoff = false;
sp->slavesMask = (1ULL << master);
sp->depth = depth;
sp->threatMove = threatMove;
sp->alpha = alpha;
@@ -286,9 +275,6 @@ Value ThreadsManager::split(Position& pos, Stack* ss, Value alpha, Value beta,
sp->nodes = 0;
sp->ss = ss;
for (i = 0; i < activeThreads; i++)
sp->is_slave[i] = false;
// If we are here it means we are not available
assert(masterThread.is_searching);
@@ -298,21 +284,25 @@ Value ThreadsManager::split(Position& pos, Stack* ss, Value alpha, Value beta,
// is_searching flag. This must be done under lock protection to avoid concurrent
// allocation of the same slave by another master.
lock_grab(threadsLock);
lock_grab(sp->lock); // To protect sp->slaves_mask
for (i = 0; !Fake && i < activeThreads && workersCnt < maxThreadsPerSplitPoint; i++)
for (i = 0; !Fake && i < activeThreads; i++)
if (threads[i].is_available_to(master))
{
workersCnt++;
sp->is_slave[i] = true;
sp->slavesMask |= (1ULL << i);
threads[i].splitPoint = sp;
// This makes the slave to exit from idle_loop()
// Allocate the slave and make it exit from idle_loop()
threads[i].is_searching = true;
if (useSleepingThreads)
threads[i].wake_up();
if (++workersCnt >= maxThreadsPerSplitPoint)
break;
}
lock_release(sp->lock);
lock_release(threadsLock);
// We failed to allocate even one slave, return
@@ -337,15 +327,17 @@ Value ThreadsManager::split(Position& pos, Stack* ss, Value alpha, Value beta,
// finished. Note that changing state and decreasing activeSplitPoints is done
// under lock protection to avoid a race with Thread::is_available_to().
lock_grab(threadsLock);
lock_grab(sp->lock); // To protect sp->nodes
masterThread.is_searching = true;
masterThread.activeSplitPoints--;
lock_release(threadsLock);
masterThread.splitPoint = sp->parent;
pos.set_nodes_searched(pos.nodes_searched() + sp->nodes);
lock_release(sp->lock);
lock_release(threadsLock);
return sp->bestValue;
}
@@ -360,7 +352,7 @@ extern void check_time();
void Thread::timer_loop() {
while (!do_terminate)
while (!do_exit)
{
lock_grab(sleepLock);
timed_wait(sleepCond, sleepLock, maxPly ? maxPly : INT_MAX);
@@ -396,7 +388,7 @@ void Thread::main_loop() {
do_sleep = true; // Always return to sleep after a search
is_searching = false;
while (do_sleep && !do_terminate)
while (do_sleep && !do_exit)
{
cond_signal(Threads.sleepCond); // Wake up UI thread if needed
cond_wait(sleepCond, sleepLock);
@@ -406,7 +398,7 @@ void Thread::main_loop() {
lock_release(sleepLock);
if (do_terminate)
if (do_exit)
return;
Search::think();