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Session::_ac_thread_active should be used with atomics to create memory barriers, even though lock ordering is likely correct now

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This commit is contained in:
Paul Davis
2016-12-19 15:33:54 +00:00
parent 3d1eb9a6e5
commit 53be243f6a
2 changed files with 8 additions and 8 deletions
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2
libs/ardour/ardour/session.h
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@@ -1523,7 +1523,7 @@ class LIBARDOUR_API Session : public PBD::StatefulDestructible, public PBD::Scop
void auto_connect_thread_terminate ();
pthread_t _auto_connect_thread;
bool _ac_thread_active;
gint _ac_thread_active;
pthread_mutex_t _auto_connect_mutex;
pthread_cond_t _auto_connect_cond;

14
libs/ardour/session.cc
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@@ -252,7 +252,7 @@ Session::Session (AudioEngine &eng,
, _ignore_skips_updates (false)
, _rt_thread_active (false)
, _rt_emit_pending (false)
, _ac_thread_active (false)
, _ac_thread_active (0)
, _latency_recompute_pending (0)
, step_speed (0)
, outbound_mtc_timecode_frame (0)
@@ -6995,7 +6995,7 @@ Session::auto_connect (const AutoConnectRequest& ar)
void
Session::auto_connect_thread_start ()
{
if (_ac_thread_active) {
if (g_atomic_int_get (&_ac_thread_active)) {
return;
}
@@ -7003,19 +7003,18 @@ Session::auto_connect_thread_start ()
_auto_connect_queue.pop ();
}
_ac_thread_active = true;
g_atomic_int_set (&_ac_thread_active, 1);
if (pthread_create (&_auto_connect_thread, NULL, auto_connect_thread, this)) {
_ac_thread_active = false;
g_atomic_int_set (&_ac_thread_active, 0);
}
}
void
Session::auto_connect_thread_terminate ()
{
if (!_ac_thread_active) {
if (!g_atomic_int_get (&_ac_thread_active)) {
return;
}
_ac_thread_active = false;
{
Glib::Threads::Mutex::Lock lx (_auto_connect_queue_lock);
@@ -7029,6 +7028,7 @@ Session::auto_connect_thread_terminate ()
*/
pthread_mutex_lock (&_auto_connect_mutex);
g_atomic_int_set (&_ac_thread_active, 0);
pthread_cond_signal (&_auto_connect_cond);
pthread_mutex_unlock (&_auto_connect_mutex);
@@ -7052,7 +7052,7 @@ Session::auto_connect_thread_run ()
SessionEvent::create_per_thread_pool (X_("autoconnect"), 1024);
PBD::notify_event_loops_about_thread_creation (pthread_self(), X_("autoconnect"), 1024);
pthread_mutex_lock (&_auto_connect_mutex);
while (_ac_thread_active) {
while (g_atomic_int_get (&_ac_thread_active)) {
if (!_auto_connect_queue.empty ()) {
// Why would we need the process lock ??