ardour/livetrax
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initial hacks towards a truly thread-safe SafeTime object, using boost::atomic

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This commit is contained in:
Paul Davis 2018-09-24 17:34:25 -04:00
parent 3c11660d2a
commit b6aefaf100
2 changed files with 36 additions and 30 deletions
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34
libs/ardour/ardour/transport_master.h
View File

@ -23,6 +23,7 @@
#include <vector>
#include <boost/optional.hpp>
#include <boost/atomic.hpp>
#include <glibmm/threads.h>
@ -282,18 +283,43 @@ class LIBARDOUR_API TransportMaster : public PBD::Stateful {
};
struct LIBARDOUR_API SafeTime {
volatile int guard1;
boost::atomic<int> guard1;
samplepos_t position;
samplepos_t timestamp;
double speed;
volatile int guard2;
boost::atomic<int> guard2;
SafeTime() {
guard1 = 0;
guard1.store (0);
position = 0;
timestamp = 0;
speed = 0;
guard2 = 0;
guard2.store (0);
}
SafeTime (SafeTime const & other)
: guard1 (other.guard1.load (boost::memory_order_acquire))
, position (other.position)
, timestamp (other.timestamp)
, speed (other.speed)
, guard2 (other.guard2.load (boost::memory_order_acquire))
{}
SafeTime& operator= (SafeTime const & other) {
guard1 = other.guard1.load (boost::memory_order_acquire);
position = other.position;
timestamp = other.timestamp;
speed = other.speed;
guard2 = other.guard2.load (boost::memory_order_acquire);
return *this;
}
void update (samplepos_t p, samplepos_t t, double s) {
guard1.fetch_add (1, boost::memory_order_acquire);
position = p;
timestamp = t;
speed = s;
guard2.fetch_add (1, boost::memory_order_acquire);
}
};

32
libs/ardour/mtc_slave.cc
View File

@ -273,7 +273,7 @@ MTC_TransportMaster::read_current (SafeTime *st) const
*st = current;
tries++;
} while (st->guard1 != st->guard2);
} while (st->guard1.load (boost::memory_order_acquire) != st->guard2.load (boost::memory_order_acquire));
}
void
@ -312,11 +312,7 @@ MTC_TransportMaster::update_mtc_qtr (Parser& p, int which_qtr, samplepos_t now)
mtc_speed = (t1 - t0) / qtr_d;
DEBUG_TRACE (DEBUG::MTC, string_compose ("qtr sample DLL t0:%1 t1:%2 err:%3 spd:%4 ddt:%5\n", t0, t1, e, mtc_speed, e2 - qtr_d));
current.guard1++;
current.position = mtc_frame;
current.timestamp = now;
current.speed = mtc_speed;
current.guard2++;
current.update (mtc_frame, now, mtc_speed);
last_inbound_frame = now;
}
@ -499,10 +495,7 @@ MTC_TransportMaster::update_mtc_time (const MIDI::byte *msg, bool was_full, samp
init_mtc_dll(mtc_frame, qtr);
mtc_frame_dll = mtc_frame;
}
current.guard1++;
current.position = mtc_frame;
current.timestamp = now;
current.guard2++;
current.update (mtc_frame, now, current.speed);
reset_window (mtc_frame);
}
}
@ -525,28 +518,15 @@ MTC_TransportMaster::update_mtc_status (MIDI::MTC_Status status)
switch (status) {
case MTC_Stopped:
current.guard1++;
current.position = mtc_frame;
current.timestamp = 0;
current.speed = 0;
current.guard2++;
current.update (mtc_frame, 0, 0);
break;
case MTC_Forward:
current.guard1++;
current.position = mtc_frame;
current.timestamp = 0;
current.speed = 0;
current.guard2++;
current.update (mtc_frame, 0, 0);
break;
case MTC_Backward:
current.guard1++;
current.position = mtc_frame;
current.timestamp = 0;
current.speed = 0;
current.guard2++;
current.update (mtc_frame, 0, 0);
break;
}
busy_guard2++;