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Drain ALSA raw-midi buffers after 64 bytes

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Very long sequence of *concurrent* events may otherwise be truncated
because the backend requests a buffer-size of 64 bytes via
snd_rawmidi_params_set_buffer_size().
This commit is contained in:
Robin Gareus
2017-04-09 04:04:57 +02:00
parent 65ff43d0a7
commit 6968c9f909
1 changed files with 19 additions and 7 deletions
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26
libs/backends/alsa/alsa_rawmidi.cc
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@@ -88,7 +88,7 @@ AlsaRawMidiIO::init (const char *device_name, const bool input)
if (snd_rawmidi_params_set_avail_min (_device, params, 1)) {
goto initerr;
}
if ( snd_rawmidi_params_set_buffer_size (_device, params, 64)) {
if (snd_rawmidi_params_set_buffer_size (_device, params, 64)) {
goto initerr;
}
if (snd_rawmidi_params_set_no_active_sensing (_device, params, 1)) {
@@ -119,7 +119,7 @@ AlsaRawMidiOut::main_process_thread ()
{
_running = true;
pthread_mutex_lock (&_notify_mutex);
bool need_drain = false;
unsigned int need_drain = 0;
while (_running) {
bool have_data = false;
struct MidiEventHeader h(0,0);
@@ -146,9 +146,9 @@ AlsaRawMidiOut::main_process_thread ()
}
if (!have_data) {
if (need_drain) {
if (need_drain > 0) {
snd_rawmidi_drain (_device);
need_drain = false;
need_drain = 0;
}
pthread_cond_wait (&_notify_ready, &_notify_mutex);
continue;
@@ -156,9 +156,9 @@ AlsaRawMidiOut::main_process_thread ()
uint64_t now = g_get_monotonic_time();
while (h.time > now + 500) {
if (need_drain) {
if (need_drain > 0) {
snd_rawmidi_drain (_device);
need_drain = false;
need_drain = 0;
} else {
select_sleep(h.time - now);
}
@@ -195,6 +195,14 @@ retry:
ssize_t err = snd_rawmidi_write (_device, data, h.size);
#if 0 // DEBUG -- not rt-safe
printf("TX [%ld | %ld]", h.size, err);
for (size_t i = 0; i < h.size; ++i) {
printf (" %02x", data[i]);
}
printf ("\n");
#endif
if ((err == -EAGAIN)) {
snd_rawmidi_drain (_device);
goto retry;
@@ -213,7 +221,11 @@ retry:
h.size -= err;
goto retry;
}
need_drain = true;
if ((need_drain += h.size) >= 64) {
snd_rawmidi_drain (_device);
need_drain = 0;
}
}
pthread_mutex_unlock (&_notify_mutex);