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{output,mixer}/alsa: use snd_pcm_poll_descriptors_revents()

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This call was missing, causing very high CPU usage when the ALSA
output plugin was used with dmix.

Closes #391
This commit is contained in:
Max Kellermann
2018-11-08 14:29:04 +01:00
parent ba5c856f15
commit fee75dc766
6 changed files with 67 additions and 0 deletions
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48
src/lib/alsa/NonBlock.cxx
View File

@@ -49,6 +49,30 @@ AlsaNonBlockPcm::PrepareSockets(MultiSocketMonitor &m, snd_pcm_t *pcm)
return std::chrono::steady_clock::duration(-1);
}
void
AlsaNonBlockPcm::DispatchSockets(MultiSocketMonitor &m,
snd_pcm_t *pcm) noexcept
{
int count = snd_pcm_poll_descriptors_count(pcm);
if (count <= 0)
return;
const auto pfds = pfd_buffer.Get(count), end = pfds + count;
auto *i = pfds;
m.ForEachReturnedEvent([&i, end](SocketDescriptor s, unsigned events){
if (i >= end)
return;
i->fd = s.Get();
i->events = i->revents = events;
++i;
});
unsigned short dummy;
snd_pcm_poll_descriptors_revents(pcm, pfds, i - pfds, &dummy);
}
std::chrono::steady_clock::duration
AlsaNonBlockMixer::PrepareSockets(MultiSocketMonitor &m, snd_mixer_t *mixer) noexcept
{
@@ -67,3 +91,27 @@ AlsaNonBlockMixer::PrepareSockets(MultiSocketMonitor &m, snd_mixer_t *mixer) noe
m.ReplaceSocketList(pfds, count);
return std::chrono::steady_clock::duration(-1);
}
void
AlsaNonBlockMixer::DispatchSockets(MultiSocketMonitor &m,
snd_mixer_t *mixer) noexcept
{
int count = snd_mixer_poll_descriptors_count(mixer);
if (count <= 0)
return;
const auto pfds = pfd_buffer.Get(count), end = pfds + count;
auto *i = pfds;
m.ForEachReturnedEvent([&i, end](SocketDescriptor s, unsigned events){
if (i >= end)
return;
i->fd = s.Get();
i->events = i->revents = events;
++i;
});
unsigned short dummy;
snd_mixer_poll_descriptors_revents(mixer, pfds, i - pfds, &dummy);
}

12
src/lib/alsa/NonBlock.hxx
View File

@@ -42,6 +42,12 @@ public:
*/
std::chrono::steady_clock::duration PrepareSockets(MultiSocketMonitor &m,
snd_pcm_t *pcm);
/**
* Wrapper for snd_pcm_poll_descriptors_revents(), to be
* called from MultiSocketMonitor::DispatchSockets().
*/
void DispatchSockets(MultiSocketMonitor &m, snd_pcm_t *pcm) noexcept;
};
/**
@@ -54,6 +60,12 @@ class AlsaNonBlockMixer {
public:
std::chrono::steady_clock::duration PrepareSockets(MultiSocketMonitor &m,
snd_mixer_t *mixer) noexcept;
/**
* Wrapper for snd_mixer_poll_descriptors_revents(), to be
* called from MultiSocketMonitor::DispatchSockets().
*/
void DispatchSockets(MultiSocketMonitor &m, snd_mixer_t *mixer) noexcept;
};
#endif