Fix pullmode data lost problem in QAudioOutput(pulseaudio)

At each userFeed, m_bytesAvailable is not updated properly in pullmode,
so the pull data size become irrelevent to the size we can actually write.
This problem is fixed by checking the actual writable size each time
before pulling the data and limit the size of the pulled and written data.

Change-Id: I6f53e6348693ddf4e3c79e90d3c3d0c1ffc713aa
Reviewed-by: Jonas Rabbe <jonas.rabbe@nokia.com>
Reviewed-by: Michael Goddard <michael.goddard@nokia.com>

src/plugins/pulseaudio/qaudiooutput_pulse.cpp

@@ -142,7 +142,6 @@ QPulseAudioOutput::QPulseAudioOutput(const QByteArray &device)
     , m_pullMode(true)
     , m_opened(false)
     , m_audioSource(0)
-    , m_bytesAvailable(0)
     , m_stream(0)
     , m_notifyInterval(1000)
     , m_periodSize(0)
@@ -292,11 +291,11 @@ bool QPulseAudioOutput::open()
     while (pa_stream_get_state(m_stream) != PA_STREAM_READY) {
         pa_threaded_mainloop_wait(pulseEngine->mainloop());
     }
-    pa_threaded_mainloop_unlock(pulseEngine->mainloop());
-
-#ifdef DEBUG_PULSE
     const pa_buffer_attr *buffer = pa_stream_get_buffer_attr(m_stream);
-
+    m_periodSize = pa_usec_to_bytes(PeriodTimeMs*1000, &spec);
+    m_bufferSize = buffer->maxlength;
+    m_audioBuffer = new char[buffer->maxlength];
+#ifdef DEBUG_PULSE
     qDebug() << "Buffering info:";
     qDebug() << "\tMax length: " << buffer->maxlength;
     qDebug() << "\tTarget length: " << buffer->tlength;
@@ -305,7 +304,8 @@ bool QPulseAudioOutput::open()
     qDebug() << "\tFragment size: " << buffer->fragsize;
 #endif
 
-    m_periodSize = pa_usec_to_bytes(PeriodTimeMs*1000, &spec);
+    pa_threaded_mainloop_unlock(pulseEngine->mainloop());
+
     m_opened = true;
     m_tickTimer->start(PeriodTimeMs);
 
@@ -316,17 +316,6 @@ bool QPulseAudioOutput::open()
     return true;
 }
 
-void QPulseAudioOutput::userFeed()
-{
-    if (m_deviceState == QAudio::StoppedState || m_deviceState == QAudio::SuspendedState)
-        return;
-
-    if (m_deviceState ==  QAudio::IdleState)
-        m_bytesAvailable = bytesFree();
-
-    deviceReady();
-}
-
 void QPulseAudioOutput::close()
 {
     m_tickTimer->stop();
@@ -334,15 +323,15 @@ void QPulseAudioOutput::close()
     if (m_stream) {
         QPulseAudioEngine *pulseEngine = QPulseAudioEngine::instance();
         pa_threaded_mainloop_lock(pulseEngine->mainloop());
-        pa_operation *o;
 
         pa_stream_set_write_callback(m_stream, NULL, NULL);
 
-        if (!(o = pa_stream_drain(m_stream, outputStreamDrainComplete, NULL))) {
+        pa_operation *o = pa_stream_drain(m_stream, outputStreamDrainComplete, NULL);
+        if (!o) {
             qWarning() << QString("pa_stream_drain(): %1").arg(pa_strerror(pa_context_errno(pa_stream_get_context(m_stream))));
-            return;
+        } else {
+            pa_operation_unref(o);
         }
-        pa_operation_unref(o);
 
         pa_stream_disconnect(m_stream);
         pa_stream_unref(m_stream);
@@ -356,42 +345,45 @@ void QPulseAudioOutput::close()
         m_audioSource = 0;
     }
     m_opened = false;
+    if (m_audioBuffer) {
+        delete[] m_audioBuffer;
+        m_audioBuffer = 0;
+    }
 }
 
-bool QPulseAudioOutput::deviceReady()
+void QPulseAudioOutput::userFeed()
 {
+    if (m_deviceState == QAudio::StoppedState || m_deviceState == QAudio::SuspendedState)
+        return;
+
     m_resuming = false;
 
     if (m_pullMode) {
-        int l = 0;
-        int chunks = m_bytesAvailable/m_periodSize;
-        if (chunks==0) {
-            m_bytesAvailable = bytesFree();
-            return false;
-        }
+        int writableSize = bytesFree();
+        int chunks = writableSize / m_periodSize;
+        if (chunks == 0)
+            return;
 
-        char buffer[m_periodSize];
+        int input = m_periodSize * chunks;
+        if (input > m_bufferSize)
+            input = m_bufferSize;
 
-        l = m_audioSource->read(buffer, m_periodSize);
-        if (l > 0) {
-            if (m_deviceState != QAudio::ActiveState)
-                return true;
-
-            qint64 bytesWritten = write(buffer, l);
-            Q_UNUSED(bytesWritten);
+        int audioBytesPulled = m_audioSource->read(m_audioBuffer, input);
+        Q_ASSERT(audioBytesPulled <= input);
+        if (audioBytesPulled > 0) {
+            qint64 bytesWritten = write(m_audioBuffer, audioBytesPulled);
+            Q_ASSERT(bytesWritten == audioBytesPulled); //unfinished write should not happen since the data provided is less than writableSize
         }
     }
 
     if (m_deviceState != QAudio::ActiveState)
-        return true;
+        return;
 
     if (m_notifyInterval && (m_timeStamp.elapsed() + m_elapsedTimeOffset) > m_notifyInterval) {
         emit notify();
         m_elapsedTimeOffset = m_timeStamp.elapsed() + m_elapsedTimeOffset - m_notifyInterval;
         m_timeStamp.restart();
     }
-
-    return true;
 }
 
 qint64 QPulseAudioOutput::write(const char *data, qint64 len)
@@ -429,7 +421,11 @@ int QPulseAudioOutput::bytesFree() const
     if (m_deviceState != QAudio::ActiveState && m_deviceState != QAudio::IdleState)
         return 0;
 
-    return pa_stream_writable_size(m_stream);
+    QPulseAudioEngine *pulseEngine = QPulseAudioEngine::instance();
+    pa_threaded_mainloop_lock(pulseEngine->mainloop());
+    int writableSize = pa_stream_writable_size(m_stream);
+    pa_threaded_mainloop_unlock(pulseEngine->mainloop());
+    return writableSize;
 }
 
 int QPulseAudioOutput::periodSize() const

src/plugins/pulseaudio/qaudiooutput_pulse.h

@@ -107,7 +107,6 @@ private:
     qint64 write(const char *data, qint64 len);
 
 private Q_SLOTS:
-    bool deviceReady();
     void userFeed();
 
 private:
@@ -119,7 +118,6 @@ private:
     bool m_pullMode;
     bool m_opened;
     QIODevice *m_audioSource;
-    int m_bytesAvailable;
     QTimer m_periodTimer;
     pa_stream *m_stream;
     int m_notifyInterval;