JACK: delete broken pause implementation

Previously, calling soundio_outstream_pause or soundio_instream_pause
during the write_callback or read_callback would cause a deadlock. Now,
attempting to pause always results in SoundIoErrorBackendIncompatible.

Closes #39

soundio/soundio.h

@@ -1006,14 +1006,15 @@ SOUNDIO_EXPORT int soundio_outstream_end_write(struct SoundIoOutStream *outstrea
 /// * #SoundIoErrorIncompatibleDevice
 SOUNDIO_EXPORT int soundio_outstream_clear_buffer(struct SoundIoOutStream *outstream);
 
-/// If the underlying device supports pausing, this pauses the stream.
+/// If the underlying backend and device support pausing, this pauses the
-/// SoundIoOutStream::write_callback may be called a few more times if the
+/// stream. SoundIoOutStream::write_callback may be called a few more times if
-/// buffer is not full.
+/// the buffer is not full.
 /// Pausing might put the hardware into a low power state which is ideal if your
 /// software is silent for some time.
-/// This function may be called from any thread.
+/// This function may be called from any thread context, including
+/// SoundIoOutStream::write_callback.
 /// Pausing when already paused or unpausing when already unpaused has no
-/// effect and always returns SoundIoErrorNone.
+/// effect and returns #SoundIoErrorNone.
 ///
 /// Possible errors:
 /// * #SoundIoErrorBackendDisconnected
@@ -1021,6 +1022,8 @@ SOUNDIO_EXPORT int soundio_outstream_clear_buffer(struct SoundIoOutStream *outst
 /// * #SoundIoErrorIncompatibleDevice - device does not support
 ///   pausing/unpausing. This error code might not be returned even if the
 ///   device does not support pausing/unpausing.
+/// * #SoundIoErrorIncompatibleBackend - backend does not support
+///   pausing/unpausing.
 /// * #SoundIoErrorInvalid - outstream not opened and started
 SOUNDIO_EXPORT int soundio_outstream_pause(struct SoundIoOutStream *outstream, bool pause);
 
@@ -1124,7 +1127,7 @@ SOUNDIO_EXPORT int soundio_instream_end_read(struct SoundIoInStream *instream);
 /// #SoundIoErrorIncompatibleDevice.
 /// This function may be called from any thread.
 /// Pausing when already paused or unpausing when already unpaused has no
-/// effect and always returns SoundIoErrorNone.
+/// effect and always returns #SoundIoErrorNone.
 ///
 /// Possible errors:
 /// * #SoundIoErrorBackendDisconnected

src/jack.cpp

@@ -426,8 +426,6 @@ static int outstream_open_jack(struct SoundIoPrivate *si, struct SoundIoOutStrea
     SoundIoDevicePrivate *dev = (SoundIoDevicePrivate *)device;
     SoundIoDeviceJack *dj = &dev->backend_data.jack;
 
-    osj->is_paused = true;
-
     if (sij->is_shutdown)
         return SoundIoErrorBackendDisconnected;
 
@@ -517,43 +515,38 @@ static int outstream_open_jack(struct SoundIoPrivate *si, struct SoundIoOutStrea
 }
 
 static int outstream_pause_jack(struct SoundIoPrivate *si, struct SoundIoOutStreamPrivate *os, bool pause) {
-    SoundIoOutStreamJack *osj = &os->backend_data.jack;
-    SoundIoOutStream *outstream = &os->pub;
     SoundIoJack *sij = &si->backend_data.jack;
+
     if (sij->is_shutdown)
         return SoundIoErrorBackendDisconnected;
 
-    int err;
+    return SoundIoErrorIncompatibleBackend;
-    if (pause) {
-        if (!osj->is_paused) {
-            if ((err = jack_deactivate(osj->client)))
-                return SoundIoErrorStreaming;
-            osj->is_paused = true;
-        }
-    } else {
-        if (osj->is_paused) {
-            if ((err = jack_activate(osj->client)))
-                return SoundIoErrorStreaming;
-
-            for (int ch = 0; ch < outstream->layout.channel_count; ch += 1) {
-                SoundIoOutStreamJackPort *osjp = &osj->ports[ch];
-                const char *dest_port_name = osjp->dest_port_name;
-                // allow unconnected ports
-                if (!dest_port_name)
-                    continue;
-                const char *source_port_name = jack_port_name(osjp->source_port);
-                if ((err = jack_connect(osj->client, source_port_name, dest_port_name)))
-                    return SoundIoErrorStreaming;
-            }
-            osj->is_paused = false;
-        }
-    }
-
-    return 0;
 }
 
 static int outstream_start_jack(struct SoundIoPrivate *si, struct SoundIoOutStreamPrivate *os) {
-    return outstream_pause_jack(si, os, false);
+    SoundIoOutStreamJack *osj = &os->backend_data.jack;
+    SoundIoOutStream *outstream = &os->pub;
+    SoundIoJack *sij = &si->backend_data.jack;
+    int err;
+
+    if (sij->is_shutdown)
+        return SoundIoErrorBackendDisconnected;
+
+    if ((err = jack_activate(osj->client)))
+        return SoundIoErrorStreaming;
+
+    for (int ch = 0; ch < outstream->layout.channel_count; ch += 1) {
+        SoundIoOutStreamJackPort *osjp = &osj->ports[ch];
+        const char *dest_port_name = osjp->dest_port_name;
+        // allow unconnected ports
+        if (!dest_port_name)
+            continue;
+        const char *source_port_name = jack_port_name(osjp->source_port);
+        if ((err = jack_connect(osj->client, source_port_name, dest_port_name)))
+            return SoundIoErrorStreaming;
+    }
+
+    return 0;
 }
 
 static int outstream_begin_write_jack(struct SoundIoPrivate *si, struct SoundIoOutStreamPrivate *os,
@@ -742,37 +735,38 @@ static int instream_open_jack(struct SoundIoPrivate *si, struct SoundIoInStreamP
 }
 
 static int instream_pause_jack(struct SoundIoPrivate *si, struct SoundIoInStreamPrivate *is, bool pause) {
-    SoundIoInStreamJack *isj = &is->backend_data.jack;
-    SoundIoInStream *instream = &is->pub;
     SoundIoJack *sij = &si->backend_data.jack;
+
     if (sij->is_shutdown)
         return SoundIoErrorBackendDisconnected;
 
-    int err;
+    return SoundIoErrorIncompatibleBackend;
-    if (pause) {
-        if ((err = jack_deactivate(isj->client)))
-            return SoundIoErrorStreaming;
-    } else {
-        if ((err = jack_activate(isj->client)))
-            return SoundIoErrorStreaming;
-
-        for (int ch = 0; ch < instream->layout.channel_count; ch += 1) {
-            SoundIoInStreamJackPort *isjp = &isj->ports[ch];
-            const char *source_port_name = isjp->source_port_name;
-            // allow unconnected ports
-            if (!source_port_name)
-                continue;
-            const char *dest_port_name = jack_port_name(isjp->dest_port);
-            if ((err = jack_connect(isj->client, source_port_name, dest_port_name)))
-                return SoundIoErrorStreaming;
-        }
-    }
-
-    return 0;
 }
 
 static int instream_start_jack(struct SoundIoPrivate *si, struct SoundIoInStreamPrivate *is) {
-    return instream_pause_jack(si, is, false);
+    SoundIoInStreamJack *isj = &is->backend_data.jack;
+    SoundIoInStream *instream = &is->pub;
+    SoundIoJack *sij = &si->backend_data.jack;
+    int err;
+
+    if (sij->is_shutdown)
+        return SoundIoErrorBackendDisconnected;
+
+    if ((err = jack_activate(isj->client)))
+        return SoundIoErrorStreaming;
+
+    for (int ch = 0; ch < instream->layout.channel_count; ch += 1) {
+        SoundIoInStreamJackPort *isjp = &isj->ports[ch];
+        const char *source_port_name = isjp->source_port_name;
+        // allow unconnected ports
+        if (!source_port_name)
+            continue;
+        const char *dest_port_name = jack_port_name(isjp->dest_port);
+        if ((err = jack_connect(isj->client, source_port_name, dest_port_name)))
+            return SoundIoErrorStreaming;
+    }
+
+    return 0;
 }
 
 static int instream_begin_read_jack(struct SoundIoPrivate *si, struct SoundIoInStreamPrivate *is,

src/jack.hpp

@@ -49,7 +49,6 @@ struct SoundIoOutStreamJack {
     jack_client_t *client;
     int period_size;
     int frames_left;
-    bool is_paused;
     double hardware_latency;
     SoundIoOutStreamJackPort ports[SOUNDIO_MAX_CHANNELS];
     SoundIoChannelArea areas[SOUNDIO_MAX_CHANNELS];