hlsdemux: implement _has_next_fragment to avoid busy looping

It will allow the demuxer to wait for a fragment to be available instead
of busy looping polling the playlist for a new fragment

ext/hls/gsthlsdemux.c

@@ -115,6 +115,8 @@ static void gst_hls_demux_finish_fragment (GstAdaptiveDemux * demux,
     GstAdaptiveDemuxStream * stream, GstBuffer ** buffer);
 static GstFlowReturn gst_hls_demux_chunk_received (GstAdaptiveDemux * demux,
     GstAdaptiveDemuxStream * stream, GstBuffer ** chunk);
+static gboolean gst_hls_demux_stream_has_next_fragment (GstAdaptiveDemuxStream *
+    stream);
 static GstFlowReturn gst_hls_demux_advance_fragment (GstAdaptiveDemuxStream *
     stream);
 static GstFlowReturn gst_hls_demux_update_fragment_info (GstAdaptiveDemuxStream
@@ -205,6 +207,8 @@ gst_hls_demux_class_init (GstHLSDemuxClass * klass)
   adaptivedemux_class->update_manifest = gst_hls_demux_update_manifest;
   adaptivedemux_class->reset = gst_hls_demux_reset;
   adaptivedemux_class->seek = gst_hls_demux_seek;
+  adaptivedemux_class->stream_has_next_fragment =
+      gst_hls_demux_stream_has_next_fragment;
   adaptivedemux_class->stream_advance_fragment = gst_hls_demux_advance_fragment;
   adaptivedemux_class->stream_update_fragment_info =
       gst_hls_demux_update_fragment_info;
@@ -721,6 +725,15 @@ gst_hls_demux_chunk_received (GstAdaptiveDemux * demux,
   return GST_FLOW_OK;
 }
 
+static gboolean
+gst_hls_demux_stream_has_next_fragment (GstAdaptiveDemuxStream * stream)
+{
+  GstHLSDemux *hlsdemux = GST_HLS_DEMUX_CAST (stream->demux);
+
+  return gst_m3u8_client_has_next_fragment (hlsdemux->client,
+      stream->demux->segment.rate > 0);
+}
+
 static GstFlowReturn
 gst_hls_demux_advance_fragment (GstAdaptiveDemuxStream * stream)
 {

ext/hls/m3u8.c

@@ -947,6 +947,28 @@ _find_current (GstM3U8MediaFile * file, GstM3U8Client * client)
   return file->sequence != client->sequence;
 }
 
+static gboolean
+has_next_fragment (GstM3U8Client * client, GList * l, gboolean forward)
+{
+  GstM3U8MediaFile *file;
+
+  if (!forward)
+    l = g_list_last (l);
+
+  while (l) {
+    file = l->data;
+
+    if (forward && file->sequence > client->sequence)
+      break;
+    else if (!forward && file->sequence < client->sequence)
+      break;
+
+    l = (forward ? l->next : l->prev);
+  }
+
+  return l != NULL;
+}
+
 static GList *
 find_next_fragment (GstM3U8Client * client, GList * l, gboolean forward)
 {
@@ -1023,6 +1045,22 @@ gst_m3u8_client_get_next_fragment (GstM3U8Client * client,
   return TRUE;
 }
 
+gboolean
+gst_m3u8_client_has_next_fragment (GstM3U8Client * client, gboolean forward)
+{
+  gboolean ret;
+
+  g_return_if_fail (client != NULL);
+  g_return_if_fail (client->current != NULL);
+
+  GST_M3U8_CLIENT_LOCK (client);
+  GST_DEBUG ("Checking if has next fragment %" G_GINT64_FORMAT,
+      client->sequence + 1);
+  ret = has_next_fragment (client, client->current->files, forward);
+  GST_M3U8_CLIENT_UNLOCK (client);
+  return ret;
+}
+
 void
 gst_m3u8_client_advance_fragment (GstM3U8Client * client, gboolean forward)
 {

ext/hls/m3u8.h

@@ -107,6 +107,7 @@ gboolean gst_m3u8_client_get_next_fragment (GstM3U8Client * client,
     gboolean * discontinuity, gchar ** uri, GstClockTime * duration,
     GstClockTime * timestamp, gint64 * range_start, gint64 * range_end,
     gchar ** key, guint8 ** iv, gboolean forward);
+gboolean gst_m3u8_client_has_next_fragment (GstM3U8Client * client, gboolean forward);
 void gst_m3u8_client_advance_fragment (GstM3U8Client * client, gboolean forward);
 GstClockTime gst_m3u8_client_get_duration (GstM3U8Client * client);
 GstClockTime gst_m3u8_client_get_target_duration (GstM3U8Client * client);