adaptivedemux2: Add new flow return value for BUSY and PREPARE stream state

Neither are used yet, they're just placeholders.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/3883>

subprojects/gst-plugins-good/ext/adaptivedemux2/gstadaptivedemux-private.h

@@ -40,6 +40,7 @@ G_BEGIN_DECLS
 
 /* Internal, so not using GST_FLOW_CUSTOM_SUCCESS_N */
 #define GST_ADAPTIVE_DEMUX_FLOW_SWITCH (GST_FLOW_CUSTOM_SUCCESS_2 + 2)
+#define GST_ADAPTIVE_DEMUX_FLOW_BUSY (GST_FLOW_CUSTOM_SUCCESS_2 + 3)
 
 #define TRACKS_GET_LOCK(d) (&GST_ADAPTIVE_DEMUX_CAST(d)->priv->tracks_lock)
 #define TRACKS_LOCK(d) g_mutex_lock (TRACKS_GET_LOCK (d))
@@ -100,6 +101,11 @@ struct _GstAdaptiveDemuxPrivate
   /* Set to TRUE if any stream is waiting on the manifest update */
   gboolean stream_waiting_for_manifest;
 
+  /* Set to TRUE if streams can download fragment data. If FALSE,
+   * they can load playlists / prepare for updata_fragment_info()
+   */
+  gboolean streams_can_download_fragments;
+
   GMutex api_lock;
 
   /* Protects demux and stream segment information
@@ -181,6 +187,7 @@ gboolean gst_adaptive_demux_is_live (GstAdaptiveDemux * demux);
 
 void gst_adaptive_demux2_stream_on_manifest_update (GstAdaptiveDemux2Stream * stream);
 void gst_adaptive_demux2_stream_on_output_space_available (GstAdaptiveDemux2Stream *stream);
+void gst_adaptive_demux2_stream_on_can_download_fragments(GstAdaptiveDemux2Stream *stream);
 
 gboolean gst_adaptive_demux2_stream_has_next_fragment (GstAdaptiveDemux2Stream * stream);
 GstFlowReturn gst_adaptive_demux2_stream_seek (GstAdaptiveDemux2Stream * stream,

subprojects/gst-plugins-good/ext/adaptivedemux2/gstadaptivedemux-stream.c

@@ -1759,6 +1759,46 @@ gst_adaptive_demux2_stream_on_manifest_update (GstAdaptiveDemux2Stream * stream)
       gst_object_ref (stream), (GDestroyNotify) gst_object_unref);
 }
 
+void
+gst_adaptive_demux2_stream_on_can_download_fragments (GstAdaptiveDemux2Stream *
+    stream)
+{
+  GstAdaptiveDemux *demux = stream->demux;
+
+  if (stream->state != GST_ADAPTIVE_DEMUX2_STREAM_STATE_WAITING_BEFORE_DOWNLOAD)
+    return;
+
+  g_assert (stream->pending_cb_id == 0);
+
+  GST_LOG_OBJECT (stream, "Scheduling load_a_fragment() call");
+  stream->pending_cb_id =
+      gst_adaptive_demux_loop_call (demux->priv->scheduler_task,
+      (GSourceFunc) gst_adaptive_demux2_stream_load_a_fragment,
+      gst_object_ref (stream), (GDestroyNotify) gst_object_unref);
+}
+
+/*
+ * Called by a subclass that has returned GST_ADAPTIVE_DEMUX_FLOW_BUSY
+ * from update_fragment_info() to indicate that it is ready to continue
+ * downloading now.
+ */
+void
+gst_adaptive_demux2_stream_mark_prepared (GstAdaptiveDemux2Stream * stream)
+{
+  GstAdaptiveDemux *demux = stream->demux;
+
+  if (stream->state != GST_ADAPTIVE_DEMUX2_STREAM_STATE_WAITING_PREPARE)
+    return;
+
+  g_assert (stream->pending_cb_id == 0);
+
+  GST_LOG_OBJECT (stream, "Scheduling load_a_fragment() call");
+  stream->pending_cb_id =
+      gst_adaptive_demux_loop_call (demux->priv->scheduler_task,
+      (GSourceFunc) gst_adaptive_demux2_stream_load_a_fragment,
+      gst_object_ref (stream), (GDestroyNotify) gst_object_unref);
+}
+
 static void
 gst_adaptive_demux2_stream_handle_playlist_eos (GstAdaptiveDemux2Stream *
     stream)
@@ -1800,9 +1840,11 @@ gst_adaptive_demux2_stream_load_a_fragment (GstAdaptiveDemux2Stream * stream)
   switch (stream->state) {
     case GST_ADAPTIVE_DEMUX2_STREAM_STATE_RESTART:
     case GST_ADAPTIVE_DEMUX2_STREAM_STATE_START_FRAGMENT:
+    case GST_ADAPTIVE_DEMUX2_STREAM_STATE_WAITING_PREPARE:
     case GST_ADAPTIVE_DEMUX2_STREAM_STATE_WAITING_LIVE:
     case GST_ADAPTIVE_DEMUX2_STREAM_STATE_WAITING_OUTPUT_SPACE:
     case GST_ADAPTIVE_DEMUX2_STREAM_STATE_WAITING_MANIFEST_UPDATE:
+    case GST_ADAPTIVE_DEMUX2_STREAM_STATE_WAITING_BEFORE_DOWNLOAD:
       /* Get information about the fragment to download */
       GST_DEBUG_OBJECT (demux, "Calling update_fragment_info");
       ret = gst_adaptive_demux2_stream_update_fragment_info (stream);
@@ -1827,6 +1869,13 @@ gst_adaptive_demux2_stream_load_a_fragment (GstAdaptiveDemux2Stream * stream)
       break;
   }
 
+  if (ret == GST_ADAPTIVE_DEMUX_FLOW_BUSY) {
+    GST_LOG_OBJECT (stream,
+        "Sub-class returned BUSY flow return. Waiting in PREPARE state");
+    stream->state = GST_ADAPTIVE_DEMUX2_STREAM_STATE_WAITING_PREPARE;
+    return FALSE;
+  }
+
   if (ret == GST_FLOW_OK) {
     /* Wait for room in the output tracks */
     if (gst_adaptive_demux2_stream_wait_for_output_space (demux, stream,
@@ -1857,10 +1906,12 @@ gst_adaptive_demux2_stream_load_a_fragment (GstAdaptiveDemux2Stream * stream)
         return FALSE;
       }
     }
+  }
 
-    if (gst_adaptive_demux2_stream_download_fragment (stream) != GST_FLOW_OK) {
-      GST_ERROR_OBJECT (demux,
-          "Failed to begin fragment download for stream %p", stream);
+  if (ret == GST_FLOW_OK) {
+    if (!demux->priv->streams_can_download_fragments) {
+      GST_LOG_OBJECT (stream, "Waiting for fragment downloads to be unblocked");
+      stream->state = GST_ADAPTIVE_DEMUX2_STREAM_STATE_WAITING_BEFORE_DOWNLOAD;
       return FALSE;
     }
   }
@@ -1869,7 +1920,13 @@ gst_adaptive_demux2_stream_load_a_fragment (GstAdaptiveDemux2Stream * stream)
    * GST_ADAPTIVE_DEMUX_FLOW_LOST_SYNC is not in the GstFlowReturn enum */
   switch ((int) ret) {
     case GST_FLOW_OK:
-      break;                    /* all is good, let's go */
+      /* all is good, let's go */
+      if (gst_adaptive_demux2_stream_download_fragment (stream) != GST_FLOW_OK) {
+        GST_ERROR_OBJECT (demux,
+            "Failed to begin fragment download for stream %p", stream);
+        return FALSE;
+      }
+      break;
     case GST_FLOW_EOS:
       GST_DEBUG_OBJECT (stream, "EOS, checking to stop download loop");
       stream->last_ret = ret;

subprojects/gst-plugins-good/ext/adaptivedemux2/gstadaptivedemux-stream.h

@@ -82,9 +82,11 @@ enum _GstAdaptiveDemux2StreamState {
   GST_ADAPTIVE_DEMUX2_STREAM_STATE_STOPPED, /* Stream was stopped */
   GST_ADAPTIVE_DEMUX2_STREAM_STATE_RESTART, /* Stream stopped but needs restart logic */
   GST_ADAPTIVE_DEMUX2_STREAM_STATE_START_FRAGMENT,
+  GST_ADAPTIVE_DEMUX2_STREAM_STATE_WAITING_PREPARE, /* Sub-class is busy and can't update_fragment_info() yet */
   GST_ADAPTIVE_DEMUX2_STREAM_STATE_WAITING_LIVE,
   GST_ADAPTIVE_DEMUX2_STREAM_STATE_WAITING_OUTPUT_SPACE,
   GST_ADAPTIVE_DEMUX2_STREAM_STATE_WAITING_MANIFEST_UPDATE,
+  GST_ADAPTIVE_DEMUX2_STREAM_STATE_WAITING_BEFORE_DOWNLOAD, /* Ready, but not allowed to download yet */
   GST_ADAPTIVE_DEMUX2_STREAM_STATE_DOWNLOADING,
   GST_ADAPTIVE_DEMUX2_STREAM_STATE_EOS,
   GST_ADAPTIVE_DEMUX2_STREAM_STATE_ERRORED
@@ -101,8 +103,9 @@ struct _GstAdaptiveDemux2StreamClass
    * Requests the stream to set the information about the current fragment to its
    * current fragment struct
    *
-   * Returns: #GST_FLOW_OK in success, #GST_FLOW_ERROR on error and #GST_FLOW_EOS
-   *          if there is no fragment.
+   * Returns: #GST_FLOW_OK in success, #GST_FLOW_ERROR on error, #GST_FLOW_EOS
+   *          if there is no fragment, or the custom GST_ADAPTIVE_DEMUX_FLOW_BUSY
+   *          if the sub-class is still preparing.
    */
   GstFlowReturn (*update_fragment_info) (GstAdaptiveDemux2Stream * stream);
 
@@ -360,6 +363,8 @@ GstFlowReturn gst_adaptive_demux2_stream_advance_fragment (GstAdaptiveDemux2Stre
 gboolean gst_adaptive_demux2_stream_handle_collection (GstAdaptiveDemux2Stream *stream,
     GstStreamCollection *collection, gboolean *had_pending_tracks);
 
+void gst_adaptive_demux2_stream_mark_prepared(GstAdaptiveDemux2Stream *stream);
+
 void gst_adaptive_demux2_stream_fragment_clear (GstAdaptiveDemux2StreamFragment * f);
 
 G_END_DECLS

subprojects/gst-plugins-good/ext/adaptivedemux2/gstadaptivedemux.c

@@ -804,6 +804,41 @@ gst_adaptive_demux_output_slot_new (GstAdaptiveDemux * demux,
   return slot;
 }
 
+static gboolean
+gst_adaptive_demux_scheduler_unblock_fragment_downloads_cb (GstAdaptiveDemux *
+    demux)
+{
+  GList *iter;
+
+  GST_INFO_OBJECT (demux, "Unblocking streams' fragment downloads");
+  demux->priv->streams_can_download_fragments = TRUE;
+
+  iter = demux->input_period->streams;
+
+  for (; iter; iter = g_list_next (iter)) {
+    GstAdaptiveDemux2Stream *stream = iter->data;
+    gst_adaptive_demux2_stream_on_can_download_fragments (stream);
+  }
+
+  return FALSE;
+}
+
+/* must be called with the scheduler lock */
+static void
+gst_adaptive_demux_set_streams_can_download_fragments (GstAdaptiveDemux * demux,
+    gboolean streams_can_download_fragments)
+{
+  if (streams_can_download_fragments) {
+    gst_adaptive_demux_loop_call (demux->priv->scheduler_task, (GSourceFunc)
+        gst_adaptive_demux_scheduler_unblock_fragment_downloads_cb, demux,
+        NULL);
+  } else {
+    demux->priv->streams_can_download_fragments =
+        streams_can_download_fragments;
+  }
+
+}
+
 /* Called:
  * * After `process_manifest` or when a period starts
  * * Or when all tracks have been created
@@ -1020,6 +1055,8 @@ handle_incoming_manifest (GstAdaptiveDemux * demux)
 
   gst_adaptive_demux_prepare_streams (demux,
       gst_adaptive_demux_is_live (demux));
+
+  gst_adaptive_demux_set_streams_can_download_fragments (demux, TRUE);
   gst_adaptive_demux_start_tasks (demux);
   gst_adaptive_demux_start_manifest_update_task (demux);
 
@@ -3711,7 +3748,7 @@ gst_adaptive_demux_has_next_period (GstAdaptiveDemux * demux)
   return ret;
 }
 
-/* must be called with manifest_lock taken */
+/* must be called from the scheduler task */
 void
 gst_adaptive_demux_advance_period (GstAdaptiveDemux * demux)
 {