decoder: use an array of units instead of a single-linked list.

Use a GArray to hold decoder units in a frame, instead of a single-linked
list. This makes 'append' calls faster, but not that much. At least, this
makes things clearer.

gst-libs/gst/vaapi/gstvaapidecoder.c

@@ -62,6 +62,11 @@ parser_state_finalize(GstVaapiParserState *ps)
         g_object_unref(ps->output_adapter);
         ps->output_adapter = NULL;
     }
+
+    if (ps->next_unit_pending) {
+        gst_vaapi_decoder_unit_clear(&ps->next_unit);
+        ps->next_unit_pending = FALSE;
+    }
 }
 
 static gboolean
@@ -77,22 +82,6 @@ parser_state_init(GstVaapiParserState *ps)
     return TRUE;
 }
 
-static inline GstVaapiDecoderUnit *
-parser_state_get_pending_unit(GstVaapiParserState *ps, GstAdapter *adapter)
-{
-    GstVaapiDecoderUnit * const unit = ps->pending_unit;
-
-    ps->pending_unit = NULL;
-    return unit;
-}
-
-static inline void
-parser_state_set_pending_unit(GstVaapiParserState *ps,
-    GstAdapter *adapter, GstVaapiDecoderUnit *unit)
-{
-    ps->pending_unit = unit;
-}
-
 static void
 parser_state_prepare(GstVaapiParserState *ps, GstAdapter *adapter)
 {
@@ -150,7 +139,6 @@ do_parse(GstVaapiDecoder *decoder,
     GstVaapiDecoderFrame *frame;
     GstVaapiDecoderUnit *unit;
     GstVaapiDecoderStatus status;
-    GSList **unit_list_ptr;
 
     *got_unit_size_ptr = 0;
     *got_frame_ptr = FALSE;
@@ -166,60 +154,42 @@ do_parse(GstVaapiDecoder *decoder,
 
     parser_state_prepare(ps, adapter);
 
-    unit = parser_state_get_pending_unit(ps, adapter);
-    if (unit)
+    unit = &ps->next_unit;
+    if (ps->next_unit_pending) {
+        ps->next_unit_pending = FALSE;
         goto got_unit;
-
-    unit = gst_vaapi_decoder_unit_new();
-    if (!unit)
-        return GST_VAAPI_DECODER_STATUS_ERROR_ALLOCATION_FAILED;
+    }
+    gst_vaapi_decoder_unit_init(unit);
 
     ps->current_frame = base_frame;
     status = GST_VAAPI_DECODER_GET_CLASS(decoder)->parse(decoder,
         adapter, at_eos, unit);
-    if (status != GST_VAAPI_DECODER_STATUS_SUCCESS) {
-        if (unit)
-            gst_vaapi_decoder_unit_unref(unit);
+    if (status != GST_VAAPI_DECODER_STATUS_SUCCESS)
         return status;
-    }
 
-    if (GST_VAAPI_DECODER_UNIT_IS_FRAME_START(unit) && frame->units) {
-        parser_state_set_pending_unit(ps, adapter, unit);
-        goto got_frame;
+    if (GST_VAAPI_DECODER_UNIT_IS_FRAME_START(unit) && frame->units->len > 0) {
+        ps->next_unit_pending = TRUE;
+        *got_frame_ptr = TRUE;
+        return GST_VAAPI_DECODER_STATUS_SUCCESS;
     }
 
 got_unit:
-    unit->offset = frame->output_offset;
-    frame->output_offset += unit->size;
-
-    if (GST_VAAPI_DECODER_UNIT_IS_SLICE(unit))
-        unit_list_ptr = &frame->units;
-    else if (GST_VAAPI_DECODER_UNIT_IS_FRAME_END(unit))
-        unit_list_ptr = &frame->post_units;
-    else
-        unit_list_ptr = &frame->pre_units;
-    *unit_list_ptr = g_slist_prepend(*unit_list_ptr, unit);
-
+    gst_vaapi_decoder_frame_append_unit(frame, unit);
     *got_unit_size_ptr = unit->size;
-    if (GST_VAAPI_DECODER_UNIT_IS_FRAME_END(unit)) {
-    got_frame:
-        frame->units      = g_slist_reverse(frame->units);
-        frame->pre_units  = g_slist_reverse(frame->pre_units);
-        frame->post_units = g_slist_reverse(frame->post_units);
-        *got_frame_ptr    = TRUE;
-    }
+    *got_frame_ptr = GST_VAAPI_DECODER_UNIT_IS_FRAME_END(unit);
     return GST_VAAPI_DECODER_STATUS_SUCCESS;
 }
 
 static GstVaapiDecoderStatus
-do_decode_list(GstVaapiDecoder *decoder, GSList *units)
+do_decode_units(GstVaapiDecoder *decoder, GArray *units)
 {
     GstVaapiDecoderClass * const klass = GST_VAAPI_DECODER_GET_CLASS(decoder);
     GstVaapiDecoderStatus status;
-    GSList *l;
+    guint i;
 
-    for (l = units; l != NULL; l = l->next) {
-        GstVaapiDecoderUnit * const unit = l->data;
+    for (i = 0; i < units->len; i++) {
+        GstVaapiDecoderUnit * const unit =
+            &g_array_index(units, GstVaapiDecoderUnit, i);
         if (GST_VAAPI_DECODER_UNIT_IS_SKIPPED(unit))
             continue;
         status = klass->decode(decoder, unit);
@@ -230,29 +200,27 @@ do_decode_list(GstVaapiDecoder *decoder, GSList *units)
 }
 
 static GstVaapiDecoderStatus
-do_decode(GstVaapiDecoder *decoder, GstVideoCodecFrame *base_frame)
+do_decode_1(GstVaapiDecoder *decoder, GstVaapiDecoderFrame *frame)
 {
     GstVaapiDecoderClass * const klass = GST_VAAPI_DECODER_GET_CLASS(decoder);
-    GstVaapiParserState * const ps = &decoder->priv->parser_state;
-    GstVaapiDecoderFrame * const frame = base_frame->user_data;
     GstVaapiDecoderStatus status;
 
-    ps->current_frame = base_frame;
-
-    if (frame->pre_units) {
-        status = do_decode_list(decoder, frame->pre_units);
+    if (frame->pre_units->len > 0) {
+        status = do_decode_units(decoder, frame->pre_units);
         if (status != GST_VAAPI_DECODER_STATUS_SUCCESS)
             return status;
     }
 
-    if (frame->units) {
+    if (frame->units->len > 0) {
         if (klass->start_frame) {
-            status = klass->start_frame(decoder, frame->units->data);
+            GstVaapiDecoderUnit * const unit =
+                &g_array_index(frame->units, GstVaapiDecoderUnit, 0);
+            status = klass->start_frame(decoder, unit);
             if (status != GST_VAAPI_DECODER_STATUS_SUCCESS)
                 return status;
         }
 
-        status = do_decode_list(decoder, frame->units);
+        status = do_decode_units(decoder, frame->units);
         if (status != GST_VAAPI_DECODER_STATUS_SUCCESS)
             return status;
 
@@ -263,14 +231,29 @@ do_decode(GstVaapiDecoder *decoder, GstVideoCodecFrame *base_frame)
         }
     }
 
-    if (frame->post_units) {
-        status = do_decode_list(decoder, frame->post_units);
+    if (frame->post_units->len > 0) {
+        status = do_decode_units(decoder, frame->post_units);
         if (status != GST_VAAPI_DECODER_STATUS_SUCCESS)
             return status;
     }
     return GST_VAAPI_DECODER_STATUS_SUCCESS;
 }
 
+static inline GstVaapiDecoderStatus
+do_decode(GstVaapiDecoder *decoder, GstVideoCodecFrame *base_frame)
+{
+    GstVaapiParserState * const ps = &decoder->priv->parser_state;
+    GstVaapiDecoderFrame * const frame = base_frame->user_data;
+    GstVaapiDecoderStatus status;
+
+    ps->current_frame = base_frame;
+
+    gst_vaapi_decoder_frame_ref(frame);
+    status = do_decode_1(decoder, frame);
+    gst_vaapi_decoder_frame_unref(frame);
+    return status;
+}
+
 static GstVaapiDecoderStatus
 decode_step(GstVaapiDecoder *decoder)
 {

gst-libs/gst/vaapi/gstvaapidecoder_frame.c

@@ -37,13 +37,29 @@ gst_vaapi_decoder_frame_class(void)
     return &GstVaapiDecoderFrameClass;
 }
 
-static inline void
-free_units(GSList **units_ptr)
+static inline gboolean
+alloc_units(GArray **units_ptr, guint size)
 {
-    GSList * const units = *units_ptr;
+    GArray *units;
+
+    units = g_array_sized_new(FALSE, FALSE, sizeof(GstVaapiDecoderUnit), size);
+    *units_ptr = units;
+    return units != NULL;
+}
+
+static inline void
+free_units(GArray **units_ptr)
+{
+    GArray * const units = *units_ptr;
+    guint i;
 
     if (units) {
-        g_slist_free_full(units, (GDestroyNotify)gst_vaapi_mini_object_unref);
+        for (i = 0; i < units->len; i++) {
+            GstVaapiDecoderUnit * const unit =
+                &g_array_index(units, GstVaapiDecoderUnit, i);
+            gst_vaapi_decoder_unit_clear(unit);
+        }
+        g_array_free(units, TRUE);
         *units_ptr = NULL;
     }
 }
@@ -58,8 +74,25 @@ free_units(GSList **units_ptr)
 GstVaapiDecoderFrame *
 gst_vaapi_decoder_frame_new(void)
 {
-    return (GstVaapiDecoderFrame *)
-        gst_vaapi_mini_object_new0(gst_vaapi_decoder_frame_class());
+    GstVaapiDecoderFrame *frame;
+
+    frame = (GstVaapiDecoderFrame *)
+        gst_vaapi_mini_object_new(gst_vaapi_decoder_frame_class());
+    if (!frame)
+        return NULL;
+
+    if (!alloc_units(&frame->pre_units, 4))
+        goto error;
+    if (!alloc_units(&frame->units, 1))
+        goto error;
+    if (!alloc_units(&frame->post_units, 1))
+        goto error;
+    frame->output_offset = 0;
+    return frame;
+
+error:
+    gst_vaapi_decoder_frame_unref(frame);
+    return NULL;
 }
 
 /**
@@ -79,3 +112,28 @@ gst_vaapi_decoder_frame_free(GstVaapiDecoderFrame *frame)
     free_units(&frame->pre_units);
     free_units(&frame->post_units);
 }
+
+/**
+ * gst_vaapi_decoder_frame_append_unit:
+ * @frame: a #GstVaapiDecoderFrame
+ * @unit: a #GstVaapiDecoderUnit
+ *
+ * Appends unit to the @frame.
+ */
+void
+gst_vaapi_decoder_frame_append_unit(GstVaapiDecoderFrame *frame,
+    GstVaapiDecoderUnit *unit)
+{
+    GArray **unit_array_ptr;
+
+    unit->offset = frame->output_offset;
+    frame->output_offset += unit->size;
+
+    if (GST_VAAPI_DECODER_UNIT_IS_SLICE(unit))
+        unit_array_ptr = &frame->units;
+    else if (GST_VAAPI_DECODER_UNIT_IS_FRAME_END(unit))
+        unit_array_ptr = &frame->post_units;
+    else
+        unit_array_ptr = &frame->pre_units;
+    g_array_append_val(*unit_array_ptr, *unit);
+}

gst-libs/gst/vaapi/gstvaapidecoder_frame.h

@@ -69,9 +69,9 @@ struct _GstVaapiDecoderFrame {
     GstVaapiMiniObject   parent_instance;
 
     guint                output_offset;
-    GSList              *units;
-    GSList              *pre_units;
-    GSList              *post_units;
+    GArray              *units;
+    GArray              *pre_units;
+    GArray              *post_units;
 };
 
 G_GNUC_INTERNAL
@@ -82,6 +82,11 @@ G_GNUC_INTERNAL
 void
 gst_vaapi_decoder_frame_free(GstVaapiDecoderFrame *frame);
 
+G_GNUC_INTERNAL
+void
+gst_vaapi_decoder_frame_append_unit(GstVaapiDecoderFrame *frame,
+    GstVaapiDecoderUnit *unit);
+
 #define gst_vaapi_decoder_frame_ref(frame) \
     gst_vaapi_mini_object_ref(GST_VAAPI_MINI_OBJECT(frame))
 

gst-libs/gst/vaapi/gstvaapidecoder_priv.h

@@ -152,7 +152,8 @@ struct _GstVaapiParserState {
     GstAdapter         *input_adapter;
     gint                input_offset2;
     GstAdapter         *output_adapter;
-    GstVaapiDecoderUnit *pending_unit;
+    GstVaapiDecoderUnit next_unit;
+    gboolean            next_unit_pending;
 };
 
 struct _GstVaapiDecoderPrivate {

gst-libs/gst/vaapi/gstvaapidecoder_unit.c

@@ -55,6 +55,8 @@ decoder_unit_init(GstVaapiDecoderUnit *unit)
 
     unit->parsed_info = NULL;
     unit->parsed_info_destroy_notify = NULL;
+
+    GST_VAAPI_DECODER_UNIT_FLAGS(unit) = 0;
 }
 
 void