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Introduce SerializedDisplayItem to reduce mem copies on DL construction #3361

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Merged
merged 1 commit into from
Nov 27, 2018
Merged

Introduce SerializedDisplayItem to reduce mem copies on DL construction #3361

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9 changes: 9 additions & 0 deletions webrender_api/src/display_item.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -66,6 +66,15 @@ pub struct GenericDisplayItem<T> {

pub type DisplayItem = GenericDisplayItem<SpecificDisplayItem>;

/// A modified version of DI where every field is borrowed instead of owned.
/// It allows us to reduce copies during serialization.
#[derive(Serialize)]
pub struct SerializedDisplayItem<'a> {
pub item: &'a SpecificDisplayItem,
pub clip_and_scroll: &'a ClipAndScrollInfo,
pub info: &'a LayoutPrimitiveInfo,
}

#[derive(Clone, Copy, Debug, Deserialize, PartialEq, Serialize)]
pub struct PrimitiveInfo<T> {
pub rect: TypedRect<f32, T>,
Expand Down
95 changes: 41 additions & 54 deletions webrender_api/src/display_list.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -23,8 +23,9 @@ use {ImageRendering, LayoutPoint, LayoutPrimitiveInfo, LayoutRect, LayoutSideOff
use {LayoutTransform, LayoutVector2D, LineDisplayItem, LineOrientation, LineStyle, MixBlendMode};
use {PipelineId, PropertyBinding, PushReferenceFrameDisplayListItem};
use {PushStackingContextDisplayItem, RadialGradient, RadialGradientDisplayItem};
use {RectangleDisplayItem, ReferenceFrame, ScrollFrameDisplayItem, ScrollSensitivity, Shadow};
use {SpecificDisplayItem, StackingContext, StickyFrameDisplayItem, StickyOffsetBounds};
use {RectangleDisplayItem, ReferenceFrame, ScrollFrameDisplayItem, ScrollSensitivity};
use {SerializedDisplayItem, Shadow, SpecificDisplayItem};
use {StackingContext, StickyFrameDisplayItem, StickyOffsetBounds};
use {TextDisplayItem, TransformStyle, YuvColorSpace, YuvData, YuvImageDisplayItem, ColorDepth};

// We don't want to push a long text-run. If a text-run is too long, split it into several parts.
Expand Down Expand Up @@ -691,16 +692,16 @@ impl<'a> Write for SizeCounter {
/// If this assumption is incorrect, the result will be Undefined Behaviour. This
/// assumption should hold for all derived Serialize impls, which is all we currently
/// use.
fn serialize_fast<T: Serialize>(vec: &mut Vec<u8>, e: &T) {
fn serialize_fast<T: Serialize>(vec: &mut Vec<u8>, e: T) {
// manually counting the size is faster than vec.reserve(bincode::serialized_size(&e) as usize) for some reason
let mut size = SizeCounter(0);
bincode::serialize_into(&mut size, e).unwrap();
bincode::serialize_into(&mut size, &e).unwrap();
vec.reserve(size.0);

let old_len = vec.len();
let ptr = unsafe { vec.as_mut_ptr().add(old_len) };
let mut w = UnsafeVecWriter(ptr);
bincode::serialize_into(&mut w, e).unwrap();
bincode::serialize_into(&mut w, &e).unwrap();

// fix up the length
unsafe { vec.set_len(old_len + size.0); }
Expand Down Expand Up @@ -964,43 +965,36 @@ impl DisplayListBuilder {
/// NOTE: It is usually preferable to use the specialized methods to push
/// display items. Pushing unexpected or invalid items here may
/// result in WebRender panicking or behaving in unexpected ways.
pub fn push_item(&mut self, item: SpecificDisplayItem, info: &LayoutPrimitiveInfo) {
pub fn push_item(&mut self, item: &SpecificDisplayItem, info: &LayoutPrimitiveInfo) {
serialize_fast(
&mut self.data,
&DisplayItem {
SerializedDisplayItem {
item,
clip_and_scroll: *self.clip_stack.last().unwrap(),
info: *info,
clip_and_scroll: self.clip_stack.last().unwrap(),
info,
},
)
}

fn push_item_with_clip_scroll_info(
&mut self,
item: SpecificDisplayItem,
item: &SpecificDisplayItem,
info: &LayoutPrimitiveInfo,
scrollinfo: ClipAndScrollInfo
clip_and_scroll: &ClipAndScrollInfo
) {
serialize_fast(
&mut self.data,
&DisplayItem {
SerializedDisplayItem {
item,
clip_and_scroll: scrollinfo,
info: *info,
clip_and_scroll,
info,
},
)
}

fn push_new_empty_item(&mut self, item: SpecificDisplayItem, clip_and_scroll: &ClipAndScrollInfo) {
let info = LayoutPrimitiveInfo::new(LayoutRect::zero());
serialize_fast(
&mut self.data,
&DisplayItem {
item,
clip_and_scroll: *clip_and_scroll,
info,
}
)
fn push_new_empty_item(&mut self, item: &SpecificDisplayItem) {
let info = &LayoutPrimitiveInfo::new(LayoutRect::zero());
self.push_item(item, info)
}

fn push_iter_impl<I>(data: &mut Vec<u8>, iter_source: I)
Expand Down Expand Up @@ -1050,11 +1044,11 @@ impl DisplayListBuilder {

pub fn push_rect(&mut self, info: &LayoutPrimitiveInfo, color: ColorF) {
let item = SpecificDisplayItem::Rectangle(RectangleDisplayItem { color });
self.push_item(item, info);
self.push_item(&item, info);
}

pub fn push_clear_rect(&mut self, info: &LayoutPrimitiveInfo) {
self.push_item(SpecificDisplayItem::ClearRectangle, info);
self.push_item(&SpecificDisplayItem::ClearRectangle, info);
}

pub fn push_line(
Expand All @@ -1072,7 +1066,7 @@ impl DisplayListBuilder {
style,
});

self.push_item(item, info);
self.push_item(&item, info);
}

pub fn push_image(
Expand All @@ -1094,7 +1088,7 @@ impl DisplayListBuilder {
color,
});

self.push_item(item, info);
self.push_item(&item, info);
}

/// Push a yuv image. All planar data in yuv image should use the same buffer type.
Expand All @@ -1112,7 +1106,7 @@ impl DisplayListBuilder {
color_space,
image_rendering,
});
self.push_item(item, info);
self.push_item(&item, info);
}

pub fn push_text(
Expand All @@ -1130,7 +1124,7 @@ impl DisplayListBuilder {
});

for split_glyphs in glyphs.chunks(MAX_TEXT_RUN_LENGTH) {
self.push_item(item, info);
self.push_item(&item, info);
self.push_iter(split_glyphs);
}
}
Expand Down Expand Up @@ -1173,7 +1167,7 @@ impl DisplayListBuilder {
) {
let item = SpecificDisplayItem::Border(BorderDisplayItem { details, widths });

self.push_item(item, info);
self.push_item(&item, info);
}

pub fn push_box_shadow(
Expand All @@ -1197,7 +1191,7 @@ impl DisplayListBuilder {
clip_mode,
});

self.push_item(item, info);
self.push_item(&item, info);
}

/// Pushes a linear gradient to be displayed.
Expand Down Expand Up @@ -1227,7 +1221,7 @@ impl DisplayListBuilder {
tile_spacing,
});

self.push_item(item, info);
self.push_item(&item, info);
}

/// Pushes a radial gradient to be displayed.
Expand All @@ -1246,7 +1240,7 @@ impl DisplayListBuilder {
tile_spacing,
});

self.push_item(item, info);
self.push_item(&item, info);
}

pub fn push_reference_frame(
Expand All @@ -1263,13 +1257,12 @@ impl DisplayListBuilder {
id,
},
});
self.push_item(item, info);
self.push_item(&item, info);
id
}

pub fn pop_reference_frame(&mut self) {
let clip_and_scroll = *self.clip_stack.last().unwrap();
self.push_new_empty_item(SpecificDisplayItem::PopReferenceFrame, &clip_and_scroll);
self.push_new_empty_item(&SpecificDisplayItem::PopReferenceFrame);
}

pub fn push_stacking_context(
Expand All @@ -1290,21 +1283,19 @@ impl DisplayListBuilder {
},
});

self.push_item(item, info);
self.push_item(&item, info);
self.push_iter(filters);
}

pub fn pop_stacking_context(&mut self) {
let clip_and_scroll = *self.clip_stack.last().unwrap();
self.push_new_empty_item(SpecificDisplayItem::PopStackingContext, &clip_and_scroll);
self.push_new_empty_item(&SpecificDisplayItem::PopStackingContext);
}

pub fn push_stops(&mut self, stops: &[GradientStop]) {
if stops.is_empty() {
return;
}
let clip_and_scroll = *self.clip_stack.last().unwrap();
self.push_new_empty_item(SpecificDisplayItem::SetGradientStops, &clip_and_scroll);
self.push_new_empty_item(&SpecificDisplayItem::SetGradientStops);
self.push_iter(stops);
}

Expand Down Expand Up @@ -1372,9 +1363,9 @@ impl DisplayListBuilder {
});

self.push_item_with_clip_scroll_info(
item,
&item,
&LayoutPrimitiveInfo::with_clip_rect(content_rect, clip_rect),
ClipAndScrollInfo::simple(parent),
&ClipAndScrollInfo::simple(parent),
);
self.push_iter(complex_clips);

Expand All @@ -1391,8 +1382,7 @@ impl DisplayListBuilder {
I::IntoIter: ExactSizeIterator + Clone,
{
let id = self.generate_clip_chain_id();
let clip_and_scroll = *self.clip_stack.last().unwrap();
self.push_new_empty_item(SpecificDisplayItem::ClipChain(ClipChainItem { id, parent }), &clip_and_scroll);
self.push_new_empty_item(&SpecificDisplayItem::ClipChain(ClipChainItem { id, parent }));
self.push_iter(clips);
id
}
Expand Down Expand Up @@ -1454,7 +1444,7 @@ impl DisplayListBuilder {

let info = LayoutPrimitiveInfo::new(clip_rect);

self.push_item_with_clip_scroll_info(item, &info, scrollinfo);
self.push_item_with_clip_scroll_info(&item, &info, &scrollinfo);
self.push_iter(complex_clips);
id
}
Expand All @@ -1477,7 +1467,7 @@ impl DisplayListBuilder {
});

let info = LayoutPrimitiveInfo::new(frame_rect);
self.push_item(item, &info);
self.push_item(&item, &info);
id
}

Expand Down Expand Up @@ -1509,24 +1499,21 @@ impl DisplayListBuilder {
pipeline_id,
ignore_missing_pipeline,
});
self.push_item(item, info);
self.push_item(&item, info);
}

pub fn push_shadow(&mut self, info: &LayoutPrimitiveInfo, shadow: Shadow) {
self.push_item(SpecificDisplayItem::PushShadow(shadow), info);
self.push_item(&SpecificDisplayItem::PushShadow(shadow), info);
}

pub fn pop_all_shadows(&mut self) {
let clip_and_scroll = *self.clip_stack.last().unwrap();
self.push_new_empty_item(SpecificDisplayItem::PopAllShadows, &clip_and_scroll);
self.push_new_empty_item(&SpecificDisplayItem::PopAllShadows);
}

pub fn finalize(self) -> (PipelineId, LayoutSize, BuiltDisplayList) {
assert!(self.save_state.is_none(), "Finalized DisplayListBuilder with a pending save");

let end_time = precise_time_ns();


(
self.pipeline_id,
self.content_size,
Expand Down