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Make FlowRef a newtype

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This creates a sharp distinction between `Arc<Flow>`s, which may be
owned by anyone, and `FlowRef`s, which may only be owned by the
traversal code. By checking the reference count, we ensure that a `Flow`
cannot be pointed to by `Arc`s and `FlowRef`s simultaneously.

This is not a complete fix for #6503, though it is a necessary start
(enforcing the no-aliasing rule of `FlowRef::deref_mut` will require far
more work).

Fixes #14014
This commit is contained in:
Michael Howell 2016-11-03 12:53:27 -07:00
parent 5b4cc9568d
commit 5f320bd2ca
10 changed files with 145 additions and 101 deletions
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68
components/layout/construct.rs
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@ -22,7 +22,7 @@ use floats::FloatKind;
use flow::{self, AbsoluteDescendants, Flow, FlowClass, ImmutableFlowUtils};
use flow::{CAN_BE_FRAGMENTED, IS_ABSOLUTELY_POSITIONED, MARGINS_CANNOT_COLLAPSE};
use flow::{MutableFlowUtils, MutableOwnedFlowUtils};
use flow_ref::{self, FlowRef};
use flow_ref::FlowRef;
use fragment::{CanvasFragmentInfo, ImageFragmentInfo, InlineAbsoluteFragmentInfo, SvgFragmentInfo};
use fragment::{Fragment, GeneratedContentInfo, IframeFragmentInfo};
use fragment::{InlineAbsoluteHypotheticalFragmentInfo, TableColumnFragmentInfo};
@ -397,9 +397,9 @@ impl<'a, ConcreteThreadSafeLayoutNode: ThreadSafeLayoutNode>
let scanned_fragments =
TextRunScanner::new().scan_for_runs(&mut self.layout_context.font_context(),
fragments.fragments);
let mut inline_flow_ref: FlowRef =
Arc::new(InlineFlow::from_fragments(scanned_fragments,
node.style(self.style_context()).writing_mode));
let mut inline_flow_ref =
FlowRef::new(Arc::new(InlineFlow::from_fragments(scanned_fragments,
node.style(self.style_context()).writing_mode)));
// Add all the inline-block fragments as children of the inline flow.
for inline_block_flow in &inline_block_flows {
@ -423,7 +423,7 @@ impl<'a, ConcreteThreadSafeLayoutNode: ThreadSafeLayoutNode>
{
// FIXME(#6503): Use Arc::get_mut().unwrap() here.
let inline_flow = flow_ref::deref_mut(&mut inline_flow_ref).as_mut_inline();
let inline_flow = FlowRef::deref_mut(&mut inline_flow_ref).as_mut_inline();
inline_flow.minimum_line_metrics =
inline_flow.minimum_line_metrics(&mut self.layout_context.font_context(),
&node.style(self.style_context()))
@ -697,8 +697,8 @@ impl<'a, ConcreteThreadSafeLayoutNode: ThreadSafeLayoutNode>
}
let fragment = self.build_fragment_for_block(node);
let flow: FlowRef =
Arc::new(BlockFlow::from_fragment_and_float_kind(fragment, float_kind));
let flow =
FlowRef::new(Arc::new(BlockFlow::from_fragment_and_float_kind(fragment, float_kind)));
self.build_flow_for_block_like(flow, node)
}
@ -1023,10 +1023,10 @@ impl<'a, ConcreteThreadSafeLayoutNode: ThreadSafeLayoutNode>
float_kind: Option<FloatKind>)
-> ConstructionResult {
let fragment = Fragment::new(node, SpecificFragmentInfo::Multicol, self.layout_context);
let mut flow: FlowRef = Arc::new(MulticolFlow::from_fragment(fragment, float_kind));
let mut flow = FlowRef::new(Arc::new(MulticolFlow::from_fragment(fragment, float_kind)));
let column_fragment = Fragment::new(node, SpecificFragmentInfo::MulticolColumn, self.layout_context);
let column_flow = Arc::new(MulticolColumnFlow::from_fragment(column_fragment));
let column_flow = FlowRef::new(Arc::new(MulticolColumnFlow::from_fragment(column_fragment)));
// First populate the column flow with its children.
let construction_result = self.build_flow_for_block_like(column_flow, node);
@ -1078,12 +1078,12 @@ impl<'a, ConcreteThreadSafeLayoutNode: ThreadSafeLayoutNode>
node.restyle_damage(),
SpecificFragmentInfo::TableWrapper);
let wrapper_float_kind = FloatKind::from_property(float_value);
let mut wrapper_flow: FlowRef =
Arc::new(TableWrapperFlow::from_fragment_and_float_kind(wrapper_fragment,
wrapper_float_kind));
let mut wrapper_flow =
FlowRef::new(Arc::new(TableWrapperFlow::from_fragment_and_float_kind(wrapper_fragment,
wrapper_float_kind)));
let table_fragment = Fragment::new(node, SpecificFragmentInfo::Table, self.layout_context);
let table_flow = Arc::new(TableFlow::from_fragment(table_fragment));
let table_flow = FlowRef::new(Arc::new(TableFlow::from_fragment(table_fragment)));
// First populate the table flow with its children.
let construction_result = self.build_flow_for_block_like(table_flow, node);
@ -1134,7 +1134,7 @@ impl<'a, ConcreteThreadSafeLayoutNode: ThreadSafeLayoutNode>
/// with possibly other `BlockFlow`s or `InlineFlow`s underneath it.
fn build_flow_for_table_caption(&mut self, node: &ConcreteThreadSafeLayoutNode) -> ConstructionResult {
let fragment = self.build_fragment_for_block(node);
let flow = Arc::new(TableCaptionFlow::from_fragment(fragment));
let flow = FlowRef::new(Arc::new(TableCaptionFlow::from_fragment(fragment)));
self.build_flow_for_block_like(flow, node)
}
@ -1143,7 +1143,7 @@ impl<'a, ConcreteThreadSafeLayoutNode: ThreadSafeLayoutNode>
fn build_flow_for_table_rowgroup(&mut self, node: &ConcreteThreadSafeLayoutNode)
-> ConstructionResult {
let fragment = Fragment::new(node, SpecificFragmentInfo::TableRow, self.layout_context);
let flow = Arc::new(TableRowGroupFlow::from_fragment(fragment));
let flow = FlowRef::new(Arc::new(TableRowGroupFlow::from_fragment(fragment)));
self.build_flow_for_block_like(flow, node)
}
@ -1151,7 +1151,7 @@ impl<'a, ConcreteThreadSafeLayoutNode: ThreadSafeLayoutNode>
/// possibly other `TableCellFlow`s underneath it.
fn build_flow_for_table_row(&mut self, node: &ConcreteThreadSafeLayoutNode) -> ConstructionResult {
let fragment = Fragment::new(node, SpecificFragmentInfo::TableRow, self.layout_context);
let flow = Arc::new(TableRowFlow::from_fragment(fragment));
let flow = FlowRef::new(Arc::new(TableRowFlow::from_fragment(fragment)));
self.build_flow_for_block_like(flow, node)
}
@ -1171,8 +1171,8 @@ impl<'a, ConcreteThreadSafeLayoutNode: ThreadSafeLayoutNode>
position == position::T::fixed
});
let flow = Arc::new(
TableCellFlow::from_node_fragment_and_visibility_flag(node, fragment, !hide));
let flow = FlowRef::new(Arc::new(
TableCellFlow::from_node_fragment_and_visibility_flag(node, fragment, !hide)));
self.build_flow_for_block_like(flow, node)
}
@ -1236,7 +1236,7 @@ impl<'a, ConcreteThreadSafeLayoutNode: ThreadSafeLayoutNode>
}
};
self.build_flow_for_block_starting_with_fragments(flow, node, initial_fragments)
self.build_flow_for_block_starting_with_fragments(FlowRef::new(flow), node, initial_fragments)
}
/// Creates a fragment for a node with `display: table-column`.
@ -1276,7 +1276,7 @@ impl<'a, ConcreteThreadSafeLayoutNode: ThreadSafeLayoutNode>
let specific = SpecificFragmentInfo::TableColumn(TableColumnFragmentInfo::new(node));
col_fragments.push(Fragment::new(node, specific, self.layout_context));
}
let mut flow: FlowRef = Arc::new(TableColGroupFlow::from_fragments(fragment, col_fragments));
let mut flow = FlowRef::new(Arc::new(TableColGroupFlow::from_fragments(fragment, col_fragments)));
flow.finish();
ConstructionResult::Flow(flow, AbsoluteDescendants::new())
@ -1288,7 +1288,7 @@ impl<'a, ConcreteThreadSafeLayoutNode: ThreadSafeLayoutNode>
float_kind: Option<FloatKind>)
-> ConstructionResult {
let fragment = self.build_fragment_for_block(node);
let flow = Arc::new(FlexFlow::from_fragment(fragment, float_kind));
let flow = FlowRef::new(Arc::new(FlexFlow::from_fragment(fragment, float_kind)));
self.build_flow_for_block_like(flow, node)
}
@ -1345,7 +1345,7 @@ impl<'a, ConcreteThreadSafeLayoutNode: ThreadSafeLayoutNode>
return false
}
let flow = flow_ref::deref_mut(flow);
let flow = FlowRef::deref_mut(flow);
flow::mut_base(flow).restyle_damage.insert(damage);
flow.repair_style_and_bubble_inline_sizes(&style);
true
@ -1370,21 +1370,21 @@ impl<'a, ConcreteThreadSafeLayoutNode: ThreadSafeLayoutNode>
match fragment.specific {
SpecificFragmentInfo::InlineBlock(ref mut inline_block_fragment) => {
let flow_ref = flow_ref::deref_mut(&mut inline_block_fragment.flow_ref);
let flow_ref = FlowRef::deref_mut(&mut inline_block_fragment.flow_ref);
flow::mut_base(flow_ref).restyle_damage.insert(damage);
// FIXME(pcwalton): Fragment restyle damage too?
flow_ref.repair_style_and_bubble_inline_sizes(&style);
}
SpecificFragmentInfo::InlineAbsoluteHypothetical(
ref mut inline_absolute_hypothetical_fragment) => {
let flow_ref = flow_ref::deref_mut(
let flow_ref = FlowRef::deref_mut(
&mut inline_absolute_hypothetical_fragment.flow_ref);
flow::mut_base(flow_ref).restyle_damage.insert(damage);
// FIXME(pcwalton): Fragment restyle damage too?
flow_ref.repair_style_and_bubble_inline_sizes(&style);
}
SpecificFragmentInfo::InlineAbsolute(ref mut inline_absolute_fragment) => {
let flow_ref = flow_ref::deref_mut(
let flow_ref = FlowRef::deref_mut(
&mut inline_absolute_fragment.flow_ref);
flow::mut_base(flow_ref).restyle_damage.insert(damage);
// FIXME(pcwalton): Fragment restyle damage too?
@ -1631,7 +1631,7 @@ impl<ConcreteThreadSafeLayoutNode> NodeUtils for ConcreteThreadSafeLayoutNode
fn set_flow_construction_result(self, mut result: ConstructionResult) {
if self.can_be_fragmented() {
if let ConstructionResult::Flow(ref mut flow, _) = result {
flow::mut_base(flow_ref::deref_mut(flow)).flags.insert(CAN_BE_FRAGMENTED);
flow::mut_base(FlowRef::deref_mut(flow)).flags.insert(CAN_BE_FRAGMENTED);
}
}
@ -1703,11 +1703,11 @@ impl FlowConstructionUtils for FlowRef {
/// Adds a new flow as a child of this flow. Fails if this flow is marked as a leaf.
fn add_new_child(&mut self, mut new_child: FlowRef) {
{
let kid_base = flow::mut_base(flow_ref::deref_mut(&mut new_child));
let kid_base = flow::mut_base(FlowRef::deref_mut(&mut new_child));
kid_base.parallel.parent = parallel::mut_owned_flow_to_unsafe_flow(self);
}
let base = flow::mut_base(flow_ref::deref_mut(self));
let base = flow::mut_base(FlowRef::deref_mut(self));
base.children.push_back(new_child);
let _ = base.parallel.children_count.fetch_add(1, Ordering::Relaxed);
}
@ -1720,8 +1720,8 @@ impl FlowConstructionUtils for FlowRef {
/// properly computed. (This is not, however, a memory safety problem.)
fn finish(&mut self) {
if !opts::get().bubble_inline_sizes_separately {
flow_ref::deref_mut(self).bubble_inline_sizes();
flow::mut_base(flow_ref::deref_mut(self)).restyle_damage.remove(BUBBLE_ISIZES);
FlowRef::deref_mut(self).bubble_inline_sizes();
flow::mut_base(FlowRef::deref_mut(self)).restyle_damage.remove(BUBBLE_ISIZES);
}
}
}
@ -1921,14 +1921,14 @@ impl Legalizer {
}
(FlowClass::Flex, FlowClass::Inline) => {
flow::mut_base(flow_ref::deref_mut(child)).flags.insert(MARGINS_CANNOT_COLLAPSE);
flow::mut_base(FlowRef::deref_mut(child)).flags.insert(MARGINS_CANNOT_COLLAPSE);
let mut block_wrapper =
Legalizer::create_anonymous_flow(stylist,
parent,
&[PseudoElement::ServoAnonymousBlock],
SpecificFragmentInfo::Generic,
BlockFlow::from_fragment);
flow::mut_base(flow_ref::deref_mut(&mut
flow::mut_base(FlowRef::deref_mut(&mut
block_wrapper)).flags
.insert(MARGINS_CANNOT_COLLAPSE);
block_wrapper.add_new_child((*child).clone());
@ -1938,7 +1938,7 @@ impl Legalizer {
}
(FlowClass::Flex, _) => {
flow::mut_base(flow_ref::deref_mut(child)).flags.insert(MARGINS_CANNOT_COLLAPSE);
flow::mut_base(FlowRef::deref_mut(child)).flags.insert(MARGINS_CANNOT_COLLAPSE);
parent.add_new_child((*child).clone());
true
}
@ -2030,7 +2030,7 @@ impl Legalizer {
let fragment = reference_block.fragment
.create_similar_anonymous_fragment(new_style,
specific_fragment_info);
Arc::new(constructor(fragment))
FlowRef::new(Arc::new(constructor(fragment)))
}
}