Auto merge of #11804 - Ms2ger:layout-thread-crate, r=jdm

Introduce a layout_thread crate; drop the dependency of layout on script.

<!-- Reviewable:start -->
This change is [<img src="https://reviewable.io/review_button.svg" height="35" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/11804)
<!-- Reviewable:end -->

9 files changed, 191 insertions, 103 deletions

diff --git a/components/layout/Cargo.toml b/components/layout/Cargo.toml
index c6b1727d1d5..9800610d6bb 100644
--- a/components/layout/Cargo.toml
+++ b/components/layout/Cargo.toml
@@ -21,7 +21,6 @@ gfx_traits = {path = "../gfx_traits"}
 heapsize = "0.3.0"
 heapsize_plugin = "0.1.2"
 ipc-channel = {git = "https://github.com/servo/ipc-channel"}
-layout_traits = {path = "../layout_traits"}
 libc = "0.2"
 log = "0.3.5"
 msg = {path = "../msg"}
@@ -30,11 +29,9 @@ plugins = {path = "../plugins"}
 profile_traits = {path = "../profile_traits"}
 range = {path = "../range"}
 rustc-serialize = "0.3"
-script = {path = "../script"}
 script_layout_interface = {path = "../script_layout_interface"}
 script_traits = {path = "../script_traits"}
 selectors = {version = "0.6", features = ["heap_size"]}
-serde_json = "0.7"
 serde_macros = "0.7"
 smallvec = "0.1"
 string_cache = {version = "0.2.20", features = ["heap_size"]}
diff --git a/components/layout/block.rs b/components/layout/block.rs
index 9fc527d98d5..f02cd54d5b8 100644
--- a/components/layout/block.rs
+++ b/components/layout/block.rs
@@ -46,7 +46,6 @@ use fragment::{CoordinateSystem, Fragment, FragmentBorderBoxIterator, HAS_LAYER,
 use gfx::display_list::{ClippingRegion, StackingContext};
 use gfx_traits::{LayerId, StackingContextId};
 use layout_debug;
-use layout_thread::DISPLAY_PORT_SIZE_FACTOR;
 use model::{CollapsibleMargins, MaybeAuto, specified, specified_or_none};
 use model::{self, IntrinsicISizes, MarginCollapseInfo};
 use rustc_serialize::{Encodable, Encoder};
@@ -64,6 +63,9 @@ use style::values::computed::{LengthOrPercentage, LengthOrPercentageOrAuto};
 use util::geometry::MAX_RECT;
 use util::print_tree::PrintTree;
 
+/// The number of screens of data we're allowed to generate display lists for in each direction.
+const DISPLAY_PORT_SIZE_FACTOR: i32 = 8;
+
 /// Information specific to floated blocks.
 #[derive(Clone, RustcEncodable)]
 pub struct FloatedBlockInfo {
diff --git a/components/layout/lib.rs b/components/layout/lib.rs
index d1eb3cf41ba..12769808d50 100644
--- a/components/layout/lib.rs
+++ b/components/layout/lib.rs
@@ -6,7 +6,6 @@
 #![feature(box_patterns)]
 #![feature(box_syntax)]
 #![feature(custom_derive)]
-#![feature(mpsc_select)]
 #![feature(nonzero)]
 #![feature(plugin)]
 #![feature(raw)]
@@ -32,7 +31,6 @@ extern crate gfx;
 extern crate gfx_traits;
 extern crate heapsize;
 extern crate ipc_channel;
-extern crate layout_traits;
 extern crate libc;
 #[macro_use]
 extern crate log;
@@ -46,11 +44,9 @@ extern crate profile_traits;
 #[macro_use]
 extern crate range;
 extern crate rustc_serialize;
-extern crate script;
 extern crate script_layout_interface;
 extern crate script_traits;
 extern crate selectors;
-extern crate serde_json;
 extern crate smallvec;
 #[macro_use(atom, ns)] extern crate string_cache;
 extern crate style;
@@ -63,32 +59,31 @@ extern crate util;
 extern crate webrender_traits;
 
 #[macro_use]
-mod layout_debug;
+pub mod layout_debug;
 
-mod animation;
+pub mod animation;
 mod block;
-mod construct;
-mod context;
+pub mod construct;
+pub mod context;
 mod data;
-mod display_list_builder;
+pub mod display_list_builder;
 mod flex;
 mod floats;
-mod flow;
+pub mod flow;
 mod flow_list;
-mod flow_ref;
+pub mod flow_ref;
 mod fragment;
 mod generated_content;
-mod incremental;
+pub mod incremental;
 mod inline;
-pub mod layout_thread;
 mod list_item;
 mod model;
 mod multicol;
 mod opaque_node;
-mod parallel;
+pub mod parallel;
 mod persistent_list;
-mod query;
-mod sequential;
+pub mod query;
+pub mod sequential;
 mod table;
 mod table_caption;
 mod table_cell;
@@ -97,9 +92,9 @@ mod table_row;
 mod table_rowgroup;
 mod table_wrapper;
 mod text;
-mod traversal;
-mod webrender_helpers;
-mod wrapper;
+pub mod traversal;
+pub mod webrender_helpers;
+pub mod wrapper;
 
 // For unit tests:
 pub use fragment::Fragment;
diff --git a/components/layout/query.rs b/components/layout/query.rs
index e558496f82d..3ce7b31bfa2 100644
--- a/components/layout/query.rs
+++ b/components/layout/query.rs
@@ -12,9 +12,9 @@ use euclid::size::Size2D;
 use flow;
 use flow_ref::FlowRef;
 use fragment::{Fragment, FragmentBorderBoxIterator, SpecificFragmentInfo};
-use gfx::display_list::OpaqueNode;
+use gfx::display_list::{DisplayItemMetadata, DisplayList, OpaqueNode, ScrollOffsetMap};
 use gfx_traits::LayerId;
-use layout_thread::LayoutThreadData;
+use ipc_channel::ipc::IpcSender;
 use opaque_node::OpaqueNodeMethods;
 use script_layout_interface::rpc::{ContentBoxResponse, ContentBoxesResponse};
 use script_layout_interface::rpc::{HitTestResponse, LayoutRPC};
@@ -35,10 +35,57 @@ use style::properties::ComputedValues;
 use style::properties::longhands::{display, position};
 use style::properties::style_structs;
 use style::selector_impl::PseudoElement;
+use style::servo::Stylist;
 use style::values::AuExtensionMethods;
 use style_traits::cursor::Cursor;
 use wrapper::ThreadSafeLayoutNodeHelpers;
 
+/// Mutable data belonging to the LayoutThread.
+///
+/// This needs to be protected by a mutex so we can do fast RPCs.
+pub struct LayoutThreadData {
+    /// The channel on which messages can be sent to the constellation.
+    pub constellation_chan: IpcSender<ConstellationMsg>,
+
+    /// The root stacking context.
+    pub display_list: Option<Arc<DisplayList>>,
+
+    /// Performs CSS selector matching and style resolution.
+    pub stylist: Arc<Stylist>,
+
+    /// A queued response for the union of the content boxes of a node.
+    pub content_box_response: Rect<Au>,
+
+    /// A queued response for the content boxes of a node.
+    pub content_boxes_response: Vec<Rect<Au>>,
+
+    /// A queued response for the client {top, left, width, height} of a node in pixels.
+    pub client_rect_response: Rect<i32>,
+
+    pub layer_id_response: Option<LayerId>,
+
+    /// A queued response for the node at a given point
+    pub hit_test_response: (Option<DisplayItemMetadata>, bool),
+
+    /// A pair of overflow property in x and y
+    pub overflow_response: NodeOverflowResponse,
+
+    /// A queued response for the scroll {top, left, width, height} of a node in pixels.
+    pub scroll_area_response: Rect<i32>,
+
+    /// A queued response for the resolved style property of an element.
+    pub resolved_style_response: Option<String>,
+
+    /// A queued response for the offset parent/rect of a node.
+    pub offset_parent_response: OffsetParentResponse,
+
+    /// A queued response for the offset parent/rect of a node.
+    pub margin_style_response: MarginStyleResponse,
+
+    /// Scroll offsets of stacking contexts. This will only be populated if WebRender is in use.
+    pub stacking_context_scroll_offsets: ScrollOffsetMap,
+}
+
 pub struct LayoutRPCImpl(pub Arc<Mutex<LayoutThreadData>>);
 
 // https://drafts.csswg.org/cssom-view/#overflow-directions
diff --git a/components/layout_thread/Cargo.toml b/components/layout_thread/Cargo.toml
new file mode 100644
index 00000000000..050fea38197
--- /dev/null
+++ b/components/layout_thread/Cargo.toml
@@ -0,0 +1,36 @@
+[package]
+name = "layout_thread"
+version = "0.0.1"
+authors = ["The Servo Project Developers"]
+publish = false
+
+[lib]
+name = "layout_thread"
+path = "lib.rs"
+
+[dependencies]
+app_units = {version = "0.2.3", features = ["plugins"]}
+azure = {git = "https://github.com/servo/rust-azure", features = ["plugins"]}
+euclid = {version = "0.6.4", features = ["plugins"]}
+fnv = "1.0"
+gfx = {path = "../gfx"}
+gfx_traits = {path = "../gfx_traits"}
+heapsize = "0.3.0"
+heapsize_plugin = "0.1.2"
+ipc-channel = {git = "https://github.com/servo/ipc-channel"}
+layout = {path = "../layout"}
+layout_traits = {path = "../layout_traits"}
+log = "0.3.5"
+msg = {path = "../msg"}
+net_traits = {path = "../net_traits"}
+plugins = {path = "../plugins"}
+profile_traits = {path = "../profile_traits"}
+script = {path = "../script"}
+script_layout_interface = {path = "../script_layout_interface"}
+script_traits = {path = "../script_traits"}
+serde_json = "0.7"
+serde_macros = "0.7"
+style = {path = "../style"}
+url = {version = "1.0.0", features = ["heap_size"]}
+util = {path = "../util"}
+webrender_traits = {git = "https://github.com/servo/webrender_traits"}
diff --git a/components/layout/layout_thread.rs b/components/layout_thread/lib.rs
index a65b1452a09..e3c904d590b 100644
--- a/components/layout/layout_thread.rs
+++ b/components/layout_thread/lib.rs
@@ -5,47 +5,83 @@
 //! The layout thread. Performs layout on the DOM, builds display lists and sends them to be
 //! painted.
 
-#![allow(unsafe_code)]
+#![feature(box_syntax)]
+#![feature(custom_derive)]
+#![feature(mpsc_select)]
+#![feature(plugin)]
+
+#![plugin(heapsize_plugin)]
+#![plugin(plugins)]
+
+extern crate app_units;
+extern crate azure;
+extern crate core;
+extern crate euclid;
+extern crate fnv;
+extern crate gfx;
+extern crate gfx_traits;
+extern crate heapsize;
+extern crate ipc_channel;
+#[macro_use]
+extern crate layout;
+extern crate layout_traits;
+#[macro_use]
+extern crate log;
+extern crate msg;
+extern crate net_traits;
+#[macro_use]
+extern crate profile_traits;
+extern crate script;
+extern crate script_layout_interface;
+extern crate script_traits;
+extern crate serde_json;
+extern crate style;
+extern crate url;
+extern crate util;
+extern crate webrender_traits;
 
-use animation;
 use app_units::Au;
 use azure::azure::AzColor;
-use construct::ConstructionResult;
-use context::{LayoutContext, SharedLayoutContext, heap_size_of_local_context};
-use display_list_builder::ToGfxColor;
 use euclid::Matrix4D;
 use euclid::point::Point2D;
 use euclid::rect::Rect;
 use euclid::scale_factor::ScaleFactor;
 use euclid::size::Size2D;
-use flow::{self, Flow, ImmutableFlowUtils, MutableOwnedFlowUtils};
-use flow_ref::{self, FlowRef};
 use fnv::FnvHasher;
-use gfx::display_list::{ClippingRegion, DisplayItemMetadata, DisplayList, LayerInfo, OpaqueNode};
-use gfx::display_list::{ScrollOffsetMap, StackingContext, StackingContextType, WebRenderImageInfo};
+use gfx::display_list::{ClippingRegion, DisplayList, LayerInfo, OpaqueNode};
+use gfx::display_list::{StackingContext, StackingContextType, WebRenderImageInfo};
 use gfx::font;
 use gfx::font_cache_thread::FontCacheThread;
 use gfx::font_context;
 use gfx::paint_thread::LayoutToPaintMsg;
 use gfx_traits::{color, Epoch, FragmentType, LayerId, ScrollPolicy, StackingContextId};
 use heapsize::HeapSizeOf;
-use incremental::{LayoutDamageComputation, REFLOW_ENTIRE_DOCUMENT};
 use ipc_channel::ipc::{self, IpcReceiver, IpcSender};
 use ipc_channel::router::ROUTER;
-use layout_debug;
+use layout::animation;
+use layout::construct::ConstructionResult;
+use layout::context::{LayoutContext, SharedLayoutContext, heap_size_of_local_context};
+use layout::display_list_builder::ToGfxColor;
+use layout::flow::{self, Flow, ImmutableFlowUtils, MutableOwnedFlowUtils};
+use layout::flow_ref::{self, FlowRef};
+use layout::incremental::{LayoutDamageComputation, REFLOW_ENTIRE_DOCUMENT};
+use layout::layout_debug;
+use layout::parallel;
+use layout::query::process_offset_parent_query;
+use layout::query::{LayoutRPCImpl, LayoutThreadData, process_content_box_request, process_content_boxes_request};
+use layout::query::{process_node_geometry_request, process_node_layer_id_request, process_node_scroll_area_request};
+use layout::query::{process_node_overflow_request, process_resolved_style_request, process_margin_style_query};
+use layout::sequential;
+use layout::traversal::RecalcStyleAndConstructFlows;
+use layout::webrender_helpers::{WebRenderDisplayListConverter, WebRenderFrameBuilder};
+use layout::wrapper::{LayoutNodeLayoutData, NonOpaqueStyleAndLayoutData};
 use layout_traits::LayoutThreadFactory;
-use log;
 use msg::constellation_msg::{PanicMsg, PipelineId};
 use net_traits::image_cache_thread::UsePlaceholder;
 use net_traits::image_cache_thread::{ImageCacheChan, ImageCacheResult, ImageCacheThread};
-use parallel;
 use profile_traits::mem::{self, Report, ReportKind, ReportsChan};
 use profile_traits::time::{TimerMetadataFrameType, TimerMetadataReflowType};
 use profile_traits::time::{self, TimerMetadata, profile};
-use query::process_offset_parent_query;
-use query::{LayoutRPCImpl, process_content_box_request, process_content_boxes_request};
-use query::{process_node_geometry_request, process_node_layer_id_request, process_node_scroll_area_request};
-use query::{process_node_overflow_request, process_resolved_style_request, process_margin_style_query};
 use script::layout_wrapper::ServoLayoutNode;
 use script_layout_interface::message::{Msg, NewLayoutThreadInfo, Reflow, ReflowQueryType, ScriptReflow};
 use script_layout_interface::reporter::CSSErrorReporter;
@@ -55,8 +91,6 @@ use script_layout_interface::wrapper_traits::LayoutNode;
 use script_layout_interface::{OpaqueStyleAndLayoutData, PartialStyleAndLayoutData};
 use script_traits::{ConstellationControlMsg, LayoutControlMsg, LayoutMsg as ConstellationMsg};
 use script_traits::{StackingContextScrollState, UntrustedNodeAddress};
-use sequential;
-use serde_json;
 use std::borrow::ToOwned;
 use std::cell::RefCell;
 use std::collections::HashMap;
@@ -77,7 +111,6 @@ use style::properties::ComputedValues;
 use style::selector_matching::USER_OR_USER_AGENT_STYLESHEETS;
 use style::servo::{SharedStyleContext, Stylesheet, Stylist};
 use style::stylesheets::CSSRuleIteratorExt;
-use traversal::RecalcStyleAndConstructFlows;
 use url::Url;
 use util::geometry::MAX_RECT;
 use util::ipc::OptionalIpcSender;
@@ -85,62 +118,10 @@ use util::opts;
 use util::thread;
 use util::thread_state;
 use util::workqueue::WorkQueue;
-use webrender_helpers::{WebRenderDisplayListConverter, WebRenderFrameBuilder};
-use webrender_traits;
-use wrapper::{LayoutNodeLayoutData, NonOpaqueStyleAndLayoutData};
-
-/// The number of screens of data we're allowed to generate display lists for in each direction.
-pub const DISPLAY_PORT_SIZE_FACTOR: i32 = 8;
 
 /// The number of screens we have to traverse before we decide to generate new display lists.
 const DISPLAY_PORT_THRESHOLD_SIZE_FACTOR: i32 = 4;
 
-/// Mutable data belonging to the LayoutThread.
-///
-/// This needs to be protected by a mutex so we can do fast RPCs.
-pub struct LayoutThreadData {
-    /// The channel on which messages can be sent to the constellation.
-    pub constellation_chan: IpcSender<ConstellationMsg>,
-
-    /// The root stacking context.
-    pub display_list: Option<Arc<DisplayList>>,
-
-    /// Performs CSS selector matching and style resolution.
-    pub stylist: Arc<Stylist>,
-
-    /// A queued response for the union of the content boxes of a node.
-    pub content_box_response: Rect<Au>,
-
-    /// A queued response for the content boxes of a node.
-    pub content_boxes_response: Vec<Rect<Au>>,
-
-    /// A queued response for the client {top, left, width, height} of a node in pixels.
-    pub client_rect_response: Rect<i32>,
-
-    pub layer_id_response: Option<LayerId>,
-
-    /// A queued response for the node at a given point
-    pub hit_test_response: (Option<DisplayItemMetadata>, bool),
-
-    /// A pair of overflow property in x and y
-    pub overflow_response: NodeOverflowResponse,
-
-    /// A queued response for the scroll {top, left, width, height} of a node in pixels.
-    pub scroll_area_response: Rect<i32>,
-
-    /// A queued response for the resolved style property of an element.
-    pub resolved_style_response: Option<String>,
-
-    /// A queued response for the offset parent/rect of a node.
-    pub offset_parent_response: OffsetParentResponse,
-
-    /// A queued response for the offset parent/rect of a node.
-    pub margin_style_response: MarginStyleResponse,
-
-    /// Scroll offsets of stacking contexts. This will only be populated if WebRender is in use.
-    pub stacking_context_scroll_offsets: ScrollOffsetMap,
-}
-
 /// Information needed by the layout thread.
 pub struct LayoutThread {
     /// The ID of the pipeline that we belong to.
diff --git a/components/servo/Cargo.lock b/components/servo/Cargo.lock
index 2c822279c77..05983de473a 100644
--- a/components/servo/Cargo.lock
+++ b/components/servo/Cargo.lock
@@ -21,6 +21,7 @@ dependencies = [
  "ipc-channel 0.2.3 (git+https://github.com/servo/ipc-channel)",
  "layout 0.0.1",
  "layout_tests 0.0.1",
+ "layout_thread 0.0.1",
  "libc 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "msg 0.0.1",
@@ -1131,7 +1132,6 @@ dependencies = [
  "heapsize 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "heapsize_plugin 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "ipc-channel 0.2.3 (git+https://github.com/servo/ipc-channel)",
- "layout_traits 0.0.1",
  "libc 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "msg 0.0.1",
@@ -1140,11 +1140,9 @@ dependencies = [
  "profile_traits 0.0.1",
  "range 0.0.1",
  "rustc-serialize 0.3.19 (registry+https://github.com/rust-lang/crates.io-index)",
- "script 0.0.1",
  "script_layout_interface 0.0.1",
  "script_traits 0.0.1",
  "selectors 0.6.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde_json 0.7.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_macros 0.7.10 (registry+https://github.com/rust-lang/crates.io-index)",
  "smallvec 0.1.7 (registry+https://github.com/rust-lang/crates.io-index)",
  "string_cache 0.2.20 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1166,6 +1164,37 @@ dependencies = [
 ]
 
 [[package]]
+name = "layout_thread"
+version = "0.0.1"
+dependencies = [
+ "app_units 0.2.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "azure 0.4.5 (git+https://github.com/servo/rust-azure)",
+ "euclid 0.6.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "fnv 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "gfx 0.0.1",
+ "gfx_traits 0.0.1",
+ "heapsize 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "heapsize_plugin 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
+ "ipc-channel 0.2.3 (git+https://github.com/servo/ipc-channel)",
+ "layout 0.0.1",
+ "layout_traits 0.0.1",
+ "log 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "msg 0.0.1",
+ "net_traits 0.0.1",
+ "plugins 0.0.1",
+ "profile_traits 0.0.1",
+ "script 0.0.1",
+ "script_layout_interface 0.0.1",
+ "script_traits 0.0.1",
+ "serde_json 0.7.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde_macros 0.7.10 (registry+https://github.com/rust-lang/crates.io-index)",
+ "style 0.0.1",
+ "url 1.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "util 0.0.1",
+ "webrender_traits 0.1.0 (git+https://github.com/servo/webrender_traits)",
+]
+
+[[package]]
 name = "layout_traits"
 version = "0.0.1"
 dependencies = [
diff --git a/components/servo/Cargo.toml b/components/servo/Cargo.toml
index dc1dc080e73..fee429f6ff1 100644
--- a/components/servo/Cargo.toml
+++ b/components/servo/Cargo.toml
@@ -57,6 +57,7 @@ util = {path = "../util"}
 script = {path = "../script"}
 script_traits = {path = "../script_traits"}
 layout = {path = "../layout"}
+layout_thread = {path = "../layout_thread"}
 gfx = {path = "../gfx"}
 style = {path = "../style"}
 canvas = {path = "../canvas"}
diff --git a/components/servo/lib.rs b/components/servo/lib.rs
index 28ccd87719f..0a3b6c2a7e4 100644
--- a/components/servo/lib.rs
+++ b/components/servo/lib.rs
@@ -31,7 +31,7 @@ pub extern crate devtools_traits;
 pub extern crate euclid;
 pub extern crate gfx;
 pub extern crate ipc_channel;
-pub extern crate layout;
+pub extern crate layout_thread;
 pub extern crate msg;
 pub extern crate net;
 pub extern crate net_traits;
@@ -233,7 +233,7 @@ fn create_constellation(opts: opts::Opts,
     };
     let constellation_chan =
         Constellation::<script_layout_interface::message::Msg,
-                        layout::layout_thread::LayoutThread,
+                        layout_thread::LayoutThread,
                         script::script_thread::ScriptThread>::start(initial_state);
 
     // Send the URL command to the constellation.
@@ -267,7 +267,7 @@ pub fn run_content_process(token: String) {
     script::init();
 
     unprivileged_content.start_all::<script_layout_interface::message::Msg,
-                                     layout::layout_thread::LayoutThread,
+                                     layout_thread::LayoutThread,
                                      script::script_thread::ScriptThread>(true);
 }