Auto merge of #18523 - asajeffrey:pipeline-id-nonzero, r=mbrubeck

Make pipeline ids non-zero so that optional ids take no extra space

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Use the NonZero trait to reduce space usage of `Option<PipelineId>`.

This needs a bump of serde to get https://github.com/serde-rs/serde/pull/1003.

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- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] There are tests for these changes OR

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components/compositing/compositor.rs

@@ -6,6 +6,7 @@ use CompositionPipeline;
 use SendableFrameTree;
 use compositor_thread::{CompositorProxy, CompositorReceiver};
 use compositor_thread::{InitialCompositorState, Msg, RenderListener};
+use core::nonzero::NonZero;
 use euclid::{Point2D, TypedPoint2D, TypedVector2D, ScaleFactor};
 use gfx_traits::Epoch;
 use gleam::gl;
@@ -61,7 +62,7 @@ impl ConvertPipelineIdFromWebRender for webrender_api::PipelineId {
     fn from_webrender(&self) -> PipelineId {
         PipelineId {
             namespace_id: PipelineNamespaceId(self.0),
-            index: PipelineIndex(self.1),
+            index: PipelineIndex(NonZero::new(self.1).expect("Webrender pipeline zero?")),
         }
     }
 }

components/compositing/lib.rs

@@ -4,7 +4,9 @@
 
 #![deny(unsafe_code)]
 #![feature(box_syntax)]
+#![feature(nonzero)]
 
+extern crate core;
 extern crate euclid;
 extern crate gfx_traits;
 extern crate gleam;

components/msg/Cargo.toml

@@ -13,5 +13,5 @@ path = "lib.rs"
 bitflags = "0.7"
 heapsize = "0.4"
 heapsize_derive = "0.1"
-serde = "1.0"
+serde = { version = "1.0.14", features = [ "unstable" ] }
 webrender_api = {git = "https://github.com/servo/webrender", features = ["ipc"]}

components/msg/constellation_msg.rs

@@ -5,6 +5,7 @@
 //! The high-level interface from script to constellation. Using this abstract interface helps
 //! reduce coupling between these two components.
 
+use core::nonzero::NonZero;
 use std::cell::Cell;
 use std::fmt;
 use webrender_api;
@@ -194,10 +195,9 @@ impl PipelineNamespace {
         });
     }
 
-    fn next_index(&mut self) -> u32 {
-        let result = self.index;
-        self.index = result + 1;
-        result
+    fn next_index(&mut self) -> NonZero<u32> {
+        self.index += 1;
+        NonZero::new(self.index).expect("pipeline id index wrapped!")
     }
 
     fn next_pipeline_id(&mut self) -> PipelineId {
@@ -220,8 +220,9 @@ thread_local!(pub static PIPELINE_NAMESPACE: Cell<Option<PipelineNamespace>> = C
 #[derive(Clone, Copy, Debug, Deserialize, Eq, Hash, HeapSizeOf, Ord, PartialEq, PartialOrd, Serialize)]
 pub struct PipelineNamespaceId(pub u32);
 
-#[derive(Clone, Copy, Debug, Deserialize, Eq, Hash, HeapSizeOf, Ord, PartialEq, PartialOrd, Serialize)]
-pub struct PipelineIndex(pub u32);
+#[derive(Clone, Copy, Debug, Deserialize, Eq, Hash, Ord, PartialEq, PartialOrd, Serialize)]
+pub struct PipelineIndex(pub NonZero<u32>);
+known_heap_size!(0, PipelineIndex);
 
 #[derive(Clone, Copy, Debug, Deserialize, Eq, Hash, HeapSizeOf, Ord, PartialEq, PartialOrd, Serialize)]
 pub struct PipelineId {
@@ -242,7 +243,7 @@ impl PipelineId {
     pub fn to_webrender(&self) -> webrender_api::PipelineId {
         let PipelineNamespaceId(namespace_id) = self.namespace_id;
         let PipelineIndex(index) = self.index;
-        webrender_api::PipelineId(namespace_id, index)
+        webrender_api::PipelineId(namespace_id, index.get())
     }
 
     pub fn root_scroll_node(&self) -> webrender_api::ClipId {
@@ -258,17 +259,18 @@ impl fmt::Display for PipelineId {
     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
         let PipelineNamespaceId(namespace_id) = self.namespace_id;
         let PipelineIndex(index) = self.index;
-        write!(fmt, "({},{})", namespace_id, index)
+        write!(fmt, "({},{})", namespace_id, index.get())
     }
 }
 
-#[derive(Clone, Copy, Debug, Deserialize, Eq, Hash, HeapSizeOf, Ord, PartialEq, PartialOrd, Serialize)]
-pub struct BrowsingContextIndex(pub u32);
+#[derive(Clone, Copy, Debug, Deserialize, Eq, Hash, Ord, PartialEq, PartialOrd, Serialize)]
+pub struct BrowsingContextIndex(pub NonZero<u32>);
+known_heap_size!(0, BrowsingContextIndex);
 
 #[derive(Clone, Copy, Debug, Deserialize, Eq, Hash, HeapSizeOf, Ord, PartialEq, PartialOrd, Serialize)]
 pub struct BrowsingContextId {
     pub namespace_id: PipelineNamespaceId,
-    pub index: BrowsingContextIndex
+    pub index: BrowsingContextIndex,
 }
 
 impl BrowsingContextId {
@@ -286,7 +288,7 @@ impl fmt::Display for BrowsingContextId {
     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
         let PipelineNamespaceId(namespace_id) = self.namespace_id;
         let BrowsingContextIndex(index) = self.index;
-        write!(fmt, "({},{})", namespace_id, index)
+        write!(fmt, "({},{})", namespace_id, index.get())
     }
 }
 
@@ -336,9 +338,12 @@ impl PartialEq<BrowsingContextId> for TopLevelBrowsingContextId {
 
 // We provide ids just for unit testing.
 pub const TEST_NAMESPACE: PipelineNamespaceId = PipelineNamespaceId(1234);
-pub const TEST_PIPELINE_INDEX: PipelineIndex = PipelineIndex(5678);
+#[allow(unsafe_code)]
+pub const TEST_PIPELINE_INDEX: PipelineIndex = unsafe { PipelineIndex(NonZero::new_unchecked(5678)) };
 pub const TEST_PIPELINE_ID: PipelineId = PipelineId { namespace_id: TEST_NAMESPACE, index: TEST_PIPELINE_INDEX };
-pub const TEST_BROWSING_CONTEXT_INDEX: BrowsingContextIndex = BrowsingContextIndex(8765);
+#[allow(unsafe_code)]
+pub const TEST_BROWSING_CONTEXT_INDEX: BrowsingContextIndex =
+    unsafe { BrowsingContextIndex(NonZero::new_unchecked(8765)) };
 pub const TEST_BROWSING_CONTEXT_ID: BrowsingContextId =
     BrowsingContextId { namespace_id: TEST_NAMESPACE, index: TEST_BROWSING_CONTEXT_INDEX };
 

components/msg/lib.rs

@@ -2,11 +2,15 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+#![feature(const_fn)]
+#![feature(const_nonzero_new)]
+#![feature(nonzero)]
 #![deny(unsafe_code)]
 
 #[macro_use]
 extern crate bitflags;
-extern crate heapsize;
+extern crate core;
+#[macro_use] extern crate heapsize;
 #[macro_use] extern crate heapsize_derive;
 #[macro_use] extern crate serde;
 extern crate webrender_api;