forked from mirrors/gecko-dev
b988a636be
<!-- Please describe your changes on the following line: --> Migrated the trace-layout code from old `rustc-serialize` to `serde_json`. This will help us iterate faster on the layout viewer (#13432), #13436, #12675 and fix #12936. --- <!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: --> - [x] `./mach build -d` does not report any errors - [x] `./mach test-tidy` does not report any errors - [x] These changes fix #12936 (github issue number if applicable). <!-- Either: --> - [ ] There are tests for these changes OR - [x] These changes do not require tests because it's a relatively low risk debug tool <!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. --> Source-Repo: https://github.com/servo/servo Source-Revision: 1c26f44cbb23e7da3b9d63f0223c8d5d43eec958
66 lines
2.2 KiB
Rust
66 lines
2.2 KiB
Rust
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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//! Reference-counted pointers to flows.
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//!
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//! Eventually, with dynamically sized types in Rust, much of this code will
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//! be superfluous. This design is largely duplicating logic of Arc<T> and
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//! Weak<T>; please see comments there for details.
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use flow::Flow;
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use std::ops::Deref;
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use std::sync::{Arc, Weak};
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#[derive(Clone,Debug)]
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pub struct FlowRef(Arc<Flow>);
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impl Deref for FlowRef {
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type Target = Flow;
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fn deref(&self) -> &Flow {
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self.0.deref()
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}
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}
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impl FlowRef {
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/// `FlowRef`s can only be made available to the traversal code.
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/// See https://github.com/servo/servo/issues/14014 for more details.
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pub fn new(mut r: Arc<Flow>) -> Self {
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// This assertion checks that this `FlowRef` does not alias normal `Arc`s.
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// If that happens, we're in trouble.
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assert!(Arc::get_mut(&mut r).is_some());
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FlowRef(r)
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}
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pub fn get_mut(this: &mut FlowRef) -> Option<&mut Flow> {
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Arc::get_mut(&mut this.0)
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}
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pub fn downgrade(this: &FlowRef) -> WeakFlowRef {
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WeakFlowRef(Arc::downgrade(&this.0))
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}
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pub fn into_arc(mut this: FlowRef) -> Arc<Flow> {
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// This assertion checks that this `FlowRef` does not alias normal `Arc`s.
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// If that happens, we're in trouble.
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assert!(FlowRef::get_mut(&mut this).is_some());
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this.0
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}
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/// WARNING: This should only be used when there is no aliasing:
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/// when the traversal ensures that no other threads accesses the same flow at the same time.
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/// See https://github.com/servo/servo/issues/6503
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/// Use Arc::get_mut instead when possible (e.g. on an Arc that was just created).
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#[allow(unsafe_code)]
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pub fn deref_mut(this: &mut FlowRef) -> &mut Flow {
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let ptr: *const Flow = &*this.0;
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unsafe { &mut *(ptr as *mut Flow) }
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}
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}
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#[derive(Clone,Debug)]
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pub struct WeakFlowRef(Weak<Flow>);
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impl WeakFlowRef {
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pub fn upgrade(&self) -> Option<FlowRef> {
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self.0.upgrade().map(FlowRef)
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}
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}
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