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110 lines
3.4 KiB
Rust
110 lines
3.4 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 https://mozilla.org/MPL/2.0/. */
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//! Supports writing a trace file created during each layout scope
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//! that can be viewed by an external tool to make layout debugging easier.
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use crate::flow::FragmentTreeRoot;
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use serde_json::{to_string, to_value, Value};
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use std::cell::RefCell;
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use std::fs::File;
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use std::io::Write;
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use std::sync::Arc;
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thread_local!(static STATE_KEY: RefCell<Option<State>> = RefCell::new(None));
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pub struct Scope;
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#[macro_export]
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macro_rules! layout_debug_scope(
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($($arg:tt)*) => (
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if cfg!(debug_assertions) {
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layout_debug::Scope::new(format!($($arg)*))
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} else {
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layout_debug::Scope
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}
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)
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);
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#[derive(Serialize)]
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struct ScopeData {
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name: String,
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pre: Value,
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post: Value,
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children: Vec<Box<ScopeData>>,
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}
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impl ScopeData {
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fn new(name: String, pre: Value) -> ScopeData {
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ScopeData {
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name: name,
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pre: pre,
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post: Value::Null,
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children: vec![],
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}
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}
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}
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struct State {
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fragment: Arc<FragmentTreeRoot>,
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scope_stack: Vec<Box<ScopeData>>,
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}
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/// A layout debugging scope. The entire state of the fragment tree
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/// will be output at the beginning and end of this scope.
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impl Scope {
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pub fn new(name: String) -> Scope {
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STATE_KEY.with(|ref r| {
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if let Some(ref mut state) = *r.borrow_mut() {
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let fragment_tree = to_value(&state.fragment).unwrap();
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let data = Box::new(ScopeData::new(name.clone(), fragment_tree));
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state.scope_stack.push(data);
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}
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});
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Scope
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}
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}
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#[cfg(debug_assertions)]
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impl Drop for Scope {
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fn drop(&mut self) {
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STATE_KEY.with(|ref r| {
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if let Some(ref mut state) = *r.borrow_mut() {
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let mut current_scope = state.scope_stack.pop().unwrap();
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current_scope.post = to_value(&state.fragment).unwrap();
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let previous_scope = state.scope_stack.last_mut().unwrap();
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previous_scope.children.push(current_scope);
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}
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});
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}
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}
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/// Begin a layout debug trace. If this has not been called,
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/// creating debug scopes has no effect.
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pub fn begin_trace(root: Arc<FragmentTreeRoot>) {
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assert!(STATE_KEY.with(|ref r| r.borrow().is_none()));
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STATE_KEY.with(|ref r| {
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let root_trace = to_value(&root).unwrap();
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let state = State {
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scope_stack: vec![Box::new(ScopeData::new("root".to_owned(), root_trace))],
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fragment: root.clone(),
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};
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*r.borrow_mut() = Some(state);
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});
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}
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/// End the debug layout trace. This will write the layout
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/// trace to disk in the current directory. The output
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/// file can then be viewed with an external tool.
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pub fn end_trace(generation: u32) {
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let mut thread_state = STATE_KEY.with(|ref r| r.borrow_mut().take().unwrap());
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assert_eq!(thread_state.scope_stack.len(), 1);
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let mut root_scope = thread_state.scope_stack.pop().unwrap();
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root_scope.post = to_value(&thread_state.fragment).unwrap();
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let result = to_string(&root_scope).unwrap();
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let mut file = File::create(format!("layout_trace-{}.json", generation)).unwrap();
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file.write_all(result.as_bytes()).unwrap();
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}
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