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/* This Source Code Form is subject to the terms of the Mozilla Public
* 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/. */
//! Supports writing a trace file created during each layout scope
//! that can be viewed by an external tool to make layout debugging easier.
#![macro_escape]
use flow_ref::FlowRef;
use serialize::json;
use std::cell::RefCell;
use std::io::File;
use std::sync::atomics::{AtomicUint, SeqCst, INIT_ATOMIC_UINT};
local_data_key!(state_key: RefCell<State>)
static mut DEBUG_ID_COUNTER: AtomicUint = INIT_ATOMIC_UINT;
pub struct Scope;
#[macro_export]
macro_rules! layout_debug_scope(
($($arg:tt)*) => (
if cfg!(not(ndebug)) {
layout_debug::Scope::new(format!($($arg)*))
} else {
layout_debug::Scope
}
)
)
#[deriving(Encodable)]
struct ScopeData {
name: String,
pre: String,
post: String,
children: Vec<Box<ScopeData>>,
}
impl ScopeData {
fn new(name: String, pre: String) -> ScopeData {
ScopeData {
name: name,
pre: pre,
post: String::new(),
children: vec!(),
}
}
}
struct State {
flow_root: FlowRef,
scope_stack: Vec<Box<ScopeData>>,
}
/// A layout debugging scope. The entire state of the flow tree
/// will be output at the beginning and end of this scope.
impl Scope {
pub fn new(name: String) -> Scope {
let maybe_refcell = state_key.get();
match maybe_refcell {
Some(refcell) => {
let mut state = refcell.borrow_mut();
let flow_trace = json::encode(&state.flow_root.get());
let data = box ScopeData::new(name, flow_trace);
state.scope_stack.push(data);
}
None => {}
}
Scope
}
}
#[cfg(not(ndebug))]
impl Drop for Scope {
fn drop(&mut self) {
let maybe_refcell = state_key.get();
match maybe_refcell {
Some(refcell) => {
let mut state = refcell.borrow_mut();
let mut current_scope = state.scope_stack.pop().unwrap();
current_scope.post = json::encode(&state.flow_root.get());
let previous_scope = state.scope_stack.mut_last().unwrap();
previous_scope.children.push(current_scope);
}
None => {}
}
}
}
/// Generate a unique ID. This is used for items such as Fragment
/// which are often reallocated but represent essentially the
/// same data.
pub fn generate_unique_debug_id() -> uint {
unsafe { DEBUG_ID_COUNTER.fetch_add(1, SeqCst) }
}
/// Begin a layout debug trace. If this has not been called,
/// creating debug scopes has no effect.
pub fn begin_trace(flow_root: FlowRef) {
assert!(state_key.get().is_none());
let flow_trace = json::encode(&flow_root.get());
let state = State {
scope_stack: vec![box ScopeData::new("root".to_string(), flow_trace)],
flow_root: flow_root,
};
state_key.replace(Some(RefCell::new(state)));
}
/// End the debug layout trace. This will write the layout
/// trace to disk in the current directory. The output
/// file can then be viewed with an external tool.
pub fn end_trace() {
let task_state_cell = state_key.replace(None).unwrap();
let mut task_state = task_state_cell.borrow_mut();
assert!(task_state.scope_stack.len() == 1);
let mut root_scope = task_state.scope_stack.pop().unwrap();
root_scope.post = json::encode(&task_state.flow_root.get());
let result = json::encode(&root_scope);
let path = Path::new("layout_trace.json");
let mut file = File::create(&path).unwrap();
file.write_str(result.as_slice()).unwrap();
}
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