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Ignore the HTML parser's borrow flag in GC tracing

Adds some other dynamic checks in debug builds.
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kmcallister committed Oct 24, 2014
1 parent 6ec0939 commit 49234484d6539a4d8df8374a9548c2004b8e68b7
@@ -6,6 +6,7 @@ use dom::bindings::trace::JSTraceable;
use js::jsapi::{JSTracer};

use servo_util::task_state;
use servo_util::task_state::{Script, InGC};

use std::cell::{Cell, UnsafeCell};
use std::kinds::marker;
@@ -33,6 +34,23 @@ impl<T> DOMRefCell<T> {
&*self.value.get()
}

/// Borrow the contents for the purpose of GC tracing.
///
/// This succeeds even if the object is mutably borrowed,
/// so you have to be careful in trace code!
pub unsafe fn borrow_for_gc_trace<'a>(&'a self) -> &'a T {
debug_assert!(task_state::get().contains(Script | InGC));
&*self.value.get()
}

/// Is the cell mutably borrowed?
///
/// For safety checks in debug builds only.
#[cfg(not(ndebug))]
pub fn is_mutably_borrowed(&self) -> bool {
self.borrow.get() == WRITING
}

pub fn try_borrow<'a>(&'a self) -> Option<Ref<'a, T>> {
debug_assert!(task_state::get().is_script());
match self.borrow.get() {
@@ -15,6 +15,8 @@ use dom::node::TrustedNodeAddress;
use dom::document::{Document, DocumentHelpers};
use parse::html::JSMessage;

use servo_util::task_state;

use std::default::Default;
use url::Url;
use js::jsapi::JSTracer;
@@ -91,15 +93,23 @@ impl tree_builder::Tracer<TrustedNodeAddress> for Tracer {

impl JSTraceable for ServoHTMLParser {
fn trace(&self, trc: *mut JSTracer) {
self.reflector_.trace(trc);

let tracer = Tracer {
trc: trc,
};
let tracer = &tracer as &tree_builder::Tracer<TrustedNodeAddress>;

self.reflector_.trace(trc);
let tokenizer = self.tokenizer.borrow();
let tree_builder = tokenizer.sink();
tree_builder.trace_handles(tracer);
tree_builder.sink().trace(trc);
unsafe {
// Assertion: If the parser is mutably borrowed, we're in the
// parsing code paths.
debug_assert!(task_state::get().contains(task_state::InHTMLParser)
|| !self.tokenizer.is_mutably_borrowed());

let tokenizer = self.tokenizer.borrow_for_gc_trace();
let tree_builder = tokenizer.sink();
tree_builder.trace_handles(tracer);
tree_builder.sink().trace(trc);
}
}
}
@@ -25,6 +25,8 @@ use encoding::types::{Encoding, DecodeReplace};
use servo_net::resource_task::{Load, LoadData, Payload, Done, ResourceTask, load_whole_resource};
use servo_msg::constellation_msg::LoadData as MsgLoadData;
use servo_util::task::spawn_named;
use servo_util::task_state;
use servo_util::task_state::InHTMLParser;
use servo_util::str::DOMString;
use std::ascii::StrAsciiExt;
use std::comm::{channel, Sender, Receiver};
@@ -480,6 +482,8 @@ pub fn parse_html(page: &Page,
let parser = ServoHTMLParser::new(js_chan.clone(), base_url.clone(), document).root();
let parser: JSRef<ServoHTMLParser> = *parser;

task_state::enter(InHTMLParser);

match input {
InputString(s) => {
parser.tokenizer().borrow_mut().feed(s);
@@ -512,6 +516,8 @@ pub fn parse_html(page: &Page,

parser.tokenizer().borrow_mut().end();

task_state::exit(InHTMLParser);

debug!("finished parsing");
js_chan.send(JSTaskExit);

@@ -60,6 +60,7 @@ use geom::point::Point2D;
use js::jsapi::{JS_SetWrapObjectCallbacks, JS_SetGCZeal, JS_DEFAULT_ZEAL_FREQ, JS_GC};
use js::jsapi::{JSContext, JSRuntime, JSTracer};
use js::jsapi::{JS_SetGCParameter, JSGC_MAX_BYTES};
use js::jsapi::{JS_SetGCCallback, JSGCStatus, JSGC_BEGIN, JSGC_END};
use js::rust::{Cx, RtUtils};
use js::rust::with_compartment;
use js;
@@ -285,6 +286,16 @@ impl ScriptTaskFactory for ScriptTask {
}
}

unsafe extern "C" fn debug_gc_callback(rt: *mut JSRuntime, status: JSGCStatus) {
js::rust::gc_callback(rt, status);

match status {
JSGC_BEGIN => task_state::enter(task_state::InGC),
JSGC_END => task_state::exit(task_state::InGC),
_ => (),
}
}

impl ScriptTask {
/// Creates a new script task.
pub fn new(id: PipelineId,
@@ -376,6 +387,13 @@ impl ScriptTask {
JS_SetGCZeal((*js_context).ptr, 0, JS_DEFAULT_ZEAL_FREQ);
}

// Needed for debug assertions about whether GC is running.
if !cfg!(ndebug) {
unsafe {
JS_SetGCCallback(js_runtime.ptr, Some(debug_gc_callback));
}
}

(js_runtime, js_context)
}

@@ -22,6 +22,8 @@ bitflags! {
static Render = 0x04,

static InWorker = 0x0100,
static InGC = 0x0200,
static InHTMLParser = 0x0400,
}
}

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