Auto merge of #12980 - jdm:proxychanges, r=nox

Fix ridiculous DOM proxy getter performance

This implements the missing shadowing checks that were causing us to take many slow paths when dealing with proxy objects. Verified by running `tests/html/binding_perf.html` before and after and observing a 12x improvement.

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- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #12357
- [X] These changes do not require tests because we can't test performance yet.

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This commit is contained in:
bors-servo 2016-08-25 06:31:46 -05:00 committed by GitHub
commit 7834475482
6 changed files with 51 additions and 16 deletions

View file

@ -10,21 +10,51 @@ use dom::bindings::conversions::is_dom_proxy;
use dom::bindings::utils::delete_property_by_id;
use js::glue::GetProxyExtra;
use js::glue::InvokeGetOwnPropertyDescriptor;
use js::glue::{GetProxyHandler, SetProxyExtra};
use js::glue::{GetProxyHandler, SetProxyExtra, GetProxyHandlerFamily};
use js::jsapi::GetObjectProto;
use js::jsapi::GetStaticPrototype;
use js::jsapi::JS_GetPropertyDescriptorById;
use js::jsapi::MutableHandleObject;
use js::jsapi::{Handle, HandleId, HandleObject, MutableHandle, ObjectOpResult};
use js::jsapi::{JSContext, JSObject, JSPROP_GETTER, PropertyDescriptor};
use js::jsapi::{JSErrNum, JS_StrictPropertyStub};
use js::jsapi::{JS_DefinePropertyById, JS_NewObjectWithGivenProto};
use js::jsapi::{JSContext, JSObject, JSPROP_GETTER, PropertyDescriptor, DOMProxyShadowsResult};
use js::jsapi::{JSErrNum, JS_StrictPropertyStub, JS_AlreadyHasOwnPropertyById};
use js::jsapi::{JS_DefinePropertyById, JS_NewObjectWithGivenProto, SetDOMProxyInformation};
use js::jsval::ObjectValue;
use libc;
use std::{mem, ptr};
static JSPROXYSLOT_EXPANDO: u32 = 0;
/// Determine if this id shadows any existing properties for this proxy.
pub unsafe extern "C" fn shadow_check_callback(cx: *mut JSContext,
object: HandleObject,
id: HandleId)
-> DOMProxyShadowsResult {
// TODO: support OverrideBuiltins when #12978 is fixed.
rooted!(in(cx) let expando = get_expando_object(object));
if !expando.get().is_null() {
let mut has_own = false;
if !JS_AlreadyHasOwnPropertyById(cx, expando.handle(), id, &mut has_own) {
return DOMProxyShadowsResult::ShadowCheckFailed;
}
if has_own {
return DOMProxyShadowsResult::ShadowsViaDirectExpando;
}
}
// Our expando, if any, didn't shadow, so we're not shadowing at all.
DOMProxyShadowsResult::DoesntShadow
}
/// Initialize the infrastructure for DOM proxy objects.
pub unsafe fn init() {
SetDOMProxyInformation(GetProxyHandlerFamily(),
JSPROXYSLOT_EXPANDO,
Some(shadow_check_callback));
}
/// Invoke the [[GetOwnProperty]] trap (`getOwnPropertyDescriptor`) on `proxy`,
/// with argument `id` and return the result, if it is not `undefined`.
/// Otherwise, walk along the prototype chain to find a property with that