When a paint worklet thread takes too long, we would like to move on,
since we have a ~16ms budget for rendering @60fps. At the moment, there
is no provision in the paintworklet spec to signal such timeouts to the
developer. ajeffrey opened an [issue][1] for this, but it got punted to
v2 of the spec. Hence we are silently timing out unresponsive paint
scripts.
The timeout value is chosen to be 10ms by default, and can be overridden
by setting the `dom.worklet.timeout_ms` pref.
In the absence of such a timeout, the reftest in this commit would fail
by timing out the testrunner itself, since the paint script never
returns. From my discussions with ajeffrey, this should do until we spec
out a way to signal timeouts to the script developer.
Since we did not have a better way to trigger a timeout than a busy
waiting loop (which would hog one core of the test machine until the
timeout was reached), we decided to implement a test only blocking
sleep, available to the PaintWorkletGlobalScope. Since
`dom.worklet.enabled` enables worklets in general, we also decided to
have another pref `dom.worklet.blockingsleep.enabled`, which, in
addition to `dom.worklet.enabled`, would be required for the blocking
sleep to be available.
This fixes#17370.
[1]: https://github.com/w3c/css-houdini-drafts/issues/507
Servo currently uses `heapsize`, but Stylo/Gecko use `malloc_size_of`.
`malloc_size_of` is better -- it handles various cases that `heapsize` does not
-- so this patch changes Servo to use `malloc_size_of`.
This patch makes the following changes to the `malloc_size_of` crate.
- Adds `MallocSizeOf` trait implementations for numerous types, some built-in
(e.g. `VecDeque`), some external and Servo-only (e.g. `string_cache`).
- Makes `enclosing_size_of_op` optional, because vanilla jemalloc doesn't
support that operation.
- For `HashSet`/`HashMap`, falls back to a computed estimate when
`enclosing_size_of_op` isn't available.
- Adds an extern "C" `malloc_size_of` function that does the actual heap
measurement; this is based on the same functions from the `heapsize` crate.
This patch makes the following changes elsewhere.
- Converts all the uses of `heapsize` to instead use `malloc_size_of`.
- Disables the "heapsize"/"heap_size" feature for the external crates that
provide it.
- Removes the `HeapSizeOf` implementation from `hashglobe`.
- Adds `ignore` annotations to a few `Rc`/`Arc`, because `malloc_size_of`
doesn't derive those types, unlike `heapsize`.
Fixes warnings from rust-lang/rust#44229 when `--enable-commonmark` is
passed to rustdoc.
This is mostly a global find-and-replace for bare URIs on lines by
themselves in doc comments.
http://www.robohornet.org gives a score of 101.36 on master,
and 102.68 with this PR. The latter is slightly better,
but probably within noise level.
So it looks like this PR does not affect DOM performance.
This is expected since `Box::new` is defined as:
```rust
impl<T> Box<T> {
#[inline(always)]
pub fn new(x: T) -> Box<T> {
box x
}
}
```
With inlining, it should compile to the same as box syntax.
In a later PR, DomRoot<T> will become a type alias of Root<Dom<T>>,
where Root<T> will be able to handle all the things that need to be
rooted that have a stable traceable address that doesn't move for the
whole lifetime of the root. Stay tuned.
I don't want to do such a gratuitous rename, but with all the other types
now having "Dom" as part of their name, and especially with "DomOnceCell",
I feel like the other cell type that we already have should also follow
the convention. That argument loses weight though when we realise there
is still DOMString and other things.
