In Rust, it is UB if a slice is mutated while borrowed except through
the slice itself, and it is also UB if a mutable slice is read while
borrowed. The op macro allows borrowing an `ArrayBuffer{,View}` as a
memory slice for the duration of an op, but this is not sound for async
ops, since the `ArrayBuffer` could be accessed from JS during the await
points. This PR therefore disallows such automatic borrowing only for
async ops.
Co-authored-by: Divy Srivastava <dj.srivastava23@gmail.com>
Currently realms are supported on `deno_core`, but there was no support
for async ops anywhere other than the main realm. The main issue is that
the `js_recv_cb` callback, which resolves promises corresponding to
async ops, was only set for the main realm, so async ops in other realms
would never resolve. Furthermore, promise ID's are specific to each
realm, which meant that async ops from other realms would result in a
wrong promise from the main realm being resolved.
This change takes the `ContextState` struct added in #17050, and adds to
it a `js_recv_cb` callback for each realm. Combined with the fact that
that same PR also added a list of known realms to `JsRuntimeState`, and
that #17174 made `OpCtx` instances realm-specific and had them include
an index into that list of known realms, this makes it possible to know
the current realm in the `queue_async_op` and `queue_fast_async_op`
methods, and therefore to send the results of promises for each realm to
that realm, and prevent the ID's from getting mixed up.
Additionally, since promise ID's are no longer unique to the isolate,
having a single set of unrefed ops doesn't work. This change therefore
also moves `unrefed_ops` from `JsRuntimeState` to `ContextState`, and
adds the lengths of the unrefed op sets for all known realms to get the
total number of unrefed ops to compare in the event loop.
This PR is a reland of #14734 after it was reverted in #16366, except
that `ContextState` and `JsRuntimeState::known_realms` were previously
relanded in #17050. Another significant difference with the original PR
is passing around an index into `JsRuntimeState::known_realms` instead
of a `v8::Global<v8::Context>` to identify the realm, because async op
queuing in fast calls cannot call into V8, and therefore cannot have
access to V8 globals. This also simplified the implementation of
`resolve_async_ops`.
Co-authored-by: Luis Malheiro <luismalheiro@gmail.com>
Fixes https://github.com/denoland/deno/issues/16934
Example compiler error:
```
error: mutable opstate is not supported in async ops
--> core/ops_builtin.rs:122:1
|
122 | #[op]
| ^^^^^
|
= note: this error originates in the attribute macro `op` (in Nightly builds, run with -Z macro-backtrace for more info)
```
Uses SeqOneByteString optimization to do zero-copy `&str` arguments in
fast calls.
- [x] Depends on https://github.com/denoland/rusty_v8/pull/1129
- [x] Depends on
https://chromium-review.googlesource.com/c/v8/v8/+/4036884
- [x] Disable in async ops
- [x] Make it work with owned `String` with an extra alloc in fast path.
- [x] Support `Cow<'_, str>`. Owned for slow case, Borrowed for fast
case
```rust
#[op]
fn op_string_len(s: &str) -> u32 {
str.len() as u32
}
```
This PR introduces Wasm ops. These calls are optimized for entry from
Wasm land.
The `#[op(wasm)]` attribute is opt-in.
Last parameter `Option<&mut [u8]>` is the memory slice of the Wasm
module *when entered from a Fast API call*. Otherwise, the user is
expected to implement logic to obtain the memory if `None`
```rust
#[op(wasm)]
pub fn op_args_get(
offset: i32,
buffer_offset: i32,
memory: Option<&mut [u8]>,
) {
// ...
}
```
- [x] Avoid copying buffers.
https://encoding.spec.whatwg.org/#dom-textdecoder-decode
> Implementations are strongly encouraged to use an implementation
strategy that avoids this copy. When doing so they will have to make
sure that changes to input do not affect future calls to
[decode()](https://encoding.spec.whatwg.org/#dom-textdecoder-decode).
- [x] Special op to avoid string label deserialization and parsing.
(Ideally we should map labels to integers in JS)
- [x] Avoid webidl `Object.assign` when options is undefined.
Implements fast scheduling of deferred op futures.
```rs
#[op(fast)]
async fn op_read(
state: Rc<RefCell<OpState>>,
rid: ResourceId,
buf: &mut [u8],
) -> Result<u32, Error> {
// ...
}
```
The future is scheduled via a fast API call and polled by the event loop
after being woken up by its waker.
V8's JIT can do a better job knowing the argument count and also enable
fast call path (in future).
This also lets us call async ops without `opAsync`:
```js
const { ops } = Deno.core;
await ops.op_void_async();
```
this patch: 4405286 ops/sec
main: 3508771 ops/sec
example writeFile benchmark:
```
# before
time 188 ms rate 53191
time 168 ms rate 59523
time 167 ms rate 59880
time 166 ms rate 60240
time 168 ms rate 59523
time 173 ms rate 57803
time 183 ms rate 54644
# after
time 157 ms rate 63694
time 152 ms rate 65789
time 151 ms rate 66225
time 151 ms rate 66225
time 152 ms rate 65789
```
This revert has been discussed at length out-of-band (including with
@andreubotella). The realms work in impeding ongoing event loop and
performance work. We very much want to land realms but it needs to wait
until these lower-level refactors are complete. We hope to bring realms
back in a couple weeks.
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This PR makes pointer read methods of `Deno.UnsafePointerView` Fast API
compliant, with the exception of `getCString` which cannot be made fast
with current V8 Fast API.
Pull request #14019 enabled initial support for realms, but it did not
include support for async ops anywhere other than the main realm. The
main issue was that the `js_recv_cb` callback, which resolves promises
corresponding to async ops, was only set for the main realm, so async
ops in other realms would never resolve. Furthermore, promise ID's are
specific to each realm, which meant that async ops from other realms
would result in a wrong promise from the main realm being resolved.
This change creates a `ContextState` struct, similar to
`JsRuntimeState` but stored in a slot of each `v8::Context`, which
contains a `js_recv_cb` callback for each realm. Combined with a new
list of known realms, which stores them as `v8::Weak<v8::Context>`,
and a change in the `#[op]` macro to pass the current context to
`queue_async_op`, this makes it possible to send the results of
promises for different realms to their realm, and prevent the ID's
from getting mixed up.
Additionally, since promise ID's are no longer unique to the isolate,
having a single set of unrefed ops doesn't work. This change therefore
also moves `unrefed_ops` from `JsRuntimeState` to `ContextState`, and
adds the lengths of the unrefed op sets for all known realms to get
the total number of unrefed ops to compare in the event loop.
Co-authored-by: Luis Malheiro <luismalheiro@gmail.com>
