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denoland-deno/core/ops.rs

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// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.
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use crate::gotham_state::GothamState;
use crate::resources::ResourceTable;
use crate::runtime::GetErrorClassFn;
use crate::OpsTracker;
use anyhow::Error;
use futures::future::maybe_done;
use futures::future::FusedFuture;
use futures::future::MaybeDone;
use futures::ready;
use futures::task::noop_waker;
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use futures::Future;
use serde::Serialize;
use std::cell::UnsafeCell;
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use std::ops::Deref;
use std::ops::DerefMut;
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use std::pin::Pin;
use std::task::Context;
use std::task::Poll;
/// Wrapper around a Future, which causes that Future to be polled immediately.
///
/// Background: ops are stored in a `FuturesUnordered` structure which polls
/// them, but without the `OpCall` wrapper this doesn't happen until the next
/// turn of the event loop, which is too late for certain ops.
pub struct OpCall<T>(MaybeDone<Pin<Box<dyn Future<Output = T>>>>);
impl<T> OpCall<T> {
/// Wraps a future, and polls the inner future immediately.
/// This should be the default choice for ops.
pub fn eager(fut: impl Future<Output = T> + 'static) -> Self {
let boxed = Box::pin(fut) as Pin<Box<dyn Future<Output = T>>>;
let mut inner = maybe_done(boxed);
let waker = noop_waker();
let mut cx = Context::from_waker(&waker);
let mut pinned = Pin::new(&mut inner);
let _ = pinned.as_mut().poll(&mut cx);
Self(inner)
}
/// Wraps a future; the inner future is polled the usual way (lazily).
pub fn lazy(fut: impl Future<Output = T> + 'static) -> Self {
let boxed = Box::pin(fut) as Pin<Box<dyn Future<Output = T>>>;
let inner = maybe_done(boxed);
Self(inner)
}
/// Create a future by specifying its output. This is basically the same as
/// `async { value }` or `futures::future::ready(value)`.
pub fn ready(value: T) -> Self {
Self(MaybeDone::Done(value))
}
}
impl<T> Future for OpCall<T> {
type Output = T;
fn poll(
self: std::pin::Pin<&mut Self>,
cx: &mut std::task::Context<'_>,
) -> std::task::Poll<Self::Output> {
let inner = unsafe { &mut self.get_unchecked_mut().0 };
let mut pinned = Pin::new(inner);
ready!(pinned.as_mut().poll(cx));
Poll::Ready(pinned.as_mut().take_output().unwrap())
}
}
impl<F> FusedFuture for OpCall<F>
where
F: Future,
{
fn is_terminated(&self) -> bool {
self.0.is_terminated()
}
}
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pub type PromiseId = i32;
pub type OpAsyncFuture = OpCall<(PromiseId, OpId, OpResult)>;
pub type OpFn =
fn(&mut v8::HandleScope, v8::FunctionCallbackArguments, v8::ReturnValue);
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pub type OpId = usize;
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pub enum Op {
Sync(OpResult),
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Async(OpAsyncFuture),
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NotFound,
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}
pub enum OpResult {
Ok(serde_v8::SerializablePkg),
Err(OpError),
}
impl OpResult {
pub fn to_v8<'a>(
&self,
scope: &mut v8::HandleScope<'a>,
) -> Result<v8::Local<'a, v8::Value>, serde_v8::Error> {
match self {
Self::Ok(x) => x.to_v8(scope),
Self::Err(err) => serde_v8::to_v8(scope, err),
}
}
}
#[derive(Serialize)]
#[serde(rename_all = "camelCase")]
pub struct OpError {
#[serde(rename = "$err_class_name")]
class_name: &'static str,
message: String,
code: Option<&'static str>,
}
impl OpError {
pub fn new(get_class: GetErrorClassFn, err: Error) -> Self {
Self {
class_name: (get_class)(&err),
message: err.to_string(),
code: crate::error_codes::get_error_code(&err),
}
}
}
pub fn to_op_result<R: Serialize + 'static>(
get_class: GetErrorClassFn,
result: Result<R, Error>,
) -> OpResult {
match result {
Ok(v) => OpResult::Ok(v.into()),
Err(err) => OpResult::Err(OpError::new(get_class, err)),
}
}
/// Maintains the resources and ops inside a JS runtime.
pub struct OpState {
pub resource_table: ResourceTable,
pub get_error_class_fn: GetErrorClassFn,
pub tracker: OpsTracker,
gotham_state: GothamState,
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}
impl OpState {
pub fn new(ops_count: usize) -> OpState {
OpState {
resource_table: Default::default(),
get_error_class_fn: &|_| "Error",
gotham_state: Default::default(),
tracker: OpsTracker {
ops: UnsafeCell::new(vec![Default::default(); ops_count]),
},
}
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}
}
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impl Deref for OpState {
type Target = GothamState;
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fn deref(&self) -> &Self::Target {
&self.gotham_state
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}
}
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impl DerefMut for OpState {
fn deref_mut(&mut self) -> &mut Self::Target {
&mut self.gotham_state
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}
}