mirror of
https://github.com/denoland/deno.git
synced 2024-11-22 15:06:54 -05:00
8fb1af1412
Also cleanup `bindings::deserialize()/decode()` so they use the `ZeroCopyBuf` abstraction rather than reimplementing it. This cleanup will facilitate moving `ZeroCopyBuf` to `serde_v8` since it's now self contained and there are no other `get_backing_store_slice()` callers.
102 lines
2.4 KiB
Rust
102 lines
2.4 KiB
Rust
// Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
|
|
|
|
use rusty_v8 as v8;
|
|
use std::cell::Cell;
|
|
use std::ops::Deref;
|
|
use std::ops::DerefMut;
|
|
|
|
/// A ZeroCopyBuf encapsulates a slice that's been borrowed from a JavaScript
|
|
/// ArrayBuffer object. JavaScript objects can normally be garbage collected,
|
|
/// but the existence of a ZeroCopyBuf inhibits this until it is dropped. It
|
|
/// behaves much like an Arc<[u8]>.
|
|
///
|
|
/// # Cloning
|
|
/// Cloning a ZeroCopyBuf does not clone the contents of the buffer,
|
|
/// it creates a new reference to that buffer.
|
|
///
|
|
/// To actually clone the contents of the buffer do
|
|
/// `let copy = Vec::from(&*zero_copy_buf);`
|
|
#[derive(Clone)]
|
|
pub struct ZeroCopyBuf {
|
|
backing_store: v8::SharedRef<v8::BackingStore>,
|
|
byte_offset: usize,
|
|
byte_length: usize,
|
|
}
|
|
|
|
unsafe impl Send for ZeroCopyBuf {}
|
|
|
|
impl ZeroCopyBuf {
|
|
pub fn new<'s>(
|
|
scope: &mut v8::HandleScope<'s>,
|
|
view: v8::Local<v8::ArrayBufferView>,
|
|
) -> Self {
|
|
let backing_store = view.buffer(scope).unwrap().get_backing_store();
|
|
let byte_offset = view.byte_offset();
|
|
let byte_length = view.byte_length();
|
|
Self {
|
|
backing_store,
|
|
byte_offset,
|
|
byte_length,
|
|
}
|
|
}
|
|
}
|
|
|
|
impl Deref for ZeroCopyBuf {
|
|
type Target = [u8];
|
|
fn deref(&self) -> &[u8] {
|
|
unsafe {
|
|
get_backing_store_slice(
|
|
&self.backing_store,
|
|
self.byte_offset,
|
|
self.byte_length,
|
|
)
|
|
}
|
|
}
|
|
}
|
|
|
|
impl DerefMut for ZeroCopyBuf {
|
|
fn deref_mut(&mut self) -> &mut [u8] {
|
|
unsafe {
|
|
get_backing_store_slice_mut(
|
|
&self.backing_store,
|
|
self.byte_offset,
|
|
self.byte_length,
|
|
)
|
|
}
|
|
}
|
|
}
|
|
|
|
impl AsRef<[u8]> for ZeroCopyBuf {
|
|
fn as_ref(&self) -> &[u8] {
|
|
&*self
|
|
}
|
|
}
|
|
|
|
impl AsMut<[u8]> for ZeroCopyBuf {
|
|
fn as_mut(&mut self) -> &mut [u8] {
|
|
&mut *self
|
|
}
|
|
}
|
|
|
|
unsafe fn get_backing_store_slice(
|
|
backing_store: &v8::SharedRef<v8::BackingStore>,
|
|
byte_offset: usize,
|
|
byte_length: usize,
|
|
) -> &[u8] {
|
|
let cells: *const [Cell<u8>] =
|
|
&backing_store[byte_offset..byte_offset + byte_length];
|
|
let bytes = cells as *const [u8];
|
|
&*bytes
|
|
}
|
|
|
|
#[allow(clippy::mut_from_ref)]
|
|
unsafe fn get_backing_store_slice_mut(
|
|
backing_store: &v8::SharedRef<v8::BackingStore>,
|
|
byte_offset: usize,
|
|
byte_length: usize,
|
|
) -> &mut [u8] {
|
|
let cells: *const [Cell<u8>] =
|
|
&backing_store[byte_offset..byte_offset + byte_length];
|
|
let bytes = cells as *const _ as *mut [u8];
|
|
&mut *bytes
|
|
}
|