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Code Issues Packages 1 Wiki Activity

cleanup(serde_v8): simpler ZeroCopyBuf (#14095)

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This commit is contained in:
Aaron O'Mullan 2022-04-02 00:10:42 +02:00 committed by David Sherret
parent 3cc14196e2
commit d3aa444755
1 changed files with 25 additions and 56 deletions
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81
serde_v8/magic/zero_copy_buf.rs
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@ -1,8 +1,8 @@
// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.
use std::cell::Cell;
use std::ops::Deref;
use std::ops::DerefMut;
use std::ops::Range;
use super::transl8::FromV8;
@ -19,9 +19,8 @@ use super::transl8::FromV8;
/// `let copy = Vec::from(&*zero_copy_buf);`
#[derive(Clone)]
pub struct ZeroCopyBuf {
backing_store: v8::SharedRef<v8::BackingStore>,
byte_offset: usize,
byte_length: usize,
store: v8::SharedRef<v8::BackingStore>,
range: Range<usize>,
}
unsafe impl Send for ZeroCopyBuf {}
@ -29,21 +28,16 @@ unsafe impl Send for ZeroCopyBuf {}
impl ZeroCopyBuf {
pub fn from_buffer(
buffer: v8::Local<v8::ArrayBuffer>,
byte_offset: usize,
byte_length: usize,
range: Range<usize>,
) -> Result<Self, v8::DataError> {
let backing_store = buffer.get_backing_store();
match backing_store.is_shared() {
true => Err(v8::DataError::BadType {
let store = buffer.get_backing_store();
if store.is_shared() {
return Err(v8::DataError::BadType {
actual: "shared ArrayBufferView",
expected: "non-shared ArrayBufferView",
}),
false => Ok(Self {
backing_store,
byte_offset,
byte_length,
}),
});
}
Ok(Self { store, range })
}
pub fn from_view(
@ -53,7 +47,17 @@ impl ZeroCopyBuf {
let buffer = view.buffer(scope).ok_or(v8::DataError::NoData {
expected: "view to have a buffer",
})?;
Self::from_buffer(buffer, view.byte_offset(), view.byte_length())
let (offset, len) = (view.byte_offset(), view.byte_length());
Self::from_buffer(buffer, offset..offset + len)
}
fn as_slice(&self) -> &[u8] {
unsafe { &*(&self.store[self.range.clone()] as *const _ as *const [u8]) }
}
#[allow(clippy::cast_ref_to_mut)]
fn as_slice_mut(&mut self) -> &mut [u8] {
unsafe { &mut *(&self.store[self.range.clone()] as *const _ as *mut [u8]) }
}
}
@ -65,7 +69,7 @@ impl FromV8 for ZeroCopyBuf {
if value.is_array_buffer() {
value
.try_into()
.and_then(|b| Self::from_buffer(b, 0, b.byte_length()))
.and_then(|b| Self::from_buffer(b, 0..b.byte_length()))
} else {
value
.try_into()
@ -78,59 +82,24 @@ impl FromV8 for ZeroCopyBuf {
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,
)
}
self.as_slice()
}
}
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,
)
}
self.as_slice_mut()
}
}
impl AsRef<[u8]> for ZeroCopyBuf {
fn as_ref(&self) -> &[u8] {
&*self
self.as_slice()
}
}
impl AsMut<[u8]> for ZeroCopyBuf {
fn as_mut(&mut self) -> &mut [u8] {
&mut *self
self.as_slice_mut()
}
}
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
}