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Change Bytes::make_mut to impl From<Bytes> for BytesMut (closes #709) (…
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…#710)

<Arc<T>>::make_mut returns a &mut T, such an API is doable for Bytes too
and thus we should reserve Bytes::make_mut for that.

Furthermore, it would be helpful to use From<Bytes> as a trait bound
in some cases with other traits such as Hyper's body trait, where Hyper
gives you Bytes values.

Finally, making it impl From<Bytes> for BytesMut means the API is more
easily discoverable as it appears on both Bytes and BytesMut.
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@nox
nox committed May 28, 2024
1 parent caf520a commit fa1daac
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Showing 4 changed files with 54 additions and 52 deletions.
44 changes: 23 additions & 21 deletions src/bytes.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -525,32 +525,12 @@ impl Bytes {
/// ```
pub fn try_into_mut(self) -> Result<BytesMut, Bytes> {
if self.is_unique() {
Ok(self.make_mut())
Ok(self.into())
} else {
Err(self)
}
}

/// Convert self into `BytesMut`.
///
/// If `self` is unique for the entire original buffer, this will return a
/// `BytesMut` with the contents of `self` without copying.
/// If `self` is not unique for the entire original buffer, this will make
/// a copy of `self` subset of the original buffer in a new `BytesMut`.
///
/// # Examples
///
/// ```
/// use bytes::{Bytes, BytesMut};
///
/// let bytes = Bytes::from(b"hello".to_vec());
/// assert_eq!(bytes.make_mut(), BytesMut::from(&b"hello"[..]));
/// ```
pub fn make_mut(self) -> BytesMut {
let bytes = ManuallyDrop::new(self);
unsafe { (bytes.vtable.to_mut)(&bytes.data, bytes.ptr, bytes.len) }
}

#[inline]
pub(crate) unsafe fn with_vtable(
ptr: *const u8,
Expand Down Expand Up @@ -932,6 +912,28 @@ impl From<Box<[u8]>> for Bytes {
}
}

impl From<Bytes> for BytesMut {
/// Convert self into `BytesMut`.
///
/// If `bytes` is unique for the entire original buffer, this will return a
/// `BytesMut` with the contents of `bytes` without copying.
/// If `bytes` is not unique for the entire original buffer, this will make
/// a copy of `bytes` subset of the original buffer in a new `BytesMut`.
///
/// # Examples
///
/// ```
/// use bytes::{Bytes, BytesMut};
///
/// let bytes = Bytes::from(b"hello".to_vec());
/// assert_eq!(BytesMut::from(bytes), BytesMut::from(&b"hello"[..]));
/// ```
fn from(bytes: Bytes) -> Self {
let bytes = ManuallyDrop::new(bytes);
unsafe { (bytes.vtable.to_mut)(&bytes.data, bytes.ptr, bytes.len) }
}
}

impl From<String> for Bytes {
fn from(s: String) -> Bytes {
Bytes::from(s.into_bytes())
Expand Down
Empty file added src/bytes/promotable.rs
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Empty file.
40 changes: 20 additions & 20 deletions tests/test_bytes.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1174,29 +1174,29 @@ fn shared_is_unique() {
}

#[test]
fn test_bytes_make_mut_static() {
fn test_bytesmut_from_bytes_static() {
let bs = b"1b23exfcz3r";

// Test STATIC_VTABLE.to_mut
let bytes_mut = Bytes::from_static(bs).make_mut();
let bytes_mut = BytesMut::from(Bytes::from_static(bs));
assert_eq!(bytes_mut, bs[..]);
}

#[test]
fn test_bytes_make_mut_bytes_mut_vec() {
fn test_bytesmut_from_bytes_bytes_mut_vec() {
let bs = b"1b23exfcz3r";
let bs_long = b"1b23exfcz3r1b23exfcz3r";

// Test case where kind == KIND_VEC
let mut bytes_mut: BytesMut = bs[..].into();
bytes_mut = bytes_mut.freeze().make_mut();
bytes_mut = BytesMut::from(bytes_mut.freeze());
assert_eq!(bytes_mut, bs[..]);
bytes_mut.extend_from_slice(&bs[..]);
assert_eq!(bytes_mut, bs_long[..]);
}

#[test]
fn test_bytes_make_mut_bytes_mut_shared() {
fn test_bytesmut_from_bytes_bytes_mut_shared() {
let bs = b"1b23exfcz3r";

// Set kind to KIND_ARC so that after freeze, Bytes will use bytes_mut.SHARED_VTABLE
Expand All @@ -1207,17 +1207,17 @@ fn test_bytes_make_mut_bytes_mut_shared() {
let b2 = b1.clone();

// shared.is_unique() = False
let mut b1m = b1.make_mut();
let mut b1m = BytesMut::from(b1);
assert_eq!(b1m, bs[..]);
b1m[0] = b'9';

// shared.is_unique() = True
let b2m = b2.make_mut();
let b2m = BytesMut::from(b2);
assert_eq!(b2m, bs[..]);
}

#[test]
fn test_bytes_make_mut_bytes_mut_offset() {
fn test_bytesmut_from_bytes_bytes_mut_offset() {
let bs = b"1b23exfcz3r";

// Test bytes_mut.SHARED_VTABLE.to_mut impl where offset != 0
Expand All @@ -1227,58 +1227,58 @@ fn test_bytes_make_mut_bytes_mut_offset() {
let b1 = bytes_mut1.freeze();
let b2 = bytes_mut2.freeze();

let b1m = b1.make_mut();
let b2m = b2.make_mut();
let b1m = BytesMut::from(b1);
let b2m = BytesMut::from(b2);

assert_eq!(b2m, bs[9..]);
assert_eq!(b1m, bs[..9]);
}

#[test]
fn test_bytes_make_mut_promotable_even_vec() {
fn test_bytesmut_from_bytes_promotable_even_vec() {
let vec = vec![33u8; 1024];

// Test case where kind == KIND_VEC
let b1 = Bytes::from(vec.clone());
let b1m = b1.make_mut();
let b1m = BytesMut::from(b1);
assert_eq!(b1m, vec);
}

#[test]
fn test_bytes_make_mut_promotable_even_arc_1() {
fn test_bytesmut_from_bytes_promotable_even_arc_1() {
let vec = vec![33u8; 1024];

// Test case where kind == KIND_ARC, ref_cnt == 1
let b1 = Bytes::from(vec.clone());
drop(b1.clone());
let b1m = b1.make_mut();
let b1m = BytesMut::from(b1);
assert_eq!(b1m, vec);
}

#[test]
fn test_bytes_make_mut_promotable_even_arc_2() {
fn test_bytesmut_from_bytes_promotable_even_arc_2() {
let vec = vec![33u8; 1024];

// Test case where kind == KIND_ARC, ref_cnt == 2
let b1 = Bytes::from(vec.clone());
let b2 = b1.clone();
let b1m = b1.make_mut();
let b1m = BytesMut::from(b1);
assert_eq!(b1m, vec);

// Test case where vtable = SHARED_VTABLE, kind == KIND_ARC, ref_cnt == 1
let b2m = b2.make_mut();
let b2m = BytesMut::from(b2);
assert_eq!(b2m, vec);
}

#[test]
fn test_bytes_make_mut_promotable_even_arc_offset() {
fn test_bytesmut_from_bytes_promotable_even_arc_offset() {
let vec = vec![33u8; 1024];

// Test case where offset != 0
let mut b1 = Bytes::from(vec.clone());
let b2 = b1.split_off(20);
let b1m = b1.make_mut();
let b2m = b2.make_mut();
let b1m = BytesMut::from(b1);
let b2m = BytesMut::from(b2);

assert_eq!(b2m, vec[20..]);
assert_eq!(b1m, vec[..20]);
Expand Down
22 changes: 11 additions & 11 deletions tests/test_bytes_odd_alloc.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,7 @@
use std::alloc::{GlobalAlloc, Layout, System};
use std::ptr;

use bytes::Bytes;
use bytes::{Bytes, BytesMut};

#[global_allocator]
static ODD: Odd = Odd;
Expand Down Expand Up @@ -97,50 +97,50 @@ fn test_bytes_into_vec() {
}

#[test]
fn test_bytes_make_mut_vec() {
fn test_bytesmut_from_bytes_vec() {
let vec = vec![33u8; 1024];

// Test case where kind == KIND_VEC
let b1 = Bytes::from(vec.clone());
let b1m = b1.make_mut();
let b1m = BytesMut::from(b1);
assert_eq!(b1m, vec);
}

#[test]
fn test_bytes_make_mut_arc_1() {
fn test_bytesmut_from_bytes_arc_1() {
let vec = vec![33u8; 1024];

// Test case where kind == KIND_ARC, ref_cnt == 1
let b1 = Bytes::from(vec.clone());
drop(b1.clone());
let b1m = b1.make_mut();
let b1m = BytesMut::from(b1);
assert_eq!(b1m, vec);
}

#[test]
fn test_bytes_make_mut_arc_2() {
fn test_bytesmut_from_bytes_arc_2() {
let vec = vec![33u8; 1024];

// Test case where kind == KIND_ARC, ref_cnt == 2
let b1 = Bytes::from(vec.clone());
let b2 = b1.clone();
let b1m = b1.make_mut();
let b1m = BytesMut::from(b1);
assert_eq!(b1m, vec);

// Test case where vtable = SHARED_VTABLE, kind == KIND_ARC, ref_cnt == 1
let b2m = b2.make_mut();
let b2m = BytesMut::from(b2);
assert_eq!(b2m, vec);
}

#[test]
fn test_bytes_make_mut_arc_offset() {
fn test_bytesmut_from_bytes_arc_offset() {
let vec = vec![33u8; 1024];

// Test case where offset != 0
let mut b1 = Bytes::from(vec.clone());
let b2 = b1.split_off(20);
let b1m = b1.make_mut();
let b2m = b2.make_mut();
let b1m = BytesMut::from(b1);
let b2m = BytesMut::from(b2);

assert_eq!(b2m, vec[20..]);
assert_eq!(b1m, vec[..20]);
Expand Down

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