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Merge branch 'master' of https://github.com/tokio-rs/bytes into get-v…
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…ec-pos-mut
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@braddunbar
braddunbar committed Feb 6, 2024
2 parents 6e8ab52 + f586ffc commit 808f639
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Showing 2 changed files with 58 additions and 61 deletions.
3 changes: 1 addition & 2 deletions src/bytes.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -828,8 +828,7 @@ impl From<&'static str> for Bytes {
}

impl From<Vec<u8>> for Bytes {
fn from(vec: Vec<u8>) -> Bytes {
let mut vec = vec;
fn from(mut vec: Vec<u8>) -> Bytes {
let ptr = vec.as_mut_ptr();
let len = vec.len();
let cap = vec.capacity();
Expand Down
116 changes: 57 additions & 59 deletions src/bytes_mut.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -247,7 +247,7 @@ impl BytesMut {
if self.kind() == KIND_VEC {
// Just re-use `Bytes` internal Vec vtable
unsafe {
let (off, _) = self.get_vec_pos();
let off = self.get_vec_pos();
let vec = rebuild_vec(self.ptr.as_ptr(), self.len, self.cap, off);
mem::forget(self);
let mut b: Bytes = vec.into();
Expand Down Expand Up @@ -596,7 +596,7 @@ impl BytesMut {
// We need to make sure that this optimization does not kill the
// amortized runtimes of BytesMut's operations.
unsafe {
let (off, prev) = self.get_vec_pos();
let off = self.get_vec_pos();

// Only reuse space if we can satisfy the requested additional space.
//
Expand All @@ -617,11 +617,11 @@ impl BytesMut {
//
// Just move the pointer back to the start after copying
// data back.
let base_ptr = self.ptr.as_ptr().offset(-(off as isize));
let base_ptr = self.ptr.as_ptr().sub(off);
// Since `off >= self.len()`, the two regions don't overlap.
ptr::copy_nonoverlapping(self.ptr.as_ptr(), base_ptr, self.len);
self.ptr = vptr(base_ptr);
self.set_vec_pos(0, prev);
self.set_vec_pos(0);

// Length stays constant, but since we moved backwards we
// can gain capacity back.
Expand Down Expand Up @@ -652,13 +652,7 @@ impl BytesMut {
// Compute the new capacity
let mut new_cap = len.checked_add(additional).expect("overflow");

let original_capacity;
let original_capacity_repr;

unsafe {
original_capacity_repr = (*shared).original_capacity_repr;
original_capacity = original_capacity_from_repr(original_capacity_repr);

// First, try to reclaim the buffer. This is possible if the current
// handle is the only outstanding handle pointing to the buffer.
if (*shared).is_unique() {
Expand Down Expand Up @@ -729,6 +723,9 @@ impl BytesMut {
}
}

let original_capacity_repr = unsafe { (*shared).original_capacity_repr };
let original_capacity = original_capacity_from_repr(original_capacity_repr);

new_cap = cmp::max(new_cap, original_capacity);

// Create a new vector to store the data
Expand Down Expand Up @@ -870,11 +867,10 @@ impl BytesMut {
// complicated. First, we have to track how far ahead the
// "start" of the byte buffer from the beginning of the vec. We
// also have to ensure that we don't exceed the maximum shift.
let (mut pos, prev) = self.get_vec_pos();
pos += start;
let pos = self.get_vec_pos() + start;

if pos <= MAX_VEC_POS {
self.set_vec_pos(pos, prev);
self.set_vec_pos(pos);
} else {
// The repr must be upgraded to ARC. This will never happen
// on 64 bit systems and will only happen on 32 bit systems
Expand Down Expand Up @@ -982,19 +978,18 @@ impl BytesMut {
}

#[inline]
unsafe fn get_vec_pos(&self) -> (usize, usize) {
unsafe fn get_vec_pos(&self) -> usize {
debug_assert_eq!(self.kind(), KIND_VEC);

let prev = self.data as usize;
(prev >> VEC_POS_OFFSET, prev)
self.data as usize >> VEC_POS_OFFSET
}

#[inline]
unsafe fn set_vec_pos(&mut self, pos: usize, prev: usize) {
unsafe fn set_vec_pos(&mut self, pos: usize) {
debug_assert_eq!(self.kind(), KIND_VEC);
debug_assert!(pos <= MAX_VEC_POS);

self.data = invalid_ptr((pos << VEC_POS_OFFSET) | (prev & NOT_VEC_POS_MASK));
self.data = invalid_ptr((pos << VEC_POS_OFFSET) | (self.data as usize & NOT_VEC_POS_MASK));
}

/// Returns the remaining spare capacity of the buffer as a slice of `MaybeUninit<u8>`.
Expand Down Expand Up @@ -1043,7 +1038,7 @@ impl Drop for BytesMut {

if kind == KIND_VEC {
unsafe {
let (off, _) = self.get_vec_pos();
let off = self.get_vec_pos();

// Vector storage, free the vector
let _ = rebuild_vec(self.ptr.as_ptr(), self.len, self.cap, off);
Expand Down Expand Up @@ -1409,56 +1404,59 @@ fn original_capacity_from_repr(repr: usize) -> usize {
1 << (repr + (MIN_ORIGINAL_CAPACITY_WIDTH - 1))
}

/*
#[test]
fn test_original_capacity_to_repr() {
assert_eq!(original_capacity_to_repr(0), 0);
#[cfg(test)]
mod tests {
use super::*;

let max_width = 32;
#[test]
fn test_original_capacity_to_repr() {
assert_eq!(original_capacity_to_repr(0), 0);

for width in 1..(max_width + 1) {
let cap = 1 << width - 1;
let max_width = 32;

let expected = if width < MIN_ORIGINAL_CAPACITY_WIDTH {
0
} else if width < MAX_ORIGINAL_CAPACITY_WIDTH {
width - MIN_ORIGINAL_CAPACITY_WIDTH
} else {
MAX_ORIGINAL_CAPACITY_WIDTH - MIN_ORIGINAL_CAPACITY_WIDTH
};
for width in 1..(max_width + 1) {
let cap = 1 << width - 1;

assert_eq!(original_capacity_to_repr(cap), expected);
let expected = if width < MIN_ORIGINAL_CAPACITY_WIDTH {
0
} else if width < MAX_ORIGINAL_CAPACITY_WIDTH {
width - MIN_ORIGINAL_CAPACITY_WIDTH
} else {
MAX_ORIGINAL_CAPACITY_WIDTH - MIN_ORIGINAL_CAPACITY_WIDTH
};

if width > 1 {
assert_eq!(original_capacity_to_repr(cap + 1), expected);
}
assert_eq!(original_capacity_to_repr(cap), expected);

if width > 1 {
assert_eq!(original_capacity_to_repr(cap + 1), expected);
}

// MIN_ORIGINAL_CAPACITY_WIDTH must be bigger than 7 to pass tests below
if width == MIN_ORIGINAL_CAPACITY_WIDTH + 1 {
assert_eq!(original_capacity_to_repr(cap - 24), expected - 1);
assert_eq!(original_capacity_to_repr(cap + 76), expected);
} else if width == MIN_ORIGINAL_CAPACITY_WIDTH + 2 {
assert_eq!(original_capacity_to_repr(cap - 1), expected - 1);
assert_eq!(original_capacity_to_repr(cap - 48), expected - 1);
// MIN_ORIGINAL_CAPACITY_WIDTH must be bigger than 7 to pass tests below
if width == MIN_ORIGINAL_CAPACITY_WIDTH + 1 {
assert_eq!(original_capacity_to_repr(cap - 24), expected - 1);
assert_eq!(original_capacity_to_repr(cap + 76), expected);
} else if width == MIN_ORIGINAL_CAPACITY_WIDTH + 2 {
assert_eq!(original_capacity_to_repr(cap - 1), expected - 1);
assert_eq!(original_capacity_to_repr(cap - 48), expected - 1);
}
}
}
}

#[test]
fn test_original_capacity_from_repr() {
assert_eq!(0, original_capacity_from_repr(0));
#[test]
fn test_original_capacity_from_repr() {
assert_eq!(0, original_capacity_from_repr(0));

let min_cap = 1 << MIN_ORIGINAL_CAPACITY_WIDTH;
let min_cap = 1 << MIN_ORIGINAL_CAPACITY_WIDTH;

assert_eq!(min_cap, original_capacity_from_repr(1));
assert_eq!(min_cap * 2, original_capacity_from_repr(2));
assert_eq!(min_cap * 4, original_capacity_from_repr(3));
assert_eq!(min_cap * 8, original_capacity_from_repr(4));
assert_eq!(min_cap * 16, original_capacity_from_repr(5));
assert_eq!(min_cap * 32, original_capacity_from_repr(6));
assert_eq!(min_cap * 64, original_capacity_from_repr(7));
assert_eq!(min_cap, original_capacity_from_repr(1));
assert_eq!(min_cap * 2, original_capacity_from_repr(2));
assert_eq!(min_cap * 4, original_capacity_from_repr(3));
assert_eq!(min_cap * 8, original_capacity_from_repr(4));
assert_eq!(min_cap * 16, original_capacity_from_repr(5));
assert_eq!(min_cap * 32, original_capacity_from_repr(6));
assert_eq!(min_cap * 64, original_capacity_from_repr(7));
}
}
*/

unsafe impl Send for BytesMut {}
unsafe impl Sync for BytesMut {}
Expand Down Expand Up @@ -1625,7 +1623,7 @@ impl From<BytesMut> for Vec<u8> {

let mut vec = if kind == KIND_VEC {
unsafe {
let (off, _) = bytes.get_vec_pos();
let off = bytes.get_vec_pos();
rebuild_vec(bytes.ptr.as_ptr(), bytes.len, bytes.cap, off)
}
} else {
Expand Down Expand Up @@ -1694,7 +1692,7 @@ fn offset_from(dst: *mut u8, original: *mut u8) -> usize {
}

unsafe fn rebuild_vec(ptr: *mut u8, mut len: usize, mut cap: usize, off: usize) -> Vec<u8> {
let ptr = ptr.offset(-(off as isize));
let ptr = ptr.sub(off);
len += off;
cap += off;

Expand Down

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