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Merge promotable implementations #489

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Merge promotable implementations #489

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71 changes: 36 additions & 35 deletions src/bytes.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -862,30 +862,55 @@ unsafe fn static_drop(_: &mut AtomicPtr<()>, _: *const u8, _: usize) {

// ===== impl PromotableVtable =====

trait PromotableEvenness {
const SLICE_PTR_IS_ODD: bool;
}

struct PromotableEven;
struct PromotableOdd;

impl PromotableEvenness for PromotableEven {
const SLICE_PTR_IS_ODD: bool = false;
}
impl PromotableEvenness for PromotableOdd {
const SLICE_PTR_IS_ODD: bool = true;
}

static PROMOTABLE_EVEN_VTABLE: Vtable = Vtable {
clone: promotable_even_clone,
drop: promotable_even_drop,
clone: promotable_clone::<PromotableEven>,
drop: promotable_drop::<PromotableEven>,
};

static PROMOTABLE_ODD_VTABLE: Vtable = Vtable {
clone: promotable_odd_clone,
drop: promotable_odd_drop,
clone: promotable_clone::<PromotableOdd>,
drop: promotable_drop::<PromotableOdd>,
};

unsafe fn promotable_even_clone(data: &AtomicPtr<()>, ptr: *const u8, len: usize) -> Bytes {
unsafe fn promotable_clone<E: PromotableEvenness>(
data: &AtomicPtr<()>,
ptr: *const u8,
len: usize,
) -> Bytes {
let shared = data.load(Ordering::Acquire);
let kind = shared as usize & KIND_MASK;

if kind == KIND_ARC {
shallow_clone_arc(shared as _, ptr, len)
} else {
debug_assert_eq!(kind, KIND_VEC);
let buf = (shared as usize & !KIND_MASK) as *mut u8;
let buf = match E::SLICE_PTR_IS_ODD {
false => (shared as usize & !KIND_MASK) as *mut u8,
true => shared as *mut u8,
};
shallow_clone_vec(data, shared, buf, ptr, len)
}
}

unsafe fn promotable_even_drop(data: &mut AtomicPtr<()>, ptr: *const u8, len: usize) {
unsafe fn promotable_drop<E: PromotableEvenness>(
data: &mut AtomicPtr<()>,
ptr: *const u8,
len: usize,
) {
data.with_mut(|shared| {
let shared = *shared;
let kind = shared as usize & KIND_MASK;
Expand All @@ -894,39 +919,15 @@ unsafe fn promotable_even_drop(data: &mut AtomicPtr<()>, ptr: *const u8, len: us
release_shared(shared as *mut Shared);
} else {
debug_assert_eq!(kind, KIND_VEC);
let buf = (shared as usize & !KIND_MASK) as *mut u8;
let buf = match E::SLICE_PTR_IS_ODD {
false => (shared as usize & !KIND_MASK) as *mut u8,
true => shared as *mut u8,
};
drop(rebuild_boxed_slice(buf, ptr, len));
}
});
}

unsafe fn promotable_odd_clone(data: &AtomicPtr<()>, ptr: *const u8, len: usize) -> Bytes {
let shared = data.load(Ordering::Acquire);
let kind = shared as usize & KIND_MASK;

if kind == KIND_ARC {
shallow_clone_arc(shared as _, ptr, len)
} else {
debug_assert_eq!(kind, KIND_VEC);
shallow_clone_vec(data, shared, shared as *mut u8, ptr, len)
}
}

unsafe fn promotable_odd_drop(data: &mut AtomicPtr<()>, ptr: *const u8, len: usize) {
data.with_mut(|shared| {
let shared = *shared;
let kind = shared as usize & KIND_MASK;

if kind == KIND_ARC {
release_shared(shared as *mut Shared);
} else {
debug_assert_eq!(kind, KIND_VEC);

drop(rebuild_boxed_slice(shared as *mut u8, ptr, len));
}
});
}

unsafe fn rebuild_boxed_slice(buf: *mut u8, offset: *const u8, len: usize) -> Box<[u8]> {
let cap = (offset as usize - buf as usize) + len;
Box::from_raw(slice::from_raw_parts_mut(buf, cap))
Expand Down