Struct triomphe::ThinArc

#[repr(transparent)]
pub struct ThinArc<H, T> { /* private fields */ }

A “thin” Arc containing dynamically sized data

This is functionally equivalent to Arc<(H, [T])>

When you create an Arc containing a dynamically sized type like HeaderSlice<H, [T]>, the Arc is represented on the stack as a “fat pointer”, where the length of the slice is stored alongside the Arc’s pointer. In some situations you may wish to have a thin pointer instead, perhaps for FFI compatibility or space efficiency.

Note that we use [T; 0] in order to have the right alignment for T.

ThinArc solves this by storing the length in the allocation itself, via HeaderSliceWithLength.

Implementations

impl<H, T> ThinArc<H, T>

pub fn with_arc<F, U>(&self, f: F) -> Uwhere
    F: FnOnce(&Arc<HeaderSlice<HeaderWithLength<H>, [T]>>) -> U,

Temporarily converts |self| into a bonafide Arc and exposes it to the provided callback. The refcount is not modified.

pub fn from_header_and_iter<I>(header: H, items: I) -> Selfwhere
    I: Iterator<Item = T> + ExactSizeIterator,

Creates a ThinArc for a HeaderSlice using the given header struct and iterator to generate the slice.

pub fn from_header_and_slice(header: H, items: &[T]) -> Selfwhere
    T: Copy,

Creates a ThinArc for a HeaderSlice using the given header struct and a slice to copy.

pub fn ptr(&self) -> *const c_void

Returns the address on the heap of the ThinArc itself – not the T within it – for memory reporting.

pub fn heap_ptr(&self) -> *const c_void

Returns the address on the heap of the Arc itself – not the T within it – for memory reporting.

pub unsafe fn from_raw(ptr: *const c_void) -> Self

Safety

Constructs an ThinArc from a raw pointer.

The raw pointer must have been previously returned by a call to ThinArc::into_raw.

The user of from_raw has to make sure a specific value of T is only dropped once.

This function is unsafe because improper use may lead to memory unsafety, even if the returned ThinArc is never accessed.

pub fn into_raw(self) -> *const c_void

Consume ThinArc and returned the wrapped pointer.

pub fn as_ptr(&self) -> *const c_void

Provides a raw pointer to the data. The counts are not affected in any way and the ThinArc is not consumed. The pointer is valid for as long as there are strong counts in the ThinArc.

Trait Implementations

impl<H, T> Clone for ThinArc<H, T>

fn clone(&self) -> Self

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<H: Debug, T: Debug> Debug for ThinArc<H, T>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<H, T> Deref for ThinArc<H, T>

type Target = HeaderSlice<HeaderWithLength<H>, [T]>

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl<H, T> Drop for ThinArc<H, T>

fn drop(&mut self)

Executes the destructor for this type.

impl<H: Hash, T: Hash> Hash for ThinArc<H, T>

fn hash<HSR: Hasher>(&self, state: &mut HSR)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)where
    H: Hasher,

Feeds a slice of this type into the given Hasher.

impl<H: PartialEq, T: PartialEq> PartialEq<ThinArc<H, T>> for ThinArc<H, T>

fn eq(&self, other: &ThinArc<H, T>) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<H, T> Pointer for ThinArc<H, T>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<H: Eq, T: Eq> Eq for ThinArc<H, T>

impl<H: Sync + Send, T: Sync + Send> Send for ThinArc<H, T>

impl<H: Sync + Send, T: Sync + Send> Sync for ThinArc<H, T>