Struct RefCount 

#[repr(C)]
pub struct RefCount {
    pub ptr: *const RefCountInner,
    pub run_destructor: bool,
}

Wrapper around a heap-allocated RefCountInner.

This is the shared metadata that all RefAny clones point to. The RefCount is responsible for all memory management:

• RefCount::clone() increments num_copies in RefCountInner
• RefCount::drop() decrements num_copies and, if it reaches 0:
  1. Frees the RefCountInner
  2. Calls the custom destructor on the data
  3. Deallocates the data memory

Why run_destructor: bool

This flag tracks whether this RefCount instance should decrement num_copies when dropped. Set to true for all clones (including those created by RefAny::clone() and AZ_REFLECT macros). Set to false after the decrement has been performed to prevent double-decrement.

Fields

ptr: *const RefCountInner

run_destructor: bool

Implementations

impl RefCount

pub fn can_be_shared(&self) -> bool

Runtime check: can we create a shared borrow?

Returns true if there are no active mutable borrows. Multiple shared borrows can coexist (like &T in Rust).

Memory Ordering

Uses SeqCst to ensure we see the most recent state from all threads. If another thread just released a mutable borrow, we’ll see it.

pub fn can_be_shared_mut(&self) -> bool

Runtime check: can we create a mutable borrow?

Returns true only if there are ZERO active borrows of any kind. This enforces Rust’s exclusive mutability rule (like &mut T).

Memory Ordering

Uses SeqCst to ensure we see all recent borrows from all threads. Both counters must be checked atomically to prevent races.

pub fn increase_ref(&self)

Increments the shared borrow counter.

Called when a Ref<T> is created. The Ref::drop will decrement it.

Memory Ordering

SeqCst ensures this increment is visible to all threads before they try to acquire a mutable borrow (which checks this counter).

pub fn decrease_ref(&self)

Decrements the shared borrow counter.

Called when a Ref<T> is dropped, indicating the borrow is released.

Memory Ordering

SeqCst ensures this decrement is immediately visible to other threads waiting to acquire a mutable borrow.

pub fn increase_refmut(&self)

Increments the mutable borrow counter.

Called when a RefMut<T> is created. Should only succeed when this counter and num_refs are both 0.

Memory Ordering

SeqCst ensures this increment is visible to all other threads, blocking them from acquiring any borrow (shared or mutable).

pub fn decrease_refmut(&self)

Decrements the mutable borrow counter.

Called when a RefMut<T> is dropped, releasing exclusive access.

Memory Ordering

SeqCst ensures this decrement is immediately visible, allowing other threads to acquire borrows.

Trait Implementations

impl Clone for RefCount

fn clone(&self) -> Self

Clones the RefCount and increments the reference count.

Safety

This is safe because:

• The ptr is valid (created from Box::into_raw)
• num_copies is atomically incremented with SeqCst ordering
• This ensures the RefCountInner is not freed while clones exist

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

Performs copy-assignment from source.

impl Debug for RefCount

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

Formats the value using the given formatter.

impl Drop for RefCount

fn drop(&mut self)

Decrements the reference count when a RefCount clone is dropped.

If this was the last reference (num_copies reaches 0), this will also free the RefCountInner and call the custom destructor.

fn pin_drop(self: Pin<&mut Self>)

🔬This is a nightly-only experimental API. (pin_ergonomics)

Execute the destructor for this type, but different to Drop::drop, it requires self to be pinned.

impl Hash for RefCount

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

Feeds this value into the given Hasher.

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

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl Ord for RefCount

fn cmp(&self, other: &RefCount) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl PartialEq for RefCount

fn eq(&self, other: &RefCount) -> bool

Tests for self and other values to be equal, and is used by ==.

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

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

impl PartialOrd for RefCount

fn partial_cmp(&self, other: &RefCount) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

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

Tests less than (for self and other) and is used by the < operator.

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

Tests less than or equal to (for self and other) and is used by the <= operator.

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

Tests greater than (for self and other) and is used by the > operator.

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

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl Eq for RefCount

impl StructuralPartialEq for RefCount