Enum KeyHolderExtensibility 

pub enum KeyHolderExtensibility {
    ForcedFinal,
    AsDeclared,
}

Whether a key holder keeps the type’s extensibility or is forced to @final.

DDSI-RTPS 2.5 §9.6.4.8 Step 1 and XTypes 1.3 §7.6.8 Step 1 both build FooKeyHolder from Foo and then say it “shall have extensibility kind ‘FINAL’”. A holder that kept the original’s kind carries the original’s framing: a DHEADER for an appendable one, PID headers and a sentinel for a mutable one under XCDR1 — and that pushes the holder over sixteen bytes, which sends Step 5 down the MD5 branch. Two peers reading the clause differently compute different instance handles for one instance.

One implementation departs, in one place

Measured with @final struct Foo { @key long id; long x; long y; } and its @appendable and @mutable variants, id = 0x12345678:

	XCDR1	XCDR2
Cyclone, all three kinds	holder 12345678, hash 12345678 + zeros	the same
Fast DDS, all three	the same	the same
RTI, @final / @appendable	the same	the same
RTI, @mutable	holder 00000004 12345678 7f020000, hash 0482916deda7e1d2459197a74346627f	12345678 + zeros

Cyclone’s key buffer still carries the framing and dds_stream_extract_keyBE_from_key(…, DDS_CDR_KEY_SERIALIZATION_KEYHASH, …) strips it. Fast DDS hard-codes PLAIN_CDR2 in the generated holder whatever the type says. RTI keeps the parameter list under XCDR1 only: maxSizeSerializedKey V1 = 28, past sixteen, so the MD5 branch is taken over the framing rather than over the key.

Variants

ForcedFinal

@final, whatever the type declares. The clause, and what four of the five measured combinations do.

AsDeclared

The type’s own kind, framing and all.

RTI Connext 7.7 under XCDR1. Select it to compute the instance handle an RTI peer computes for a @mutable keyed type there; under XCDR2 RTI forces final like everyone else, which is why Dialect::key_holder_extensibility takes the encoding.

Implementations

impl KeyHolderExtensibility

pub const ALL: [Self; 2]

Both.

pub const fn is_default(self) -> bool

Whether this is the default.

pub const fn as_str(self) -> &'static str

Short name, for configuration and diagnostics.

pub fn parse(value: &str) -> Option<Self>

Parse a configuration value.

An unknown value returns None rather than falling back to the default: a typo here changes every instance handle.

Trait Implementations

impl Clone for KeyHolderExtensibility

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for KeyHolderExtensibility

impl Debug for KeyHolderExtensibility

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

Formats the value using the given formatter.

impl Default for KeyHolderExtensibility

fn default() -> Self

Returns the “default value” for a type.

impl Eq for KeyHolderExtensibility

impl Hash for KeyHolderExtensibility

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 KeyHolderExtensibility

fn cmp(&self, other: &Self) -> 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.

fn clamp_to<R>(self, range: R) -> Self

where Self: Sized, R: ClampBounds<Self>,

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

Restrict a value to a certain range.

impl PartialEq for KeyHolderExtensibility

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

Equality operator ==.

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

Inequality operator !=.

impl PartialOrd for KeyHolderExtensibility

fn partial_cmp(&self, other: &Self) -> 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 StructuralPartialEq for KeyHolderExtensibility