Struct SubscriptionOptionsBits 

pub struct SubscriptionOptionsBits {
    pub reserved_bits: u8,
    pub retain_handling: u8,
    pub retain_as_published: u8,
    pub no_local: u8,
    pub qos: u8,
}

Subscription options using bebytes for bit field operations This demonstrates the hybrid approach for complex packet variable headers Bit fields are ordered from MSB to LSB (bits 7-0)

Fields

reserved_bits: u8

Reserved bits (bits 7-6) - must be 0

retain_handling: u8

Retain Handling (bits 5-4)

retain_as_published: u8

Retain As Published flag (bit 3)

no_local: u8

No Local flag (bit 2)

qos: u8

QoS level (bits 1-0)

Implementations

impl SubscriptionOptionsBits

pub fn new( reserved_bits: u8, retain_handling: u8, retain_as_published: u8, no_local: u8, qos: u8, ) -> Self

pub const fn supports_raw_pointer_encoding() -> bool

Check if this struct supports raw pointer encoding

pub const fn optimal_serialization_method() -> &'static str

Get the optimal serialization method for this struct Returns the method name as a static string for performance guidance

pub fn to_be_bytes_optimal(&self) -> Result<Bytes, BeBytesError>

Automatically select the optimal serialization method (big-endian) This method chooses the best approach based on struct characteristics

pub fn to_le_bytes_optimal(&self) -> Result<Bytes, BeBytesError>

Automatically select the optimal serialization method (little-endian) This method chooses the best approach based on struct characteristics

pub fn create_batch_buffer_be(capacity: usize) -> BytesMut

Create a pre-sized buffer for batch serialization (big-endian) This helps avoid repeated allocations when serializing multiple instances

pub fn create_batch_buffer_le(capacity: usize) -> BytesMut

Create a pre-sized buffer for batch serialization (little-endian) This helps avoid repeated allocations when serializing multiple instances

pub fn encode_be_to_reused( &self, buf: &mut BytesMut, ) -> Result<(), BeBytesError>

Encode to a reusable buffer with optimal method selection (big-endian) This method automatically chooses the best encoding approach for performance

pub fn encode_le_to_reused( &self, buf: &mut BytesMut, ) -> Result<(), BeBytesError>

Encode to a reusable buffer with optimal method selection (little-endian) This method automatically chooses the best encoding approach for performance

impl SubscriptionOptionsBits

pub fn from_options(options: &SubscriptionOptions) -> Self

Creates subscription options bits from high-level SubscriptionOptions Bebytes handles bit field layout, Rust handles type safety and validation

pub fn to_options(&self) -> Result<SubscriptionOptions>

Converts bebytes bit fields back to high-level SubscriptionOptions Bebytes provides the bits, Rust handles validation and type conversion

Errors

Returns an error if reserved bits are set, or if QoS or retain handling values are invalid

Trait Implementations

impl BeBytes for SubscriptionOptionsBits

Performance Characteristics

• Expected improvement: 2.3f32x over Vec approach
• Allocation pattern: Single allocation with reuse potential
• Recommendation: Good: Use Bytes buffer methods for better performance

Optimization Hint: Consider using to_be_bytes_buf() for better performance (2.3x improvement)

fn to_be_bytes_buf(&self) -> Bytes

Convert to big-endian bytes as a zero-copy Bytes buffer

fn to_le_bytes_buf(&self) -> Bytes

Convert to little-endian bytes as a zero-copy Bytes buffer

fn field_size() -> usize

fn try_from_be_bytes(bytes: &[u8]) -> Result<(Self, usize), BeBytesError>

Try to parse a struct from big-endian bytes

fn to_be_bytes(&self) -> Vec<u8>

fn try_from_le_bytes(bytes: &[u8]) -> Result<(Self, usize), BeBytesError>

Try to parse a struct from little-endian bytes

fn to_le_bytes(&self) -> Vec<u8>

fn encode_be_to<B: BufMut>(&self, buf: &mut B) -> Result<(), BeBytesError>

Encode directly to a buffer in big-endian format

fn encode_le_to<B: BufMut>(&self, buf: &mut B) -> Result<(), BeBytesError>

Encode directly to a buffer in little-endian format

impl Clone for SubscriptionOptionsBits

fn clone(&self) -> SubscriptionOptionsBits

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for SubscriptionOptionsBits

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

Formats the value using the given formatter.

impl PartialEq for SubscriptionOptionsBits

fn eq(&self, other: &SubscriptionOptionsBits) -> 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 Copy for SubscriptionOptionsBits

impl Eq for SubscriptionOptionsBits

impl StructuralPartialEq for SubscriptionOptionsBits