Enum ValueStorage 

#[repr(C)]
pub enum ValueStorage {
    Inline {
        len: u8,
        data: [u8; 56],
    },
    Heap(Box<[u8]>),
    Tombstone,
}

Optimized value storage with inline allocation for small values

For typical database workloads, 80%+ of values are < 56 bytes. Storing these inline eliminates heap allocation and pointer chasing.

Cache Analysis

Current path: DashMap lookup → Version ptr → Value ptr (Vec data) Cache misses: 2-3 (worst case)

Inline path: DashMap lookup → Version with inline value Cache misses: 1

Expected speedup: 2-2.5× for reads on small values

Variants

Inline

Value stored inline (most common case for small values)

Fields

len: u8

data: [u8; 56]

Heap(Box<[u8]>)

Value stored on heap (for large values > 56 bytes)

Tombstone

Tombstone marker (key was deleted)

Implementations

impl ValueStorage

pub fn new(value: Option<&[u8]>) -> Self

Create new value storage, preferring inline when possible

pub fn as_bytes(&self) -> Option<&[u8]>

Get value as byte slice

pub fn is_tombstone(&self) -> bool

Check if this is a tombstone

pub fn is_inline(&self) -> bool

Check if value is stored inline

pub fn len(&self) -> usize

Get the size of the stored value

pub fn is_empty(&self) -> bool

Check if the stored value is empty

Trait Implementations

impl Debug for ValueStorage

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

Formats the value using the given formatter.