Struct ConcurrentSkipList 

pub struct ConcurrentSkipList<K: Ord + Clone, V: Clone> { /* private fields */ }

A concurrent skip list optimized for offset lookups

Provides O(log n) lookups for finding messages by offset, which is critical for efficient consumer fetching.

Design: Append-Only

This skip list intentionally does not implement remove(). It is designed for append-only offset indexing where:

1. Entries are never deleted individually — the entire skip list is dropped when the corresponding segment is compacted or deleted
2. Memory lifecycle is tied to segment lifetime — when a segment is removed, the skip list is dropped via the Drop implementation, which properly deallocates all nodes
3. Offset indices are monotonically increasing — no reuse of keys

This design provides better performance than a skip list with remove support:

• No ABA problem handling required
• Simpler atomic operations (no backlink management)
• Predictable memory layout

Implementations

impl<K: Ord + Clone + Default, V: Clone + Default> ConcurrentSkipList<K, V>

pub fn new() -> Self

Create a new concurrent skip list

pub fn insert(&self, key: K, value: V)

Insert a key-value pair

pub fn get(&self, key: &K) -> Option<V>

Find a value by key

pub fn floor(&self, key: &K) -> Option<(K, V)>

Find the greatest key less than or equal to the given key This is useful for finding the closest offset <= target

pub fn ceiling(&self, key: &K) -> Option<(K, V)>

Find the smallest key greater than or equal to the given key

pub fn len(&self) -> usize

Get number of elements

pub fn is_empty(&self) -> bool

Check if empty

pub fn range(&self, start: &K, end: &K, limit: usize) -> Vec<(K, V)>

Get a range of entries

Trait Implementations

impl<K: Ord + Clone + Default, V: Clone + Default> Default for ConcurrentSkipList<K, V>

fn default() -> Self

Returns the “default value” for a type.

impl<K: Ord + Clone, V: Clone> Drop for ConcurrentSkipList<K, V>

fn drop(&mut self)

Executes the destructor for this type.

impl<K: Ord + Clone + Send, V: Clone + Send> Send for ConcurrentSkipList<K, V>

impl<K: Ord + Clone + Sync, V: Clone + Sync> Sync for ConcurrentSkipList<K, V>