Crate kovan 

Kovan: High-performance wait-free memory reclamation for lock-free data structures. Bounded memory usage, predictable latency.

Kovan implements a wait-free safe memory reclamation (SMR) algorithm based on the Crystalline / ASMR design. Unlike epoch-based reclamation (EBR) or hazard pointers, kovan guarantees bounded worst-case latency for every operation — no thread can be starved, even under contention.

Key Properties

• Wait-Free Progress: Every operation completes in a bounded number of steps, regardless of what other threads are doing. Stalled threads are helped to completion by concurrent threads.
• Zero Read Overhead: Object loads require only a single atomic read — the same cost as a raw AtomicPtr::load.
• Bounded Memory: Retired nodes are reclaimed in bounded batches. The reclamation system cannot accumulate unbounded garbage, even with stalled threads.
• no_std Compatible: Uses only alloc. No standard library required.

Architecture

• Per-thread epoch slots: Each thread maintains a slot recording its current epoch. Slots are protected by 128-bit DCAS (double compare-and-swap).
• Batch retirement: Retired nodes are accumulated in thread-local batches of 64 and distributed across active slots via try_retire.
• Wait-free helping: Threads in the slow path publish their state so other threads can help them complete, ensuring system-wide progress.

Example

use kovan::Atom;

// High-level API: safe, zero-overhead reads
let config = Atom::new(vec![1, 2, 3]);
let guard = config.load();
assert_eq!(guard.len(), 3);

Structs

Atom

A lock-free single-value container with safe memory reclamation.

AtomGuard

RAII guard returned by Atom::load().

AtomMap

A projected view into an Atom<T>, created by Atom::map().

AtomMapGuard

Guard for a mapped/projected load.

AtomOption

Like Atom<T> but allows a null/empty state.

Atomic

A pointer to a heap-allocated value with atomic operations.

BirthEra

Birth era for a node

Guard

RAII guard representing an active critical section.

Removed

A value removed from an Atom or AtomOption.

RetiredNode

Node structure embedded in user’s data structure.

Shared

A pointer to a heap-allocated value protected by a guard.

Enums

Ordering

Atomic memory orderings

Traits

Reclaimable

Trait for types that can be reclaimed by the wait-free memory reclamation system.

Functions

current_era

Get current global era

flush

Flush all retired nodes on the calling thread.

pin

Enter a critical section.

retire^⚠

Retire a node for later reclamation.