Struct AtomicClaimManager 

pub struct AtomicClaimManager { /* private fields */ }

Atomic claim manager for queue task ownership

This provides the CAS-based claim protocol that ensures linearizable task ownership under concurrent access.

Thread Safety

All operations are thread-safe. The manager uses fine-grained locking to minimize contention:

• Per-queue locks for claim operations
• Read-write locks for statistics

Durability

In production, claims should be persisted to storage with WAL durability. This in-memory implementation is for reference and testing.

Implementations

impl AtomicClaimManager

pub fn new() -> Self

Create a new claim manager

pub fn claim( &self, queue_id: &str, task_id: &str, owner: &str, lease_duration_ms: u64, ) -> ClaimResult

Attempt to claim a task

This is the atomic CAS operation that establishes ownership.

Semantics

• If task is unclaimed: creates claim, returns Success
• If task is claimed by other worker with valid lease: returns AlreadyClaimed
• If task is claimed but lease expired: creates new claim, returns TookOver

Complexity

O(1) hash lookups + lock acquisition

pub fn release(&self, token: &ClaimToken) -> Result<(), String>

Release a claim (acknowledge successful processing)

The claim token must be valid and owned by the caller.

pub fn extend( &self, queue_id: &str, token: &ClaimToken, additional_ms: u64, ) -> Result<ClaimToken, String>

Extend a claim’s lease duration

Useful when processing takes longer than expected.

pub fn is_claimed(&self, queue_id: &str, task_id: &str) -> Option<(String, u64)>

Check if a task is currently claimed

pub fn get_token( &self, queue_id: &str, task_id: &str, owner: &str, ) -> Option<ClaimToken>

Get the current claim token for a task (if owned by the given worker)

pub fn cleanup_expired(&self) -> usize

Clean up expired claims

This should be called periodically (e.g., every few seconds). Returns the number of claims cleaned up.

pub fn stats(&self) -> ClaimStats

Get statistics

pub fn active_claims(&self, queue_id: &str) -> usize

Get number of active claims for a queue

pub fn list_claims(&self, queue_id: &str) -> Vec<ClaimToken>

Get all active claims for a queue (for monitoring)

Trait Implementations

impl Default for AtomicClaimManager

fn default() -> Self

Returns the “default value” for a type.