Struct RequestIdAllocator 

pub struct RequestIdAllocator {
    role: Role,
    next_id: u64,
    max_id: u64,
}

Allocates and validates request IDs per the MoQT spec.

• Client: even IDs (0, 2, 4, …)
• Server: odd IDs (1, 3, 5, …)
• Default MAX_REQUEST_ID: 0 (no requests until increased)
• MAX_REQUEST_ID can only increase

Fields

role: Role

next_id: u64

max_id: u64

Implementations

impl RequestIdAllocator

pub fn new(role: Role) -> Self

Create a new allocator for the given role, starting at ID 0 or 1.

pub fn allocate(&mut self) -> Result<VarInt, RequestIdError>

Allocate the next request ID.

pub fn update_max(&mut self, new_max: u64) -> Result<(), RequestIdError>

Update the maximum allowed request ID (can only increase).

pub fn validate_peer_id(&self, id: u64) -> Result<(), RequestIdError>

Validate a request ID the peer put on the wire.

Draft-19 Section 10.1: “The client generates even numbered Request IDs, starting at 0, and the server generates odd numbered Request IDs, starting at 1.” The parity checked here is therefore the peer’s, the opposite of this allocator’s own — a client validates odd ids.

The same section makes a wrong bit fatal to the session: “If an endpoint receives a Request ID where the least significant bit is incorrect for the sender, or a duplicate Request ID, it MUST close the session with INVALID_REQUEST_ID.” Only the first half is answered here. Duplicate detection needs memory of every id the peer has already spent, which this allocator does not keep and cannot keep without taking &mut self; it lives on the endpoint instead.

The parity rule is also what makes one HashMap per request kind enough for both directions: an id this endpoint allocates and an id the peer allocates can never be equal, so a peer’s request cannot collide with one of ours.

Errors

• RequestIdError::WrongParity carrying the id and the peer’s role, so the message names the endpoint that broke the rule rather than the one that caught it.
• RequestIdError::ExceedsMax if the id is past the current MAX_REQUEST_ID. Draft-17 removed MAX_REQUEST_ID and draft-19 keeps it gone, and RequestIdAllocator::new sets the ceiling to u64::MAX, so on this draft the check cannot fire for any id a varint can carry.

pub fn is_blocked(&self) -> bool

Check if we are blocked (max_id is 0 or next_id > max_id).

pub fn max_id(&self) -> u64

Get the current maximum request ID.