Struct RequestIdempotency 

pub struct RequestIdempotency { /* private fields */ }

Whether one outbound request may be replayed byte-for-byte without an idempotency key — the single fact a retry middleware needs and cannot work out for itself.

Attached to every request this crate sends as a reqwest_middleware request extension, so a middleware reads it with extensions.get::<RequestIdempotency>(). Only observable under the middleware feature: reqwest 0.13 keeps reqwest::Request::extensions_mut() pub(crate), so a bare reqwest::Client has no extension map a caller can write to (see client::http::HttpRequestBuilder::with_extension).

Absent means “assume not idempotent.” A middleware that finds no RequestIdempotency in the extensions is talking to something other than this client, or to a build where the extension could not be attached; failing closed there is the same rule the rest of this crate follows.

How the value is chosen

By default it is derived from the HTTP method (RequestIdempotency::for_method, RFC 9110 §9.2.2), which is exactly right for REST CRUD: GET/DELETE are idempotent, POST/PATCH are not. It is not right for two cases the method alone cannot express, and for those the caller overrides it with CratestackClient::with_idempotency:

• RPC. Every RPC call is POST /rpc/{op_id}, so the method carries no information at all. The op’s real answer is the idempotent_by_default field on the OpDescriptor the schema macro emits for that op (cratestack_core::OpDescriptor) — true for reads and @query procedures, false for mutations.
• REST procedures. POST /$procs/<name> is a POST whatever the procedure does, so a @query procedure looks non-idempotent to the method-derived default.

Note that the REST-transport descriptor (cratestack_core::RouteTransportDescriptor) does not carry an idempotent_by_default field today — only the RPC-transport OpDescriptor does. Wiring either descriptor through the generated client so callers don’t have to pass it by hand is follow-up work; this type and CratestackClient::with_idempotency are the runtime half that makes it expressible at all.

Implementations

impl RequestIdempotency

pub const IDEMPOTENT: Self

The request may be retried as-is.

pub const NOT_IDEMPOTENT: Self

The request must not be retried without an idempotency key.

pub const fn new(idempotent: bool) -> Self

Wraps a raw flag — e.g. an OpDescriptor’s idempotent_by_default.

pub const fn is_idempotent(self) -> bool

pub fn for_method(method: &Method) -> Self

The RFC 9110 §9.2.2 answer for a method: GET, HEAD, PUT, DELETE, OPTIONS and TRACE are idempotent; everything else — POST and PATCH included — is not.

PATCH is deliberately in the second group: RFC 5789 §2 makes it explicitly non-idempotent, and cratestack’s generated PATCH route is a partial update, which a retry after an unseen success can re-apply against a changed row.

Trait Implementations

impl Clone for RequestIdempotency

fn clone(&self) -> RequestIdempotency

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for RequestIdempotency

impl Debug for RequestIdempotency

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

Formats the value using the given formatter.

impl Eq for RequestIdempotency

impl Hash for RequestIdempotency

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for RequestIdempotency

fn eq(&self, other: &RequestIdempotency) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for RequestIdempotency