pub trait Policy<Req, Res, E>: Sized {
type Future: Future<Output = Self>;
// Required methods
fn retry(&self, req: &Req, result: Result<&Res, &E>) -> Option<Self::Future>;
fn clone_request(&self, req: &Req) -> Option<Req>;
}
Expand description
A “retry policy” to classify if a request should be retried.
§Example
use tower::retry::Policy;
use futures_util::future;
type Req = String;
type Res = String;
struct Attempts(usize);
impl<E> Policy<Req, Res, E> for Attempts {
type Future = future::Ready<Self>;
fn retry(&self, req: &Req, result: Result<&Res, &E>) -> Option<Self::Future> {
match result {
Ok(_) => {
// Treat all `Response`s as success,
// so don't retry...
None
},
Err(_) => {
// Treat all errors as failures...
// But we limit the number of attempts...
if self.0 > 0 {
// Try again!
Some(future::ready(Attempts(self.0 - 1)))
} else {
// Used all our attempts, no retry...
None
}
}
}
}
fn clone_request(&self, req: &Req) -> Option<Req> {
Some(req.clone())
}
}
Required Associated Types§
sourcetype Future: Future<Output = Self>
type Future: Future<Output = Self>
The Future
type returned by Policy::retry
.
Required Methods§
sourcefn retry(&self, req: &Req, result: Result<&Res, &E>) -> Option<Self::Future>
fn retry(&self, req: &Req, result: Result<&Res, &E>) -> Option<Self::Future>
Check the policy if a certain request should be retried.
This method is passed a reference to the original request, and either
the Service::Response
or Service::Error
from the inner service.
If the request should not be retried, return None
.
If the request should be retried, return Some
future of a new
policy that would apply for the next request attempt.
sourcefn clone_request(&self, req: &Req) -> Option<Req>
fn clone_request(&self, req: &Req) -> Option<Req>
Tries to clone a request before being passed to the inner service.
If the request cannot be cloned, return None
.
Object Safety§
This trait is not object safe.