reqwest_chain/
chainable.rs

1use reqwest_middleware::reqwest::{Request, Response};
2use reqwest_middleware::Error;
3
4/// Describes:
5///
6/// - which request outcomes should be retried
7/// - how the request should be updated to retry
8#[async_trait::async_trait]
9pub trait Chainer {
10    type State: Sync + Send + Default;
11
12    /// Inspect the result of the previous request, to decide whether to make
13    /// another request.
14    ///
15    /// - If another request is required, update the previous request to form the
16    /// next request in the chain, and return `Ok(None)`.
17    /// - If the response is ready, return it inside `Ok(Some(response))`.
18    /// - If an error occurs and you cannot continue, return `Err(error)`.
19    ///
20    /// Returning a response, or an error, will result in termination of the chain.
21    ///
22    /// Information is available from:
23    ///
24    /// - self (global state, instantiated at middleware creation)
25    /// - result (the result of the previous request)
26    /// - state (local state, instantiated for each request chain)
27    ///
28    /// Global side effects can be managed via interior mutability of `self`.
29    async fn chain(
30        &self,
31        result: Result<Response, Error>,
32        state: &mut Self::State,
33        request: &mut Request,
34    ) -> Result<Option<Response>, Error>;
35
36    /// Safety valve to protect against infinite chaining.
37    ///
38    /// This value may be overriden by the user.
39    fn max_chain_length(&self) -> u32 {
40        /// We limit the number of retries to avoid stack-overflow issues due to the recursion.
41        ///
42        /// This can be increased by the user.
43        const DEFAULT_MAXIMUM_CHAIN_LENGTH: u32 = 7;
44        DEFAULT_MAXIMUM_CHAIN_LENGTH
45    }
46}
47
48pub struct ChainMiddleware<T> {
49    inner: T,
50}
51
52impl<T> ChainMiddleware<T> {
53    pub fn new(inner: T) -> Self {
54        Self { inner }
55    }
56
57    pub(crate) fn inner(&self) -> &T {
58        &self.inner
59    }
60}
reqwest_chain/chainable.rs

reqwest_chain/
chainable.rs
