Add retry delays

Factors in two possible ways Github can indicate a retry delay. But then
falls back to an exponentially increasing value. But in both cases, will
cap the delay.

Cargo.toml

@@ -47,7 +47,9 @@ serde_path_to_error = "0.1.4"
 serde_urlencoded = "0.7.1"
 snafu = { version = "0.7", features = ["backtraces"] }
 tokio = { version = "1.17.0", default-features = false, optional = true }
-tower = { version = "0.4.13", default-features = false, features = ["util", "buffer"] }
+# This has on-master-but-unreleased improvements to the retry code, merged shortly after 0.4.13.
+# Can be changed to a version again once https://github.com/tower-rs/tower/pull/681 lands.
+tower = { git = "https://github.com/tower-rs/tower", rev = "aec7b8f417b101d57f85c7ede05275dd61a48597", default-features = false, features = ["util", "buffer"] }
 tower-http = { version = "0.4.0", features = ["map-response-body", "trace"] }
 tracing = { version = "0.1.37", features = ["log"], optional = true }
 url = { version = "2.2.2", features = ["serde"] }

src/lib.rs

@@ -230,6 +230,7 @@ pub use self::{
 pub type Result<T, E = error::Error> = std::result::Result<T, E>;
 
 const GITHUB_BASE_URI: &str = "https://api.github.com";
+const MAX_RETRIES: usize = 3;
 
 static STATIC_INSTANCE: Lazy<arc_swap::ArcSwap<Octocrab>> =
     Lazy::new(|| arc_swap::ArcSwap::from_pointee(Octocrab::default()));
@@ -695,7 +696,7 @@ impl Default for DefaultOctocrabBuilderConfig {
             write_timeout: None,
             base_uri: None,
             #[cfg(feature = "retry")]
-            retry_config: RetryConfig::Simple(3),
+            retry_config: RetryConfig::Simple(MAX_RETRIES),
         }
     }
 }
@@ -1463,4 +1464,43 @@ mod tests {
             .await
             .unwrap();
     }
+
+    #[tokio::test]
+    async fn default_retries_on_unauth_only() {
+        use http::StatusCode;
+        use wiremock::{matchers, Mock, MockServer, ResponseTemplate};
+        let mock_server = MockServer::start().await;
+        Mock::given(matchers::method("GET"))
+            .and(matchers::path_regex(".*"))
+            .respond_with(ResponseTemplate::new(StatusCode::INTERNAL_SERVER_ERROR))
+            .expect(1)
+            .mount(&mock_server)
+            .await;
+        let result = crate::OctocrabBuilder::default()
+            .base_uri(mock_server.uri())
+            .unwrap()
+            .build()
+            .unwrap()
+            .orgs("hello")
+            .get()
+            .await;
+        assert_eq!(result.is_err(), true);
+
+        let mock_server = MockServer::start().await;
+        Mock::given(matchers::method("GET"))
+            .and(matchers::path_regex(".*"))
+            .respond_with(ResponseTemplate::new(StatusCode::UNAUTHORIZED))
+            .expect(3)
+            .mount(&mock_server)
+            .await;
+        let result = crate::OctocrabBuilder::default()
+            .base_uri(mock_server.uri())
+            .unwrap()
+            .build()
+            .unwrap()
+            .orgs("hello")
+            .get()
+            .await;
+        assert_eq!(result.is_err(), true);
+    }
 }