Add exponential backoff fix #38, cleanup some `regional_requester` code

riven/src/req/rate_limit.rs

@@ -96,15 +96,18 @@ impl RateLimit {
         self.retry_after.read().and_then(|i| Instant::now().checked_duration_since(i))
     }
 
-    pub fn on_response(&self, config: &RiotApiConfig, response: &Response) {
+    /// Update retry-after and rate limits based on an API response.
-        self.on_response_retry_after(response);
+    /// Returns the retry-after delay if set.
+    pub fn on_response(&self, config: &RiotApiConfig, response: &Response) -> Option<Duration> {
+        let retry_after = self.on_response_retry_after(response);
         self.on_response_rate_limits(config, response);
+        retry_after
     }
 
     /// `on_response` helper for retry after check.
+    /// Returns the retry-after delay if set.
     #[inline]
-    fn on_response_retry_after(&self, response: &Response) {
+    fn on_response_retry_after(&self, response: &Response) -> Option<Duration> {
-        if let Some(retry_after) = || -> Option<Instant> {
         // Only care about 429s.
         if StatusCode::TOO_MANY_REQUESTS != response.status() {
             return None;
@@ -125,39 +128,51 @@ impl RateLimit {
 
             // This match checks the valid possibilities. Otherwise returns none to ignore.
             // `Application` handles "application", `Method` handles all other values.
-                let application_should_handle = match header_opt {
+            let is_responsible = match header_opt {
-                    Some(Self::HEADER_XRATELIMITTYPE_APPLICATION) => true,
+                Some(Self::HEADER_XRATELIMITTYPE_APPLICATION) => {
-                    Some(Self::HEADER_XRATELIMITTYPE_METHOD | Self::HEADER_XRATELIMITTYPE_SERVICE) => false,
+                    self.rate_limit_type == RateLimitType::Application
+                }
+                Some(Self::HEADER_XRATELIMITTYPE_METHOD | Self::HEADER_XRATELIMITTYPE_SERVICE) => {
+                    self.rate_limit_type == RateLimitType::Method
+                }
                 other => {
-                        // Method handles unknown values.
+                    // RateLimitType::Method handles unknown values.
+                    if self.rate_limit_type == RateLimitType::Method {
                         log::warn!(
                             "429 response has None (missing or invalid) or unknown {} header value {:?}, {:?} rate limit obeying retry-after.",
                             Self::HEADER_XRATELIMITTYPE, other, self.rate_limit_type);
+                        true
+                    } else {
                         false
-                    },
+                    }
+                }
             };
-
+            if !is_responsible {
-                if (self.rate_limit_type == RateLimitType::Application) != application_should_handle {
                 return None;
             }
         }
 
         // Get retry after header. Only care if it exists.
         let retry_after_header = response.headers()
-                .get(reqwest::header::RETRY_AFTER)?.to_str()
+            .get(reqwest::header::RETRY_AFTER)
-                .expect("Failed to read retry-after header as string.");
+            .and_then(|h| h
+                .to_str()
+                .map_err(|e| log::error!("Failed to read retry-after header as visible ASCII string: {:?}.", e)).ok())?;
 
         log::info!("429 response, rate limit {:?}, retry-after {} secs.", self.rate_limit_type, retry_after_header);
 
         // Header currently only returns ints, but float is more general. Can be zero.
-            let retry_after_secs: f32 = retry_after_header.parse()
+        let retry_after_secs = retry_after_header
-                .expect("Failed to parse retry-after header as f32.");
+            .parse::<f32>()
+            .map_err(|e| log::error!("Failed to parse read-after header as f32: {:?}.", e))
+            .ok()?;
+
         // Add 0.5 seconds to account for rounding, cases when response is zero.
         let delay = Duration::from_secs_f32(0.5 + retry_after_secs);
-            Some(Instant::now() + delay)
+
-        }() {
+        // Set `self.retry_after`.
-            *self.retry_after.write() = Some(retry_after);
+        *self.retry_after.write() = Some(Instant::now() + delay);
-        }
+        Some(delay)
     }
 
     #[inline]
@@ -165,9 +180,9 @@ impl RateLimit {
         // Check if rate limits changed.
         let headers = response.headers();
         let limit_header_opt = headers.get(self.rate_limit_type.limit_header())
-            .map(|h| h.to_str().expect("Failed to read limit header as string."));
+            .and_then(|h| h.to_str().map_err(|e| log::error!("Failed to read limit header as visible ASCII string: {:?}.", e)).ok());
         let count_header_opt = headers.get(self.rate_limit_type.count_header())
-            .map(|h| h.to_str().expect("Failed to read count header as string."));
+            .and_then(|h| h.to_str().map_err(|e| log::error!("Failed to read count header as visible ASCII string: {:?}.", e)).ok());
 
         if let (Some(limit_header), Some(count_header)) = (limit_header_opt, count_header_opt) {
             {
@@ -231,13 +246,3 @@ fn buckets_from_header(config: &RiotApiConfig, limit_header: &str, count_header:
     log::debug!("Set buckets to {} limit, {} count.", limit_header, count_header);
     out
 }
-
-#[cfg(test)]
-mod tests {
-    // use super::*;
-
-    // fn send_sync() {
-    //     fn is_send_sync<T: Send + Sync>() {}
-    //     is_send_sync::<RateLimit>();
-    // }
-}

riven/src/req/regional_requester.rs

@@ -69,8 +69,10 @@ impl RegionalRequester {
                     .map_err(|e| RiotApiError::new(e, retries, None, None))?;
 
                 // Maybe update rate limits (based on response headers).
-                self.app_rate_limit.on_response(config, &response);
+                // Use single bar for no short circuiting.
-                method_rate_limit.on_response(config, &response);
+                let retry_after_app = self.app_rate_limit.on_response(config, &response);
+                let retry_after_method = method_rate_limit.on_response(config, &response);
+                let retry_after = retry_after_app.or(retry_after_method); // Note: Edge case if both are Some(_) not handled.
 
                 let status = response.status();
                 // Handle normal success / failure cases.
@@ -96,8 +98,22 @@ impl RegionalRequester {
                     log::debug!("Response {} (retried {} times), failure, returning error.", status, retries);
                     break Err(RiotApiError::new(err, retries, Some(response), Some(status)));
                 }
-                log::debug!("Response {} (retried {} times), retrying.", status, retries);
 
+                // Is retryable, do exponential backoff if retry-after wasn't specified.
+                // 1 sec, 2 sec, 4 sec, 8 sec.
+                match retry_after {
+                    None => {
+                        let delay = std::time::Duration::from_secs(2_u64.pow(retries as u32));
+                        log::debug!("Response {} (retried {} times), NO `retry-after`, using exponential backoff, retrying after {:?}.", status, retries, delay);
+                        let backoff = tokio::time::sleep(delay);
+                        #[cfg(feature = "tracing")]
+                        let backoff = backoff.instrument(tracing::info_span!("backoff"));
+                        backoff.await;
+                    }
+                    Some(delay) => {
+                        log::debug!("Response {} (retried {} times), `retry-after` set, retrying after {:?}.", status, retries, delay);
+                    }
+                }
                 retries += 1;
             }
         }