Tiltify API query backoff (#6447)

* Tiltify API querying backoff

* fix backoff

* fix clippy

* fix2

apps/labrinth/src/util/tiltify.rs

@@ -1,6 +1,6 @@
 use std::time::{Duration, Instant};
 
-use eyre::eyre;
+use eyre::{Result, eyre};
 use serde::Deserialize;
 use serde_json::json;
 use tokio::sync::Mutex;
@@ -13,7 +13,24 @@ use crate::{
 #[derive(Debug)]
 pub struct TiltifyClient {
     http: HttpClient,
-    token: Mutex<Option<TiltifyAccessToken>>,
+    state: Mutex<TiltifyState>,
+}
+
+#[derive(Debug)]
+struct TiltifyState {
+    token: Option<TiltifyAccessToken>,
+    rate_limited_until: Instant,
+    rate_limit_backoff: Duration,
+}
+
+impl TiltifyState {
+    fn set_fetch_backoff(&mut self) {
+        self.rate_limited_until = Instant::now() + self.rate_limit_backoff;
+        self.rate_limit_backoff = self
+            .rate_limit_backoff
+            .saturating_mul(2)
+            .min(TILTIFY_MAX_RATE_LIMIT_BACKOFF);
+    }
 }
 
 #[derive(Debug)]
@@ -28,38 +45,34 @@ struct TiltifyTokenResponse {
     expires_in: u64,
 }
 
+const TILTIFY_INITIAL_RATE_LIMIT_BACKOFF: Duration = Duration::from_secs(60);
+const TILTIFY_MAX_RATE_LIMIT_BACKOFF: Duration = Duration::from_secs(15 * 60);
+
 impl TiltifyClient {
     pub fn new(http: HttpClient) -> Self {
         Self {
             http,
-            token: Mutex::new(None),
+            state: Mutex::new(TiltifyState {
+                token: None,
+                rate_limited_until: Instant::now(),
+                rate_limit_backoff: TILTIFY_INITIAL_RATE_LIMIT_BACKOFF,
+            }),
         }
     }
 
-    pub async fn access_token(&self) -> eyre::Result<String> {
-        let mut token = self.token.lock().await;
+    pub async fn access_token(&self) -> Result<String> {
+        let mut state = self.state.lock().await;
 
-        if let Some(token) = token.as_ref()
+        if let Some(token) = state.token.as_ref()
             && token.expires_at > Instant::now()
         {
             return Ok(token.access_token.clone());
         }
 
-        let response = self.fetch_access_token().await?;
-        let expires_at = Instant::now()
-            + Duration::from_secs(response.expires_in)
-                .saturating_sub(Duration::from_secs(60));
-        let access_token = response.access_token;
+        if state.rate_limited_until > Instant::now() {
+            return Err(eyre!("waiting for rate limit to reset"));
+        }
 
-        *token = Some(TiltifyAccessToken {
-            access_token: access_token.clone(),
-            expires_at,
-        });
-
-        Ok(access_token)
-    }
-
-    async fn fetch_access_token(&self) -> eyre::Result<TiltifyTokenResponse> {
         if ENV.TILTIFY_CLIENT_ID.is_empty()
             || ENV.TILTIFY_CLIENT_SECRET.is_empty()
         {
@@ -79,13 +92,33 @@ impl TiltifyClient {
             }))
             .send()
             .await
-            .wrap_err("fetching OAuth token")?
-            .error_for_status()
-            .wrap_err("fetching OAuth token")?
+            .inspect_err(|_| state.set_fetch_backoff())
+            .wrap_err("fetching OAuth token")?;
+
+        let response = match response.error_for_status() {
+            Ok(response) => response,
+            Err(error) => {
+                state.set_fetch_backoff();
+                return Err(error).wrap_err("fetching OAuth token");
+            }
+        };
+
+        let response = response
             .json::<TiltifyTokenResponse>()
             .await
             .wrap_err("parsing OAuth token response")?;
 
-        Ok(response)
+        let expires_at = Instant::now()
+            + Duration::from_secs(response.expires_in)
+                .saturating_sub(Duration::from_secs(60));
+        let access_token = response.access_token;
+
+        state.token = Some(TiltifyAccessToken {
+            access_token: access_token.clone(),
+            expires_at,
+        });
+        state.rate_limit_backoff = TILTIFY_INITIAL_RATE_LIMIT_BACKOFF;
+
+        Ok(access_token)
     }
 }