various: get retries with backoff working; take a RetryConfig for sources

Signed-off-by: NotAShelf <raf@notashelf.dev>
Change-Id: I27d0b21c117c5654536ac3f665efc7876a6a6964

src/main.rs

@@ -1,6 +1,7 @@
 mod config;
 mod core;
 mod crypto;
+mod retry;
 mod sinks;
 mod sources;
 mod storage;

src/retry.rs

@@ -0,0 +1,116 @@
+use std::time::Duration;
+
+use tracing::{debug, warn};
+
+use crate::config::RetryConfig;
+
+/// Classification of an error for retry purposes.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum ErrorKind {
+  /// Transient error - safe to retry (network failure, rate limit, 5xx).
+  Transient,
+  /// Permanent error - retrying will not help (4xx, auth failure, etc.).
+  Permanent,
+}
+
+/// Classify a `reqwest::Error` for retry purposes.
+pub fn classify_reqwest_error(err: &reqwest::Error) -> ErrorKind {
+  if err.is_connect() || err.is_timeout() || err.is_request() {
+    return ErrorKind::Transient;
+  }
+
+  if let Some(status) = err.status() {
+    return classify_status_code(status.as_u16());
+  }
+
+  // Unknown - assume transient to avoid silently dropping operations.
+  ErrorKind::Transient
+}
+
+/// Classify an HTTP status code for retry purposes.
+pub const fn classify_status_code(status: u16) -> ErrorKind {
+  match status {
+    // Rate limit and server-side errors - back off and retry.
+    429 | 500..=599 => ErrorKind::Transient,
+    // Client errors - permanent; retrying changes nothing.
+    400..=499 => ErrorKind::Permanent,
+    // Unexpected codes - assume transient.
+    _ => ErrorKind::Transient,
+  }
+}
+
+/// Scale `backoff_ms` by `multiplier` using integer arithmetic.
+///
+/// The multiplier is represented as a fixed-point ratio (numerator / 1000) to
+/// avoid any floating-point casts in the hot retry loop. Overflow is clamped
+/// via saturating arithmetic.
+fn scale_backoff(backoff_ms: u64, multiplier: f64) -> u64 {
+  // Convert the multiplier to an integer numerator over 1000.
+  // e.g. 2.0 -> 2000 / 1000, 1.5 -> 1500 / 1000.
+  // The cast is intentional: we truncate sub-millisecond precision, which is
+  // acceptable for backoff timing.
+  #[allow(clippy::cast_possible_truncation, clippy::cast_sign_loss)]
+  let scale_num = (multiplier * 1000.0) as u64;
+  backoff_ms.saturating_mul(scale_num).saturating_div(1000)
+}
+
+/// Execute `operation` with exponential backoff retries governed by `config`.
+///
+/// `classify` converts the error type into an [`ErrorKind`]; only
+/// [`ErrorKind::Transient`] errors are retried. A [`ErrorKind::Permanent`]
+/// error is returned immediately without further attempts.
+///
+/// Returns the last error after all attempts are exhausted.
+pub async fn execute_with_retry<F, Fut, T, E, C>(
+  config: &RetryConfig,
+  operation_name: &str,
+  classify: C,
+  mut operation: F,
+) -> Result<T, E>
+where
+  F: FnMut() -> Fut,
+  Fut: std::future::Future<Output = Result<T, E>>,
+  E: std::fmt::Display,
+  C: Fn(&E) -> ErrorKind,
+{
+  let mut attempt = 0u32;
+  let mut backoff_ms = config.initial_backoff_ms;
+
+  loop {
+    match operation().await {
+      Ok(value) => return Ok(value),
+      Err(err) => {
+        let kind = classify(&err);
+
+        if kind == ErrorKind::Permanent {
+          debug!(
+            operation = operation_name,
+            attempt, "Permanent error, not retrying: {err}"
+          );
+          return Err(err);
+        }
+
+        if attempt >= config.max_retries {
+          warn!(
+            operation = operation_name,
+            attempt,
+            max_retries = config.max_retries,
+            "All retry attempts exhausted: {err}"
+          );
+          return Err(err);
+        }
+
+        warn!(
+          operation = operation_name,
+          attempt, backoff_ms, "Transient error, retrying after backoff: {err}"
+        );
+
+        tokio::time::sleep(Duration::from_millis(backoff_ms)).await;
+
+        attempt += 1;
+        backoff_ms = scale_backoff(backoff_ms, config.backoff_multiplier)
+          .min(config.max_backoff_ms);
+      },
+    }
+  }
+}

src/sources/forgejo.rs

@@ -7,13 +7,15 @@ use tokio::{fs::File, io::AsyncWriteExt};
 use urlencoding::encode;
 
 use crate::{
-  config::ForgejoSourceConfig,
+  config::{ForgejoSourceConfig, RetryConfig},
   core::types::ContentHash,
   crypto::StreamingHasher,
+  retry::{ErrorKind, classify_reqwest_error, execute_with_retry},
 };
 
 pub struct ForgejoSource {
   config: ForgejoSourceConfig,
+  retry:  RetryConfig,
   client: reqwest::Client,
 }
 
@@ -25,7 +27,10 @@ pub struct Repository {
 }
 
 impl ForgejoSource {
-  pub fn new(config: ForgejoSourceConfig) -> anyhow::Result<Self> {
+  pub fn new(
+    config: ForgejoSourceConfig,
+    retry: RetryConfig,
+  ) -> anyhow::Result<Self> {
     let mut headers = HeaderMap::new();
     headers.insert(
       header::AUTHORIZATION,
@@ -39,7 +44,11 @@ impl ForgejoSource {
       .timeout(std::time::Duration::from_secs(300))
       .build()?;
 
-    Ok(Self { config, client })
+    Ok(Self {
+      config,
+      retry,
+      client,
+    })
   }
 
   pub async fn list_repositories(&self) -> anyhow::Result<Vec<Repository>> {
@@ -85,14 +94,33 @@ impl ForgejoSource {
       encode(org),
       page
     );
-    let response = self.client.get(&url).send().await?;
+
+    let response = execute_with_retry(
+      &self.retry,
+      "fetch_org_repos_page",
+      |err: &reqwest::Error| classify_reqwest_error(err),
+      || self.client.get(&url).send(),
+    )
+    .await
+    .map_err(|e| anyhow::anyhow!("Failed to fetch repos for org {org}: {e}"))?;
 
     if !response.status().is_success() {
+      // Classify the HTTP error code: non-2xx from the server may be transient
+      // (5xx, 429). For those we already retried inside execute_with_retry via
+      // the reqwest error path; here we handle the case where the response
+      // arrived successfully but carries an error status.
+      let status = response.status().as_u16();
+      match crate::retry::classify_status_code(status) {
+        ErrorKind::Transient => {
           anyhow::bail!(
-        "Failed to fetch repos for org {}: {}",
-        org,
-        response.status()
+            "Transient HTTP {status} fetching repos for org {org} (retries \
+             exhausted)"
           );
+        },
+        ErrorKind::Permanent => {
+          anyhow::bail!("HTTP {status} fetching repos for org {org}");
+        },
+      }
     }
 
     let api_repos: Vec<ApiRepository> = response.json().await?;
@@ -130,7 +158,20 @@ impl ForgejoSource {
       encode(&repo.default_branch)
     );
 
-    let response = self.client.get(&url).send().await?;
+    let response = execute_with_retry(
+      &self.retry,
+      "download_archive",
+      |err: &reqwest::Error| classify_reqwest_error(err),
+      || self.client.get(&url).send(),
+    )
+    .await
+    .map_err(|e| {
+      anyhow::anyhow!(
+        "Failed to download archive for {}/{}: {e}",
+        repo.owner,
+        repo.name
+      )
+    })?;
 
     if !response.status().is_success() {
       anyhow::bail!(

src/storage/mod.rs

@@ -11,6 +11,7 @@ use crate::core::types::{
   SinkJobState,
 };
 
+#[derive(Clone)]
 pub struct Storage {
   pool: Pool<Sqlite>,
 }