config: change ServiceConfig.concurrency_limit default to 4

Signed-off-by: NotAShelf <raf@notashelf.dev>
Change-Id: I922cd160b642faaa1218b5f1dd89a53f6a6a6964

src/config.rs

@@ -100,10 +100,55 @@ pub struct ServiceConfig {
   pub concurrency_limit: usize,
   pub temp_dir:          String,
   pub state_db_path:     String,
+  #[serde(default)]
+  pub retry:             RetryConfig,
 }
 
 const fn default_concurrency_limit() -> usize {
-  10
+  4
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct RetryConfig {
+  /// Maximum number of retry attempts before giving up.
+  #[serde(default = "default_max_retries")]
+  pub max_retries:        u32,
+  /// Initial backoff duration in milliseconds before the first retry.
+  #[serde(default = "default_initial_backoff_ms")]
+  pub initial_backoff_ms: u64,
+  /// Multiplier applied to the backoff on each successive retry.
+  #[serde(default = "default_backoff_multiplier")]
+  pub backoff_multiplier: f64,
+  /// Maximum backoff duration in milliseconds, capping exponential growth.
+  #[serde(default = "default_max_backoff_ms")]
+  pub max_backoff_ms:     u64,
+}
+
+impl Default for RetryConfig {
+  fn default() -> Self {
+    Self {
+      max_retries:        default_max_retries(),
+      initial_backoff_ms: default_initial_backoff_ms(),
+      backoff_multiplier: default_backoff_multiplier(),
+      max_backoff_ms:     default_max_backoff_ms(),
+    }
+  }
+}
+
+const fn default_max_retries() -> u32 {
+  3
+}
+
+const fn default_initial_backoff_ms() -> u64 {
+  500
+}
+
+const fn default_backoff_multiplier() -> f64 {
+  2.0
+}
+
+const fn default_max_backoff_ms() -> u64 {
+  30_000
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]