refactor(http): improve pd_types.rs documentation and style (#16319)

sgl-model-gateway/src/routers/http/pd_types.rs

@@ -1,4 +1,6 @@
-// Custom error type for PD router operations
+//! Types and utilities for the prefill-decode (PD) disaggregated router.
+
+/// Custom error type for PD router operations
 #[derive(Debug, thiserror::Error)]
 pub enum PDRouterError {
     #[error("Worker already exists: {url}")]
@@ -23,9 +25,9 @@ pub enum PDRouterError {
     Timeout { url: String },
 }
 
-// Helper functions for workers
+/// Construct a full API URL from a base URL and path.
 pub fn api_path(url: &str, api_path: &str) -> String {
-    if api_path.starts_with("/") {
+    if api_path.starts_with('/') {
         format!("{}{}", url, api_path)
     } else {
         format!("{}/{}", url, api_path)
@@ -34,7 +36,7 @@ pub fn api_path(url: &str, api_path: &str) -> String {
 
 use serde::Serialize;
 
-// Optimized bootstrap wrapper for single requests
+/// Optimized bootstrap wrapper for single requests.
 #[derive(Serialize)]
 pub struct RequestWithBootstrap<'a, T: Serialize> {
     #[serde(flatten)]
@@ -44,7 +46,7 @@ pub struct RequestWithBootstrap<'a, T: Serialize> {
     pub bootstrap_room: u64,
 }
 
-// Optimized bootstrap wrapper for batch requests
+/// Optimized bootstrap wrapper for batch requests.
 #[derive(Serialize)]
 pub struct BatchRequestWithBootstrap<'a, T: Serialize> {
     #[serde(flatten)]
@@ -54,13 +56,13 @@ pub struct BatchRequestWithBootstrap<'a, T: Serialize> {
     pub bootstrap_room: Vec<u64>,
 }
 
-// Helper to generate bootstrap room ID
+/// Generate a random bootstrap room ID.
 pub fn generate_room_id() -> u64 {
     // Generate a value in the range [0, 2^63 - 1] to match Python's random.randint(0, 2**63 - 1)
     rand::random::<u64>() & (i64::MAX as u64)
 }
 
-// PD-specific routing policies
+/// PD-specific routing policies.
 #[derive(Debug, Clone, PartialEq)]
 pub enum PDSelectionPolicy {
     Random,