docs: server entry add documentation

src/async_resolver/server_entry.rs

@@ -3,26 +3,34 @@ use crate::async_resolver::server_info::ServerInfo;
 /// Struct that holds the state of a single server for a request.
 #[derive(Clone)]
 pub struct ServerEntry {
+    /// Information about the server.
     info: ServerInfo,
+    /// The work counter to limit the amount of work done on a single server.
+    /// 
+    /// If the counter reaches zero, the resolver must return a response to the client.
     work_counter: u16,
 }
 
 impl ServerEntry {
+    /// Creates a new ServerEntry for a request.
     pub fn new(info: ServerInfo, work_counter: u16) -> ServerEntry {
         ServerEntry {
             info,
             work_counter: work_counter,
         }
     }
 
+    /// Returns a reference to the ServerInfo of the server.
     pub fn get_info(&self) -> &ServerInfo {
         &self.info // TODO: see if this is necessary to use clone or not, in order to reuse TCP connections
     }
 
+    /// Returns the work counter of the server.
     pub fn get_work_counter(&self) -> u16 {
         self.work_counter
     }
 
+    /// Decrements the work counter of the server.
     pub fn decrement_work_counter(&mut self) {
         self.work_counter -= 1;
     }