refactor connection counter (#343)

* Remove restart_worker test

* Remove Slab

* Rework counter

* Make counter limit switch accurate

* Remove backpressure. Add pause state

* make changes for review

* fix doc comment for counter

actix-server/src/lib.rs

@@ -26,28 +26,6 @@ use std::future::Future;
 use std::pin::Pin;
 use std::task::{Context, Poll};
 
-/// Socket ID token
-#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
-pub(crate) struct Token(usize);
-
-impl Default for Token {
-    fn default() -> Self {
-        Self::new()
-    }
-}
-
-impl Token {
-    fn new() -> Self {
-        Self(0)
-    }
-
-    pub(crate) fn next(&mut self) -> Token {
-        let token = Token(self.0);
-        self.0 += 1;
-        token
-    }
-}
-
 /// Start server building process
 pub fn new() -> ServerBuilder {
     ServerBuilder::default()