feat(client): implement connection pooling for Client

Closes #830
Closes #848

src/http/h1/parse.rs

@@ -31,6 +31,10 @@ impl Http1Message for ServerMessage {
         Next::new(Next_::Read)
     }
 
+    fn keep_alive_interest() -> Next {
+        Next::new(Next_::Read)
+    }
+
     fn parse(buf: &[u8]) -> ParseResult<RequestLine> {
         let mut headers = [httparse::EMPTY_HEADER; MAX_HEADERS];
         trace!("Request.parse([Header; {}], [u8; {}])", headers.len(), buf.len());
@@ -114,6 +118,10 @@ impl Http1Message for ClientMessage {
         Next::new(Next_::Write)
     }
 
+    fn keep_alive_interest() -> Next {
+        Next::new(Next_::Wait)
+    }
+
     fn parse(buf: &[u8]) -> ParseResult<RawStatus> {
         let mut headers = [httparse::EMPTY_HEADER; MAX_HEADERS];
         trace!("Response.parse([Header; {}], [u8; {}])", headers.len(), buf.len());