updated session logic to support login and logout functionality

.gitignore

@@ -2,6 +2,7 @@ Cargo.lock
 target/
 guide/build/
 /gh-pages
+/.history
 
 *.so
 *.out

src/session.rs

@@ -1,10 +1,7 @@
-use std::collections::HashMap;
-use std::iter;
-use std::rc::Rc;
-
+use std::{collections::HashMap, iter, rc::Rc};
 use actix::prelude::*;
 use actix_service::{Service, Transform};
-use actix_session::Session;
+use actix_session::{Session, SessionStatus};
 use actix_utils::cloneable::CloneableService;
 use actix_web::cookie::{Cookie, CookieJar, Key, SameSite};
 use actix_web::dev::{ServiceRequest, ServiceResponse};
@@ -14,7 +11,7 @@ use futures::future::{err, ok, Either, Future, FutureResult};
 use futures::Poll;
 use rand::{distributions::Alphanumeric, rngs::OsRng, Rng};
 use redis_async::resp::RespValue;
-use time::Duration;
+use time::{self, Duration};
 
 use crate::redis::{Command, RedisActor};
 
@@ -147,10 +144,32 @@ where
             };
 
             srv.call(req).and_then(move |mut res| {
-                if let Some(state) = Session::get_changes(&mut res) {
-                    Either::A(inner.update(res, state, value))
-                } else {
-                    Either::B(ok(res))
+                match Session::get_changes(&mut res) {
+                    (SessionStatus::Unchanged, _) =>
+                        Either::A(Either::A(ok(res))),
+                    (SessionStatus::Changed, Some(state)) =>
+                        Either::B(Either::A(inner.update(res, state, value))),
+                    (SessionStatus::Purged, Some(_)) => {
+                        Either::B(Either::B(
+                            inner.clear_cache(value)
+                                 .and_then(move |_| 
+                                    match inner.remove_cookie(&mut res){
+                                        Ok(_) => Either::A(ok(res)),
+                                        Err(_err) => Either::B(err(
+                                            error::ErrorInternalServerError(_err)))
+                                  })
+                        ))
+                    },
+                    (SessionStatus::Renewed, Some(state)) => { 
+                            Either::A(
+                                Either::B(
+                                inner.clear_cache(value)
+                                     .and_then(move |_|
+                                        inner.update(res, state, None))
+                                )
+                            )
+                    },
+                    (_, None) => unreachable!()
                 }
             })
         }))
@@ -289,4 +308,42 @@ impl Inner {
             ),
         }
     }
+
+    /// removes cache entry 
+    fn clear_cache(&self, value: Option<String>)
+                    -> impl Future<Item=(), Error=Error> {
+        if let Some(key) = value {
+            Either::A(
+                self.addr
+                .send(Command(resp_array!["DEL", key]))
+                .map_err(Error::from)
+                .and_then(|res| 
+                    match res {
+                        // redis responds with number of deleted records
+                        Ok(RespValue::Integer(x)) if x > 0 => Ok(()),
+                        _ => Err(error::ErrorInternalServerError(
+                            "failed to remove session from cache"))
+                    }
+                )
+            )
+        } else {
+            Either::B(err(error::ErrorInternalServerError(
+                                "missing session key - unexpected")))
+        }
+    } 
+
+    /// invalidates session cookie
+    fn remove_cookie<B>(&self, res: &mut ServiceResponse<B>)
+                    -> Result<(), Error> {
+        let mut cookie = Cookie::named(self.name.clone());
+        cookie.set_value("");
+        cookie.set_max_age(Duration::seconds(0));
+        cookie.set_expires(time::now() - Duration::days(365));
+
+        let val = HeaderValue::from_str(&cookie.to_string())
+                    .map_err(|err| error::ErrorInternalServerError(err))?;
+        res.headers_mut().append(header::SET_COOKIE, val);
+
+        Ok(())
+    }
 }