feat(session): use real async traits (#365)

actix-session/src/storage/cookie.rs

@@ -49,7 +49,6 @@ use crate::storage::{
 #[non_exhaustive]
 pub struct CookieSessionStore;
 
-#[async_trait::async_trait(?Send)]
 impl SessionStore for CookieSessionStore {
     async fn load(&self, session_key: &SessionKey) -> Result<Option<SessionState>, LoadError> {
         serde_json::from_str(session_key.as_ref())
@@ -67,10 +66,10 @@ impl SessionStore for CookieSessionStore {
             .map_err(anyhow::Error::new)
             .map_err(SaveError::Serialization)?;
 
-        Ok(session_key
+        session_key
             .try_into()
             .map_err(Into::into)
-            .map_err(SaveError::Other)?)
+            .map_err(SaveError::Other)
     }
 
     async fn update(

actix-session/src/storage/interface.rs

@@ -1,4 +1,4 @@
-use std::collections::HashMap;
+use std::{collections::HashMap, future::Future};
 
 use actix_web::cookie::time::Duration;
 use derive_more::Display;
@@ -10,41 +10,39 @@ pub(crate) type SessionState = HashMap<String, String>;
 /// The interface to retrieve and save the current session data from/to the chosen storage backend.
 ///
 /// You can provide your own custom session store backend by implementing this trait.
-///
-/// [`async-trait`](https://docs.rs/async-trait) is used for this trait's definition. Therefore, it
-/// is required for implementations, too. In particular, we use the send-optional variant:
-/// `#[async_trait(?Send)]`.
-#[async_trait::async_trait(?Send)]
 pub trait SessionStore {
     /// Loads the session state associated to a session key.
-    async fn load(&self, session_key: &SessionKey) -> Result<Option<SessionState>, LoadError>;
+    fn load(
+        &self,
+        session_key: &SessionKey,
+    ) -> impl Future<Output = Result<Option<SessionState>, LoadError>>;
 
     /// Persist the session state for a newly created session.
     ///
     /// Returns the corresponding session key.
-    async fn save(
+    fn save(
         &self,
         session_state: SessionState,
         ttl: &Duration,
-    ) -> Result<SessionKey, SaveError>;
+    ) -> impl Future<Output = Result<SessionKey, SaveError>>;
 
     /// Updates the session state associated to a pre-existing session key.
-    async fn update(
+    fn update(
         &self,
         session_key: SessionKey,
         session_state: SessionState,
         ttl: &Duration,
-    ) -> Result<SessionKey, UpdateError>;
+    ) -> impl Future<Output = Result<SessionKey, UpdateError>>;
 
     /// Updates the TTL of the session state associated to a pre-existing session key.
-    async fn update_ttl(
+    fn update_ttl(
         &self,
         session_key: &SessionKey,
         ttl: &Duration,
-    ) -> Result<(), anyhow::Error>;
+    ) -> impl Future<Output = Result<(), anyhow::Error>>;
 
     /// Deletes a session from the store.
-    async fn delete(&self, session_key: &SessionKey) -> Result<(), anyhow::Error>;
+    fn delete(&self, session_key: &SessionKey) -> impl Future<Output = Result<(), anyhow::Error>>;
 }
 
 // We cannot derive the `Error` implementation using `derive_more` for our custom errors:

actix-session/src/storage/redis_actor.rs

@@ -118,7 +118,6 @@ impl RedisActorSessionStoreBuilder {
     }
 }
 
-#[async_trait::async_trait(?Send)]
 impl SessionStore for RedisActorSessionStore {
     async fn load(&self, session_key: &SessionKey) -> Result<Option<SessionState>, LoadError> {
         let cache_key = (self.configuration.cache_keygen)(session_key.as_ref());

actix-session/src/storage/redis_rs.rs

@@ -132,7 +132,6 @@ impl RedisSessionStoreBuilder {
     }
 }
 
-#[async_trait::async_trait(?Send)]
 impl SessionStore for RedisSessionStore {
     async fn load(&self, session_key: &SessionKey) -> Result<Option<SessionState>, LoadError> {
         let cache_key = (self.configuration.cache_keygen)(session_key.as_ref());