Some extra effects doc (#111)

akka-persistence-rs/src/effect.rs

@@ -1,5 +1,15 @@
 //! Effects that are lazily performed as a result of performing a command
-//! of an entity. Effects can be chained with other effects.
+//! of an entity. Effects can be chained with other effects and are guaranteed
+//! to be applied (run) before the next command for an entity id is processed.
+//!
+//! Convience methods are providing for commonly chained operations, and take
+//! the form of `and_then` as the prefix. By Rust convention, `and_then`
+//! provides the result of the previous operation and expects a result provided
+//! given some closure.
+//!
+//! In the case where there is no convenience method, a generalized `and`
+//! operation can be used to chain any effect found here, or a customized
+//! effect.
 
 use async_trait::async_trait;
 use chrono::Utc;

akka-persistence-rs/src/entity.rs

@@ -35,6 +35,8 @@ pub trait EventSourcedBehavior {
     /// State can also be associated with the behavior so that other effects can be
     /// performed. For example, a behavior might be created with a channel sender
     /// so that data can be sent as an effect of performing a command.
+    /// Effects can be chained and are guaranteed to be applied in their entirety
+    /// before the next command for their entity id is processed.
     fn for_command(
         context: &Context,
         state: &Self::State,

akka-persistence-rs/src/entity_manager.rs

@@ -303,7 +303,7 @@ where
 
 #[cfg(test)]
 mod tests {
-    use std::{io, pin::Pin, sync::Arc};
+    use std::{future, io, pin::Pin, sync::Arc};
 
     use super::*;
     use crate::{
@@ -378,13 +378,11 @@ mod tests {
                         .and_then(|behavior: &Self, new_state, prev_result| {
                             let updated = behavior.updated.clone();
                             let temp = new_state.map_or(0, |s| s.temp);
-                            async move {
-                                if prev_result.is_ok() {
-                                    updated.notify_one();
-                                    println!("Updated with {}!", temp);
-                                }
-                                prev_result
+                            if prev_result.is_ok() {
+                                updated.notify_one();
+                                println!("Updated with {}!", temp);
                             }
+                            future::ready(prev_result)
                         })
                         .boxed()
                 }