Hands-On Microservices with Rust

Handler

To add support for incoming message types, we have to implement the Handler trait for our actor. Let's implement Handler of Count messages for our CountActor:

impl Handler<Count> for CountActor {    type Result = Value;    fn handle(&mut self, Count(path): Count, _: &mut Context<Self>) -> Self::Result {        let value = self.counter.entry(path).or_default();        *value = *value + 1;        *value    }}

We also have to set the associated type with the same type of a result.

Handling occurs in the body of the handle method of the Handler trait. We'll get entry for a provided String value with the Count message and extract the entry of HashMap. If no entry is found, we'll get a default value that equals 0 for u64 type (Value alias) and add 1 to that value.