Service Implementation

We can now implement the AIDL service:

birthday_service/src/lib.rs:

//! Implementation of the `IBirthdayService` AIDL interface.
use com_example_birthdayservice::aidl::com::example::birthdayservice::IBirthdayService::IBirthdayService;
use com_example_birthdayservice::binder;

/// The `IBirthdayService` implementation.
pub struct BirthdayService;

impl binder::Interface for BirthdayService {}

impl IBirthdayService for BirthdayService {
    fn wishHappyBirthday(&self, name: &str, years: i32) -> binder::Result<String> {
        Ok(format!("Happy Birthday {name}, congratulations with the {years} years!"))
    }
}

birthday_service/Android.bp:

rust_library {
    name: "libbirthdayservice",
    srcs: ["src/lib.rs"],
    crate_name: "birthdayservice",
    rustlibs: [
        "com.example.birthdayservice-rust",
        "libbinder_rs",
    ],
}

Point out the path to the generated IBirthdayService trait, and explain why each of the segments is necessary.
Note that wishHappyBirthday and other AIDL IPC methods take &self (instead of &mut self).
- This is necessary because binder responds to incoming requests on a thread pool, allowing for multiple requests to be processed in parallel. This requires that the service methods only get a shared reference to self.
- Any state that needs to be modified by the service will have to be put in something like a Mutex to allow for safe mutation.
- The correct approach for managing service state depends heavily on the details of your service.
TODO: What does the binder::Interface trait do? Are there methods to override? Where source?

Comprehensive Rust 🦀

Service Implementation