Function update_module

crates/core/src/host/host_controller.rs:845–867

Update a module. If the `db` is not initialized yet (i.e. its program hash is `None`), return an error. Otherwise, if `db.program_hash` matches the given `program_hash`, do nothing and return an empty `UpdateDatabaseResult`. Otherwise, invoke `module.update_database` and return the result.

(
    db: &RelationalDB,
    module: &ModuleHost,
    program: Program,
    old_module_info: Arc<ModuleInfo>,
    policy: MigrationPolicy,
)

///
/// Otherwise, invoke `module.update_database` and return the result.
async fn update_module(
    db: &RelationalDB,
    module: &ModuleHost,
    program: Program,
    old_module_info: Arc<ModuleInfo>,
    policy: MigrationPolicy,
) -> anyhow::Result<UpdateDatabaseResult> {
    let addr = db.database_identity();
    match stored_program_hash(db)? {
        None => Err(anyhow!("database `{addr}` not yet initialized")),
        Some(stored) => {
            let res = if stored == program.hash {
                info!("database `{}` up to date with program `{}`", addr, program.hash);
                UpdateDatabaseResult::NoUpdateNeeded
            } else {
                info!("updating `{}` from {} to {}", addr, stored, program.hash);
                module.update_database(program, old_module_info, policy).await?
            };

            Ok(res)
        }
    }
}

/// Encapsulates a database, associated module, and auxiliary state.
struct Host {