northbound: replace callback-based model with struct-based model

Refactor the northbound layer to move away from a callback-based
design and implement YANG-related logic directly on the
auto-generated YANG structs. This ensures that when a YANG module
is added or modified, the code must be updated accordingly or it
will fail to compile. Previously, missing callbacks went unnoticed
at build time and were only detected at daemon startup.

This change applies to YANG-modeled state and RPCs. Configuration
handling will be refactored separately.

As a positive side effect, implementing logic directly on YANG
structs results in cleaner code compared to callbacks initialized
via the builder pattern.

Signed-off-by: Renato Westphal <renato@opensourcerouting.org>

Author: rwestphal

Cargo.lock

@@ -64,6 +64,7 @@ netlink-packet-route = "0.28"
 netlink-sys = "0.8"
 num-derive = "0.4"
 num-traits = "0.2"
+phf = { version = "0.13", features = ["macros"] }
 pickledb = "0.5"
 prefix-trie = { version = "0.8", default-features = false, features = ["ipnetwork"]  }
 prost = "0.14"
@@ -97,6 +98,7 @@ borrowed_box = "allow"
 field_reassign_with_default = "allow"
 large_enum_variant = "allow"
 manual_range_contains = "allow"
+match_single_binding = "allow"
 single_match = "allow"
 too_many_arguments = "allow"
 

Cargo.toml

@@ -18,6 +18,7 @@ libc.workspace = true
 nix.workspace = true
 num-derive.workspace = true
 num-traits.workspace = true
+phf.workspace = true
 rand.workspace = true
 serde.workspace = true
 serde_json.workspace = true

holo-bfd/Cargo.toml

@@ -4,7 +4,13 @@
 // SPDX-License-Identifier: MIT
 //
 
+use holo_northbound::yang_codegen;
+use holo_yang as yang;
+
 fn main() {
-    let modules = holo_yang::implemented_modules::BFD;
-    holo_northbound::yang_codegen::build(modules);
+    let mut yang_ctx = yang::new_context();
+    let modules = yang::implemented_modules::BFD;
+    yang::load_modules(&mut yang_ctx, modules);
+    yang_codegen::build_yang_objects(&yang_ctx, modules, "yang_objects.rs");
+    yang_codegen::build_yang_ops(&yang_ctx, modules, None, "yang_ops.rs");
 }

holo-bfd/build.rs

@@ -19,8 +19,14 @@ use crate::master::Master;
 // Autogenerated code from YANG modules.
 #[allow(unused_imports, unused_variables)]
 pub mod yang_gen {
-    pub use crate::northbound::yang_gen::routing::control_plane_protocols::control_plane_protocol::bfd;
-    include!(concat!(env!("OUT_DIR"), "/yang_gen.rs"));
+    pub use routing::control_plane_protocols::control_plane_protocol::bfd;
+
+    include!(concat!(env!("OUT_DIR"), "/yang_objects.rs"));
+    pub mod ops {
+        use crate::master::Master;
+        type Provider = Master;
+        include!(concat!(env!("OUT_DIR"), "/yang_ops.rs"));
+    }
 }
 
 // ===== impl Master =====

holo-bfd/src/northbound/mod.rs

@@ -4,24 +4,11 @@
 // SPDX-License-Identifier: MIT
 //
 
-use std::sync::LazyLock as Lazy;
-
-use holo_northbound::rpc::{Callbacks, CallbacksBuilder, Provider};
+use holo_northbound::rpc::{Provider, YangOps};
 
 use crate::master::Master;
-
-pub static CALLBACKS: Lazy<Callbacks<Master>> = Lazy::new(load_callbacks);
-
-// ===== callbacks =====
-
-fn load_callbacks() -> Callbacks<Master> {
-    CallbacksBuilder::<Master>::default().build()
-}
-
-// ===== impl Master =====
+use crate::northbound::yang_gen;
 
 impl Provider for Master {
-    fn callbacks() -> &'static Callbacks<Master> {
-        &CALLBACKS
-    }
+    const YANG_OPS: YangOps<Self> = yang_gen::ops::YANG_OPS_RPC;
 }