feat(hermes): Initialize module via direct function call, not an event (#528)

* Call init instead of emitting an init event

* Remove `InitEvent`

* Fix `ApplicationName`

* Revert `Vfs` visibiliy

* Update docs

* Report failed module in logs

* Clean-up app initialization

* Improve error handling

* Fix module initialization

* Fix component build in the integration tests

* Add integration test for failed module initialization

* Fix formatting

* Satisfy Lints

* Add TODO

* Update hermes/bin/src/cli/run.rs

Co-authored-by: Vladislav Borbut <[email protected]>

* Add missing import

* Temporarily disable `parallel_execution` test

---------

Co-authored-by: Vladislav Borbut <[email protected]>

Author: rafal-ch

hermes/Cargo.lock

@@ -3,7 +3,8 @@ resolver = "2"
 members = [
     "bin",
     "bin/tests/integration/components/http_request_rte_01",
-    "bin/tests/integration/components/sleep_component",
+    "bin/tests/integration/components/failed_init",
+    "bin/tests/integration/components/sleep_component"
 ]
 default-members = [
     "bin",

hermes/Cargo.toml

@@ -93,6 +93,16 @@ impl Application {
         }
     }
 
+    /// Initialize every module.
+    pub(crate) fn init(&self) -> anyhow::Result<()> {
+        for module in self.indexed_modules.values() {
+            if let Err(e) = module.init(self.name.clone(), Arc::clone(&self.vfs)) {
+                anyhow::bail!("Failed to initialize module {}: {}", module.id(), e)
+            }
+        }
+        Ok(())
+    }
+
     /// Dispatch event for the target module by the `module_id`.
     pub(crate) fn dispatch_event_for_target_module(
         &self,

hermes/bin/src/app.rs

@@ -62,6 +62,8 @@ impl Run {
             Emoji::new("🛠️", ""),
             app.name()
         );
+        // TODO[RC]: Prevent the app from receiving any events until it is fully initialized.
+        // TODO[RC]: Currently, when a module fails to initialize, the whole app fails to run.
         reactor::load_app(app)?;
 
         let exit = if let Some(timeout_ms) = self.timeout_ms {

hermes/bin/src/cli/run.rs

@@ -6,7 +6,6 @@ use once_cell::sync::OnceCell;
 use crate::{
     app::{Application, ApplicationName},
     event::{self, queue::ExitLock},
-    runtime_extensions::hermes::init,
 };
 
 /// Global Hermes reactor state
@@ -45,7 +44,6 @@ pub(crate) fn init() -> anyhow::Result<ExitLock> {
 /// # Errors
 ///
 /// - Reactor not initialized.
-/// - Cannot send initialization event to the application.
 pub(crate) fn load_app(app: Application) -> anyhow::Result<()> {
     let reactor = REACTOR_STATE.get().ok_or(anyhow::anyhow!(
         "Reactor not been initialized. Call `HermesEventQueue::init` first."
@@ -54,8 +52,13 @@ pub(crate) fn load_app(app: Application) -> anyhow::Result<()> {
     let app_name = app.name().clone();
     reactor.apps.insert(app_name.clone(), app);
 
-    init::emit_init_event(app_name)?;
-    Ok(())
+    init_app(&app_name)
+}
+
+/// Initialize the Application.
+pub(crate) fn init_app(app_name: &ApplicationName) -> anyhow::Result<()> {
+    let app = get_app(app_name)?;
+    app.init()
 }
 
 /// Get Hermes application from the Hermes Reactor.

hermes/bin/src/reactor.rs

@@ -1,21 +1,3 @@
 //! Init runtime extension implementation.
 
-use crate::{
-    app::ApplicationName,
-    event as hermes_event,
-    event::{HermesEvent, TargetApp, TargetModule},
-};
-
-mod event;
 mod host;
-
-/// Emit Init event for a provided Hermes app target
-pub(crate) fn emit_init_event(target_app: ApplicationName) -> anyhow::Result<()> {
-    let init_event = HermesEvent::new(
-        event::InitEvent {},
-        TargetApp::List(vec![target_app]),
-        TargetModule::All,
-    );
-    hermes_event::queue::send(init_event)?;
-    Ok(())
-}

hermes/bin/src/runtime_extensions/hermes/init/event.rs

@@ -6,7 +6,10 @@
 
 use std::{
     io::Read,
-    sync::atomic::{AtomicU32, Ordering},
+    sync::{
+        atomic::{AtomicU32, Ordering},
+        Arc,
+    },
 };
 
 use rusty_ulid::Ulid;
@@ -22,7 +25,9 @@ use crate::{
     runtime_extensions::{
         bindings::{self, LinkOptions},
         init::trait_module::{RteInitModule, RteModule},
+        new_context,
     },
+    vfs::Vfs,
     wasm::engine::Engine,
 };
 
@@ -117,6 +122,33 @@ impl Module {
         })
     }
 
+    /// Initializes the WASM module by calling its `init` function.
+    pub(crate) fn init(
+        &self,
+        app_name: ApplicationName,
+        vfs: Arc<Vfs>,
+    ) -> anyhow::Result<()> {
+        let runtime_ctx = HermesRuntimeContext::new(
+            app_name,
+            self.id.clone(),
+            "init_function_call".to_string(),
+            0,
+            vfs,
+        );
+
+        new_context(&runtime_ctx);
+
+        let mut store = WasmStore::new(&self.engine, runtime_ctx);
+        //let instance = self.pre_instance.instantiate(store).unwrap();
+        let instance =
+            bindings::HermesPre::new(self.pre_instance.clone())?.instantiate(&mut store)?;
+        let init_result = instance.hermes_init_event().call_init(&mut store)?;
+        if !init_result {
+            anyhow::bail!("WASM module init function returned false")
+        }
+        Ok(())
+    }
+
     /// Instantiate WASM module reader
     ///
     /// # Errors

hermes/bin/src/runtime_extensions/hermes/init/mod.rs

@@ -0,0 +1,14 @@
+[package]
+name = "failed_init"
+version = "0.1.0"
+edition.workspace = true
+license.workspace = true
+
+[lib]
+crate-type = ["cdylib"]
+
+[dependencies]
+wit-bindgen = "0.43.0"
+
+[lints]
+workspace = true

hermes/bin/src/wasm/module.rs

@@ -0,0 +1,2 @@
+{
+}