sausage core: modules per topic, journal writer thread with WAL and batches, hash cache by metadata, 49 tests per rule

Blank stdout lines give no warning. core.exit requests the exit in its
own handler.

cli/src/native.rs

@@ -0,0 +1,35 @@
+//! Native plugin futures and their process context.
+use crate::{Host, RpcResult};
+use serde_json::{Value, json};
+use std::{future::Future, pin::Pin, sync::Arc};
+use uuid::Uuid;
+/// The cancellable future of a native process.
+pub type NativeFuture = Pin<Box<dyn Future<Output = RpcResult> + Send>>;
+/// A handler for the methods of one native plugin.
+pub type NativePlugin = Arc<dyn Fn(NativeContext, String, Value) -> NativeFuture + Send + Sync>;
+#[derive(Clone)]
+/// The process identity and host access supplied to a native handler.
+pub struct NativeContext {
+    /// The host that owns this native process.
+    pub host: Host,
+    /// The ID assigned to this native process.
+    pub pid: String,
+}
+impl NativeContext {
+    /// Make an outgoing call with this native process as its caller.
+    pub async fn call(&self, method: &str, params: Value) -> RpcResult {
+        self.host
+            .route(
+                self.pid.clone(),
+                Some(json!(Uuid::now_v7().to_string())),
+                method.into(),
+                params,
+                false,
+            )
+            .await
+    }
+    /// Send progress to this process's caller while its call remains unanswered.
+    pub fn notify(&self, name: &str, params: Value) {
+        self.host.notify(&self.pid, name, params);
+    }
+}