chore: export health check API (#92)

Author: alissa-tung

src/hstreamdb/src/client.rs

@@ -1,7 +1,7 @@
 use common::{Stream, Subscription};
 use hstreamdb_pb::h_stream_api_client::HStreamApiClient;
 use hstreamdb_pb::{
-    CompressionType, DeleteStreamRequest, DeleteSubscriptionRequest, GetStreamRequest,
+    CompressionType, DeleteStreamRequest, DeleteSubscriptionRequest, EchoRequest, GetStreamRequest,
     GetSubscriptionRequest, ListConsumersRequest, ListStreamsRequest, ListSubscriptionsRequest,
     LookupSubscriptionRequest, NodeState,
 };
@@ -111,6 +111,20 @@ pub(crate) async fn get_available_node_addrs(
     Ok(cluster_addrs)
 }
 
+impl Client {
+    pub async fn echo<T: Into<String>>(&self, msg: T) -> common::Result<String> {
+        let msg = self
+            .channels
+            .channel()
+            .await
+            .echo(EchoRequest { msg: msg.into() })
+            .await?
+            .into_inner()
+            .msg;
+        Ok(msg)
+    }
+}
+
 impl Client {
     pub async fn create_stream(&self, stream: Stream) -> common::Result<Stream> {
         let stream = self.channels.channel().await.create_stream(stream).await?;

src/x/hstreamdb-erl-nifs/src/lib.rs

@@ -30,6 +30,7 @@ rustler::atoms! {
     max_batch_len, max_batch_size, batch_deadline,
     on_flush,
     start_client_reply,
+    echo_reply,
     create_stream_reply,
     create_subscription_reply,
     earliest, latest,
@@ -48,6 +49,7 @@ rustler::init!(
     "hstreamdb",
     [
         async_start_client,
+        async_echo,
         async_create_stream,
         async_create_subscription,
         async_start_producer,
@@ -206,6 +208,21 @@ fn from_start_client_options(proplists: Term) -> hstreamdb::Result<ChannelProvid
     Ok(channel_provider_settings.build())
 }
 
+#[rustler::nif]
+fn async_echo(pid: LocalPid, client: ResourceArc<NifClient>, msg: String) {
+    let future = async move {
+        let client = &client.0;
+        let mut env = OwnedEnv::new();
+        match client.echo(msg).await {
+            Ok(msg) => env.send_and_clear(&pid, |env| (echo_reply(), ok(), msg).encode(env)),
+            Err(err) => env.send_and_clear(&pid, |env| {
+                (echo_reply(), error(), err.to_string()).encode(env)
+            }),
+        }
+    };
+    runtime::spawn(future);
+}
+
 #[rustler::nif]
 fn async_create_stream(
     pid: LocalPid,