RSDK-2123 - fix streaming over rust-utils (#30)

Co-authored-by: Cheuk <[email protected]>

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "viam-rust-utils"
-version = "0.0.10"
+version = "0.0.11"
 edition = "2021"
 license = "Apache-2.0"
 description = "Utilities designed for use with Viamrobotics's SDKs"

examples/src/echo/main.rs

@@ -9,6 +9,7 @@ use viam::rpc::dial;
 /// Tests unary, server, and bidi streaming with simple echo requests. To run, simply
 /// update the credentials and uri as necessary.
 async fn main() -> Result<()> {
+    env_logger::init();
     let creds = dial::RPCCredentials::new(
         None,
         "robot-location-secret".to_string(),

src/rpc/dial.rs

@@ -18,7 +18,7 @@ use crate::{
     },
     rpc::webrtc::PollableAtomicBool,
 };
-use ::http::header::{HeaderName, TRAILER};
+use ::http::header::HeaderName;
 use ::http::{
     uri::{Authority, Parts, PathAndQuery, Scheme},
     HeaderValue, Version,
@@ -129,34 +129,17 @@ impl Service<http::Request<BoxBody>> for ViamChannel {
                         }
                     };
 
-                    // TODO(RSDK-654) if and when we need to provide better support for
-                    // bidi streaming, we'll need to find a better solution than this for
-                    // handling empty messages
-                    let mut body = hyper::body::to_bytes(body).await.unwrap().to_vec();
-                    if body.is_empty() {
-                        // the body is empty if we make a call that returns an error on the RDK
-                        // side. Python's grpc library expects to see messages with, at a minimum,
-                        // a grpc header, so returning an empty body leads to error. In such a
-                        // case, we instead return a body that just consists of empty header bytes
-                        // to indicate an empty message.
-                        body = vec![0, 0, 0, 0, 0];
-                        status_code = STATUS_CODE_UNKNOWN;
-                    }
-                    let grpc_message = channel.error.read().unwrap().clone();
                     let response = http::response::Response::builder()
                         // standardized gRPC headers.
                         .header("content-type", "application/grpc")
-                        .header("te", "trailers")
-                        .header(TRAILER, "Grpc-Status")
-                        .header(TRAILER, "Grpc-Message")
-                        .header(TRAILER, "Grpc-Status-Details-Bin")
-                        .header("grpc-status", &status_code.to_string())
                         .version(Version::HTTP_2);
 
-                    let response = match grpc_message {
-                        None => response,
-                        Some(message) => response.header("grpc-message", message),
+                    let response = if status_code != STATUS_CODE_OK {
+                        response.header("grpc-status", &status_code.to_string())
+                    } else {
+                        response
                     };
+
                     let response = response.body(Body::from(body)).unwrap();
                     Ok(response)
                 };