tonic-build: option to emit Arc<Self> as server receiver (#1352)

This implements an option to emit `Arc<Self>` instead of `&self` in
server traits. This enables implementor to reference `Self` data for
indefinite duration, which may be useful for streaming requests.

Fixes: #1351

tests/use_arc_self/Cargo.toml

@@ -0,0 +1,18 @@
+[package]
+authors = ["Aurimas Blažulionis <[email protected]>"]
+edition = "2021"
+license = "MIT"
+name = "use_arc_self"
+publish = false
+version = "0.1.0"
+
+[dependencies]
+futures = "0.3"
+prost = "0.11"
+tonic = {path = "../../tonic", features = ["gzip"]}
+
+[build-dependencies]
+tonic-build = {path = "../../tonic-build" }
+
+[package.metadata.cargo-machete]
+ignored = ["prost"]

tests/use_arc_self/LICENSE

@@ -0,0 +1,19 @@
+Copyright (c) 2020 Lucio Franco
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.

tests/use_arc_self/build.rs

@@ -0,0 +1,6 @@
+fn main() {
+    tonic_build::configure()
+        .use_arc_self(true)
+        .compile(&["proto/test.proto"], &["proto"])
+        .unwrap();
+}

tests/use_arc_self/proto/test.proto

@@ -0,0 +1,12 @@
+syntax = "proto3";
+
+package test;
+
+service Test {
+  rpc TestRequest(SomeData) returns (SomeData);
+}
+
+message SomeData {
+  // include a bunch of data so there actually is something to compress
+  bytes data = 1;
+}

tests/use_arc_self/src/lib.rs

@@ -0,0 +1,20 @@
+#![allow(unused_imports)]
+
+use futures::{Stream, StreamExt};
+use std::sync::Arc;
+use tonic::{Request, Response, Status};
+
+tonic::include_proto!("test");
+
+#[derive(Debug, Default)]
+struct Svc;
+
+#[tonic::async_trait]
+impl test_server::Test for Svc {
+    async fn test_request(
+        self: Arc<Self>,
+        req: Request<SomeData>,
+    ) -> Result<Response<SomeData>, Status> {
+        Ok(Response::new(req.into_inner()))
+    }
+}