Implement block on connect with Rust SDK

- Uses a simple polling mechanism to confirm the connection is live
- Tweaks the conformance tests to add a random delay to ensure future
  testing of SDK blocking.
- Add `ready` to the SDK documentation.

Fixes #938

build/includes/sdk.mk

@@ -122,15 +122,17 @@ run-sdk-conformance-local: ensure-agones-sdk-image
 	 -e "TEST=$(TESTS)" -e "TIMEOUT=$(TIMEOUT)" $(sidecar_tag)
 
 # Run SDK conformance test, previously built, for a specific SDK_FOLDER
+# Sleeps the start of the sidecar to test that the SDK blocks on connection correctly
 run-sdk-conformance-no-build: TIMEOUT ?= 30
+run-sdk-conformance-no-build: RANDOM := $(shell bash -c 'echo $$RANDOM')
+run-sdk-conformance-no-build: DELAY ?= $(shell bash -c "echo $$[ ($(RANDOM) % 5 ) + 1 ]s")
 run-sdk-conformance-no-build: TESTS ?= ready,allocate,setlabel,setannotation,gameserver,health,shutdown,watch
 run-sdk-conformance-no-build: ensure-agones-sdk-image
 run-sdk-conformance-no-build: ensure-build-sdk-image
-	sleep 2s && DOCKER_RUN_ARGS="--network=host $(DOCKER_RUN_ARGS)" COMMAND=sdktest $(MAKE) run-sdk-command & \
-	docker run -p 59357:59357 -e "ADDRESS=" \
+	DOCKER_RUN_ARGS="--network=host $(DOCKER_RUN_ARGS)" COMMAND=sdktest $(MAKE) run-sdk-command & \
+	sleep $(DELAY) && docker run -p 59357:59357 -e "ADDRESS=" \
 	 -e "TEST=$(TESTS)" -e "TIMEOUT=$(TIMEOUT)" --net=host  $(sidecar_tag)
 
-
 # Run SDK conformance test for a specific SDK_FOLDER
 run-sdk-conformance-test:
 	$(MAKE) run-sdk-command COMMAND=build-sdk-test

sdks/rust/src/sdk.rs

@@ -12,15 +12,18 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-use futures::{Future, Sink, Stream};
-use grpcio;
 use std::sync::{Arc, Mutex};
+use std::thread::sleep;
 use std::time::Duration;
 
+use futures::{Future, Sink, Stream};
+use grpcio;
+use grpcio::CallOption;
+use protobuf::Message;
+
 use errors::*;
 use grpc::sdk;
 use grpc::sdk_grpc;
-use protobuf::Message;
 use types::*;
 
 const PORT: i32 = 59357;
@@ -34,7 +37,7 @@ pub struct Sdk {
 impl Sdk {
     /// Starts a new SDK instance, and connects to localhost on port 59357.
     /// Blocks until connection and handshake are made.
-    /// Times out after 30 seconds.
+    /// Times out after ~30 seconds.
     pub fn new() -> Result<Sdk> {
         let addr = format!("localhost:{}", PORT);
         let env = Arc::new(grpcio::EnvBuilder::new().build());
@@ -43,7 +46,24 @@ impl Sdk {
             .connect(&addr);
         let cli = sdk_grpc::SdkClient::new(ch);
         let req = sdk::Empty::new();
-        let _ = cli.ready(&req).map(Box::new)?;
+
+        // Unfortunately there isn't a native way to block until connected
+        // so we had to roll our own.
+        let mut counter = 0;
+        loop {
+            counter += 1;
+            match cli.get_game_server(&req) {
+                Ok(_) => break,
+                Err(e) => {
+                    if counter > 30 {
+                        return Err(ErrorKind::Grpc(e).into());
+                    }
+                    sleep(Duration::from_secs(1));
+                    continue;
+                }
+            }
+        }
+
         let (sender, _) = cli.health()?;
         Ok(Sdk {
             client: Arc::new(cli),
@@ -58,15 +78,13 @@ impl Sdk {
         Ok(res)
     }
 
-
-    /// Allocate the Game Server 
+    /// Allocate the Game Server
     pub fn allocate(&self) -> Result<()> {
         let req = sdk::Empty::default_instance();
         let res = self.client.allocate(req).map(|_| ())?;
         Ok(res)
     }
 
-
     /// Marks the Game Server as ready to shutdown
     pub fn shutdown(&self) -> Result<()> {
         let req = sdk::Empty::default_instance();

site/content/en/docs/Guides/Client SDKs/rust.md

@@ -46,6 +46,15 @@ if sdk.health().is_ok() {
 }
 ```
 
+{{% feature publishVersion="0.12.0" %}}
+
+To mark the [game session as ready]({{< relref "_index.md#ready" >}}) call `sdk.ready()`.
+
+```rust
+if sdk.ready()?
+```
+{{% /feature %}}
+
 To mark that the [game session is completed]({{< relref "_index.md#shutdown" >}}) and the game server should be shut down call `sdk.shutdown()`. 
 
 ```rust

test/sdk/rust/.gitignore

@@ -0,0 +1,16 @@
+# Copyright 2019 Google LLC All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software