rpc: add Client::wait_until_healthy method

Adds a method which repeatedly polls the `/health` endpoint until it
returns a successful response or a specified timeout elapses.

This is useful when writing tests that need to wait for a node to boot
up (e.g. inside of a docker container).

rpc/src/client.rs

@@ -14,14 +14,17 @@ pub use transport::websocket::{WebSocketClient, WebSocketClientDriver, WebSocket
 
 use crate::endpoint::validators::DEFAULT_VALIDATORS_PER_PAGE;
 use crate::endpoint::*;
+use crate::error::Error;
 use crate::paging::Paging;
 use crate::query::Query;
 use crate::{Order, Result, SimpleRequest};
 use async_trait::async_trait;
+use std::time::Duration;
 use tendermint::abci::{self, Transaction};
 use tendermint::block::Height;
 use tendermint::evidence::Evidence;
 use tendermint::Genesis;
+use tokio::time;
 
 /// Provides lightweight access to the Tendermint RPC. It gives access to all
 /// endpoints with the exception of the event subscription-related ones.
@@ -221,6 +224,31 @@ pub trait Client {
  .await
  }
 
+ /// Poll the `/health` endpoint until it returns a successful result or
+ /// the given `timeout` has elapsed.
+ async fn wait_until_healthy<T>(&self, timeout: T) -> Result<()>
+ where
+ T: Into<Duration> + Send
+ {
+ let timeout = timeout.into();
+ let poll_interval = Duration::from_millis(200);
+ let mut attempts_remaining = timeout.as_millis() / poll_interval.as_millis();
+
+ while let Err(_) = self.health().await {
+ if attempts_remaining == 0 {
+ return Err(Error::client_internal_error(format!(
+ "timed out waiting for healthy response after {}ms",
+ timeout.as_millis()
+ )));
+ }
+
+ attempts_remaining -= 1;
+ time::sleep(poll_interval).await;
+ }
+
+ Ok(())
+ }
+
  /// Perform a request against the RPC endpoint
  async fn perform<R>(&self, request: R) -> Result<R::Response>
  where