fix: intermittent failure in dfx start

src/dfx/src/commands/start.rs

@@ -10,6 +10,7 @@ use crate::lib::replica_config::ReplicaConfig;
 use clap::{App, Arg, ArgMatches, SubCommand};
 use crossbeam::channel::{Receiver, Sender};
 use crossbeam::unbounded;
+use delay::{Delay, Waiter};
 use futures::future::Future;
 use ic_agent::{Agent, AgentConfig};
 use indicatif::{ProgressBar, ProgressDrawTarget};
@@ -56,14 +57,24 @@ fn ping_and_wait(frontend_url: &str) -> DfxResult {
     })?;
 
     // wait for frontend to come up
-    use std::{thread, time};
-    let three_secs = time::Duration::from_secs(3);
-    thread::sleep(three_secs);
-
-    runtime
-        .block_on(agent.status())
-        .map(|_| ())
-        .map_err(DfxError::from)
+    let mut waiter = Delay::builder()
+        .timeout(std::time::Duration::from_secs(30))
+        .throttle(std::time::Duration::from_secs(1))
+        .build();
+
+    runtime.block_on(async {
+        waiter.start();
+        loop {
+            let status = agent.status().await;
+            if status.is_ok() {
+                break;
+            }
+            waiter
+                .wait()
+                .map_err(|_| DfxError::AgentError(status.unwrap_err()))?;
+        }
+        Ok(())
+    })
 }
 
 // TODO(eftychis)/In progress: Rename to replica.