From 572df4f37e093c08d1c1a63d047969c5e3ee0781 Mon Sep 17 00:00:00 2001
From: Paul Hauner <paul@paulhauner.com>
Date: Wed, 4 Sep 2019 13:56:30 +1000
Subject: [PATCH] Make bootstrapper block til connection established

---
 .../beacon_chain/src/beacon_chain_builder.rs  |  2 +-
 beacon_node/src/config.rs                     |  4 +-
 eth2/utils/lighthouse_bootstrap/Cargo.toml    |  1 +
 eth2/utils/lighthouse_bootstrap/src/lib.rs    | 37 +++++++++++++++++--
 validator_client/src/main.rs                  | 11 ++++--
 5 files changed, 44 insertions(+), 11 deletions(-)

diff --git a/beacon_node/beacon_chain/src/beacon_chain_builder.rs b/beacon_node/beacon_chain/src/beacon_chain_builder.rs
index ef25c33ec..2a3537020 100644
--- a/beacon_node/beacon_chain/src/beacon_chain_builder.rs
+++ b/beacon_node/beacon_chain/src/beacon_chain_builder.rs
@@ -87,7 +87,7 @@ impl<T: BeaconChainTypes> BeaconChainBuilder<T> {
     }
 
     pub fn http_bootstrap(server: &str, spec: ChainSpec, log: Logger) -> Result<Self, String> {
-        let bootstrapper = Bootstrapper::from_server_string(server.to_string())
+        let bootstrapper = Bootstrapper::connect(server.to_string(), &log)
             .map_err(|e| format!("Failed to initialize bootstrap client: {}", e))?;
 
         let (genesis_state, genesis_block) = bootstrapper
diff --git a/beacon_node/src/config.rs b/beacon_node/src/config.rs
index f2c56c524..6a13a9aae 100644
--- a/beacon_node/src/config.rs
+++ b/beacon_node/src/config.rs
@@ -310,7 +310,7 @@ impl<'a> ConfigBuilder<'a> {
         server: &str,
         port: Option<u16>,
     ) -> Result<()> {
-        let bootstrapper = Bootstrapper::from_server_string(server.to_string())?;
+        let bootstrapper = Bootstrapper::connect(server.to_string(), &self.log)?;
 
         if let Some(server_multiaddr) = bootstrapper.best_effort_multiaddr(port) {
             info!(
@@ -347,7 +347,7 @@ impl<'a> ConfigBuilder<'a> {
 
     /// Imports an `Eth2Config` from `server`, returning an error if this fails.
     pub fn import_bootstrap_eth2_config(&mut self, server: &str) -> Result<()> {
-        let bootstrapper = Bootstrapper::from_server_string(server.to_string())?;
+        let bootstrapper = Bootstrapper::connect(server.to_string(), &self.log)?;
 
         self.update_eth2_config(bootstrapper.eth2_config()?);
 
diff --git a/eth2/utils/lighthouse_bootstrap/Cargo.toml b/eth2/utils/lighthouse_bootstrap/Cargo.toml
index 3f48505b8..cfc4c6baf 100644
--- a/eth2/utils/lighthouse_bootstrap/Cargo.toml
+++ b/eth2/utils/lighthouse_bootstrap/Cargo.toml
@@ -13,3 +13,4 @@ reqwest = "0.9"
 url = "1.2"
 types = { path = "../../types" }
 serde = "1.0"
+slog = { version = "^2.2.3" , features = ["max_level_trace", "release_max_level_trace"] }
diff --git a/eth2/utils/lighthouse_bootstrap/src/lib.rs b/eth2/utils/lighthouse_bootstrap/src/lib.rs
index dc70c6d21..92a587ff2 100644
--- a/eth2/utils/lighthouse_bootstrap/src/lib.rs
+++ b/eth2/utils/lighthouse_bootstrap/src/lib.rs
@@ -5,11 +5,16 @@ use eth2_libp2p::{
 };
 use reqwest::{Error as HttpError, Url};
 use serde::Deserialize;
+use slog::{error, Logger};
 use std::borrow::Cow;
 use std::net::Ipv4Addr;
+use std::time::Duration;
 use types::{BeaconBlock, BeaconState, Checkpoint, EthSpec, Hash256, Slot};
 use url::Host;
 
+pub const RETRY_SLEEP_MILLIS: u64 = 100;
+pub const RETRY_WARN_INTERVAL: u64 = 30;
+
 #[derive(Debug)]
 enum Error {
     InvalidUrl,
@@ -31,11 +36,35 @@ pub struct Bootstrapper {
 }
 
 impl Bootstrapper {
-    /// Parses the given `server` as a URL, instantiating `Self`.
-    pub fn from_server_string(server: String) -> Result<Self, String> {
-        Ok(Self {
+    /// Parses the given `server` as a URL, instantiating `Self` and blocking until a connection
+    /// can be made with the server.
+    ///
+    /// Never times out.
+    pub fn connect(server: String, log: &Logger) -> Result<Self, String> {
+        let bootstrapper = Self {
             url: Url::parse(&server).map_err(|e| format!("Invalid bootstrap server url: {}", e))?,
-        })
+        };
+
+        let mut retry_count = 0;
+        loop {
+            match bootstrapper.enr() {
+                Ok(_) => break,
+                Err(_) => {
+                    if retry_count % RETRY_WARN_INTERVAL == 0 {
+                        error!(
+                            log,
+                            "Failed to contact bootstrap server";
+                            "retry_count" => retry_count,
+                            "retry_delay_millis" => RETRY_SLEEP_MILLIS,
+                        );
+                    }
+                    retry_count += 1;
+                    std::thread::sleep(Duration::from_millis(RETRY_SLEEP_MILLIS));
+                }
+            }
+        }
+
+        Ok(bootstrapper)
     }
 
     /// Build a multiaddr using the HTTP server URL that is not guaranteed to be correct.
diff --git a/validator_client/src/main.rs b/validator_client/src/main.rs
index d5d2fc27f..39b2e3eae 100644
--- a/validator_client/src/main.rs
+++ b/validator_client/src/main.rs
@@ -247,10 +247,13 @@ fn process_testnet_subcommand(
 ) -> Result<(ClientConfig, Eth2Config)> {
     let eth2_config = if cli_args.is_present("bootstrap") {
         info!(log, "Connecting to bootstrap server");
-        let bootstrapper = Bootstrapper::from_server_string(format!(
-            "http://{}:{}",
-            client_config.server, client_config.server_http_port
-        ))?;
+        let bootstrapper = Bootstrapper::connect(
+            format!(
+                "http://{}:{}",
+                client_config.server, client_config.server_http_port
+            ),
+            &log,
+        )?;
 
         let eth2_config = bootstrapper.eth2_config()?;