Add Eth2Config to runtime

beacon_node/client/src/eth2_config.rs

@@ -0,0 +1,48 @@
+use clap::ArgMatches;
+use serde_derive::{Deserialize, Serialize};
+use std::time::SystemTime;
+use types::ChainSpec;
+
+/// The core configuration of a Lighthouse beacon node.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(default)]
+pub struct Eth2Config {
+    pub spec_constants: String,
+    pub spec: ChainSpec,
+}
+
+impl Default for Eth2Config {
+    fn default() -> Self {
+        Self {
+            spec_constants: "minimal".to_string(),
+            spec: ChainSpec::minimal(),
+        }
+    }
+}
+
+impl Eth2Config {
+    /// Apply the following arguments to `self`, replacing values if they are specified in `args`.
+    ///
+    /// Returns an error if arguments are obviously invalid. May succeed even if some values are
+    /// invalid.
+    pub fn apply_cli_args(&mut self, args: &ArgMatches) -> Result<(), &'static str> {
+        if args.is_present("recent_genesis") {
+            self.spec.genesis_time = recent_genesis_time()
+        }
+
+        Ok(())
+    }
+}
+
+/// Returns the system time, mod 30 minutes.
+///
+/// Used for easily creating testnets.
+fn recent_genesis_time() -> u64 {
+    let now = SystemTime::now()
+        .duration_since(SystemTime::UNIX_EPOCH)
+        .unwrap()
+        .as_secs();
+    let secs_after_last_period = now.checked_rem(30 * 60).unwrap_or(0);
+    // genesis is now the last 30 minute block.
+    now - secs_after_last_period
+}