feat(reth-bench): accept short notation for --target-gas-limit (#21273)

bin/reth-bench/src/bench/gas_limit_ramp.rs

@@ -22,6 +22,29 @@ use reth_primitives_traits::constants::{GAS_LIMIT_BOUND_DIVISOR, MAXIMUM_GAS_LIM
 use std::{path::PathBuf, time::Instant};
 use tracing::info;
 
+/// Parses a gas limit value with optional suffix: K for thousand, M for million, G for billion.
+///
+/// Examples: "30000000", "30M", "1G", "2G"
+fn parse_gas_limit(s: &str) -> eyre::Result<u64> {
+    let s = s.trim();
+    if s.is_empty() {
+        return Err(eyre::eyre!("empty value"));
+    }
+
+    let (num_str, multiplier) = if let Some(prefix) = s.strip_suffix(['G', 'g']) {
+        (prefix, 1_000_000_000u64)
+    } else if let Some(prefix) = s.strip_suffix(['M', 'm']) {
+        (prefix, 1_000_000u64)
+    } else if let Some(prefix) = s.strip_suffix(['K', 'k']) {
+        (prefix, 1_000u64)
+    } else {
+        (s, 1u64)
+    };
+
+    let base: u64 = num_str.trim().parse()?;
+    base.checked_mul(multiplier).ok_or_else(|| eyre::eyre!("value overflow"))
+}
+
 /// `reth benchmark gas-limit-ramp` command.
 #[derive(Debug, Parser)]
 pub struct Command {
@@ -31,7 +54,9 @@ pub struct Command {
 
     /// Target gas limit to ramp up to. The benchmark will generate blocks until the gas limit
     /// reaches or exceeds this value. Mutually exclusive with --blocks.
-    #[arg(long, value_name = "TARGET_GAS_LIMIT", conflicts_with = "blocks")]
+    /// Accepts short notation: K for thousand, M for million, G for billion (e.g., 2G = 2
+    /// billion).
+    #[arg(long, value_name = "TARGET_GAS_LIMIT", conflicts_with = "blocks", value_parser = parse_gas_limit)]
     target_gas_limit: Option<u64>,
 
     /// The Engine API RPC URL.
@@ -212,3 +237,50 @@ const fn should_stop(mode: RampMode, blocks_processed: u64, current_gas_limit: u
         RampMode::TargetGasLimit(target) => current_gas_limit >= target,
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_parse_gas_limit_plain_number() {
+        assert_eq!(parse_gas_limit("30000000").unwrap(), 30_000_000);
+        assert_eq!(parse_gas_limit("1").unwrap(), 1);
+        assert_eq!(parse_gas_limit("0").unwrap(), 0);
+    }
+
+    #[test]
+    fn test_parse_gas_limit_k_suffix() {
+        assert_eq!(parse_gas_limit("1K").unwrap(), 1_000);
+        assert_eq!(parse_gas_limit("30k").unwrap(), 30_000);
+        assert_eq!(parse_gas_limit("100K").unwrap(), 100_000);
+    }
+
+    #[test]
+    fn test_parse_gas_limit_m_suffix() {
+        assert_eq!(parse_gas_limit("1M").unwrap(), 1_000_000);
+        assert_eq!(parse_gas_limit("30m").unwrap(), 30_000_000);
+        assert_eq!(parse_gas_limit("100M").unwrap(), 100_000_000);
+    }
+
+    #[test]
+    fn test_parse_gas_limit_g_suffix() {
+        assert_eq!(parse_gas_limit("1G").unwrap(), 1_000_000_000);
+        assert_eq!(parse_gas_limit("2g").unwrap(), 2_000_000_000);
+        assert_eq!(parse_gas_limit("10G").unwrap(), 10_000_000_000);
+    }
+
+    #[test]
+    fn test_parse_gas_limit_with_whitespace() {
+        assert_eq!(parse_gas_limit(" 1G ").unwrap(), 1_000_000_000);
+        assert_eq!(parse_gas_limit("2 M").unwrap(), 2_000_000);
+    }
+
+    #[test]
+    fn test_parse_gas_limit_errors() {
+        assert!(parse_gas_limit("").is_err());
+        assert!(parse_gas_limit("abc").is_err());
+        assert!(parse_gas_limit("G").is_err());
+        assert!(parse_gas_limit("-1G").is_err());
+    }
+}