Scaffold utility and library (#3)

Signed-off-by: Cyrill Leutwiler <bigcyrill@hotmail.com>
Signed-off-by: xermicus <bigcyrill@hotmail.com>

crates/node/src/pool.rs

@@ -0,0 +1,68 @@
+//! This crate implements concurrent handling of testing node.
+
+use std::{
+    fs::read_to_string,
+    sync::atomic::{AtomicUsize, Ordering},
+    thread,
+};
+
+use anyhow::Context;
+use revive_dt_config::Arguments;
+
+use crate::Node;
+
+/// The node pool starts one or more [Node] which then can be accessed
+/// in a round robbin fasion.
+pub struct NodePool<T> {
+    next: AtomicUsize,
+    nodes: Vec<T>,
+}
+
+impl<T> NodePool<T>
+where
+    T: Node + Send + 'static,
+{
+    /// Create a new Pool. This will start as many nodes as there are workers in `config`.
+    pub fn new(config: &Arguments) -> anyhow::Result<Self> {
+        let nodes = config.workers;
+        let genesis = read_to_string(&config.genesis_file).context(format!(
+            "can not read genesis file: {}",
+            config.genesis_file.display()
+        ))?;
+
+        let mut handles = Vec::with_capacity(nodes);
+        for _ in 0..nodes {
+            let config = config.clone();
+            let genesis = genesis.clone();
+            handles.push(thread::spawn(move || spawn_node::<T>(&config, genesis)));
+        }
+
+        let mut nodes = Vec::with_capacity(nodes);
+        for handle in handles {
+            nodes.push(
+                handle
+                    .join()
+                    .map_err(|error| anyhow::anyhow!("failed to spawn node: {:?}", error))?
+                    .map_err(|error| anyhow::anyhow!("node failed to spawn: {error}"))?,
+            );
+        }
+
+        Ok(Self {
+            nodes,
+            next: Default::default(),
+        })
+    }
+
+    /// Get a handle to the next node.
+    pub fn round_robbin(&self) -> &T {
+        let current = self.next.fetch_add(1, Ordering::SeqCst) % self.nodes.len();
+        self.nodes.get(current).unwrap()
+    }
+}
+
+fn spawn_node<T: Node + Send>(args: &Arguments, genesis: String) -> anyhow::Result<T> {
+    let mut node = T::new(args);
+    log::info!("starting node: {}", node.connection_string());
+    node.spawn(genesis)?;
+    Ok(node)
+}