headers(part 3) feat: implement Linear downloader (#119)

* feat: add headers downloaders crate

* feat: more scaffolding

* interfaces: generalize retryable erros

* feat: implement linear downloader

* fix linear downloader tests & add builder

* extend & reverse

* feat: linear downloader generics behind arc and reversed return order (#120)

* put client & consensus behind arc and return headers in rev

* cleanup

Co-authored-by: Roman Krasiuk <rokrassyuk@gmail.com>

Cargo.toml

@@ -13,6 +13,7 @@ members = [
     "crates/net/rpc",
     "crates/net/rpc-api",
     "crates/net/rpc-types",
+    "crates/net/headers-downloaders",
     "crates/primitives",
     "crates/stages",
     "crates/transaction-pool",

crates/interfaces/src/consensus.rs

@@ -7,7 +7,8 @@ use tokio::sync::watch::Receiver;
 /// Consensus is a protocol that chooses canonical chain.
 /// We are checking validity of block header here.
 #[async_trait]
-pub trait Consensus {
+#[auto_impl::auto_impl(&, Arc)]
+pub trait Consensus: Send + Sync {
     /// Get a receiver for the fork choice state
     fn fork_choice_state(&self) -> Receiver<ForkchoiceState>;
 

crates/interfaces/src/p2p/headers/downloader.rs

@@ -50,15 +50,16 @@ pub enum DownloadError {
 }
 
 impl DownloadError {
-    /// Returns bool indicating whether this error is retryable or fatal
+    /// Returns bool indicating whether this error is retryable or fatal, in the cases
+    /// where the peer responds with no headers, or times out.
     pub fn is_retryable(&self) -> bool {
-        matches!(self, DownloadError::NoHeaderResponse { .. })
+        matches!(self, DownloadError::NoHeaderResponse { .. } | DownloadError::Timeout { .. })
     }
 }
 
 /// The header downloading strategy
 #[async_trait]
-pub trait Downloader: Sync + Send + Debug {
+pub trait Downloader: Sync + Send {
     /// The Consensus used to verify block validity when
     /// downloading
     type Consensus: Consensus;

crates/net/headers-downloaders/Cargo.toml

@@ -0,0 +1,22 @@
+[package]
+name = "reth-headers-downloaders"
+version = "0.1.0"
+edition = "2021"
+license = "MIT OR Apache-2.0"
+repository = "https://github.com/foundry-rs/reth"
+readme = "README.md"
+description = "Implementations of various header downloader"
+
+[dependencies]
+async-trait = "0.1.58"
+reth-interfaces = { path = "../../interfaces" }
+reth-primitives = { path = "../../primitives" }
+reth-rpc-types = { path = "../rpc-types" }
+
+[dev-dependencies]
+assert_matches = "1.5.0"
+once_cell = "1.15.0"
+rand = "0.8.5"
+reth-interfaces = { path = "../../interfaces", features = ["test-helpers"] }
+tokio = { version = "1.21.2", features = ["full"] }
+serial_test = "0.9.0"

crates/net/headers-downloaders/src/lib.rs

@@ -0,0 +1,11 @@
+#![warn(missing_docs, unreachable_pub)]
+#![deny(unused_must_use, rust_2018_idioms)]
+#![doc(test(
+    no_crate_inject,
+    attr(deny(warnings, rust_2018_idioms), allow(dead_code, unused_variables))
+))]
+
+//! Implements Header Downloader algorithms
+
+/// A Linear downloader implementation.
+pub mod linear;