From debf21d34e833083d398426def9b50d387a18211 Mon Sep 17 00:00:00 2001
From: Matthias Seitz <matthias.seitz@outlook.de>
Date: Tue, 3 Jan 2023 13:56:50 +0100
Subject: [PATCH] feat: add SyncState traits (#693)

* feat: add SyncState traits

* docs: clarify execution stage
---
 crates/interfaces/src/lib.rs      |  3 ++
 crates/interfaces/src/sync.rs     | 77 +++++++++++++++++++++++++++++++
 crates/net/network/src/network.rs | 23 ++++++++-
 3 files changed, 101 insertions(+), 2 deletions(-)
 create mode 100644 crates/interfaces/src/sync.rs

diff --git a/crates/interfaces/src/lib.rs b/crates/interfaces/src/lib.rs
index 0ec6c0001f..3c42c98f1a 100644
--- a/crates/interfaces/src/lib.rs
+++ b/crates/interfaces/src/lib.rs
@@ -22,6 +22,9 @@ pub mod db;
 /// P2P traits.
 pub mod p2p;
 
+/// Syncing related traits.
+pub mod sync;
+
 /// Possible errors when interacting with the chain.
 mod error;
 
diff --git a/crates/interfaces/src/sync.rs b/crates/interfaces/src/sync.rs
new file mode 100644
index 0000000000..642c55e96f
--- /dev/null
+++ b/crates/interfaces/src/sync.rs
@@ -0,0 +1,77 @@
+//! Traits used when interacting with the sync status of the network.
+
+use reth_primitives::BlockNumber;
+
+/// A type that provides information about whether the node is currently syncing and the network is
+/// currently serving syncing related requests.
+#[auto_impl::auto_impl(&, Arc, Box)]
+pub trait SyncStateProvider: Send + Sync {
+    /// Returns `true` if the network is undergoing sync.
+    fn is_syncing(&self) -> bool;
+}
+
+/// An updater for updating the [SyncState] of the network.
+///
+/// The chain sync pipeline consists of several sequential Stages, like the `HeaderStage` for
+/// downloading bodies, or `ExecutionStage` for process all downloaded data.
+///
+/// Some stage transitions will result in an update of the [SyncState] of the network. For example,
+/// the transition from a download stage (`Headers`, `Bodies`) to a processing stage (`Sender
+/// Recovery`, `Execution`) marks a transition from [`SyncState::Downloading`] to
+/// [`SyncState::Executing`]. Since the execution takes some time, after the first pass the node
+/// will not be synced ([`SyncState::Idle`]) yet and instead transition back to download data, but
+/// now with a higher `block_target`. This cycle will continue until the node has caught up with the
+/// chain and will transition to [`SyncState::Idle`] sync.
+#[auto_impl::auto_impl(&, Arc, Box)]
+pub trait SyncStateUpdater: SyncStateProvider {
+    /// Notifies about an [SyncState] update.
+    fn update_sync_state(&self, state: SyncState);
+}
+
+/// The state the network is currently in when it comes to synchronization.
+#[derive(Clone, Eq, PartialEq, Debug)]
+pub enum SyncState {
+    /// Node sync is complete.
+    ///
+    /// The network just serves requests to keep up of the chain.
+    Idle,
+    /// Network is syncing and downloading up to the `target_block`.
+    ///
+    /// This represents the headers and bodies stage.
+    Downloading {
+        /// The block to which the node is downloading state.
+        target_block: BlockNumber,
+    },
+    /// All headers and bodies up to the `target_block` have been downloaded and are now being
+    /// executed.
+    ///
+    /// This represents stages that execute/recover the downloaded data.
+    Executing {
+        /// The block to which the node executes downloaded state.
+        target_block: BlockNumber,
+    },
+}
+
+impl SyncState {
+    /// Whether the node is currently syncing.
+    ///
+    /// Note: this does not include keep-up sync when the state is idle.
+    pub fn is_syncing(&self) -> bool {
+        !matches!(self, SyncState::Idle)
+    }
+}
+
+/// A [SyncStateUpdater] implementation that does nothing.
+#[derive(Debug, Clone, Default)]
+#[non_exhaustive]
+pub struct NoopSyncStateUpdate;
+
+impl SyncStateProvider for NoopSyncStateUpdate {
+    fn is_syncing(&self) -> bool {
+        false
+    }
+}
+
+impl SyncStateUpdater for NoopSyncStateUpdate {
+    fn update_sync_state(&self, _state: SyncState) {}
+}
diff --git a/crates/net/network/src/network.rs b/crates/net/network/src/network.rs
index 4a41c56f4a..1015b12d8d 100644
--- a/crates/net/network/src/network.rs
+++ b/crates/net/network/src/network.rs
@@ -8,12 +8,15 @@ use crate::{
 };
 use parking_lot::Mutex;
 use reth_eth_wire::{DisconnectReason, NewBlock, NewPooledTransactionHashes, SharedTransactions};
-use reth_interfaces::p2p::headers::client::StatusUpdater;
+use reth_interfaces::{
+    p2p::headers::client::StatusUpdater,
+    sync::{SyncState, SyncStateProvider, SyncStateUpdater},
+};
 use reth_primitives::{PeerId, TransactionSigned, TxHash, H256, U256};
 use std::{
     net::SocketAddr,
     sync::{
-        atomic::{AtomicUsize, Ordering},
+        atomic::{AtomicBool, AtomicUsize, Ordering},
         Arc,
     },
 };
@@ -48,6 +51,7 @@ impl NetworkHandle {
             local_peer_id,
             peers,
             network_mode,
+            is_syncing: Arc::new(Default::default()),
         };
         Self { inner: Arc::new(inner) }
     }
@@ -187,6 +191,19 @@ impl StatusUpdater for NetworkHandle {
     }
 }
 
+impl SyncStateProvider for NetworkHandle {
+    fn is_syncing(&self) -> bool {
+        self.inner.is_syncing.load(Ordering::Relaxed)
+    }
+}
+
+impl SyncStateUpdater for NetworkHandle {
+    fn update_sync_state(&self, state: SyncState) {
+        let is_syncing = state.is_syncing();
+        self.inner.is_syncing.store(is_syncing, Ordering::Relaxed)
+    }
+}
+
 #[derive(Debug)]
 struct NetworkInner {
     /// Number of active peer sessions the node's currently handling.
@@ -201,6 +218,8 @@ struct NetworkInner {
     peers: PeersHandle,
     /// The mode of the network
     network_mode: NetworkMode,
+    /// Represents if the network is currently syncing.
+    is_syncing: Arc<AtomicBool>,
 }
 
 /// Internal messages that can be passed to the  [`NetworkManager`](crate::NetworkManager).