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Documents and simplifies syncing code (#738)

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* Add duplication prevention to gossipsub

* Clean up topic logs

* Add content addressed messages for gossip

* Support BlocksByRange step parameter

* Add initial docs to syncing

* Adds documentation and simplify code in sync

* Remove unnecessary comment

* Fix fmt issue

* Add batch log to sync
This commit is contained in:
Age Manning 2019-12-23 21:23:14 +11:00 committed by GitHub
parent 3acb3cc640
commit 01ac60d638
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5 changed files with 369 additions and 242 deletions
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2
beacon_node/eth2-libp2p/src/rpc/mod.rs
View File

@ -66,7 +66,7 @@ pub struct RPC<TSubstream> {
/// Queue of events to processed.
events: Vec<NetworkBehaviourAction<RPCEvent, RPCMessage>>,
/// Pins the generic substream.
marker: PhantomData<(TSubstream)>,
marker: PhantomData<TSubstream>,
/// Slog logger for RPC behaviour.
log: slog::Logger,
}

31
beacon_node/network/src/sync/manager.rs
View File

@ -16,36 +16,11 @@
//! further peers connect, this process is run in parallel with those peers, until our head is
//! within `SLOT_IMPORT_TOLERANCE` of all connected peers.
//!
//! Batch Syncing
//! ## Batch Syncing
//!
//! This syncing process start by requesting `BLOCKS_PER_REQUEST` blocks from a peer with an
//! unknown chain (with a greater slot height) starting from our current head slot. If the earliest
//! block returned is known to us, then the group of blocks returned form part of a known chain,
//! and we process this batch of blocks, before requesting more batches forward and processing
//! those in turn until we reach the peer's chain's head. If the first batch doesn't contain a
//! block we know of, we must iteratively request blocks backwards (until our latest finalized head
//! slot) until we find a common ancestor before we can start processing the blocks. If no common
//! ancestor is found, the peer has a chain which is not part of our finalized head slot and we
//! drop the peer and the downloaded blocks.
//! Once we are fully synced with all known peers, the state of the manager becomes `Regular` which
//! then allows for parent lookups of propagated blocks.
//! See `RangeSync` for further details.
//!
//! A schematic version of this logic with two chain variations looks like the following.
//!
//! |----------------------|---------------------------------|
//! ^finalized head ^current local head ^remotes head
//!
//!
//! An example of the remotes chain diverging before our current head.
//! |---------------------------|
//! ^---------------------------------------------|
//! ^chain diverges |initial batch| ^remotes head
//!
//! In this example, we cannot process the initial batch as it is not on a known chain. We must
//! then backwards sync until we reach a common chain to begin forwarding batch syncing.
//!
//!
//! Parent Lookup
//! ## Parent Lookup
//!
//! When a block with an unknown parent is received and we are in `Regular` sync mode, the block is
//! queued for lookup. A round-robin approach is used to request the parent from the known list of

140
beacon_node/network/src/sync/range_sync/chain.rs
View File

@ -23,6 +23,7 @@ const BLOCKS_PER_BATCH: u64 = 50;
/// The number of times to retry a batch before the chain is considered failed and removed.
const MAX_BATCH_RETRIES: u8 = 5;
/// A collection of sequential blocks that are requested from peers in a single RPC request.
#[derive(PartialEq)]
pub struct Batch<T: EthSpec> {
/// The ID of the batch, batches are ID's sequentially.
@ -55,6 +56,9 @@ impl<T: EthSpec> PartialOrd for Batch<T> {
}
}
/// A return type for functions that act on a `Chain` which informs the caller whether the chain
/// has been completed and should be removed or to be kept if further processing is
/// required.
pub enum ProcessingResult {
KeepChain,
RemoveChain,
@ -86,6 +90,9 @@ impl<T: EthSpec> Batch<T> {
}
}
/// A chain of blocks that need to be downloaded. Peers who claim to contain the target head
/// root are grouped into the peer pool and queried for batches when downloading the
/// chain.
pub struct SyncingChain<T: BeaconChainTypes> {
/// The original start slot when this chain was initialised.
pub start_slot: Slot,
@ -127,7 +134,7 @@ pub enum ChainSyncingState {
/// The chain is undergoing syncing.
Syncing,
/// The chain is temporarily paused whilst an error is rectified.
Paused,
_Paused,
}
impl<T: BeaconChainTypes> SyncingChain<T> {
@ -154,6 +161,12 @@ impl<T: BeaconChainTypes> SyncingChain<T> {
}
}
/// A batch of blocks has been received. This function gets run on all chains and should
/// return Some if the request id matches a pending request on this chain, or None if it does
/// not.
///
/// If the request corresponds to a pending batch, this function processes the completed
/// batch.
pub fn on_block_response(
&mut self,
chain: &Weak<BeaconChain<T>>,
@ -174,6 +187,9 @@ impl<T: BeaconChainTypes> SyncingChain<T> {
}
}
/// A completed batch has been received, process the batch.
/// This will return `ProcessingResult::KeepChain` if the chain has not completed or
/// failed indicating that further batches are required.
fn process_completed_batch(
&mut self,
chain: Weak<BeaconChain<T>>,
@ -226,57 +242,52 @@ impl<T: BeaconChainTypes> SyncingChain<T> {
//blocks here, manage the queue and process them in another thread as they become
//available.
if self.state != ChainSyncingState::Paused {
if self.state == ChainSyncingState::Syncing {
// pre-emptively request more blocks from peers whilst we process current blocks,
self.send_range_request(network, current_peer);
self.send_range_request(network, current_peer, log);
}
// Try and process batches sequentially in the ordered list.
let current_process_id = self.to_be_processed_id;
// keep track of the number of successful batches to decide whether to run fork choice
let mut successful_block_process = false;
for batch in self
.completed_batches
.iter()
.filter(|batch| batch.id >= current_process_id)
{
if batch.id == self.to_be_processed_id {
if batch.id != self.to_be_processed_id {
// there are no batches to be processed at the moment
break;
}
if batch.downloaded_blocks.is_empty() {
// the batch was empty, progress to the next block
self.to_be_processed_id += 1;
continue;
} else {
let mut successes = 0;
}
// process the batch
// Keep track of successful batches. Run fork choice after all waiting batches have
// been processed.
debug!(log, "Processing batch"; "batch_id" => batch.id);
match process_batch(chain.clone(), batch, &mut successes, log) {
match process_batch(chain.clone(), batch, log) {
Ok(_) => {
// batch was successfully processed
self.last_processed_id = self.to_be_processed_id;
self.to_be_processed_id += 1;
if let Some(chain) = chain.upgrade() {
match chain.fork_choice() {
Ok(()) => trace!(
log,
"Fork choice success";
"location" => "batch import success"
),
Err(e) => error!(
log,
"Fork choice failed";
"error" => format!("{:?}", e),
"location" => "batch import success"
),
}
}
successful_block_process = true;
}
Err(e) => {
warn!(log, "Block processing error"; "error"=> format!("{:?}", e));
if successes > 0 {
if successful_block_process {
if let Some(chain) = chain.upgrade() {
match chain.fork_choice() {
Ok(()) => trace!(
log,
"Fork choice success";
"block_imports" => successes,
"location" => "batch import error"
),
Err(e) => error!(
@ -299,30 +310,41 @@ impl<T: BeaconChainTypes> SyncingChain<T> {
}
}
}
} else {
// there are no more batches to be processed, end
break;
// If we have processed batches, run fork choice
if successful_block_process {
if let Some(chain) = chain.upgrade() {
match chain.fork_choice() {
Ok(()) => trace!(
log,
"Fork choice success";
"location" => "batch import success"
),
Err(e) => error!(
log,
"Fork choice failed";
"error" => format!("{:?}", e),
"location" => "batch import success"
),
}
}
}
// remove any validated batches
let last_processed_id = self.last_processed_id;
self.completed_batches
.retain(|batch| batch.id >= last_processed_id);
// check if the chain has completed syncing, if not, request another batch from this peer
if self.start_slot + self.last_processed_id * BLOCKS_PER_BATCH >= self.target_head_slot
{
// check if the chain has completed syncing
if self.start_slot + self.last_processed_id * BLOCKS_PER_BATCH >= self.target_head_slot {
// chain is completed
ProcessingResult::RemoveChain
} else {
// chain is not completed
ProcessingResult::KeepChain
}
} else {
ProcessingResult::KeepChain
}
}
/// An invalid batch has been received that could not be processed.
fn handle_invalid_batch(
&mut self,
_chain: Weak<BeaconChain<T>>,
@ -340,9 +362,10 @@ impl<T: BeaconChainTypes> SyncingChain<T> {
//
//TODO: Implement this logic
// Currently just fail the chain, and drop all associated peers
for peer_id in self.peer_pool.iter() {
network.downvote_peer(peer_id.clone());
// Currently just fail the chain, and drop all associated peers, removing them from the
// peer pool, to prevent re-status
for peer_id in self.peer_pool.drain() {
network.downvote_peer(peer_id);
}
ProcessingResult::RemoveChain
}
@ -352,6 +375,9 @@ impl<T: BeaconChainTypes> SyncingChain<T> {
}
// Either a new chain, or an old one with a peer list
/// This chain has been requested to start syncing.
///
/// This could be new chain, or an old chain that is being resumed.
pub fn start_syncing(
&mut self,
network: &mut SyncNetworkContext,
@ -415,14 +441,15 @@ impl<T: BeaconChainTypes> SyncingChain<T> {
for peer_id in peers {
// send a blocks by range request to the peer
self.send_range_request(network, peer_id);
self.send_range_request(network, peer_id, log);
}
self.state = ChainSyncingState::Syncing;
}
// A peer has been added, start batch requests for this peer
// this should only be called for a syncing chain
/// A peer has been added.
///
/// If the chain is active, this starts requesting batches from this peer.
pub fn peer_added(
&mut self,
network: &mut SyncNetworkContext,
@ -436,24 +463,32 @@ impl<T: BeaconChainTypes> SyncingChain<T> {
}
// find the next batch and request it from the peer
self.send_range_request(network, peer_id);
self.send_range_request(network, peer_id, log);
}
// Re-STATUS all the peers in this chain
/// Sends a STATUS message to all peers in the peer pool.
pub fn status_peers(&self, chain: Weak<BeaconChain<T>>, network: &mut SyncNetworkContext) {
for peer_id in self.peer_pool.iter() {
network.status_peer(chain.clone(), peer_id.clone());
}
}
fn send_range_request(&mut self, network: &mut SyncNetworkContext, peer_id: PeerId) {
/// Requests the next required batch from the provided peer.
fn send_range_request(
&mut self,
network: &mut SyncNetworkContext,
peer_id: PeerId,
log: &slog::Logger,
) {
// find the next pending batch and request it from the peer
if let Some(batch) = self.get_next_batch(peer_id) {
debug!(log, "Requesting batch"; "start_slot" => batch.start_slot, "end_slot" => batch.end_slot, "id" => batch.id, "peer" => format!("{:?}", batch.current_peer), "head_root"=> format!("{}", batch.head_root));
// send the batch
self.send_batch(network, batch);
}
}
/// Requests the provided batch from the provided peer.
fn send_batch(&mut self, network: &mut SyncNetworkContext, batch: Batch<T::EthSpec>) {
let request = batch.to_blocks_by_range_request();
if let Ok(request_id) = network.blocks_by_range_request(batch.current_peer.clone(), request)
@ -463,6 +498,8 @@ impl<T: BeaconChainTypes> SyncingChain<T> {
}
}
/// Returns the next required batch from the chain if it exists. If there are no more batches
/// required, `None` is returned.
fn get_next_batch(&mut self, peer_id: PeerId) -> Option<Batch<T::EthSpec>> {
let batch_start_slot =
self.start_slot + self.to_be_downloaded_id.saturating_sub(1) * BLOCKS_PER_BATCH;
@ -493,9 +530,12 @@ impl<T: BeaconChainTypes> SyncingChain<T> {
))
}
// Checks if the request_id is associated with this chain. If so, attempts to re-request the
// batch. If the batch has exceeded the number of retries, returns Some(true), indicating
// the chain should be dropped.
/// An RPC error has occurred.
///
/// Checks if the request_id is associated with this chain. If so, attempts to re-request the
/// batch. If the batch has exceeded the number of retries, returns
/// Some(`ProcessingResult::RemoveChain)`. Returns `None` if the request isn't related to
/// this chain.
pub fn inject_error(
&mut self,
network: &mut SyncNetworkContext,
@ -512,6 +552,11 @@ impl<T: BeaconChainTypes> SyncingChain<T> {
}
}
/// A batch has failed.
///
/// Attempts to re-request from another peer in the peer pool (if possible) and returns
/// `ProcessingResult::RemoveChain` if the number of retries on the batch exceeds
/// `MAX_BATCH_RETRIES`.
pub fn failed_batch(
&mut self,
network: &mut SyncNetworkContext,
@ -542,7 +587,6 @@ impl<T: BeaconChainTypes> SyncingChain<T> {
fn process_batch<T: BeaconChainTypes>(
chain: Weak<BeaconChain<T>>,
batch: &Batch<T::EthSpec>,
successes: &mut usize,
log: &Logger,
) -> Result<(), String> {
for block in &batch.downloaded_blocks {
@ -558,8 +602,6 @@ fn process_batch<T: BeaconChainTypes>(
"slot" => block.slot,
"block_root" => format!("{}", block_root),
);
*successes += 1
}
BlockProcessingOutcome::ParentUnknown { parent } => {
// blocks should be sequential and all parents should exist

204
beacon_node/network/src/sync/range_sync/chain_collection.rs
View File

@ -1,3 +1,8 @@
//! This provides the logic for the finalized and head chains.
//!
//! Each chain type is stored in it's own vector. A variety of helper functions are given along
//! with this struct to to simplify the logic of the other layers of sync.
use super::chain::{ChainSyncingState, ProcessingResult, SyncingChain};
use crate::message_processor::PeerSyncInfo;
use crate::sync::network_context::SyncNetworkContext;
@ -8,32 +13,47 @@ use std::sync::Weak;
use types::EthSpec;
use types::{Hash256, Slot};
/// The state of the long range/batch sync.
pub enum SyncState {
/// A finalized chain is being synced.
Finalized,
/// There are no finalized chains and we are syncing one more head chains.
Head,
/// There are no head or finalized chains and no long range sync is in progress.
Idle,
}
/// A collection of finalized and head chains currently being processed.
pub struct ChainCollection<T: BeaconChainTypes> {
/// The beacon chain for processing.
beacon_chain: Weak<BeaconChain<T>>,
/// The set of finalized chains being synced.
finalized_chains: Vec<SyncingChain<T>>,
/// The set of head chains being synced.
head_chains: Vec<SyncingChain<T>>,
/// The current sync state of the process.
sync_state: SyncState,
}
impl<T: BeaconChainTypes> ChainCollection<T> {
pub fn new() -> Self {
pub fn new(beacon_chain: Weak<BeaconChain<T>>) -> Self {
ChainCollection {
sync_state: SyncState::Idle,
finalized_chains: Vec::new(),
head_chains: Vec::new(),
beacon_chain,
}
}
/// The current syncing state.
pub fn sync_state(&self) -> &SyncState {
&self.sync_state
}
// if a finalized chain just completed, we assume we waiting for head syncing, unless a fully
// sync peer joins.
/// A fully synced peer has joined.
///
/// We could be awaiting a head sync. If we are in the head syncing state, without any head
/// chains, then update the state to idle.
pub fn fully_synced_peer_found(&mut self) {
if let SyncState::Head = self.sync_state {
if self.head_chains.is_empty() {
@ -42,47 +62,15 @@ impl<T: BeaconChainTypes> ChainCollection<T> {
}
}
// after a finalized chain completes, the state should be waiting for a head chain
/// After a finalized chain completes this function is called. It ensures the state is set to
/// `SyncState::Head` indicating we are awaiting new peers to connect before we can consider
/// the state as idle.
pub fn set_head_sync(&mut self) {
if let SyncState::Idle = self.sync_state {
self.sync_state = SyncState::Head;
}
}
fn finalized_syncing_index(&self) -> Option<usize> {
self.finalized_chains
.iter()
.enumerate()
.find_map(|(index, chain)| {
if chain.state == ChainSyncingState::Syncing {
Some(index)
} else {
None
}
})
}
pub fn purge_finalized(&mut self, local_finalized_slot: Slot) {
self.finalized_chains
.retain(|chain| chain.target_head_slot > local_finalized_slot);
}
pub fn purge_head(&mut self, head_slot: Slot) {
self.head_chains
.retain(|chain| chain.target_head_slot > head_slot);
}
fn get_chain<'a>(
chain: &'a mut [SyncingChain<T>],
target_head_root: Hash256,
target_head_slot: Slot,
) -> Option<&'a mut SyncingChain<T>> {
chain.iter_mut().find(|iter_chain| {
iter_chain.target_head_root == target_head_root
&& iter_chain.target_head_slot == target_head_slot
})
}
/// Finds any finalized chain if it exists.
pub fn get_finalized_mut(
&mut self,
@ -109,35 +97,23 @@ impl<T: BeaconChainTypes> ChainCollection<T> {
)
}
/// Checks if a new finalized state should become the syncing chain. Updates the state of the
/// collection.
pub fn update_finalized(
&mut self,
beacon_chain: Weak<BeaconChain<T>>,
network: &mut SyncNetworkContext,
log: &slog::Logger,
) {
let local_info = match beacon_chain.upgrade() {
Some(chain) => PeerSyncInfo::from(&chain),
/// Updates the state of the chain collection.
///
/// This removes any out-dated chains, swaps to any higher priority finalized chains and
/// updates the state of the collection.
pub fn update_finalized(&mut self, network: &mut SyncNetworkContext, log: &slog::Logger) {
let local_slot = match self.beacon_chain.upgrade() {
Some(chain) => PeerSyncInfo::from(&chain)
.finalized_epoch
.start_slot(T::EthSpec::slots_per_epoch()),
None => {
warn!(log, "Beacon chain dropped. Chains not updated");
return;
}
};
let local_slot = local_info
.finalized_epoch
.start_slot(T::EthSpec::slots_per_epoch());
// Remove any outdated finalized chains
self.purge_finalized(local_slot);
self.finalized_chains
.retain(|chain| !chain.peer_pool.is_empty());
// Remove any outdated head chains
self.purge_head(local_info.head_slot);
self.finalized_chains
.retain(|chain| !chain.peer_pool.is_empty());
self.purge_outdated_chains(network);
// Check if any chains become the new syncing chain
if let Some(index) = self.finalized_syncing_index() {
@ -172,7 +148,7 @@ impl<T: BeaconChainTypes> ChainCollection<T> {
chain.start_syncing(network, local_slot, log);
self.sync_state = SyncState::Finalized;
} else {
// There are no finalized chains, update the state
// There are no finalized chains, update the state.
if self.head_chains.is_empty() {
self.sync_state = SyncState::Idle;
} else {
@ -181,7 +157,7 @@ impl<T: BeaconChainTypes> ChainCollection<T> {
}
}
/// Add a new finalized chain to the collection
/// Add a new finalized chain to the collection.
pub fn new_finalized_chain(
&mut self,
local_finalized_slot: Slot,
@ -197,7 +173,7 @@ impl<T: BeaconChainTypes> ChainCollection<T> {
));
}
/// Add a new finalized chain to the collection
/// Add a new finalized chain to the collection and starts syncing it.
pub fn new_head_chain(
&mut self,
network: &mut SyncNetworkContext,
@ -221,10 +197,14 @@ impl<T: BeaconChainTypes> ChainCollection<T> {
self.head_chains.push(new_head_chain);
}
/// Returns if `true` if any finalized chains exist, `false` otherwise.
pub fn is_finalizing_sync(&self) -> bool {
!self.finalized_chains.is_empty()
}
/// Given a chain iterator, runs a given function on each chain until the function returns
/// `Some`. This allows the `RangeSync` struct to loop over chains and optionally remove the
/// chain from the collection if the function results in completing the chain.
fn request_function<'a, F, I>(chain: I, mut func: F) -> Option<(usize, ProcessingResult)>
where
I: Iterator<Item = &'a mut SyncingChain<T>>,
@ -235,6 +215,7 @@ impl<T: BeaconChainTypes> ChainCollection<T> {
.find_map(|(index, chain)| Some((index, func(chain)?)))
}
/// Runs a function on all finalized chains.
pub fn finalized_request<F>(&mut self, func: F) -> Option<(usize, ProcessingResult)>
where
F: FnMut(&mut SyncingChain<T>) -> Option<ProcessingResult>,
@ -242,6 +223,7 @@ impl<T: BeaconChainTypes> ChainCollection<T> {
ChainCollection::request_function(self.finalized_chains.iter_mut(), func)
}
/// Runs a function on all head chains.
pub fn head_request<F>(&mut self, func: F) -> Option<(usize, ProcessingResult)>
where
F: FnMut(&mut SyncingChain<T>) -> Option<ProcessingResult>,
@ -249,7 +231,7 @@ impl<T: BeaconChainTypes> ChainCollection<T> {
ChainCollection::request_function(self.head_chains.iter_mut(), func)
}
#[allow(dead_code)]
/// Runs a function on all finalized and head chains.
pub fn head_finalized_request<F>(&mut self, func: F) -> Option<(usize, ProcessingResult)>
where
F: FnMut(&mut SyncingChain<T>) -> Option<ProcessingResult>,
@ -262,10 +244,53 @@ impl<T: BeaconChainTypes> ChainCollection<T> {
)
}
/// Removes any outdated finalized or head chains.
///
/// This removes chains with no peers, or chains whose start block slot is less than our current
/// finalized block slot.
pub fn purge_outdated_chains(&mut self, network: &mut SyncNetworkContext) {
// Remove any chains that have no peers
self.finalized_chains
.retain(|chain| !chain.peer_pool.is_empty());
self.head_chains.retain(|chain| !chain.peer_pool.is_empty());
let local_info = match self.beacon_chain.upgrade() {
Some(chain) => PeerSyncInfo::from(&chain),
None => {
return;
}
};
let local_finalized_slot = local_info
.finalized_epoch
.start_slot(T::EthSpec::slots_per_epoch());
// Remove chains that are out-dated and re-status their peers
let beacon_chain_clone = self.beacon_chain.clone();
self.finalized_chains.retain(|chain| {
if chain.target_head_slot <= local_finalized_slot {
chain.status_peers(beacon_chain_clone.clone(), network);
false
} else {
true
}
});
self.head_chains.retain(|chain| {
if chain.target_head_slot <= local_finalized_slot {
chain.status_peers(beacon_chain_clone.clone(), network);
false
} else {
true
}
});
}
/// Removes and returns a finalized chain from the collection.
pub fn remove_finalized_chain(&mut self, index: usize) -> SyncingChain<T> {
self.finalized_chains.swap_remove(index)
}
/// Removes and returns a head chain from the collection.
pub fn remove_head_chain(&mut self, index: usize) -> SyncingChain<T> {
self.head_chains.swap_remove(index)
}
@ -273,12 +298,55 @@ impl<T: BeaconChainTypes> ChainCollection<T> {
/// Removes a chain from either finalized or head chains based on the index. Using a request
/// iterates of finalized chains before head chains. Thus an index that is greater than the
/// finalized chain length, indicates a head chain.
pub fn remove_chain(&mut self, index: usize) -> SyncingChain<T> {
if index >= self.finalized_chains.len() {
///
/// This will re-status the chains peers on removal. The index must exist.
pub fn remove_chain(
&mut self,
network: &mut SyncNetworkContext,
index: usize,
log: &slog::Logger,
) {
let chain = if index >= self.finalized_chains.len() {
let index = index - self.finalized_chains.len();
self.head_chains.swap_remove(index)
let chain = self.head_chains.swap_remove(index);
chain.status_peers(self.beacon_chain.clone(), network);
chain
} else {
self.finalized_chains.swap_remove(index)
let chain = self.finalized_chains.swap_remove(index);
chain.status_peers(self.beacon_chain.clone(), network);
chain
};
debug!(log, "Chain was removed"; "start_slot" => chain.start_slot.as_u64(), "end_slot" => chain.target_head_slot.as_u64());
// update the state
self.update_finalized(network, log);
}
/// Returns the index of finalized chain that is currently syncing. Returns `None` if no
/// finalized chain is currently syncing.
fn finalized_syncing_index(&self) -> Option<usize> {
self.finalized_chains
.iter()
.enumerate()
.find_map(|(index, chain)| {
if chain.state == ChainSyncingState::Syncing {
Some(index)
} else {
None
}
})
}
/// Returns a chain given the target head root and slot.
fn get_chain<'a>(
chain: &'a mut [SyncingChain<T>],
target_head_root: Hash256,
target_head_slot: Slot,
) -> Option<&'a mut SyncingChain<T>> {
chain.iter_mut().find(|iter_chain| {
iter_chain.target_head_root == target_head_root
&& iter_chain.target_head_slot == target_head_slot
})
}
}

138
beacon_node/network/src/sync/range_sync/range.rs
View File

@ -1,3 +1,44 @@
//! This contains the logic for the long range (batch) sync strategy.
//!
//! The general premise is to group peers by their self-proclaimed finalized blocks and head
//! blocks. Once grouped, the peers become sources to download a specific `Chain`. A `Chain` is a
//! collection of blocks that terminates at the specified target head.
//!
//! This sync strategy can be separated into two distinct forms:
//! - Finalized Chain Sync
//! - Head Chain Sync
//!
//! ## Finalized chain sync
//!
//! This occurs when a peer connects that claims to have a finalized head slot that is greater
//! than our own. In this case, we form a chain from our last finalized slot, to their claimed
//! finalized slot. Any peer that also claims to have this last finalized slot is added to a pool
//! of peers from which batches of blocks may be downloaded. Blocks are downloaded until
//! the finalized slot of the chain is reached. Once reached, all peers within the pool are sent a
//! STATUS message to potentially start a head chain sync, or check if further finalized chains
//! need to be downloaded.
//!
//! A few interesting notes about finalized chain syncing:
//! - Only one finalized chain can sync at a time.
//! - The finalized chain with the largest peer pool takes priority.
//! - As one finalized chain completes, others are checked to see if we they can be continued,
//! otherwise they are removed.
//!
//! ## Head Chain Sync
//!
//! If a peer joins and there is no active finalized chains being synced, and it's head is
//! beyond our `SLOT_IMPORT_TOLERANCE` a chain is formed starting from this peers finalized slot
//! (this has been necessarily downloaded by our node, otherwise we would start a finalized chain
//! sync) to this peers head slot. Any other peers that match this head slot and head root, are
//! added to this chain's peer pool, which will be downloaded in parallel.
//!
//! Unlike finalized chains, head chains can be synced in parallel.
//!
//! ## Batch Syncing
//!
//! Each chain is downloaded in batches of blocks. The batched blocks are processed sequentially
//! and further batches are requested as current blocks are being processed.
use super::chain::ProcessingResult;
use super::chain_collection::{ChainCollection, SyncState};
use crate::message_processor::PeerSyncInfo;
@ -10,38 +51,50 @@ use std::collections::HashSet;
use std::sync::Weak;
use types::{BeaconBlock, EthSpec};
//TODO: The code becomes cleaner if finalized_chains and head_chains were merged into a single
// object. This will prevent code duplication. Rather than keeping the current syncing
// finalized chain in index 0, it should be stored in this object under an option. Then lookups can
// occur over the single object containing both finalized and head chains, which would then
// behave similarly.
/// The primary object dealing with long range/batch syncing. This contains all the active and
/// non-active chains that need to be processed before the syncing is considered complete. This
/// holds the current state of the long range sync.
pub struct RangeSync<T: BeaconChainTypes> {
/// The beacon chain for processing
/// The beacon chain for processing.
beacon_chain: Weak<BeaconChain<T>>,
/// A collection of chains that need to be downloaded. This stores any head or finalized chains
/// that need to be downloaded.
chains: ChainCollection<T>,
/// Known peers to the RangeSync, that need to be re-status'd once finalized chains are
/// completed.
/// Peers that join whilst a finalized chain is being download, sit in this set. Once the
/// finalized chain(s) complete, these peer's get STATUS'ed to update their head slot before
/// the head chains are formed and downloaded.
awaiting_head_peers: HashSet<PeerId>,
/// The syncing logger.
log: slog::Logger,
}
impl<T: BeaconChainTypes> RangeSync<T> {
pub fn new(beacon_chain: Weak<BeaconChain<T>>, log: slog::Logger) -> Self {
RangeSync {
beacon_chain,
chains: ChainCollection::new(),
beacon_chain: beacon_chain.clone(),
chains: ChainCollection::new(beacon_chain),
awaiting_head_peers: HashSet::new(),
log,
}
}
// Notify the collection that a fully synced peer was found. This allows updating the state
// if we were awaiting a head state.
/// The `chains` collection stores the current state of syncing. Once a finalized chain
/// completes, it's state is pre-emptively set to `SyncState::Head`. This ensures that
/// during the transition period of finalized to head, the sync manager doesn't start
/// requesting blocks from gossipsub.
///
/// On re-status, a peer that has no head to download indicates that this state can be set to
/// idle as there are in fact no head chains to download. This function notifies the chain
/// collection that the state can safely be set to idle.
pub fn fully_synced_peer_found(&mut self) {
self.chains.fully_synced_peer_found()
}
/// A useful peer has been added. The SyncManager has identified this peer as needing either
/// a finalized or head chain sync. This processes the peer and starts/resumes any chain that
/// may need to be synced as a result. A new peer, may increase the peer pool of a finalized
/// chain, this may result in a different finalized chain from syncing as finalized chains are
/// prioritised by peer-pool size.
pub fn add_peer(
&mut self,
network: &mut SyncNetworkContext,
@ -70,13 +123,12 @@ impl<T: BeaconChainTypes> RangeSync<T> {
.finalized_epoch
.start_slot(T::EthSpec::slots_per_epoch());
// firstly, remove any out-of-date chains
self.chains.purge_finalized(local_finalized_slot);
self.chains.purge_head(local_info.head_slot);
// remove peer from any chains
self.remove_peer(network, &peer_id);
// remove any out-of-date chains
self.chains.purge_outdated_chains(network);
if remote_finalized_slot > local_info.head_slot {
debug!(self.log, "Finalization sync peer joined"; "peer_id" => format!("{:?}", peer_id));
// Finalized chain search
@ -97,8 +149,7 @@ impl<T: BeaconChainTypes> RangeSync<T> {
chain.peer_added(network, peer_id, &self.log);
// check if the new peer's addition will favour a new syncing chain.
self.chains
.update_finalized(self.beacon_chain.clone(), network, &self.log);
self.chains.update_finalized(network, &self.log);
} else {
// there is no finalized chain that matches this peer's last finalized target
// create a new finalized chain
@ -110,8 +161,7 @@ impl<T: BeaconChainTypes> RangeSync<T> {
remote_finalized_slot,
peer_id,
);
self.chains
.update_finalized(self.beacon_chain.clone(), network, &self.log);
self.chains.update_finalized(network, &self.log);
}
} else {
if self.chains.is_finalizing_sync() {
@ -145,11 +195,14 @@ impl<T: BeaconChainTypes> RangeSync<T> {
&self.log,
);
}
self.chains
.update_finalized(self.beacon_chain.clone(), network, &self.log);
self.chains.update_finalized(network, &self.log);
}
}
/// A `BlocksByRange` response has been received from the network.
///
/// This function finds the chain that made this request. Once found, processes the result.
/// This request could complete a chain or simply add to its progress.
pub fn blocks_by_range_response(
&mut self,
network: &mut SyncNetworkContext,
@ -162,7 +215,6 @@ impl<T: BeaconChainTypes> RangeSync<T> {
// `connected_peers` number of head chains, which should be relatively small and this
// lookup should not be very expensive. However, we could add an extra index that maps the
// request id to index of the vector to avoid O(N) searches and O(N) hash lookups.
// Note to future sync-rewriter/profiler: Michael approves of these O(N) searches.
let chain_ref = &self.beacon_chain;
let log_ref = &self.log;
@ -177,8 +229,7 @@ impl<T: BeaconChainTypes> RangeSync<T> {
chain.status_peers(self.beacon_chain.clone(), network);
// update the state of the collection
self.chains
.update_finalized(self.beacon_chain.clone(), network, &self.log);
self.chains.update_finalized(network, &self.log);
// set the state to a head sync, to inform the manager that we are awaiting a
// head chain.
@ -207,8 +258,7 @@ impl<T: BeaconChainTypes> RangeSync<T> {
chain.status_peers(self.beacon_chain.clone(), network);
// update the state of the collection
self.chains
.update_finalized(self.beacon_chain.clone(), network, &self.log);
self.chains.update_finalized(network, &self.log);
}
Some(_) => {}
None => {
@ -221,6 +271,7 @@ impl<T: BeaconChainTypes> RangeSync<T> {
}
}
/// Public method to indicate the current state of the long range sync.
pub fn is_syncing(&self) -> bool {
match self.chains.sync_state() {
SyncState::Finalized => true,
@ -229,6 +280,8 @@ impl<T: BeaconChainTypes> RangeSync<T> {
}
}
/// A peer has disconnected. This removes the peer from any ongoing chains and mappings. A
/// disconnected peer could remove a chain
pub fn peer_disconnect(&mut self, network: &mut SyncNetworkContext, peer_id: &PeerId) {
// if the peer is in the awaiting head mapping, remove it
self.awaiting_head_peers.remove(&peer_id);
@ -237,8 +290,7 @@ impl<T: BeaconChainTypes> RangeSync<T> {
self.remove_peer(network, peer_id);
// update the state of the collection
self.chains
.update_finalized(self.beacon_chain.clone(), network, &self.log);
self.chains.update_finalized(network, &self.log);
}
/// When a peer gets removed, both the head and finalized chains need to be searched to check which pool the peer is in. The chain may also have a batch or batches awaiting
@ -271,22 +323,17 @@ impl<T: BeaconChainTypes> RangeSync<T> {
}) {
Some((index, ProcessingResult::RemoveChain)) => {
// the chain needed to be removed
let chain = self.chains.remove_chain(index);
debug!(self.log, "Chain was removed due batch failing"; "start_slot" => chain.start_slot.as_u64(), "end_slot" => chain.target_head_slot.as_u64());
// the chain has been removed, re-status it's peers
chain.status_peers(self.beacon_chain.clone(), network);
// update the state of the collection
self.chains
.update_finalized(self.beacon_chain.clone(), network, &self.log);
debug!(self.log, "Chain being removed due to failed batch");
self.chains.remove_chain(network, index, &self.log);
}
_ => {} // chain didn't need to be removed, ignore
}
// remove any chains that no longer have any peers
}
// An RPC Error occurred, if it's a pending batch, re-request it if possible, if there have
// been too many attempts, remove the chain
/// An RPC error has occurred.
///
/// Check to see if the request corresponds to a pending batch. If so, re-request it if possible, if there have
/// been too many failed attempts for the batch, remove the chain.
pub fn inject_error(
&mut self,
network: &mut SyncNetworkContext,
@ -300,13 +347,8 @@ impl<T: BeaconChainTypes> RangeSync<T> {
}) {
Some((_, ProcessingResult::KeepChain)) => {} // error handled chain persists
Some((index, ProcessingResult::RemoveChain)) => {
let chain = self.chains.remove_chain(index);
debug!(self.log, "Chain was removed due to error"; "start_slot" => chain.start_slot.as_u64(), "end_slot" => chain.target_head_slot.as_u64());
// the chain has failed, re-status it's peers
chain.status_peers(self.beacon_chain.clone(), network);
// update the state of the collection
self.chains
.update_finalized(self.beacon_chain.clone(), network, &self.log);
debug!(self.log, "Chain being removed due to RPC error");
self.chains.remove_chain(network, index, &self.log)
}
None => {} // request wasn't in the finalized chains, check the head chains
}