Zebra/zebra-state/src/service/memory_state.rs

875 lines
29 KiB
Rust

//! Non-finalized chain state management as defined by [RFC0005]
//!
//! [RFC0005]: https://zebra.zfnd.org/dev/rfcs/0005-state-updates.html
#![allow(dead_code)]
use std::{
cmp::Ordering,
collections::{BTreeMap, BTreeSet, HashMap, HashSet},
mem,
ops::Deref,
sync::Arc,
};
use tracing::{debug_span, instrument, trace};
use zebra_chain::{
block::{self, Block},
primitives::Groth16Proof,
sapling, sprout,
transaction::{self, Transaction},
transparent,
work::difficulty::PartialCumulativeWork,
};
use crate::request::HashOrHeight;
use crate::service::QueuedBlock;
#[derive(Default, Clone)]
struct Chain {
blocks: BTreeMap<block::Height, Arc<Block>>,
height_by_hash: HashMap<block::Hash, block::Height>,
tx_by_hash: HashMap<transaction::Hash, (block::Height, usize)>,
created_utxos: HashMap<transparent::OutPoint, transparent::Output>,
spent_utxos: HashSet<transparent::OutPoint>,
sprout_anchors: HashSet<sprout::tree::Root>,
sapling_anchors: HashSet<sapling::tree::Root>,
sprout_nullifiers: HashSet<sprout::Nullifier>,
sapling_nullifiers: HashSet<sapling::Nullifier>,
partial_cumulative_work: PartialCumulativeWork,
}
impl Chain {
/// Push a contextually valid non-finalized block into a chain as the new tip.
#[instrument(skip(self), fields(%block))]
pub fn push(&mut self, block: Arc<Block>) {
let block_height = block
.coinbase_height()
.expect("valid non-finalized blocks have a coinbase height");
trace!(?block_height, "Pushing new block into chain state");
// update cumulative data members
self.update_chain_state_with(&block);
self.blocks.insert(block_height, block);
}
/// Remove the lowest height block of the non-finalized portion of a chain.
#[instrument(skip(self))]
pub fn pop_root(&mut self) -> Arc<Block> {
let block_height = self.lowest_height();
// remove the lowest height block from self.blocks
let block = self
.blocks
.remove(&block_height)
.expect("only called while blocks is populated");
// update cumulative data members
self.revert_chain_state_with(&block);
// return the block
block
}
fn lowest_height(&self) -> block::Height {
self.blocks
.keys()
.next()
.cloned()
.expect("only called while blocks is populated")
}
/// Fork a chain at the block with the given hash, if it is part of this
/// chain.
pub fn fork(&self, fork_tip: block::Hash) -> Option<Self> {
if !self.height_by_hash.contains_key(&fork_tip) {
return None;
}
let mut forked = self.clone();
while forked.non_finalized_tip_hash() != fork_tip {
forked.pop_tip();
}
Some(forked)
}
fn non_finalized_tip_hash(&self) -> block::Hash {
self.blocks
.values()
.next_back()
.expect("only called while blocks is populated")
.hash()
}
/// Remove the highest height block of the non-finalized portion of a chain.
fn pop_tip(&mut self) {
let block_height = self.non_finalized_tip_height();
let block = self
.blocks
.remove(&block_height)
.expect("only called while blocks is populated");
assert!(
!self.blocks.is_empty(),
"Non-finalized chains must have at least one block to be valid"
);
self.revert_chain_state_with(&block);
}
fn non_finalized_tip_height(&self) -> block::Height {
*self
.blocks
.keys()
.next_back()
.expect("only called while blocks is populated")
}
}
/// Helper trait to organize inverse operations done on the `Chain` type. Used to
/// overload the `update_chain_state_with` and `revert_chain_state_with` methods
/// based on the type of the argument.
///
/// This trait was motivated by the length of the `push` and `pop_root` functions
/// and fear that it would be easy to introduce bugs when updating them unless
/// the code was reorganized to keep related operations adjacent to eachother.
trait UpdateWith<T> {
/// Update `Chain` cumulative data members to add data that are derived from
/// `T`
fn update_chain_state_with(&mut self, _: &T);
/// Update `Chain` cumulative data members to remove data that are derived
/// from `T`
fn revert_chain_state_with(&mut self, _: &T);
}
impl UpdateWith<Arc<Block>> for Chain {
fn update_chain_state_with(&mut self, block: &Arc<Block>) {
let block_height = block
.coinbase_height()
.expect("valid non-finalized blocks have a coinbase height");
let block_hash = block.hash();
// add hash to height_by_hash
let prior_height = self.height_by_hash.insert(block_hash, block_height);
assert!(
prior_height.is_none(),
"block heights must be unique within a single chain"
);
// add work to partial cumulative work
let block_work = block
.header
.difficulty_threshold
.to_work()
.expect("work has already been validated");
self.partial_cumulative_work += block_work;
// for each transaction in block
for (transaction_index, transaction) in block.transactions.iter().enumerate() {
let (inputs, outputs, shielded_data, joinsplit_data) = match transaction.deref() {
transaction::Transaction::V4 {
inputs,
outputs,
shielded_data,
joinsplit_data,
..
} => (inputs, outputs, shielded_data, joinsplit_data),
_ => unreachable!(
"older transaction versions only exist in finalized blocks pre sapling",
),
};
// add key `transaction.hash` and value `(height, tx_index)` to `tx_by_hash`
let transaction_hash = transaction.hash();
let prior_pair = self
.tx_by_hash
.insert(transaction_hash, (block_height, transaction_index));
assert!(
prior_pair.is_none(),
"transactions must be unique within a single chain"
);
// add the utxos this produced
self.update_chain_state_with(&(transaction_hash, outputs));
// add the utxos this consumed
self.update_chain_state_with(inputs);
// add sprout anchor and nullifiers
self.update_chain_state_with(joinsplit_data);
// add sapling anchor and nullifier
self.update_chain_state_with(shielded_data);
}
}
#[instrument(skip(self), fields(%block))]
fn revert_chain_state_with(&mut self, block: &Arc<Block>) {
let block_hash = block.hash();
// remove the blocks hash from `height_by_hash`
assert!(
self.height_by_hash.remove(&block_hash).is_some(),
"hash must be present if block was"
);
// remove work from partial_cumulative_work
let block_work = block
.header
.difficulty_threshold
.to_work()
.expect("work has already been validated");
self.partial_cumulative_work -= block_work;
// for each transaction in block
for transaction in &block.transactions {
let (inputs, outputs, shielded_data, joinsplit_data) = match transaction.deref() {
transaction::Transaction::V4 {
inputs,
outputs,
shielded_data,
joinsplit_data,
..
} => (inputs, outputs, shielded_data, joinsplit_data),
_ => unreachable!(
"older transaction versions only exist in finalized blocks pre sapling",
),
};
// remove `transaction.hash` from `tx_by_hash`
let transaction_hash = transaction.hash();
assert!(
self.tx_by_hash.remove(&transaction_hash).is_some(),
"transactions must be present if block was"
);
// remove the utxos this produced
self.revert_chain_state_with(&(transaction_hash, outputs));
// remove the utxos this consumed
self.revert_chain_state_with(inputs);
// remove sprout anchor and nullifiers
self.revert_chain_state_with(joinsplit_data);
// remove sapling anchor and nullfier
self.revert_chain_state_with(shielded_data);
}
}
}
impl UpdateWith<(transaction::Hash, &Vec<transparent::Output>)> for Chain {
fn update_chain_state_with(
&mut self,
(transaction_hash, outputs): &(transaction::Hash, &Vec<transparent::Output>),
) {
for (utxo_index, output) in outputs.iter().enumerate() {
self.created_utxos.insert(
transparent::OutPoint {
hash: *transaction_hash,
index: utxo_index as u32,
},
output.clone(),
);
}
}
fn revert_chain_state_with(
&mut self,
(transaction_hash, outputs): &(transaction::Hash, &Vec<transparent::Output>),
) {
for (utxo_index, _) in outputs.iter().enumerate() {
assert!(
self.created_utxos
.remove(&transparent::OutPoint {
hash: *transaction_hash,
index: utxo_index as u32,
})
.is_some(),
"created_utxos must be present if block was"
);
}
}
}
impl UpdateWith<Vec<transparent::Input>> for Chain {
fn update_chain_state_with(&mut self, inputs: &Vec<transparent::Input>) {
for consumed_utxo in inputs {
match consumed_utxo {
transparent::Input::PrevOut { outpoint, .. } => {
self.spent_utxos.insert(*outpoint);
}
transparent::Input::Coinbase { .. } => {}
}
}
}
fn revert_chain_state_with(&mut self, inputs: &Vec<transparent::Input>) {
for consumed_utxo in inputs {
match consumed_utxo {
transparent::Input::PrevOut { outpoint, .. } => {
assert!(
self.spent_utxos.remove(outpoint),
"spent_utxos must be present if block was"
);
}
transparent::Input::Coinbase { .. } => {}
}
}
}
}
impl UpdateWith<Option<transaction::JoinSplitData<Groth16Proof>>> for Chain {
#[instrument(skip(self, joinsplit_data))]
fn update_chain_state_with(
&mut self,
joinsplit_data: &Option<transaction::JoinSplitData<Groth16Proof>>,
) {
if let Some(joinsplit_data) = joinsplit_data {
for sprout::JoinSplit { nullifiers, .. } in joinsplit_data.joinsplits() {
let span = debug_span!("revert_chain_state_with", ?nullifiers);
let _entered = span.enter();
trace!("Adding sprout nullifiers.");
self.sprout_nullifiers.insert(nullifiers[0]);
self.sprout_nullifiers.insert(nullifiers[1]);
}
}
}
#[instrument(skip(self, joinsplit_data))]
fn revert_chain_state_with(
&mut self,
joinsplit_data: &Option<transaction::JoinSplitData<Groth16Proof>>,
) {
if let Some(joinsplit_data) = joinsplit_data {
for sprout::JoinSplit { nullifiers, .. } in joinsplit_data.joinsplits() {
let span = debug_span!("revert_chain_state_with", ?nullifiers);
let _entered = span.enter();
trace!("Removing sprout nullifiers.");
assert!(
self.sprout_nullifiers.remove(&nullifiers[0]),
"nullifiers must be present if block was"
);
assert!(
self.sprout_nullifiers.remove(&nullifiers[1]),
"nullifiers must be present if block was"
);
}
}
}
}
impl UpdateWith<Option<transaction::ShieldedData>> for Chain {
fn update_chain_state_with(&mut self, shielded_data: &Option<transaction::ShieldedData>) {
if let Some(shielded_data) = shielded_data {
for sapling::Spend { nullifier, .. } in shielded_data.spends() {
self.sapling_nullifiers.insert(*nullifier);
}
}
}
fn revert_chain_state_with(&mut self, shielded_data: &Option<transaction::ShieldedData>) {
if let Some(shielded_data) = shielded_data {
for sapling::Spend { nullifier, .. } in shielded_data.spends() {
assert!(
self.sapling_nullifiers.remove(nullifier),
"nullifier must be present if block was"
);
}
}
}
}
impl PartialEq for Chain {
fn eq(&self, other: &Self) -> bool {
self.partial_cmp(other) == Some(Ordering::Equal)
}
}
impl Eq for Chain {}
impl PartialOrd for Chain {
fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
Some(self.cmp(other))
}
}
impl Ord for Chain {
fn cmp(&self, other: &Self) -> Ordering {
if self.partial_cumulative_work != other.partial_cumulative_work {
self.partial_cumulative_work
.cmp(&other.partial_cumulative_work)
} else {
let self_hash = self
.blocks
.values()
.last()
.expect("always at least 1 element")
.hash();
let other_hash = other
.blocks
.values()
.last()
.expect("always at least 1 element")
.hash();
// This comparison is a tie-breaker within the local node, so it does not need to
// be consistent with the ordering on `ExpandedDifficulty` and `block::Hash`.
match self_hash.0.cmp(&other_hash.0) {
Ordering::Equal => unreachable!("Chain tip block hashes are always unique"),
ordering => ordering,
}
}
}
}
/// The state of the chains in memory, incuding queued blocks.
#[derive(Default)]
pub struct NonFinalizedState {
/// Verified, non-finalized chains, in ascending order.
///
/// The best chain is `chain_set.last()` or `chain_set.iter().next_back()`.
chain_set: BTreeSet<Box<Chain>>,
}
impl NonFinalizedState {
/// Finalize the lowest height block in the non-finalized portion of the best
/// chain and update all side-chains to match.
pub fn finalize(&mut self) -> Arc<Block> {
let chains = mem::take(&mut self.chain_set);
let mut chains = chains.into_iter();
// extract best chain
let mut best_chain = chains.next_back().expect("there's at least one chain");
// extract the rest into side_chains so they can be mutated
let side_chains = chains;
// remove the lowest height block from the best_chain as finalized_block
let finalized_block = best_chain.pop_root();
// add best_chain back to `self.chain_set`
self.chain_set.insert(best_chain);
// for each remaining chain in side_chains
for mut chain in side_chains {
// remove the first block from `chain`
let chain_start = chain.pop_root();
// if block equals finalized_block
if chain_start == finalized_block {
// add the chain back to `self.chain_set`
self.chain_set.insert(chain);
} else {
// else discard `chain`
drop(chain);
}
}
// return the finalized block
finalized_block
}
/// Commit block to the non-finalize state.
pub fn commit_block(&mut self, block: Arc<Block>) {
let parent_hash = block.header.previous_block_hash;
let mut parent_chain = self
.take_chain_if(|chain| chain.non_finalized_tip_hash() == parent_hash)
.or_else(|| {
self.chain_set
.iter()
.find_map(|chain| chain.fork(parent_hash))
.map(Box::new)
})
.expect("commit_block is only called with blocks that are ready to be commited");
parent_chain.push(block);
self.chain_set.insert(parent_chain);
}
/// Commit block to the non-finalized state as a new chain where its parent
/// is the finalized tip.
pub fn commit_new_chain(&mut self, block: Arc<Block>) {
let mut chain = Chain::default();
chain.push(block);
self.chain_set.insert(Box::new(chain));
}
/// Returns the length of the non-finalized portion of the current best chain.
pub fn best_chain_len(&self) -> block::Height {
block::Height(
self.best_chain()
.expect("only called after inserting a block")
.blocks
.len() as u32,
)
}
/// Returns `true` if `hash` is contained in the non-finalized portion of any
/// known chain.
pub fn any_chain_contains(&self, hash: &block::Hash) -> bool {
self.chain_set
.iter()
.any(|chain| chain.height_by_hash.contains_key(hash))
}
/// Remove and return the first chain satisfying the given predicate.
fn take_chain_if<F>(&mut self, predicate: F) -> Option<Box<Chain>>
where
F: Fn(&Chain) -> bool,
{
let chains = mem::take(&mut self.chain_set);
let mut best_chain_iter = chains.into_iter().rev();
while let Some(next_best_chain) = best_chain_iter.next() {
// if the predicate says we should remove it
if predicate(&next_best_chain) {
// add back the remaining chains
for remaining_chain in best_chain_iter {
self.chain_set.insert(remaining_chain);
}
// and return the chain
return Some(next_best_chain);
} else {
// add the chain back to the set and continue
self.chain_set.insert(next_best_chain);
}
}
None
}
/// Returns the `transparent::Output` pointed to by the given
/// `transparent::OutPoint` if it is present.
pub fn utxo(&self, outpoint: &transparent::OutPoint) -> Option<transparent::Output> {
for chain in self.chain_set.iter().rev() {
if let Some(output) = chain.created_utxos.get(outpoint) {
return Some(output.clone());
}
}
None
}
/// Returns the `block` at a given height or hash in the best chain.
pub fn block(&self, hash_or_height: HashOrHeight) -> Option<Arc<Block>> {
let best_chain = self.best_chain()?;
let height =
hash_or_height.height_or_else(|hash| best_chain.height_by_hash.get(&hash).cloned())?;
best_chain.blocks.get(&height).cloned()
}
/// Returns the hash for a given `block::Height` if it is present in the best chain.
pub fn hash(&self, height: block::Height) -> Option<block::Hash> {
self.block(height.into()).map(|block| block.hash())
}
/// Returns the tip of the best chain.
pub fn tip(&self) -> Option<(block::Height, block::Hash)> {
let best_chain = self.best_chain()?;
let height = best_chain.non_finalized_tip_height();
let hash = best_chain.non_finalized_tip_hash();
Some((height, hash))
}
/// Returns the depth of `hash` in the best chain.
pub fn height(&self, hash: block::Hash) -> Option<block::Height> {
let best_chain = self.best_chain()?;
let height = *best_chain.height_by_hash.get(&hash)?;
Some(height)
}
/// Returns the given transaction if it exists in the best chain.
pub fn transaction(&self, hash: transaction::Hash) -> Option<Arc<Transaction>> {
let best_chain = self.best_chain()?;
best_chain.tx_by_hash.get(&hash).map(|(height, index)| {
let block = &best_chain.blocks[height];
block.transactions[*index].clone()
})
}
/// Return the non-finalized portion of the current best chain
fn best_chain(&self) -> Option<&Chain> {
self.chain_set
.iter()
.next_back()
.map(|box_chain| box_chain.deref())
}
}
/// A queue of blocks, awaiting the arrival of parent blocks.
#[derive(Default)]
pub struct QueuedBlocks {
/// Blocks awaiting their parent blocks for contextual verification.
blocks: HashMap<block::Hash, QueuedBlock>,
/// Hashes from `queued_blocks`, indexed by parent hash.
by_parent: HashMap<block::Hash, HashSet<block::Hash>>,
/// Hashes from `queued_blocks`, indexed by block height.
by_height: BTreeMap<block::Height, HashSet<block::Hash>>,
}
impl QueuedBlocks {
/// Queue a block for eventual verification and commit.
///
/// # Panics
///
/// - if a block with the same `block::Hash` has already been queued.
pub fn queue(&mut self, new: QueuedBlock) {
let new_hash = new.block.hash();
let new_height = new
.block
.coinbase_height()
.expect("validated non-finalized blocks have a coinbase height");
let parent_hash = new.block.header.previous_block_hash;
let replaced = self.blocks.insert(new_hash, new);
assert!(replaced.is_none(), "hashes must be unique");
let inserted = self
.by_height
.entry(new_height)
.or_default()
.insert(new_hash);
assert!(inserted, "hashes must be unique");
let inserted = self
.by_parent
.entry(parent_hash)
.or_default()
.insert(new_hash);
assert!(inserted, "hashes must be unique");
tracing::trace!(num_blocks = %self.blocks.len(), %parent_hash, ?new_height, "Finished queueing a new block");
}
/// Dequeue and return all blocks that were waiting for the arrival of
/// `parent`.
#[instrument(skip(self))]
pub fn dequeue_children(&mut self, parent: block::Hash) -> Vec<QueuedBlock> {
let queued_children = self
.by_parent
.remove(&parent)
.unwrap_or_default()
.into_iter()
.map(|hash| {
self.blocks
.remove(&hash)
.expect("block is present if its hash is in by_parent")
})
.collect::<Vec<_>>();
for queued in &queued_children {
let height = queued.block.coinbase_height().unwrap();
self.by_height.remove(&height);
}
tracing::trace!(num_blocks = %self.blocks.len(), "Finished dequeuing blocks waiting for parent hash",);
queued_children
}
/// Remove all queued blocks whose height is less than or equal to the given
/// `finalized_tip_height`.
pub fn prune_by_height(&mut self, finalized_tip_height: block::Height) {
// split_off returns the values _greater than or equal to_ the key. What
// we need is the keys that are less than or equal to
// `finalized_tip_height`. To get this we have split at
// `finalized_tip_height + 1` and swap the removed portion of the list
// with the remainder.
let split_height = finalized_tip_height + 1;
let split_height =
split_height.expect("height after finalized tip won't exceed max height");
let mut by_height = self.by_height.split_off(&split_height);
mem::swap(&mut self.by_height, &mut by_height);
for hash in by_height.into_iter().flat_map(|(_, hashes)| hashes) {
let expired = self.blocks.remove(&hash).expect("block is present");
let parent_hash = &expired.block.header.previous_block_hash;
self.by_parent
.get_mut(parent_hash)
.expect("parent is present")
.remove(&hash);
}
}
/// Return the queued block if it has already been registered
pub fn get_mut(&mut self, hash: &block::Hash) -> Option<&mut QueuedBlock> {
self.blocks.get_mut(&hash)
}
}
#[cfg(test)]
mod tests {
use transaction::Transaction;
use std::{env, fmt, mem};
use zebra_chain::serialization::ZcashDeserializeInto;
use zebra_chain::{
parameters::{Network, NetworkUpgrade},
LedgerState,
};
use zebra_test::prelude::*;
use self::assert_eq;
use super::*;
struct SummaryDebug<T>(T);
impl<T> fmt::Debug for SummaryDebug<Vec<T>> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "{}, len={}", std::any::type_name::<T>(), self.0.len())
}
}
/// Helper trait for constructing "valid" looking chains of blocks
trait FakeChainHelper {
fn make_fake_child(&self) -> Arc<Block>;
}
impl FakeChainHelper for Block {
fn make_fake_child(&self) -> Arc<Block> {
let parent_hash = self.hash();
let mut child = Block::clone(self);
let mut transactions = mem::take(&mut child.transactions);
let mut tx = transactions.remove(0);
let input = match Arc::make_mut(&mut tx) {
Transaction::V1 { inputs, .. } => &mut inputs[0],
Transaction::V2 { inputs, .. } => &mut inputs[0],
Transaction::V3 { inputs, .. } => &mut inputs[0],
Transaction::V4 { inputs, .. } => &mut inputs[0],
};
match input {
transparent::Input::Coinbase { height, .. } => height.0 += 1,
_ => panic!("block must have a coinbase height to create a child"),
}
child.transactions.push(tx);
child.header.previous_block_hash = parent_hash;
Arc::new(child)
}
}
#[test]
fn construct_empty() {
zebra_test::init();
let _chain = Chain::default();
}
#[test]
fn construct_single() -> Result<()> {
zebra_test::init();
let block = zebra_test::vectors::BLOCK_MAINNET_434873_BYTES.zcash_deserialize_into()?;
let mut chain = Chain::default();
chain.push(block);
assert_eq!(1, chain.blocks.len());
Ok(())
}
#[test]
fn construct_many() -> Result<()> {
zebra_test::init();
let mut block: Arc<Block> =
zebra_test::vectors::BLOCK_MAINNET_434873_BYTES.zcash_deserialize_into()?;
let mut blocks = vec![];
while blocks.len() < 100 {
let next_block = block.make_fake_child();
blocks.push(block);
block = next_block;
}
let mut chain = Chain::default();
for block in blocks {
chain.push(block);
}
assert_eq!(100, chain.blocks.len());
Ok(())
}
fn arbitrary_chain(tip_height: block::Height) -> BoxedStrategy<Vec<Arc<Block>>> {
Block::partial_chain_strategy(LedgerState::new(tip_height, Network::Mainnet), 100)
}
prop_compose! {
fn arbitrary_chain_and_count()
(chain in arbitrary_chain(NetworkUpgrade::Blossom.activation_height(Network::Mainnet).unwrap()))
(count in 1..chain.len(), chain in Just(chain)) -> (SummaryDebug<Vec<Arc<Block>>>, usize)
{
(SummaryDebug(chain), count)
}
}
#[test]
fn forked_equals_pushed() -> Result<()> {
zebra_test::init();
proptest!(ProptestConfig::with_cases(env::var("PROPTEST_CASES")
.ok()
.and_then(|v| v.parse().ok())
.unwrap_or(1)),
|((chain, count) in arbitrary_chain_and_count())| {
let chain = chain.0;
let fork_tip_hash = chain[count - 1].hash();
let mut full_chain = Chain::default();
let mut partial_chain = Chain::default();
for block in chain.iter().take(count) {
partial_chain.push(block.clone());
}
for block in chain {
full_chain.push(block);
}
let forked = full_chain.fork(fork_tip_hash).expect("hash is present");
prop_assert_eq!(forked.blocks.len(), partial_chain.blocks.len());
});
Ok(())
}
#[test]
fn finalized_equals_pushed() -> Result<()> {
zebra_test::init();
proptest!(ProptestConfig::with_cases(env::var("PROPTEST_CASES")
.ok()
.and_then(|v| v.parse().ok())
.unwrap_or(1)),
|((chain, end_count) in arbitrary_chain_and_count())| {
let chain = chain.0;
let finalized_count = chain.len() - end_count;
let mut full_chain = Chain::default();
let mut partial_chain = Chain::default();
for block in chain.iter().skip(finalized_count) {
partial_chain.push(block.clone());
}
for block in chain {
full_chain.push(block);
}
for _ in 0..finalized_count {
let _finalized = full_chain.pop_root();
}
prop_assert_eq!(full_chain.blocks.len(), partial_chain.blocks.len());
});
Ok(())
}
}