reth_provider/providers/consistent_view.rs
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use crate::{BlockNumReader, DatabaseProviderFactory, HeaderProvider};
use alloy_primitives::B256;
use reth_errors::ProviderError;
use reth_primitives::GotExpected;
use reth_storage_api::{BlockReader, DBProvider};
use reth_storage_errors::provider::ProviderResult;
use reth_trie::HashedPostState;
use reth_trie_db::DatabaseHashedPostState;
pub use reth_storage_errors::provider::ConsistentViewError;
/// A consistent view over state in the database.
///
/// View gets initialized with the latest or provided tip.
/// Upon every attempt to create a database provider, the view will
/// perform a consistency check of current tip against the initial one.
///
/// ## Usage
///
/// The view should only be used outside of staged-sync.
/// Otherwise, any attempt to create a provider will result in [`ConsistentViewError::Syncing`].
///
/// When using the view, the consumer should either
/// 1) have a failover for when the state changes and handle [`ConsistentViewError::Inconsistent`]
/// appropriately.
/// 2) be sure that the state does not change.
#[derive(Clone, Debug)]
pub struct ConsistentDbView<Factory> {
factory: Factory,
tip: Option<B256>,
}
impl<Factory> ConsistentDbView<Factory>
where
Factory: DatabaseProviderFactory<Provider: BlockReader>,
{
/// Creates new consistent database view.
pub const fn new(factory: Factory, tip: Option<B256>) -> Self {
Self { factory, tip }
}
/// Creates new consistent database view with latest tip.
pub fn new_with_latest_tip(provider: Factory) -> ProviderResult<Self> {
let provider_ro = provider.database_provider_ro()?;
let last_num = provider_ro.last_block_number()?;
let tip = provider_ro.sealed_header(last_num)?.map(|h| h.hash());
Ok(Self::new(provider, tip))
}
/// Retrieve revert hashed state down to the given block hash.
pub fn revert_state(&self, block_hash: B256) -> ProviderResult<HashedPostState> {
let provider = self.provider_ro()?;
let block_number = provider
.block_number(block_hash)?
.ok_or(ProviderError::BlockHashNotFound(block_hash))?;
if block_number == provider.best_block_number()? &&
block_number == provider.last_block_number()?
{
Ok(HashedPostState::default())
} else {
Ok(HashedPostState::from_reverts(provider.tx_ref(), block_number + 1)?)
}
}
/// Creates new read-only provider and performs consistency checks on the current tip.
pub fn provider_ro(&self) -> ProviderResult<Factory::Provider> {
// Create a new provider.
let provider_ro = self.factory.database_provider_ro()?;
// Check that the latest stored header number matches the number
// that consistent view was initialized with.
// The mismatch can happen if a new block was appended while
// the view was being used.
// We compare block hashes instead of block numbers to account for reorgs.
let last_num = provider_ro.last_block_number()?;
let tip = provider_ro.sealed_header(last_num)?.map(|h| h.hash());
if self.tip != tip {
return Err(ConsistentViewError::Inconsistent {
tip: GotExpected { got: tip, expected: self.tip },
}
.into())
}
// Check that the best block number is the same as the latest stored header.
// This ensures that the consistent view cannot be used for initializing new providers
// if the node fell back to the staged sync.
let best_block_number = provider_ro.best_block_number()?;
if last_num != best_block_number {
return Err(ConsistentViewError::Syncing {
best_block: GotExpected { got: best_block_number, expected: last_num },
}
.into())
}
Ok(provider_ro)
}
}