starknet_committer: impl metadata for FactsDb

crates/starknet_committer/Cargo.toml

@@ -10,6 +10,7 @@ description = "Computes and manages Starknet state."
 testing = ["starknet_patricia/testing"]
 
 [dependencies]
+async-trait.workspace = true
 csv.workspace = true
 ethnum.workspace = true
 hex.workspace = true

crates/starknet_committer/src/db/facts_db.rs

@@ -6,7 +6,7 @@ use starknet_patricia::patricia_merkle_tree::node_data::leaf::LeafModifications;
 use starknet_patricia::patricia_merkle_tree::original_skeleton_tree::tree::OriginalSkeletonTreeImpl;
 use starknet_patricia::patricia_merkle_tree::types::{NodeIndex, SortedLeafIndices};
 use starknet_patricia_storage::map_storage::MapStorage;
-use starknet_patricia_storage::storage_trait::Storage;
+use starknet_patricia_storage::storage_trait::{create_db_key, DbKey, DbKeyPrefix, Storage};
 
 use crate::block_committer::input::{
     contract_address_into_node_index,
@@ -18,7 +18,7 @@ use crate::db::create_facts_tree::{
     create_original_skeleton_tree,
     create_original_skeleton_tree_and_get_previous_leaves,
 };
-use crate::db::forest_trait::{ForestReader, ForestWriter};
+use crate::db::forest_trait::{ForestMetadata, ForestMetadataType, ForestReader, ForestWriter};
 use crate::forest::filled_forest::FilledForest;
 use crate::forest::forest_errors::{ForestError, ForestResult};
 use crate::forest::original_skeleton_forest::{ForestSortedIndices, OriginalSkeletonForest};
@@ -37,6 +37,9 @@ pub struct FactsDb<S: Storage> {
 }
 
 impl<S: Storage> FactsDb<S> {
+    pub const COMMITMENT_OFFSET_KEY: &[u8; 17] = b"commitment_offset";
+    pub const STATE_DIFF_HASH_PREFIX: &[u8; 15] = b"state_diff_hash";
+
     pub fn new(storage: S) -> Self {
         Self { storage }
     }
@@ -163,3 +166,18 @@ impl<S: Storage> ForestWriter for FactsDb<S> {
         filled_forest.write_to_storage(&mut self.storage).await
     }
 }
+
+impl<S: Storage> ForestMetadata for FactsDb<S> {
+    /// Returns the db key for the metadata type.
+    /// The data keys in a facts DB are the result of a hash function; therefore, they are not
+    /// expected to collide with these metadata keys.
+    fn metadata_key(metadata_type: ForestMetadataType) -> DbKey {
+        match metadata_type {
+            ForestMetadataType::CommitmentOffset => DbKey(Self::COMMITMENT_OFFSET_KEY.to_vec()),
+            ForestMetadataType::StateDiffHash(block_number) => {
+                let state_diff_hash_key_prefix = DbKeyPrefix::new(Self::STATE_DIFF_HASH_PREFIX);
+                create_db_key(state_diff_hash_key_prefix, &block_number.0.to_be_bytes())
+            }
+        }
+    }
+}

crates/starknet_committer/src/db/forest_trait.rs

@@ -1,10 +1,13 @@
 use std::collections::HashMap;
 use std::future::Future;
 
+use async_trait::async_trait;
+use starknet_api::block::BlockNumber;
 use starknet_api::core::ContractAddress;
 use starknet_api::hash::HashOutput;
 use starknet_patricia::patricia_merkle_tree::node_data::leaf::LeafModifications;
 use starknet_patricia::patricia_merkle_tree::types::NodeIndex;
+use starknet_patricia_storage::storage_trait::{DbHashMap, DbKey, DbValue, Storage};
 
 use crate::block_committer::input::{ConfigImpl, StarknetStorageValue};
 use crate::forest::filled_forest::FilledForest;
@@ -13,6 +16,37 @@ use crate::forest::original_skeleton_forest::{ForestSortedIndices, OriginalSkele
 use crate::patricia_merkle_tree::leaf::leaf_impl::ContractState;
 use crate::patricia_merkle_tree::types::CompiledClassHash;
 
+pub enum ForestMetadataType {
+    CommitmentOffset,
+    StateDiffHash(BlockNumber),
+}
+
+#[async_trait]
+pub trait ForestMetadata {
+    /// Returns the db key for the metadata type.
+    fn metadata_key(metadata_type: ForestMetadataType) -> DbKey;
+
+    /// Reads the metadata from the storage.
+    async fn read_metadata(
+        &self,
+        storage: &mut impl Storage,
+        metadata_type: ForestMetadataType,
+    ) -> ForestResult<Option<DbValue>> {
+        let db_key = Self::metadata_key(metadata_type);
+        Ok(storage.get(&db_key).await?)
+    }
+
+    /// Adds the metadata to updates map. Returns the previous value if it existed.
+    fn insert_metadata(
+        updates: &mut DbHashMap,
+        metadata_type: ForestMetadataType,
+        value: DbValue,
+    ) -> Option<DbValue> {
+        let db_key = Self::metadata_key(metadata_type);
+        updates.insert(db_key, value)
+    }
+}
+
 /// Trait for reading an original skeleton forest from some storage.
 /// The implementation may depend on the underlying storage layout.
 pub trait ForestReader<'a> {

crates/starknet_committer/src/forest/forest_errors.rs

@@ -2,6 +2,7 @@ use starknet_api::core::ContractAddress;
 use starknet_patricia::patricia_merkle_tree::filled_tree::errors::FilledTreeError;
 use starknet_patricia::patricia_merkle_tree::original_skeleton_tree::errors::OriginalSkeletonTreeError;
 use starknet_patricia::patricia_merkle_tree::updated_skeleton_tree::errors::UpdatedSkeletonTreeError;
+use starknet_patricia_storage::storage_trait::PatriciaStorageError;
 use thiserror::Error;
 use tokio::task::JoinError;
 
@@ -12,6 +13,8 @@ pub enum ForestError {
     #[error(transparent)]
     OriginalSkeleton(#[from] OriginalSkeletonTreeError),
     #[error(transparent)]
+    PatriciaStorage(#[from] PatriciaStorageError),
+    #[error(transparent)]
     UpdatedSkeleton(#[from] UpdatedSkeletonTreeError),
     #[error("Couldn't create Classes Trie: {0}")]
     ClassesTrie(#[source] FilledTreeError),