Improve performance when importing a single header based on the chain head

Author: lithp

eth/db/chain.py

@@ -93,15 +93,18 @@ def get_block_uncles(self, uncles_hash: Hash32) -> Tuple[BlockHeaderAPI, ...]:
     def _set_as_canonical_chain_head(
             cls,
             db: DatabaseAPI,
-            block_hash: Hash32,
+            header: BlockHeaderAPI,
             genesis_parent_hash: Hash32,
     ) -> Tuple[Tuple[BlockHeaderAPI, ...], Tuple[BlockHeaderAPI, ...]]:
+        # performance optimization, short circuit if we're just adding a single header
         try:
-            header = cls._get_block_header_by_hash(db, block_hash)
-        except HeaderNotFound:
-            raise ValueError(
-                f"Cannot use unknown block hash as canonical head: {header.hash}"
-            )
+            current_canonical_head = cls._get_canonical_head_hash(db)
+        except CanonicalHeadNotFound:
+            current_canonical_head = None
+        if current_canonical_head and header.parent_hash == current_canonical_head:
+            cls._add_block_number_to_hash_lookup(db, header)
+            db.set(SchemaV1.make_canonical_head_hash_lookup_key(), header.hash)
+            return (header,), tuple()
 
         new_canonical_headers = tuple(reversed(
             cls._find_new_ancestors(db, header, genesis_parent_hash)))

eth/db/header.py

@@ -83,11 +83,15 @@ def get_canonical_head(self) -> BlockHeaderAPI:
 
     @classmethod
     def _get_canonical_head(cls, db: DatabaseAPI) -> BlockHeaderAPI:
+        canonical_head_hash = cls._get_canonical_head_hash(db)
+        return cls._get_block_header_by_hash(db, Hash32(canonical_head_hash))
+
+    @classmethod
+    def _get_canonical_head_hash(cls, db: DatabaseAPI) -> Hash32:
         try:
-            canonical_head_hash = db[SchemaV1.make_canonical_head_hash_lookup_key()]
+            return db[SchemaV1.make_canonical_head_hash_lookup_key()]
         except KeyError:
             raise CanonicalHeadNotFound("No canonical head set for this chain")
-        return cls._get_block_header_by_hash(db, Hash32(canonical_head_hash))
 
     #
     # Header API
@@ -173,7 +177,7 @@ def _persist_checkpoint_header(
         )
         previous_score = score - header.difficulty
         cls._set_hash_scores_to_db(db, header, previous_score)
-        cls._set_as_canonical_chain_head(db, header.hash, header.parent_hash)
+        cls._set_as_canonical_chain_head(db, header, header.parent_hash)
 
     @classmethod
     def _persist_header_chain(
@@ -226,21 +230,21 @@ def _persist_header_chain(
             score = cls._set_hash_scores_to_db(db, curr_chain_head, score)
 
         try:
-            previous_canonical_head = cls._get_canonical_head(db).hash
+            previous_canonical_head = cls._get_canonical_head_hash(db)
             head_score = cls._get_score(db, previous_canonical_head)
         except CanonicalHeadNotFound:
-            return cls._set_as_canonical_chain_head(db, curr_chain_head.hash, genesis_parent_hash)
+            return cls._set_as_canonical_chain_head(db, curr_chain_head, genesis_parent_hash)
 
         if score > head_score:
-            return cls._set_as_canonical_chain_head(db, curr_chain_head.hash, genesis_parent_hash)
+            return cls._set_as_canonical_chain_head(db, curr_chain_head, genesis_parent_hash)
 
         return tuple(), tuple()
 
     @classmethod
     def _set_as_canonical_chain_head(
         cls,
         db: DatabaseAPI,
-        block_hash: Hash32,
+        header: BlockHeaderAPI,
         genesis_parent_hash: Hash32,
     ) -> Tuple[Tuple[BlockHeaderAPI, ...], Tuple[BlockHeaderAPI, ...]]:
         """
@@ -250,12 +254,15 @@ def _set_as_canonical_chain_head(
         :return: a tuple of the headers that are newly in the canonical chain, and the headers that
             are no longer in the canonical chain
         """
+        # performance optimization, short circuit if we're just adding a single header
         try:
-            header = cls._get_block_header_by_hash(db, block_hash)
-        except HeaderNotFound:
-            raise ValueError(
-                f"Cannot use unknown block hash as canonical head: {block_hash}"
-            )
+            current_canonical_head = cls._get_canonical_head_hash(db)
+        except CanonicalHeadNotFound:
+            current_canonical_head = None
+        if current_canonical_head and header.parent_hash == current_canonical_head:
+            cls._add_block_number_to_hash_lookup(db, header)
+            db.set(SchemaV1.make_canonical_head_hash_lookup_key(), header.hash)
+            return (header,), tuple()
 
         new_canonical_headers = tuple(reversed(
             cls._find_new_ancestors(db, header, genesis_parent_hash)))