Pass block hash through parse_block_identifier instead of resolving it

newsfragments/3646.performance.rst

@@ -0,0 +1,4 @@
+``parse_block_identifier`` / ``async_parse_block_identifier`` now forward a
+block hash to the JSON-RPC node directly instead of resolving it to a block
+number first. This removes an extra ``eth_getBlockBy*`` round-trip on every
+contract call that targets a specific block hash.

tests/core/contracts/test_contract_util_functions.py

@@ -32,13 +32,13 @@ def test_parse_block_identifier_int_and_string(w3, block_identifier, expected_ou
 def test_parse_block_identifier_bytes_and_hex(w3):
     block_0 = w3.eth.get_block(0)
     block_0_hash = block_0["hash"]
-    # test retrieve by bytes
-    block_id_by_hash = parse_block_identifier(w3, block_0_hash)
-    assert block_id_by_hash == 0
-    # test retrieve by hexstring
     block_0_hexstring = w3.to_hex(block_0_hash)
-    block_id_by_hex = parse_block_identifier(w3, block_0_hexstring)
-    assert block_id_by_hex == 0
+    # Block hashes are passed through unchanged so the RPC node receives them
+    # directly. This avoids an extra eth_getBlockBy* round-trip just to look
+    # up a block number that the major clients already accept as a
+    # default-block parameter. See issue #3646.
+    assert parse_block_identifier(w3, block_0_hash) == block_0_hexstring
+    assert parse_block_identifier(w3, block_0_hexstring) == block_0_hexstring
 
 
 @pytest.mark.parametrize(
@@ -98,13 +98,16 @@ async def test_async_parse_block_identifier_int_and_string(
 async def test_async_parse_block_identifier_bytes_and_hex(async_w3):
     block_0 = await async_w3.eth.get_block(0)
     block_0_hash = block_0["hash"]
-    # test retrieve by bytes
-    block_id_by_hash = await async_parse_block_identifier(async_w3, block_0_hash)
-    assert block_id_by_hash == 0
-    # test retrieve by hexstring
     block_0_hexstring = async_w3.to_hex(block_0_hash)
-    block_id_by_hex = await async_parse_block_identifier(async_w3, block_0_hexstring)
-    assert block_id_by_hex == 0
+    # See test_parse_block_identifier_bytes_and_hex for rationale.
+    assert (
+        await async_parse_block_identifier(async_w3, block_0_hash)
+        == block_0_hexstring
+    )
+    assert (
+        await async_parse_block_identifier(async_w3, block_0_hexstring)
+        == block_0_hexstring
+    )
 
 
 @pytest.mark.asyncio

web3/_utils/contracts.py

@@ -64,6 +64,9 @@
     abi_ens_resolver,
     abi_string_to_text,
 )
+from web3._utils.type_conversion import (
+    to_hex_if_bytes,
+)
 from web3.exceptions import (
     BlockNumberOutOfRange,
     Web3TypeError,
@@ -342,7 +345,13 @@ def parse_block_identifier(
     elif isinstance(block_identifier, bytes) or is_hex_encoded_block_hash(
         block_identifier
     ):
-        return w3.eth.get_block(block_identifier)["number"]
+        # Forward the block hash to the JSON-RPC call instead of resolving it to
+        # a block number first. The execution-apis spec lists block hashes as a
+        # valid default-block parameter and the major clients (geth, reth,
+        # erigon, nethermind) accept them for eth_call/eth_estimateGas, so we
+        # avoid an extra eth_getBlockBy* round-trip. If a node rejects the
+        # hash, the underlying RPC error propagates to the caller unchanged.
+        return to_hex_if_bytes(block_identifier)
     else:
         raise BlockNumberOutOfRange
 
@@ -370,8 +379,9 @@ async def async_parse_block_identifier(
     elif isinstance(block_identifier, bytes) or is_hex_encoded_block_hash(
         block_identifier
     ):
-        requested_block = await async_w3.eth.get_block(block_identifier)
-        return requested_block["number"]
+        # See parse_block_identifier for rationale. Pass the hash through so a
+        # single eth_call request is enough.
+        return to_hex_if_bytes(block_identifier)
     else:
         raise BlockNumberOutOfRange