Cache eth.chain_id in simple_cache_middleware (ethereum#2425)

* Add caching for sync chain_id

* Remove async chainId setter

Will add async chainId to the cache once the simple_cache_middleware is available on async

* Add docs

* Add newsfragment for simple_cache_middleware, take out old, confusing newsfragment

docs/web3.eth.rst

@@ -216,6 +216,18 @@ The following properties are available on the ``web3.eth`` namespace.
        >>> web3.eth.chain_id
        61
 
+   .. note::
+
+      This property gets called frequently in validation middleware,
+      but `chain_id` is added to the ``simple_cache_middleware`` by default.
+      Add the :meth:`simple_cache_middleware<web3.middleware.construct_simple_cache_middleware>`
+      to the ``middleware_onion`` to increase performance:
+
+       .. code-block:: python
+
+          >>> from web3.middleware import simple_cache_middleware
+          >>> w3.middleware_onion.add(simple_cache_middleare)
+
 
 .. py:attribute:: Eth.chainId
 

newsfragments/2425.feature.rst

@@ -0,0 +1 @@
+Add sync chain_id to ``simple_middleware_cache``

tests/core/eth-module/test_eth_properties.py

@@ -1,23 +1,5 @@
 import pytest
 
-from web3 import Web3
-from web3.eth import (
-    AsyncEth,
-)
-from web3.providers.eth_tester.main import (
-    AsyncEthereumTesterProvider,
-)
-
-
-@pytest.fixture
-def async_w3():
-    return Web3(
-        AsyncEthereumTesterProvider(),
-        middlewares=[],
-        modules={
-            'eth': (AsyncEth,),
-        })
-
 
 def test_eth_protocol_version(w3):
     with pytest.warns(DeprecationWarning):
@@ -36,24 +18,3 @@ def test_eth_chain_id(w3):
 def test_eth_chainId(w3):
     with pytest.warns(DeprecationWarning):
         assert w3.eth.chainId == 61
-
-
-def test_set_chain_id(w3):
-    assert w3.eth.chain_id == 61
-
-    w3.eth.chain_id = 72
-    assert w3.eth.chain_id == 72
-
-    w3.eth.chain_id = None
-    assert w3.eth.chain_id == 61
-
-
-@pytest.mark.asyncio
-async def test_async_set_chain_id(async_w3):
-    assert await async_w3.eth.chain_id == 61
-
-    async_w3.eth.chain_id = 72
-    assert await async_w3.eth.chain_id == 72
-
-    async_w3.eth.chain_id = None
-    assert await async_w3.eth.chain_id == 61

web3/eth.py

@@ -114,7 +114,6 @@
 class BaseEth(Module):
     _default_account: Union[ChecksumAddress, Empty] = empty
     _default_block: BlockIdentifier = "latest"
-    _default_chain_id: Optional[int] = None
     gasPriceStrategy = None
 
     _gas_price: Method[Callable[[], Wei]] = Method(
@@ -358,14 +357,7 @@ async def block_number(self) -> BlockNumber:
 
     @property
     async def chain_id(self) -> int:
-        if self._default_chain_id is None:
-            return await self._chain_id()  # type: ignore
-        else:
-            return self._default_chain_id
-
-    @chain_id.setter
-    def chain_id(self, value: int) -> None:
-        self._default_chain_id = value
+        return await self._chain_id()  # type: ignore
 
     @property
     async def coinbase(self) -> ChecksumAddress:
@@ -637,14 +629,7 @@ def blockNumber(self) -> BlockNumber:
 
     @property
     def chain_id(self) -> int:
-        if self._default_chain_id is None:
-            return self._chain_id()
-        else:
-            return self._default_chain_id
-
-    @chain_id.setter
-    def chain_id(self, value: int) -> None:
-        self._default_chain_id = value
+        return self._chain_id()
 
     @property
     def chainId(self) -> int:

web3/middleware/cache.py

@@ -82,6 +82,7 @@
     # 'eth_getWork',
     # 'eth_submitWork',
     # 'eth_submitHashrate',
+    'eth_chainId',
 })