uniswap-python · ErikBjare · Oct 12, 2022 · Sep 28, 2022 · Sep 28, 2022 · Sep 28, 2022
diff --git a/uniswap/constants.py b/uniswap/constants.py
@@ -1,3 +1,17 @@
+from typing import Set, cast
+from web3.types import (  # noqa: F401
+    RPCEndpoint,
+)
+
+# look at web3/middleware/cache.py for reference
+# RPC methods that will be cached inside _get_eth_simple_cache_middleware
+SIMPLE_CACHE_RPC_WHITELIST = cast(
+    Set[RPCEndpoint],
+    {
+        "eth_chainId",
+    },
+)
+
 ETH_ADDRESS = "0x0000000000000000000000000000000000000000"
 WETH9_ADDRESS = "0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2"


diff --git a/uniswap/uniswap.py b/uniswap/uniswap.py
@@ -23,6 +23,7 @@
 from .token import ERC20Token
 from .exceptions import InvalidToken, InsufficientBalance
 from .util import (
+    _get_eth_simple_cache_middleware,
    _str_to_addr,
    _addr_to_str,
    _validate_address,
@@ -78,6 +79,7 @@ def __init__(
        # use_eip1559: bool = True,
        factory_contract_addr: str = None,
        router_contract_addr: str = None,
+        enable_caching: bool = False,
    ) -> None:
        """
        :param address: The public address of the ETH wallet to use.
@@ -88,6 +90,7 @@ def __init__(
        :param default_slippage: Default slippage for a trade, as a float (0.01 is 1%). WARNING: slippage is untested.
        :param factory_contract_addr: Can be optionally set to override the address of the factory contract.
        :param router_contract_addr: Can be optionally set to override the address of the router contract (v2 only).
+        :param enable_caching: Optionally enables middleware caching RPC method calls.
        """
        self.address = _str_to_addr(
            address or "0x0000000000000000000000000000000000000000"
@@ -115,7 +118,9 @@ def __init__(
                provider = os.environ["PROVIDER"]
            self.w3 = Web3(Web3.HTTPProvider(provider, request_kwargs={"timeout": 60}))

-        # Cache netid to avoid extra RPC calls
+        if enable_caching:
+            self.w3.middleware_onion.inject(_get_eth_simple_cache_middleware(), layer=0)
+
        self.netid = int(self.w3.net.version)
        if self.netid in _netid_to_name:
            self.netname = _netid_to_name[self.netid]

diff --git a/uniswap/util.py b/uniswap/util.py
@@ -2,16 +2,27 @@
 import json
 import math
 import functools
-from typing import Any, Generator, Sequence, Union, List, Tuple
+import lru
+
+from typing import Any, Generator, Sequence, Union, List, Tuple, Type, Dict, cast

 from web3 import Web3
 from web3.exceptions import NameNotFound
 from web3.contract import Contract
+from web3.middleware.cache import construct_simple_cache_middleware
+from web3.types import Middleware

-from .constants import MIN_TICK, MAX_TICK, _tick_spacing
+from .constants import MIN_TICK, MAX_TICK, _tick_spacing, SIMPLE_CACHE_RPC_WHITELIST
 from .types import AddressLike, Address


+def _get_eth_simple_cache_middleware() -> Middleware:
+    return construct_simple_cache_middleware(
+        cache_class=cast(Type[Dict[Any, Any]], functools.partial(lru.LRU, 256)),
+        rpc_whitelist=SIMPLE_CACHE_RPC_WHITELIST,
+    )
+
+
 def _str_to_addr(s: Union[AddressLike, str]) -> Address:
    """Idempotent"""
    if isinstance(s, str):