New ImmutableSerializable with a memoizable .hash property

evm/rlp/headers.py

@@ -28,6 +28,7 @@
     ValidationError,
 )
 
+from evm.rlp.immutable import ImmutableSerializable
 from evm.utils.hexadecimal import (
     encode_hex,
 )
@@ -58,7 +59,7 @@
 )
 
 
-class BlockHeader(rlp.Serializable):
+class BlockHeader(ImmutableSerializable):
     fields = [
         ('parent_hash', hash32),
         ('uncles_hash', hash32),
@@ -119,10 +120,6 @@ def __repr__(self) -> str:
             encode_hex(self.hash)[2:10],
         )
 
-    @property
-    def hash(self) -> bytes:
-        return keccak(rlp.encode(self))
-
     @property
     def mining_hash(self) -> bytes:
         return keccak(

evm/rlp/immutable.py

@@ -0,0 +1,39 @@
+import functools
+
+import rlp
+
+from eth_utils import keccak
+
+
+# TODO: Document, and explain that it must only be used on methods with no arguments as well as
+# subclasses of ImmutableSerializable. Maybe instead of a decorator it should actually be a method
+# on ImmutableSerializable?
+def memoize(method):
+    attr_name = '_memoized_' + method.__name__
+
+    @functools.wraps(method)
+    def memoized_method(obj):
+        if not hasattr(obj, attr_name):
+            setattr(obj, attr_name, method(obj))
+        return getattr(obj, attr_name)
+
+    return memoized_method
+
+
+class ImmutableSerializable(rlp.Serializable):
+
+    _hash = None
+
+    @classmethod
+    def deserialize(cls, serial, exclude=None, mutable=False, **kwargs):
+        obj = super().deserialize(serial, exclude=exclude, mutable=True, **kwargs)
+        obj._cached_rlp = rlp.codec.encode_raw(serial)
+        return rlp.sedes.make_immutable(obj)
+
+    @property
+    @memoize
+    def hash(self) -> bytes:
+        if self._cached_rlp:
+            return keccak(self._cached_rlp)
+        else:
+            return keccak(rlp.encode(self))

evm/rlp/transactions.py

@@ -12,14 +12,11 @@
     binary,
 )
 
-from eth_utils import (
-    keccak,
-)
-
 from evm.exceptions import (
     ValidationError,
 )
 
+from evm.rlp.immutable import ImmutableSerializable
 from evm.rlp.sedes import (
     address,
 )
@@ -29,7 +26,7 @@
 )
 
 
-class BaseTransaction(rlp.Serializable, metaclass=ABCMeta):
+class BaseTransaction(ImmutableSerializable, metaclass=ABCMeta):
     fields = [
         ('nonce', big_endian_int),
         ('gas_price', big_endian_int),
@@ -46,10 +43,6 @@ class BaseTransaction(rlp.Serializable, metaclass=ABCMeta):
     def from_base_transaction(cls, transaction: 'BaseTransaction') -> 'BaseTransaction':
         return rlp.decode(rlp.encode(transaction), sedes=cls)
 
-    @property
-    def hash(self) -> bytes:
-        return keccak(rlp.encode(self))
-
     @property
     def sender(self) -> bytes:
         """

evm/vm/forks/frontier/transactions.py

@@ -16,6 +16,7 @@
     validate_canonical_address,
 )
 
+from evm.rlp.immutable import memoize
 from evm.rlp.transactions import (
     BaseTransaction,
     BaseUnsignedTransaction,
@@ -65,6 +66,7 @@ def get_sender(self):
     def get_intrinsic_gas(self):
         return _get_frontier_intrinsic_gas(self.data)
 
+    @memoize
     def get_message_for_signing(self):
         return rlp.encode(FrontierUnsignedTransaction(
             nonce=self.nonce,

evm/vm/forks/homestead/transactions.py

@@ -7,6 +7,7 @@
     GAS_TXDATANONZERO,
     CREATE_CONTRACT_ADDRESS,
 )
+from evm.rlp.immutable import memoize
 from evm.validation import (
     validate_lt_secpk1n2,
 )
@@ -29,6 +30,7 @@ def validate(self):
     def get_intrinsic_gas(self):
         return _get_homestead_intrinsic_gas(self)
 
+    @memoize
     def get_message_for_signing(self):
         return rlp.encode(HomesteadUnsignedTransaction(
             nonce=self.nonce,

evm/vm/forks/spurious_dragon/transactions.py

@@ -1,5 +1,6 @@
 import rlp
 
+from evm.rlp.immutable import memoize
 from evm.vm.forks.homestead.transactions import (
     HomesteadTransaction,
     HomesteadUnsignedTransaction,
@@ -16,6 +17,8 @@
 
 
 class SpuriousDragonTransaction(HomesteadTransaction):
+
+    @memoize
     def get_message_for_signing(self):
         if is_eip_155_signed_transaction(self):
             txn_parts = rlp.decode(rlp.encode(self))