Implement EIP-1283

Author: cburgdorf

eth/db/account.py

@@ -239,11 +239,11 @@ def has_root(self, state_root: bytes) -> bool:
     #
     # Storage
     #
-    def get_storage(self, address, slot):
+    def get_storage(self, address, slot, from_journal=True):
         validate_canonical_address(address, title="Storage Address")
         validate_uint256(slot, title="Storage Slot")
 
-        account = self._get_account(address)
+        account = self._get_account(address, from_journal)
         storage = HashTrie(HexaryTrie(self._journaldb, account.storage_root))
 
         slot_as_key = pad32(int_to_big_endian(slot))
@@ -375,8 +375,8 @@ def account_is_empty(self, address):
     #
     # Internal
     #
-    def _get_account(self, address):
-        rlp_account = self._journaltrie.get(address, b'')
+    def _get_account(self, address, from_journal=True):
+        rlp_account = (self._journaltrie if from_journal else self._trie_cache).get(address, b'')
         if rlp_account:
             account = rlp.decode(rlp_account, sedes=Account)
         else:

eth/vm/computation.py

@@ -130,7 +130,7 @@ def __init__(self,
 
         self._memory = Memory()
         self._stack = Stack()
-        self._gas_meter = GasMeter(message.gas)
+        self._gas_meter = self.get_gas_meter()
 
         self.children = []
         self.accounts_to_delete = {}
@@ -406,6 +406,9 @@ def add_log_entry(self, account: Address, topics: List[int], data: bytes) -> Non
     #
     # Getters
     #
+    def get_gas_meter(self) -> GasMeter:
+        return GasMeter(self.msg.gas)
+
     def get_accounts_for_deletion(self) -> Tuple[Tuple[bytes, bytes], ...]:
         if self.is_error:
             return tuple()

eth/vm/forks/constantinople/computation.py

@@ -8,6 +8,10 @@
 from eth.vm.forks.byzantium.computation import (
     ByzantiumComputation
 )
+from eth.vm.gas_meter import (
+    allow_negative_refund_strategy,
+    GasMeter,
+)
 
 from .opcodes import CONSTANTINOPLE_OPCODES
 
@@ -27,3 +31,9 @@ class ConstantinopleComputation(ByzantiumComputation):
     # Override
     opcodes = CONSTANTINOPLE_OPCODES
     _precompiles = CONSTANTINOPLE_PRECOMPILES
+
+    def get_gas_meter(self) -> GasMeter:
+        return GasMeter(
+            self.msg.gas,
+            allow_negative_refund_strategy
+        )

eth/vm/forks/constantinople/constants.py

@@ -2,5 +2,11 @@
 
 
 GAS_EXTCODEHASH_EIP1052 = 400
+GAS_SSTORE_EIP1283_NOOP = 200
+GAS_SSTORE_EIP1283_INIT = 20000
+GAS_SSTORE_EIP1283_CLEAN = 5000
+GAS_SSTORE_EIP1283_CLEAR_REFUND = 15000
+GAS_SSTORE_EIP1283_RESET_CLEAR_REFUND = 19800
+GAS_SSTORE_EIP1283_RESET_REFUND = 4800
 
 EIP1234_BLOCK_REWARD = 2 * denoms.ether

eth/vm/forks/constantinople/opcodes.py

@@ -16,6 +16,9 @@
 from eth.vm.forks.constantinople.constants import (
     GAS_EXTCODEHASH_EIP1052
 )
+from eth.vm.forks.constantinople.storage import (
+    sstore_eip1283,
+)
 from eth.vm.logic import (
     arithmetic,
     context,
@@ -52,6 +55,11 @@
         mnemonic=mnemonics.CREATE2,
         gas_cost=constants.GAS_CREATE,
     )(),
+    opcode_values.SSTORE: as_opcode(
+        logic_fn=sstore_eip1283,
+        mnemonic=mnemonics.SSTORE,
+        gas_cost=constants.GAS_NULL,
+    ),
 }
 
 CONSTANTINOPLE_OPCODES = merge(

eth/vm/forks/constantinople/storage.py

@@ -0,0 +1,73 @@
+from eth.constants import (
+    UINT256
+)
+from eth.vm.forks.constantinople import (
+    constants
+)
+
+from eth.utils.hexadecimal import (
+    encode_hex,
+)
+
+
+def sstore_eip1283(computation):
+    slot, value = computation.stack_pop(num_items=2, type_hint=UINT256)
+
+    current_value = computation.state.account_db.get_storage(
+        address=computation.msg.storage_address,
+        slot=slot,
+    )
+
+    original_value = computation.state.account_db.get_storage(
+        address=computation.msg.storage_address,
+        slot=slot,
+        from_journal=False
+    )
+
+    gas_refund = 0
+
+    if current_value == value:
+        gas_cost = constants.GAS_SSTORE_EIP1283_NOOP
+    else:
+        if original_value == current_value:
+            if original_value == 0:
+                gas_cost = constants.GAS_SSTORE_EIP1283_INIT
+            else:
+                gas_cost = constants.GAS_SSTORE_EIP1283_CLEAN
+
+                if value == 0:
+                    gas_refund += constants.GAS_SSTORE_EIP1283_CLEAR_REFUND
+        else:
+            gas_cost = constants.GAS_SSTORE_EIP1283_NOOP
+
+            if original_value != 0:
+                if current_value == 0:
+                    gas_refund -= constants.GAS_SSTORE_EIP1283_CLEAR_REFUND
+                if value == 0:
+                    gas_refund += constants.GAS_SSTORE_EIP1283_CLEAR_REFUND
+
+            if original_value == value:
+                if original_value == 0:
+                    gas_refund += constants.GAS_SSTORE_EIP1283_RESET_CLEAR_REFUND
+                else:
+                    gas_refund += constants.GAS_SSTORE_EIP1283_RESET_REFUND
+
+    computation.consume_gas(
+        gas_cost,
+        reason="SSTORE: {0}[{1}] -> {2} (current: {3} / original: {4})".format(
+            encode_hex(computation.msg.storage_address),
+            slot,
+            value,
+            current_value,
+            original_value,
+        )
+    )
+
+    if gas_refund:
+        computation.refund_gas(gas_refund)
+
+    computation.state.account_db.set_storage(
+        address=computation.msg.storage_address,
+        slot=slot,
+        value=value,
+    )

eth/vm/gas_meter.py

@@ -1,6 +1,7 @@
 import logging
 from typing import (
-    cast
+    Callable,
+    cast,
 )
 from eth_utils import (
     ValidationError,
@@ -16,17 +17,35 @@
 )
 
 
+def default_refund_strategy(gas_refunded_total: int, amount: int) -> int:
+    if amount < 0:
+        raise ValidationError("Gas refund amount must be positive")
+
+    return gas_refunded_total + amount
+
+
+def allow_negative_refund_strategy(gas_refunded_total: int, amount: int) -> int:
+    return gas_refunded_total + amount
+
+
+RefundStrategy = Callable[[int, int], int]
+
+
 class GasMeter(object):
+
     start_gas = None  # type: int
 
     gas_refunded = None  # type: int
     gas_remaining = None  # type: int
 
     logger = cast(TraceLogger, logging.getLogger('eth.gas.GasMeter'))
 
-    def __init__(self, start_gas: int) -> None:
+    def __init__(self,
+                 start_gas: int,
+                 refund_strategy: RefundStrategy = default_refund_strategy) -> None:
         validate_uint256(start_gas, title="Start Gas")
 
+        self.refund_strategy = refund_strategy
         self.start_gas = start_gas
 
         self.gas_remaining = self.start_gas
@@ -70,10 +89,7 @@ def return_gas(self, amount: int) -> None:
         )
 
     def refund_gas(self, amount: int) -> None:
-        if amount < 0:
-            raise ValidationError("Gas refund amount must be positive")
-
-        self.gas_refunded += amount
+        self.gas_refunded = self.refund_strategy(self.gas_refunded, amount)
 
         self.logger.trace(
             'GAS REFUND: %s + %s -> %s',