refactor: create non-null hash property (#967)

Author: glevco

hathor/transaction/base_transaction.py

@@ -168,7 +168,7 @@ def __init__(self,
         self.outputs = outputs or []
         self.parents = parents or []
         self.storage = storage
-        self.hash = hash  # Stored as bytes.
+        self._hash: VertexId | None = hash  # Stored as bytes.
 
     @classproperty
     def log(cls):
@@ -253,7 +253,7 @@ def __eq__(self, other: object) -> bool:
         """
         if not isinstance(other, BaseTransaction):
             return NotImplemented
-        if self.hash and other.hash:
+        if self._hash and other._hash:
             return self.hash == other.hash
         return False
 
@@ -265,7 +265,6 @@ def __bytes__(self) -> bytes:
         return self.get_struct()
 
     def __hash__(self) -> int:
-        assert self.hash is not None
         return hash(self.hash)
 
     @abstractmethod
@@ -276,10 +275,19 @@ def calculate_height(self) -> int:
     def calculate_min_height(self) -> int:
         raise NotImplementedError
 
+    @property
+    def hash(self) -> VertexId:
+        assert self._hash is not None, 'Vertex hash must be initialized.'
+        return self._hash
+
+    @hash.setter
+    def hash(self, value: VertexId) -> None:
+        self._hash = value
+
     @property
     def hash_hex(self) -> str:
         """Return the current stored hash in hex string format"""
-        if self.hash is not None:
+        if self._hash is not None:
             return self.hash.hex()
         else:
             return ''
@@ -332,7 +340,7 @@ def is_genesis(self) -> bool:
 
         :rtype: bool
         """
-        if self.hash is None:
+        if self._hash is None:
             return False
         from hathor.transaction.genesis import is_genesis
         return is_genesis(self.hash, settings=self._settings)
@@ -451,7 +459,7 @@ def can_validate_full(self) -> bool:
         """ Check if this transaction is ready to be fully validated, either all deps are full-valid or one is invalid.
         """
         assert self.storage is not None
-        assert self.hash is not None
+        assert self._hash is not None
         if self.is_genesis:
             return True
         deps = self.get_all_dependencies()
@@ -608,7 +616,6 @@ def get_metadata(self, *, force_reload: bool = False, use_storage: bool = True)
         else:
             metadata = getattr(self, '_metadata', None)
         if not metadata and use_storage and self.storage:
-            assert self.hash is not None
             metadata = self.storage.get_metadata(self.hash)
             self._metadata = metadata
         if not metadata:
@@ -619,15 +626,15 @@ def get_metadata(self, *, force_reload: bool = False, use_storage: bool = True)
             score = self.weight if self.is_genesis else 0
 
             metadata = TransactionMetadata(
-                hash=self.hash,
+                hash=self._hash,
                 accumulated_weight=self.weight,
                 height=height,
                 score=score,
                 min_height=0,
             )
             self._metadata = metadata
         if not metadata.hash:
-            metadata.hash = self.hash
+            metadata.hash = self._hash
         metadata._tx_ref = weakref.ref(self)
         return metadata
 
@@ -638,7 +645,7 @@ def reset_metadata(self) -> None:
         from hathor.transaction.transaction_metadata import ValidationState
         assert self.storage is not None
         score = self.weight if self.is_genesis else 0
-        self._metadata = TransactionMetadata(hash=self.hash,
+        self._metadata = TransactionMetadata(hash=self._hash,
                                              score=score,
                                              accumulated_weight=self.weight)
         if self.is_genesis:
@@ -724,7 +731,7 @@ def _update_reward_lock_metadata(self) -> None:
 
     def _update_parents_children_metadata(self) -> None:
         """Update the txs/block parent's children metadata."""
-        assert self.hash is not None
+        assert self._hash is not None
         assert self.storage is not None
 
         for parent in self.get_parents(existing_only=True):
@@ -792,7 +799,6 @@ def to_json(self, decode_script: bool = False, include_metadata: bool = False) -
         return data
 
     def to_json_extended(self) -> dict[str, Any]:
-        assert self.hash is not None
         assert self.storage is not None
 
         def serialize_output(tx: BaseTransaction, tx_out: TxOutput) -> dict[str, Any]:
@@ -824,7 +830,6 @@ def serialize_output(tx: BaseTransaction, tx_out: TxOutput) -> dict[str, Any]:
             tx2 = self.storage.get_transaction(tx_in.tx_id)
             tx2_out = tx2.outputs[tx_in.index]
             output = serialize_output(tx2, tx2_out)
-            assert tx2.hash is not None
             output['tx_id'] = tx2.hash_hex
             output['index'] = tx_in.index
             ret['inputs'].append(output)

hathor/transaction/token_creation_tx.py

@@ -65,7 +65,6 @@ def update_hash(self) -> None:
         """ When we update the hash, we also have to update the tokens uid list
         """
         super().update_hash()
-        assert self.hash is not None
         self.tokens = [self.hash]
 
     def get_funds_fields_from_struct(self, buf: bytes, *, verbose: VerboseCallback = None) -> bytes:
@@ -221,7 +220,6 @@ def _get_token_info_from_inputs(self) -> dict[TokenUid, TokenInfo]:
         token_dict = super()._get_token_info_from_inputs()
 
         # we add the created token's info to token_dict, as the creation tx allows for mint/melt
-        assert self.hash is not None
         token_dict[self.hash] = TokenInfo(0, True, True)
 
         return token_dict

hathor/transaction/transaction.py

@@ -360,7 +360,7 @@ def is_double_spending(self) -> bool:
             tx = self.storage.get_transaction(tx_in.tx_id)
             meta = tx.get_metadata()
             spent_by = meta.get_output_spent_by(tx_in.index)
-            if spent_by and spent_by != self.hash:
+            if spent_by and spent_by != self._hash:
                 return True
         return False
 

tests/utils.py

@@ -5,7 +5,7 @@
 import time
 import urllib.parse
 from dataclasses import dataclass
-from typing import Optional, cast
+from typing import Optional
 
 import requests
 from hathorlib.scripts import DataScript
@@ -378,7 +378,7 @@ def create_tokens(manager: 'HathorManager', address_b58: Optional[str] = None, m
         assert genesis_hash is not None
         deposit_input = [TxInput(genesis_hash, 0, b'')]
         change_output = TxOutput(genesis_block.outputs[0].value - deposit_amount, script, 0)
-        parents = [cast(bytes, tx.hash) for tx in genesis_txs]
+        parents = [tx.hash for tx in genesis_txs]
         timestamp = int(manager.reactor.seconds())
     else:
         total_reward = 0