refactor(feature-activation): improve usage check and signal verification

Author: glevco

hathor/builder/builder.py

@@ -74,7 +74,7 @@ class BuildArtifacts(NamedTuple):
 
 
 _VertexVerifiersBuilder: TypeAlias = Callable[
-    [HathorSettingsType, DifficultyAdjustmentAlgorithm, FeatureService],
+    [HathorSettingsType, DifficultyAdjustmentAlgorithm],
     VertexVerifiers
 ]
 
@@ -473,24 +473,20 @@ def _get_or_create_bit_signaling_service(self) -> BitSignalingService:
     def _get_or_create_verification_service(self) -> VerificationService:
         if self._verification_service is None:
             verifiers = self._get_or_create_vertex_verifiers()
-            self._verification_service = VerificationService(verifiers=verifiers)
+            feature_service = self._get_or_create_feature_service()
+            self._verification_service = VerificationService(verifiers=verifiers, feature_service=feature_service)
 
         return self._verification_service
 
     def _get_or_create_vertex_verifiers(self) -> VertexVerifiers:
         if self._vertex_verifiers is None:
             settings = self._get_or_create_settings()
-            feature_service = self._get_or_create_feature_service()
             daa = self._get_or_create_daa()
 
             if self._vertex_verifiers_builder:
-                self._vertex_verifiers = self._vertex_verifiers_builder(settings, daa, feature_service)
+                self._vertex_verifiers = self._vertex_verifiers_builder(settings, daa)
             else:
-                self._vertex_verifiers = VertexVerifiers.create_defaults(
-                    settings=settings,
-                    daa=daa,
-                    feature_service=feature_service,
-                )
+                self._vertex_verifiers = VertexVerifiers.create_defaults(settings=settings, daa=daa)
 
         return self._vertex_verifiers
 

hathor/builder/cli_builder.py

@@ -222,12 +222,8 @@ def create_manager(self, reactor: Reactor) -> HathorManager:
 
         daa = DifficultyAdjustmentAlgorithm(settings=settings, test_mode=test_mode)
 
-        vertex_verifiers = VertexVerifiers.create_defaults(
-            settings=settings,
-            daa=daa,
-            feature_service=self.feature_service
-        )
-        verification_service = VerificationService(verifiers=vertex_verifiers)
+        vertex_verifiers = VertexVerifiers.create_defaults(settings=settings, daa=daa)
+        verification_service = VerificationService(verifiers=vertex_verifiers, feature_service=self.feature_service)
 
         cpu_mining_service = CpuMiningService()
 

hathor/feature_activation/bit_signaling_service.py

@@ -58,6 +58,9 @@ def start(self) -> None:
         Log information related to bit signaling. Must be called after the storage is ready and migrations have
         been applied.
         """
+        if not self._feature_service.is_usage_enabled():
+            return
+
         best_block = self._tx_storage.get_best_block()
 
         self._warn_non_signaling_features(best_block)
@@ -74,6 +77,9 @@ def generate_signal_bits(self, *, block: Block, log: bool = False) -> int:
 
         Returns: a number that represents the signal bits in binary.
         """
+        if not self._feature_service.is_usage_enabled():
+            return 0
+
         signaling_features = self._get_signaling_features(block)
         signal_bits = 0
 

hathor/feature_activation/feature_service.py

@@ -25,10 +25,14 @@
     from hathor.transaction.storage import TransactionStorage
 
 
+@dataclass(frozen=True, slots=True)
+class FeatureActivationIsDisabled:
+    """Represent that Feature Activation is disabled and therefore the block signaling state cannot be calculated."""
+
+
 @dataclass(frozen=True, slots=True)
 class BlockIsSignaling:
     """Represent that a block is correctly signaling support for all currently mandatory features."""
-    pass
 
 
 @dataclass(frozen=True, slots=True)
@@ -37,7 +41,7 @@ class BlockIsMissingSignal:
     feature: Feature
 
 
-BlockSignalingState: TypeAlias = BlockIsSignaling | BlockIsMissingSignal
+BlockSignalingState: TypeAlias = FeatureActivationIsDisabled | BlockIsSignaling | BlockIsMissingSignal
 
 
 class FeatureService:
@@ -47,8 +51,13 @@ def __init__(self, *, feature_settings: FeatureSettings, tx_storage: 'Transactio
         self._feature_settings = feature_settings
         self._tx_storage = tx_storage
 
+    def is_usage_enabled(self) -> bool:
+        """Return whether Feature Activation usage is enabled."""
+        return self._feature_settings.enable_usage
+
     def is_feature_active(self, *, block: 'Block', feature: Feature) -> bool:
         """Returns whether a Feature is active at a certain block."""
+        assert self.is_usage_enabled()
         state = self.get_state(block=block, feature=feature)
 
         return state == FeatureState.ACTIVE
@@ -58,6 +67,9 @@ def is_signaling_mandatory_features(self, block: 'Block') -> BlockSignalingState
         Return whether a block is signaling features that are mandatory, that is, any feature currently in the
         MUST_SIGNAL phase.
         """
+        if not self.is_usage_enabled():
+            return FeatureActivationIsDisabled()
+
         bit_counts = block.get_feature_activation_bit_counts()
         height = block.get_height()
         offset_to_boundary = height % self._feature_settings.evaluation_interval
@@ -82,6 +94,7 @@ def is_signaling_mandatory_features(self, block: 'Block') -> BlockSignalingState
 
     def get_state(self, *, block: 'Block', feature: Feature) -> FeatureState:
         """Returns the state of a feature at a certain block. Uses block metadata to cache states."""
+        assert self.is_usage_enabled()
 
         # per definition, the genesis block is in the DEFINED state for all features
         if block.is_genesis:
@@ -190,6 +203,7 @@ def _calculate_new_state(
 
     def get_bits_description(self, *, block: 'Block') -> dict[Feature, FeatureDescription]:
         """Returns the criteria definition and feature state for all features at a certain block."""
+        assert self.is_usage_enabled()
         return {
             feature: FeatureDescription(
                 criteria=criteria,

hathor/manager.py

@@ -1061,7 +1061,7 @@ def tx_fully_validated(self, tx: BaseTransaction, *, quiet: bool) -> None:
 
     def _log_feature_states(self, vertex: BaseTransaction) -> None:
         """Log features states for a block. Used as part of the Feature Activation Phased Testing."""
-        if not self._settings.FEATURE_ACTIVATION.enable_usage or not isinstance(vertex, Block):
+        if not self._feature_service.is_usage_enabled() or not isinstance(vertex, Block):
             return
 
         feature_descriptions = self._feature_service.get_bits_description(block=vertex)

hathor/simulator/simulator.py

@@ -24,7 +24,6 @@
 from hathor.conf.get_settings import get_settings
 from hathor.conf.settings import HathorSettings
 from hathor.daa import DifficultyAdjustmentAlgorithm
-from hathor.feature_activation.feature_service import FeatureService
 from hathor.manager import HathorManager
 from hathor.p2p.peer_id import PeerId
 from hathor.simulator.clock import HeapClock, MemoryReactorHeapClock
@@ -243,17 +242,12 @@ def run(self,
         return True
 
 
-def _build_vertex_verifiers(
-    settings: HathorSettings,
-    daa: DifficultyAdjustmentAlgorithm,
-    feature_service: FeatureService
-) -> VertexVerifiers:
+def _build_vertex_verifiers(settings: HathorSettings, daa: DifficultyAdjustmentAlgorithm) -> VertexVerifiers:
     """
     A custom VertexVerifiers builder to be used by the simulator.
     """
     return VertexVerifiers.create(
         settings=settings,
         vertex_verifier=SimulatorVertexVerifier(settings=settings, daa=daa),
         daa=daa,
-        feature_service=feature_service,
     )

hathor/verification/block_verifier.py

@@ -12,9 +12,16 @@
 #  See the License for the specific language governing permissions and
 #  limitations under the License.
 
+from typing_extensions import assert_never
+
 from hathor.conf.settings import HathorSettings
 from hathor.daa import DifficultyAdjustmentAlgorithm
-from hathor.feature_activation.feature_service import BlockIsMissingSignal, BlockIsSignaling, FeatureService
+from hathor.feature_activation.feature_service import (
+    BlockIsMissingSignal,
+    BlockIsSignaling,
+    BlockSignalingState,
+    FeatureActivationIsDisabled,
+)
 from hathor.transaction import Block
 from hathor.transaction.exceptions import (
     BlockMustSignalError,
@@ -28,18 +35,16 @@
 
 
 class BlockVerifier:
-    __slots__ = ('_settings', '_daa', '_feature_service')
+    __slots__ = ('_settings', '_daa')
 
     def __init__(
         self,
         *,
         settings: HathorSettings,
         daa: DifficultyAdjustmentAlgorithm,
-        feature_service: FeatureService | None = None
     ) -> None:
         self._settings = settings
         self._daa = daa
-        self._feature_service = feature_service
 
     def verify_height(self, block: Block) -> None:
         """Validate that the block height is enough to confirm all transactions being confirmed."""
@@ -80,22 +85,14 @@ def verify_data(self, block: Block) -> None:
         if len(block.data) > self._settings.BLOCK_DATA_MAX_SIZE:
             raise TransactionDataError('block data has {} bytes'.format(len(block.data)))
 
-    def verify_mandatory_signaling(self, block: Block) -> None:
+    def verify_mandatory_signaling(self, signaling_state: BlockSignalingState) -> None:
         """Verify whether this block is missing mandatory signaling for any feature."""
-        if not self._settings.FEATURE_ACTIVATION.enable_usage:
-            return
-
-        assert self._feature_service is not None
-
-        signaling_state = self._feature_service.is_signaling_mandatory_features(block)
-
         match signaling_state:
-            case BlockIsSignaling():
+            case FeatureActivationIsDisabled() | BlockIsSignaling():
                 return
             case BlockIsMissingSignal(feature):
                 raise BlockMustSignalError(
                     f"Block must signal support for feature '{feature.value}' during MUST_SIGNAL phase."
                 )
             case _:
-                # TODO: This will be changed to assert_never() so mypy can check it.
-                raise NotImplementedError
+                assert_never(signaling_state)

hathor/verification/verification_service.py

@@ -14,6 +14,7 @@
 
 from typing_extensions import assert_never
 
+from hathor.feature_activation.feature_service import BlockSignalingState, FeatureService
 from hathor.profiler import get_cpu_profiler
 from hathor.transaction import BaseTransaction, Block, MergeMinedBlock, Transaction, TxVersion
 from hathor.transaction.token_creation_tx import TokenCreationTransaction
@@ -26,10 +27,11 @@
 
 
 class VerificationService:
-    __slots__ = ('verifiers', )
+    __slots__ = ('verifiers', '_feature_service')
 
-    def __init__(self, *, verifiers: VertexVerifiers) -> None:
+    def __init__(self, *, verifiers: VertexVerifiers, feature_service: FeatureService | None = None) -> None:
         self.verifiers = verifiers
+        self._feature_service = feature_service
 
     def validate_basic(self, vertex: BaseTransaction, *, skip_block_weight_verification: bool = False) -> bool:
         """ Run basic validations (all that are possible without dependencies) and update the validation state.
@@ -124,14 +126,17 @@ def verify(self, vertex: BaseTransaction, *, reject_locked_reward: bool = True)
         """Run all verifications. Raises on error.
 
         Used by `self.validate_full`. Should not modify the validation state."""
+        assert self._feature_service is not None
         # We assert with type() instead of isinstance() because each subclass has a specific branch.
         match vertex.version:
             case TxVersion.REGULAR_BLOCK:
                 assert type(vertex) is Block
-                self._verify_block(vertex)
+                signaling_state = self._feature_service.is_signaling_mandatory_features(vertex)
+                self._verify_block(vertex, signaling_state)
             case TxVersion.MERGE_MINED_BLOCK:
                 assert type(vertex) is MergeMinedBlock
-                self._verify_merge_mined_block(vertex)
+                signaling_state = self._feature_service.is_signaling_mandatory_features(vertex)
+                self._verify_merge_mined_block(vertex, signaling_state)
             case TxVersion.REGULAR_TRANSACTION:
                 assert type(vertex) is Transaction
                 self._verify_tx(vertex, reject_locked_reward=reject_locked_reward)
@@ -142,7 +147,7 @@ def verify(self, vertex: BaseTransaction, *, reject_locked_reward: bool = True)
                 assert_never(vertex.version)
 
     @cpu.profiler(key=lambda _, block: 'block-verify!{}'.format(block.hash.hex()))
-    def _verify_block(self, block: Block) -> None:
+    def _verify_block(self, block: Block, signaling_state: BlockSignalingState) -> None:
         """
             (1) confirms at least two pending transactions and references last block
             (2) solves the pow with the correct weight (done in HathorManager)
@@ -163,10 +168,10 @@ def _verify_block(self, block: Block) -> None:
 
         self.verifiers.block.verify_height(block)
 
-        self.verifiers.block.verify_mandatory_signaling(block)
+        self.verifiers.block.verify_mandatory_signaling(signaling_state)
 
-    def _verify_merge_mined_block(self, block: MergeMinedBlock) -> None:
-        self._verify_block(block)
+    def _verify_merge_mined_block(self, block: MergeMinedBlock, signaling_state: BlockSignalingState) -> None:
+        self._verify_block(block, signaling_state)
 
     @cpu.profiler(key=lambda _, tx: 'tx-verify!{}'.format(tx.hash.hex()))
     def _verify_tx(

hathor/verification/vertex_verifiers.py

@@ -16,7 +16,6 @@
 
 from hathor.conf.settings import HathorSettings
 from hathor.daa import DifficultyAdjustmentAlgorithm
-from hathor.feature_activation.feature_service import FeatureService
 from hathor.verification.block_verifier import BlockVerifier
 from hathor.verification.merge_mined_block_verifier import MergeMinedBlockVerifier
 from hathor.verification.token_creation_transaction_verifier import TokenCreationTransactionVerifier
@@ -33,13 +32,7 @@ class VertexVerifiers(NamedTuple):
     token_creation_tx: TokenCreationTransactionVerifier
 
     @classmethod
-    def create_defaults(
-        cls,
-        *,
-        settings: HathorSettings,
-        daa: DifficultyAdjustmentAlgorithm,
-        feature_service: FeatureService | None = None,
-    ) -> 'VertexVerifiers':
+    def create_defaults(cls, *, settings: HathorSettings, daa: DifficultyAdjustmentAlgorithm) -> 'VertexVerifiers':
         """
         Create a VertexVerifiers instance using the default verifier for each vertex type,
         from all required dependencies.
@@ -50,7 +43,6 @@ def create_defaults(
             settings=settings,
             vertex_verifier=vertex_verifier,
             daa=daa,
-            feature_service=feature_service
         )
 
     @classmethod
@@ -60,12 +52,11 @@ def create(
         settings: HathorSettings,
         vertex_verifier: VertexVerifier,
         daa: DifficultyAdjustmentAlgorithm,
-        feature_service: FeatureService | None = None,
     ) -> 'VertexVerifiers':
         """
         Create a VertexVerifiers instance using a custom vertex_verifier.
         """
-        block_verifier = BlockVerifier(settings=settings, daa=daa, feature_service=feature_service)
+        block_verifier = BlockVerifier(settings=settings, daa=daa)
         merge_mined_block_verifier = MergeMinedBlockVerifier()
         tx_verifier = TransactionVerifier(settings=settings, daa=daa)
         token_creation_tx_verifier = TokenCreationTransactionVerifier(settings=settings)