Make VC driver for signing process

Author: adiasg

figures/dv-attestation-production-process.png

@@ -6,6 +6,10 @@
     SignedBeaconBlock,
 )
 
+from .networking import (
+    broadcast_threshold_signed_attestation,
+    broadcast_threshold_signed_block
+)
 from .utils.types import (
     AttestationDuty,
     BLSSignature,
@@ -66,18 +70,42 @@ def bn_submit_block(block: SignedBeaconBlock) -> None:
 
 # Validator Client Interface
 
-
-def vc_sign_attestation(attestation_data: AttestationData, attestation_duty: AttestationDuty) -> Attestation:
-    """Returns a signed attestations that is constructed using the given attestation data & attestation duty.
-    This endpoint does not exist in beacon-APIs.
+"""
+The VC is connected to the BN through the DVC. The DVC pretends to be a proxy for the BN, except
+when:
+- VC asks for new attestation data or blocks using the following methods:
+    - https://ethereum.github.io/beacon-APIs/#/ValidatorRequiredApi/produceAttestationData
+    - https://ethereum.github.io/beacon-APIs/#/ValidatorRequiredApi/produceBlockV2
+- VC submits new threshold signed attestations or blocks using the following methods:
+    - https://ethereum.github.io/beacon-APIs/#/Beacon/submitPoolAttestations
+    - https://ethereum.github.io/beacon-APIs/#/ValidatorRequiredApi/publishBlock
+"""
+
+def cache_attestation_data_for_vc(attestation_data: AttestationData, attestation_duty: AttestationDuty) -> None:
+    """Cache attestation data to provide to VC when it seeks new attestation data using the following method:
+    https://ethereum.github.io/beacon-APIs/#/ValidatorRequiredApi/produceAttestationData
     """
-    # See note about attestation construction here:
-    # https://github.com/ethereum/beacon-APIs/blame/05c1bc142e1a3fb2a63c79098743776241341d08/validator-flow.md#L35-L37
     pass
 
 
-def vc_sign_block(block: BeaconBlock, proposer_duty: ProposerDuty) -> SignedBeaconBlock:
-    """Returns a signed beacon block using the validator index given in the proposer duty.
-    This endpoint does not exist in beacon-APIs.
+def cache_block_for_vc(block: BeaconBlock, proposer_duty: ProposerDuty) -> None:
+    """Cache block to provide to VC when it seeks a new block using the following method:
+    https://ethereum.github.io/beacon-APIs/#/ValidatorRequiredApi/produceAttestationData
     """
     pass
+
+
+def capture_threshold_signed_attestation(threshold_signed_attestation: Attestation) -> None:
+    """Captures a threshold signed attestation provided by the VC and starts the recombination process to
+    construct a complete signed attestation to submit to the BN. The VC submits the attestation using the following method:
+    https://ethereum.github.io/beacon-APIs/#/Beacon/submitPoolAttestations
+    """
+    broadcast_threshold_signed_attestation(threshold_signed_attestation)
+
+
+def capture_threhold_signed_block(threshold_signed_block: SignedBeaconBlock) -> None:
+    """Captures a threshold signed block provided by the VC and starts the recombination process to
+    construct a complete signed block to submit to the BN. The VC submits the block using the following method:
+    https://ethereum.github.io/beacon-APIs/#/ValidatorRequiredApi/publishBlock
+    """
+    broadcast_threshold_signed_block(threshold_signed_block)

figures/dv-block-production-process.png

@@ -3,21 +3,21 @@
     List,
 )
 
+from eth2spec.phase0.mainnet import Attestation
+
 from .eth_node_interface import (
     AttestationDuty,
+    ProposerDuty,
     bn_submit_attestation,
     bn_submit_block,
-    ProposerDuty,
-    vc_sign_attestation,
-    vc_sign_block,
+    cache_attestation_data_for_vc,
+    cache_block_for_vc,
 )
 from .consensus import (
     consensus_on_attestation,
     consensus_on_block,
 )
 from .networking import (
-    broadcast_threshold_signed_attestation,
-    broadcast_threshold_signed_block,
     construct_signed_attestation,
     construct_signed_block,
     listen_for_threshold_signed_attestations,
@@ -81,11 +81,9 @@ def serve_attestation_duty(attestation_duty: AttestationDuty) -> None:
     # Only a single consensus_on_attestation instance should be
     # running at any given time
     attestation_data = consensus_on_attestation(attestation_duty)
-    # Threshold sign attestation from local VC
-    threshold_signed_attestation = vc_sign_attestation(attestation_data, attestation_duty)
     # Release lock on consensus_on_attestation here.
-    # Broadcast threshold signed attestation
-    broadcast_threshold_signed_attestation(threshold_signed_attestation)
+    # Cache decided attestation data value to provide to VC
+    cache_block_for_vc(attestation_data, attestation_duty)
 
 
 def serve_proposer_duty(proposer_duty: ProposerDuty) -> None:
@@ -102,12 +100,9 @@ def serve_proposer_duty(proposer_duty: ProposerDuty) -> None:
     # Only a single consensus_on_block instance should be
     # running at any given time
     block = consensus_on_block(proposer_duty)
-
-    # Threshold sign block from local VC
-    threshold_signed_block = vc_sign_block(block, proposer_duty)
     # Release lock on consensus_on_block here.
-    # Broadcast threshold signed block
-    broadcast_threshold_signed_block(threshold_signed_block)
+    # Cache decided block value to provide to VC
+    cache_attestation_data_for_vc(block, proposer_duty)
 
 
 def threshold_attestation_combination() -> None: