Merge pull request #2613 from mkalinin/execution-engine-update

Update execution engine calls
ethereum · Sep 24, 2021 · 940d6b1 · 940d6b1
2 parents 3f885c6 + 11840ce
commit 940d6b1
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Showing 6 changed files with 126 additions and 70 deletions.
diff --git a/setup.py b/setup.py
@@ -522,16 +522,23 @@ def get_pow_chain_head() -> PowBlock:
 
 class NoopExecutionEngine(ExecutionEngine):
 
-    def on_payload(self, execution_payload: ExecutionPayload) -> bool:
+    def execute_payload(self: ExecutionEngine, execution_payload: ExecutionPayload) -> bool:
         return True
 
-    def set_head(self, block_hash: Hash32) -> bool:
-        return True
+    def notify_consensus_validated(self: ExecutionEngine, block_hash: Hash32, valid: bool) -> None:
+        pass
 
-    def finalize_block(self, block_hash: Hash32) -> bool:
-        return True
+    def notify_forkchoice_updated(self: ExecutionEngine, head_block_hash: Hash32, finalized_block_hash: Hash32) -> None:
+        pass
+
+    def prepare_payload(self: ExecutionEngine,
+                        parent_hash: Hash32,
+                        timestamp: uint64,
+                        random: Bytes32,
+                        feeRecipient: ExecutionAddress) -> PayloadId:
+        raise NotImplementedError("no default block production")
 
-    def assemble_block(self, block_hash: Hash32, timestamp: uint64, random: Bytes32) -> ExecutionPayload:
+    def get_payload(self: ExecutionEngine, payload_id: PayloadId) -> ExecutionPayload:
         raise NotImplementedError("no default block production")
 
 

diff --git a/specs/merge/beacon-chain.md b/specs/merge/beacon-chain.md
@@ -31,7 +31,8 @@
     - [`compute_timestamp_at_slot`](#compute_timestamp_at_slot)
 - [Beacon chain state transition function](#beacon-chain-state-transition-function)
   - [Execution engine](#execution-engine)
-    - [`on_payload`](#on_payload)
+    - [`execute_payload`](#execute_payload)
+    - [`notify_consensus_validated`](#notify_consensus_validated)
   - [Block processing](#block-processing)
   - [Execution payload processing](#execution-payload-processing)
     - [`is_valid_gas_limit`](#is_valid_gas_limit)
@@ -53,6 +54,7 @@ This patch adds transaction execution to the beacon chain as part of the Merge f
 | - | - | - |
 | `OpaqueTransaction` | `ByteList[MAX_BYTES_PER_OPAQUE_TRANSACTION]` | a [typed transaction envelope](https://eips.ethereum.org/EIPS/eip-2718#opaque-byte-array-rather-than-an-rlp-array) structured as `TransactionType \|\| TransactionPayload` |
 | `Transaction` | `Union[OpaqueTransaction]` | a transaction |
+| `ExecutionAddress` | `Bytes20` | Address of account on the execution layer |
 
 ## Constants
 
@@ -158,7 +160,7 @@ class BeaconState(Container):
 class ExecutionPayload(Container):
     # Execution block header fields
     parent_hash: Hash32
-    coinbase: Bytes20  # 'beneficiary' in the yellow paper
+    coinbase: ExecutionAddress  # 'beneficiary' in the yellow paper
     state_root: Bytes32
     receipt_root: Bytes32  # 'receipts root' in the yellow paper
     logs_bloom: ByteVector[BYTES_PER_LOGS_BLOOM]
@@ -180,7 +182,7 @@ class ExecutionPayload(Container):
 class ExecutionPayloadHeader(Container):
     # Execution block header fields
     parent_hash: Hash32
-    coinbase: Bytes20
+    coinbase: ExecutionAddress
     state_root: Bytes32
     receipt_root: Bytes32
     logs_bloom: ByteVector[BYTES_PER_LOGS_BLOOM]
@@ -240,19 +242,38 @@ def compute_timestamp_at_slot(state: BeaconState, slot: Slot) -> uint64:
 The implementation-dependent `ExecutionEngine` protocol encapsulates the execution sub-system logic via:
 
 * a state object `self.execution_state` of type `ExecutionState`
-* a state transition function `self.on_payload` which mutates `self.execution_state`
+* a state transition function `self.execute_payload` which applies changes to the `self.execution_state`
+* a function `self.notify_consensus_validated` which signals that the beacon block containing the execution payload
+is valid with respect to the consensus rule set
 
-#### `on_payload`
+*Note*: `execute_payload` and `notify_consensus_validated` are functions accessed through the `EXECUTION_ENGINE` module which instantiates the `ExecutionEngine` protocol.
+
+The body of each of these functions is implementation dependent.
+The Engine API may be used to implement them with an external execution engine.
+
+#### `execute_payload`
 
 ```python
-def on_payload(self: ExecutionEngine, execution_payload: ExecutionPayload) -> bool:
+def execute_payload(self: ExecutionEngine, execution_payload: ExecutionPayload) -> bool:
     """
     Returns ``True`` iff ``execution_payload`` is valid with respect to ``self.execution_state``.
     """
     ...
 ```
 
-The above function is accessed through the `EXECUTION_ENGINE` module which instantiates the `ExecutionEngine` protocol.
+#### `notify_consensus_validated`
+
+```python
+def notify_consensus_validated(self: ExecutionEngine, block_hash: Hash32, valid: bool) -> None:
+    ...
+```
+
+The inputs to this function depend on the result of the state transition. A call to `notify_consensus_validated` must be made after the [`state_transition`](../phase0/beacon-chain.md#beacon-chain-state-transition-function) function finishes. The value of the `valid` parameter must be set as follows:
+
+* `True` if `state_transition` function call succeeds
+* `False` if `state_transition` function call fails
+
+*Note*: The call of the `notify_consensus_validated` function with `valid = True` maps on the `POS_CONSENSUS_VALIDATED` event defined in the [EIP-3675](https://eips.ethereum.org/EIPS/eip-3675#definitions).
 
 ### Block processing
 
@@ -309,7 +330,7 @@ def process_execution_payload(state: BeaconState, payload: ExecutionPayload, exe
     # Verify timestamp
     assert payload.timestamp == compute_timestamp_at_slot(state, state.slot)
     # Verify the execution payload is valid
-    assert execution_engine.on_payload(payload)
+    assert execution_engine.execute_payload(payload)
     # Cache execution payload header
     state.latest_execution_payload_header = ExecutionPayloadHeader(
         parent_hash=payload.parent_hash,

diff --git a/specs/merge/fork-choice.md b/specs/merge/fork-choice.md
@@ -10,8 +10,7 @@
 - [Introduction](#introduction)
 - [Protocols](#protocols)
   - [`ExecutionEngine`](#executionengine)
-    - [`set_head`](#set_head)
-    - [`finalize_block`](#finalize_block)
+    - [`notify_forkchoice_updated`](#notify_forkchoice_updated)
 - [Helpers](#helpers)
   - [`PowBlock`](#powblock)
   - [`get_pow_block`](#get_pow_block)
@@ -32,39 +31,25 @@ This is the modification of the fork choice according to the executable beacon c
 
 ### `ExecutionEngine`
 
-The following methods are added to the `ExecutionEngine` protocol for use in the fork choice:
-
-#### `set_head`
-
-Re-organizes the execution payload chain and corresponding state to make `block_hash` the head.
+*Note*: The `notify_forkchoice_updated` function is added to the `ExecutionEngine` protocol to signal the fork choice updates.
 
 The body of this function is implementation dependent.
-The Consensus API may be used to implement this with an external execution engine.
+The Engine API may be used to implement it with an external execution engine.
 
-```python
-def set_head(self: ExecutionEngine, block_hash: Hash32) -> bool:
-    """
-    Returns True if the ``block_hash`` was successfully set as head of the execution payload chain.
-    """
-    ...
-```
+#### `notify_forkchoice_updated`
 
-#### `finalize_block`
-
-Applies finality to the execution state: it irreversibly persists the chain of all execution payloads
-and corresponding state, up to and including `block_hash`.
-
-The body of this function is implementation dependent.
-The Consensus API may be used to implement this with an external execution engine.
+This function performs two actions *atomically*:
+* Re-organizes the execution payload chain and corresponding state to make `head_block_hash` the head.
+* Applies finality to the execution state: it irreversibly persists the chain of all execution payloads
+and corresponding state, up to and including `finalized_block_hash`.
 
 ```python
-def finalize_block(self: ExecutionEngine, block_hash: Hash32) -> bool:
-    """
-    Returns True if the data up to and including ``block_hash`` was successfully finalized.
-    """
+def notify_forkchoice_updated(self: ExecutionEngine, head_block_hash: Hash32, finalized_block_hash: Hash32) -> None:
     ...
 ```
 
+*Note*: The call of the `notify_forkchoice_updated` function maps on the `POS_FORKCHOICE_UPDATED` event defined in the [EIP-3675](https://eips.ethereum.org/EIPS/eip-3675#definitions).
+
 ## Helpers
 
 ### `PowBlock`

diff --git a/specs/merge/validator.md b/specs/merge/validator.md
@@ -10,13 +10,15 @@
 
 - [Introduction](#introduction)
 - [Prerequisites](#prerequisites)
+- [Custom types](#custom-types)
 - [Protocols](#protocols)
   - [`ExecutionEngine`](#executionengine)
-    - [`assemble_block`](#assemble_block)
+    - [`prepare_payload`](#prepare_payload)
+    - [`get_payload`](#get_payload)
 - [Beacon chain responsibilities](#beacon-chain-responsibilities)
   - [Block proposal](#block-proposal)
     - [Constructing the `BeaconBlockBody`](#constructing-the-beaconblockbody)
-      - [Execution Payload](#execution-payload)
+      - [ExecutionPayload](#executionpayload)
 
 <!-- END doctoc generated TOC please keep comment here to allow auto update -->
 <!-- /TOC -->
@@ -33,22 +35,48 @@ All behaviors and definitions defined in this document, and documents it extends
 All terminology, constants, functions, and protocol mechanics defined in the updated Beacon Chain doc of [The Merge](./beacon-chain.md) are requisite for this document and used throughout.
 Please see related Beacon Chain doc before continuing and use them as a reference throughout.
 
+## Custom types
+
+| Name | SSZ equivalent | Description |
+| - | - | - |
+| `PayloadId` | `uint64` | Identifier of a payload building process |
+
 ## Protocols
 
 ### `ExecutionEngine`
 
-The following methods are added to the `ExecutionEngine` protocol for use as a validator:
+*Note*: `prepare_payload` and `get_payload` functions are added to the `ExecutionEngine` protocol for use as a validator.
 
-#### `assemble_block`
+The body of each of these functions is implementation dependent.
+The Engine API may be used to implement them with an external execution engine.
 
-Produces a new instance of an execution payload, with the specified `timestamp`,
-on top of the execution payload chain tip identified by `block_hash`.
+#### `prepare_payload`
 
-The body of this function is implementation dependent.
-The Consensus API may be used to implement this with an external execution engine.
+Given the set of execution payload attributes, `prepare_payload` initiates a process of building an execution payload
+on top of the execution chain tip identified by `parent_hash`.
 
 ```python
-def assemble_block(self: ExecutionEngine, block_hash: Hash32, timestamp: uint64, random: Bytes32) -> ExecutionPayload:
+def prepare_payload(self: ExecutionEngine,
+                    parent_hash: Hash32,
+                    timestamp: uint64,
+                    random: Bytes32,
+                    fee_recipient: ExecutionAddress) -> PayloadId:
+    """
+    Return ``payload_id`` that is used to obtain the execution payload in a subsequent ``get_payload`` call.
+    """
+    ...
+```
+
+#### `get_payload`
+
+Given the `payload_id`, `get_payload` returns the most recent version of the execution payload that
+has been built since the corresponding call to `prepare_payload` method.
+
+```python
+def get_payload(self: ExecutionEngine, payload_id: PayloadId) -> ExecutionPayload:
+    """
+    Return ``execution_payload`` object.
+    """
     ...
 ```
 
@@ -60,9 +88,14 @@ All validator responsibilities remain unchanged other than those noted below. Na
 
 #### Constructing the `BeaconBlockBody`
 
-##### Execution Payload
+##### ExecutionPayload
+
+To obtain an execution payload, a block proposer building a block on top of a `state` must take the following actions:
 
-* Set `block.body.execution_payload = get_execution_payload(state, execution_engine, pow_chain)` where:
+1. Set `payload_id = prepare_execution_payload(state, pow_chain, fee_recipient, execution_engine)`, where:
+    * `state` is the state object after applying `process_slots(state, slot)` transition to the resulting state of the parent block processing
+    * `pow_chain` is a list that abstractly represents all blocks in the PoW chain
+    * `fee_recipient` is the value suggested to be used for the `coinbase` field of the execution payload
 
 ```python
 def get_pow_block_at_total_difficulty(total_difficulty: uint256, pow_chain: Sequence[PowBlock]) -> Optional[PowBlock]:
@@ -75,27 +108,37 @@ def get_pow_block_at_total_difficulty(total_difficulty: uint256, pow_chain: Sequ
     return None
 
 
-def produce_execution_payload(state: BeaconState,
-                              parent_hash: Hash32,
-                              execution_engine: ExecutionEngine) -> ExecutionPayload:
-    timestamp = compute_timestamp_at_slot(state, state.slot)
-    randao_mix = get_randao_mix(state, get_current_epoch(state))
-    return execution_engine.assemble_block(parent_hash, timestamp, randao_mix)
-
-
-def get_execution_payload(state: BeaconState,
-                          execution_engine: ExecutionEngine,
-                          pow_chain: Sequence[PowBlock]) -> ExecutionPayload:
+def prepare_execution_payload(state: BeaconState,
+                              pow_chain: Sequence[PowBlock],
+                              fee_recipient: ExecutionAddress,
+                              execution_engine: ExecutionEngine) -> Optional[PayloadId]:
     if not is_merge_complete(state):
         terminal_pow_block = get_pow_block_at_total_difficulty(TERMINAL_TOTAL_DIFFICULTY, pow_chain)
         if terminal_pow_block is None:
-            # Pre-merge, empty payload
-            return ExecutionPayload()
+            # Pre-merge, no prepare payload call is needed
+            return None
         else:
             # Signify merge via producing on top of the last PoW block
-            return produce_execution_payload(state, terminal_pow_block.block_hash, execution_engine)
+            parent_hash = terminal_pow_block.block_hash
+    else:
+        # Post-merge, normal payload
+        parent_hash = state.latest_execution_payload_header.block_hash
 
-    # Post-merge, normal payload
-    parent_hash = state.latest_execution_payload_header.block_hash
-    return produce_execution_payload(state, parent_hash, execution_engine)
+    timestamp = compute_timestamp_at_slot(state, state.slot)
+    random = get_randao_mix(state, get_current_epoch(state))
+    return execution_engine.prepare_payload(parent_hash, timestamp, random, fee_recipient)
 ```
+
+2. Set `block.body.execution_payload = get_execution_payload(payload_id, execution_engine)`, where:
+
+```python
+def get_execution_payload(payload_id: Optional[PayloadId], execution_engine: ExecutionEngine) -> ExecutionPayload:
+    if payload_id is None:
+        # Pre-merge, empty payload
+        return ExecutionPayload()
+    else:
+        return execution_engine.get_payload(payload_id)
+```
+
+*Note*: It is recommended for a validator to call `prepare_execution_payload` as soon as input parameters become known,
+and make subsequent calls to this function when any of these parameters gets updated.
diff --git a/tests/core/pyspec/eth2spec/test/helpers/execution_payload.py b/tests/core/pyspec/eth2spec/test/helpers/execution_payload.py
@@ -11,7 +11,7 @@ def build_empty_execution_payload(spec, state, randao_mix=None):
 
     payload = spec.ExecutionPayload(
         parent_hash=latest.block_hash,
-        coinbase=spec.Bytes20(),
+        coinbase=spec.ExecutionAddress(),
         state_root=latest.state_root,  # no changes to the state
         receipt_root=b"no receipts here" + b"\x00" * 16,  # TODO: root of empty MPT may be better.
         logs_bloom=spec.ByteVector[spec.BYTES_PER_LOGS_BLOOM](),  # TODO: zeroed logs bloom for empty logs ok?

diff --git a/tests/core/pyspec/eth2spec/test/merge/block_processing/test_process_execution_payload.py b/tests/core/pyspec/eth2spec/test/merge/block_processing/test_process_execution_payload.py
@@ -25,7 +25,7 @@ def run_execution_payload_processing(spec, state, execution_payload, valid=True,
     called_new_block = False
 
     class TestEngine(spec.NoopExecutionEngine):
-        def on_payload(self, payload) -> bool:
+        def execute_payload(self, payload) -> bool:
             nonlocal called_new_block, execution_valid
             called_new_block = True
             assert payload == execution_payload