7.0 KiB
Ethereum 2.0 The Merge
Warning: This document is currently based on Phase 0 but will be rebased to Altair once the latter is shipped.
Notice: This document is a work-in-progress for researchers and implementers.
Table of contents
Introduction
This is a patch implementing the executable beacon chain proposal. It enshrines transaction execution and validity as a first class citizen at the core of the beacon chain.
Custom types
We define the following Python custom types for type hinting and readability:
Name | SSZ equivalent | Description |
---|---|---|
OpaqueTransaction |
ByteList[MAX_BYTES_PER_OPAQUE_TRANSACTION] |
a byte-list containing a single typed transaction envelope structured as TransactionType || TransactionPayload |
Constants
Execution
Name | Value |
---|---|
MAX_BYTES_PER_OPAQUE_TRANSACTION |
uint64(2**20) (= 1,048,576) |
MAX_EXECUTION_TRANSACTIONS |
uint64(2**14) (= 16,384) |
BYTES_PER_LOGS_BLOOM |
uint64(2**8) (= 256) |
Configuration
Warning: this configuration is not definitive.
Name | Value |
---|---|
MERGE_FORK_VERSION |
Version('0x02000000') |
MERGE_FORK_EPOCH |
Epoch(18446744073709551615) TBD |
TRANSITION_TOTAL_DIFFICULTY |
TBD |
Containers
Extended containers
Note: Extended SSZ containers inherit all fields from the parent in the original order and append any additional fields to the end.
BeaconBlockBody
Note: BeaconBlockBody
fields remain unchanged other than the addition of execution_payload
.
class BeaconBlockBody(phase0.BeaconBlockBody):
execution_payload: ExecutionPayload # [New in Merge]
BeaconState
Note: BeaconState
fields remain unchanged other than addition of latest_execution_payload_header
.
class BeaconState(phase0.BeaconState):
# Execution-layer
latest_execution_payload_header: ExecutionPayloadHeader # [New in Merge]
New containers
ExecutionPayload
The execution payload included in a BeaconBlockBody
.
class ExecutionPayload(Container):
block_hash: Hash32 # Hash of execution block
parent_hash: Hash32
coinbase: Bytes20
state_root: Bytes32
number: uint64
gas_limit: uint64
gas_used: uint64
timestamp: uint64
receipt_root: Bytes32
logs_bloom: ByteVector[BYTES_PER_LOGS_BLOOM]
transactions: List[OpaqueTransaction, MAX_EXECUTION_TRANSACTIONS]
ExecutionPayloadHeader
The execution payload header included in a BeaconState
.
Note: Holds execution payload data without transaction bodies.
class ExecutionPayloadHeader(Container):
block_hash: Hash32 # Hash of execution block
parent_hash: Hash32
coinbase: Bytes20
state_root: Bytes32
number: uint64
gas_limit: uint64
gas_used: uint64
timestamp: uint64
receipt_root: Bytes32
logs_bloom: ByteVector[BYTES_PER_LOGS_BLOOM]
transactions_root: Root
Helper functions
Misc
is_transition_completed
def is_transition_completed(state: BeaconState) -> bool:
return state.latest_execution_payload_header != ExecutionPayloadHeader()
is_transition_block
def is_transition_block(state: BeaconState, block: BeaconBlock) -> bool:
return not is_transition_completed(state) and block.body.execution_payload != ExecutionPayload()
compute_time_at_slot
Note: This function is unsafe with respect to overflows and underflows.
def compute_time_at_slot(state: BeaconState, slot: Slot) -> uint64:
slots_since_genesis = slot - GENESIS_SLOT
return uint64(state.genesis_time + slots_since_genesis * SECONDS_PER_SLOT)
Block processing
def process_block(state: BeaconState, block: BeaconBlock) -> None:
process_block_header(state, block)
process_randao(state, block.body)
process_eth1_data(state, block.body)
process_operations(state, block.body)
# Pre-merge, skip execution payload processing
if is_transition_completed(state) or is_transition_block(state, block):
process_execution_payload(state, block.body.execution_payload) # [New in Merge]
Execution payload processing
verify_execution_state_transition
Let verify_execution_state_transition(execution_payload: ExecutionPayload) -> bool
be the function that verifies given ExecutionPayload
with respect to execution state transition.
The body of the function is implementation dependent.
process_execution_payload
def process_execution_payload(state: BeaconState, execution_payload: ExecutionPayload) -> None:
"""
Note: This function is designed to be able to be run in parallel with the other `process_block` sub-functions
"""
if is_transition_completed(state):
assert execution_payload.parent_hash == state.latest_execution_payload_header.block_hash
assert execution_payload.number == state.latest_execution_payload_header.number + 1
assert execution_payload.timestamp == compute_time_at_slot(state, state.slot)
assert verify_execution_state_transition(execution_payload)
state.latest_execution_payload_header = ExecutionPayloadHeader(
block_hash=execution_payload.block_hash,
parent_hash=execution_payload.parent_hash,
coinbase=execution_payload.coinbase,
state_root=execution_payload.state_root,
number=execution_payload.number,
gas_limit=execution_payload.gas_limit,
gas_used=execution_payload.gas_used,
timestamp=execution_payload.timestamp,
receipt_root=execution_payload.receipt_root,
logs_bloom=execution_payload.logs_bloom,
transactions_root=hash_tree_root(execution_payload.transactions),
)