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 application-layer 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
Transition
Name | Value |
---|---|
TRANSITION_TOTAL_DIFFICULTY |
TBD |
Execution
Name | Value |
---|---|
MAX_BYTES_PER_OPAQUE_TRANSACTION |
uint64(2**20) (= 1,048,576) |
MAX_APPLICATION_TRANSACTIONS |
uint64(2**14) (= 16,384) |
BYTES_PER_LOGS_BLOOM |
uint64(2**8) (= 256) |
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 application_payload
.
class BeaconBlockBody(phase0.BeaconBlockBody):
application_payload: ApplicationPayload # [New in Merge] application payload
BeaconState
Note: BeaconState
fields remain unchanged other than addition of latest_application_block_header
.
class BeaconState(phase0.BeaconState):
# Application-layer
latest_application_block_header: ApplicationBlockHeader # [New in Merge]
New containers
ApplicationPayload
The application payload included in a BeaconBlockBody
.
class ApplicationPayload(Container):
block_hash: Bytes32 # Hash of application block
parent_hash: Bytes32
coinbase: Bytes20
state_root: Bytes32
number: uint64
gas_limit: uint64
gas_used: uint64
receipt_root: Bytes32
logs_bloom: ByteVector[BYTES_PER_LOGS_BLOOM]
transactions: List[OpaqueTransaction, MAX_APPLICATION_TRANSACTIONS]
ApplicationBlockHeader
The application block header included in a BeaconState
.
Note: Holds application payload data without transaction list.
class ApplicationBlockHeader(Container):
block_hash: Bytes32 # Hash of application block
parent_hash: Bytes32
coinbase: Bytes20
state_root: Bytes32
number: uint64
gas_limit: uint64
gas_used: 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) -> boolean:
return state.latest_application_block_header.block_hash != Bytes32()
is_transition_block
def is_transition_block(state: BeaconState, block_body: BeaconBlockBody) -> boolean:
return state.latest_application_block_header.block_hash == Bytes32() and block_body.application_payload.block_hash != Bytes32()
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)
process_application_payload(state, block.body) # [New in Merge]
Application payload processing
get_application_state
Note: ApplicationState
class is an abstract class representing ethereum application state.
Let get_application_state(application_state_root: Bytes32) -> ApplicationState
be the function that given the root hash returns a copy of ethereum application state.
The body of the function is implementation dependent.
application_state_transition
Let application_state_transition(application_state: ApplicationState, application_payload: ApplicationPayload) -> None
be the transition function of ethereum application state.
The body of the function is implementation dependent.
Note: application_state_transition
must throw AssertionError
if either the transition itself or one of the post-transition verifications has failed.
process_application_payload
def process_application_payload(state: BeaconState, body: BeaconBlockBody) -> None:
"""
Note: This function is designed to be able to be run in parallel with the other `process_block` sub-functions
"""
if not is_transition_completed(state):
assert body.application_payload == ApplicationPayload()
return
if not is_transition_block(state, body):
assert body.application_payload.parent_hash == state.latest_application_block_header.block_hash
assert body.application_payload.number == state.latest_application_block_header.number + 1
application_state = get_application_state(state.latest_application_block_header.state_root)
application_state_transition(application_state, body.application_payload)
state.latest_application_block_header = ApplicationBlockHeader(
block_hash=application_payload.block_hash,
parent_hash=application_payload.parent_hash,
coinbase=application_payload.coinbase,
state_root=application_payload.state_root,
number=application_payload.number,
gas_limit=application_payload.gas_limit,
gas_used=application_payload.gas_used,
receipt_root=application_payload.receipt_root,
logs_bloom=application_payload.logs_bloom,
transactions_root=hash_tree_root(application_payload.transactions),
)