Merge branch 'dev' into fork-choice-epoch

scripts/build_spec.py

@@ -25,8 +25,6 @@ from dataclasses import (
     field,
 )
 
-from copy import deepcopy
-
 from eth2spec.utils.ssz.ssz_impl import (
     hash_tree_root,
     signing_root,
@@ -60,8 +58,6 @@ from dataclasses import (
     field,
 )
 
-from copy import deepcopy
-
 from eth2spec.utils.ssz.ssz_impl import (
     hash_tree_root,
     signing_root,

specs/core/0_fork-choice.md

@@ -47,10 +47,11 @@ The head block root associated with a `store` is defined as `get_head(store)`. A
 
 *Notes*:
 
-1) **Leap seconds**: Slots will last `SECONDS_PER_SLOT + 1` or `SECONDS_PER_SLOT - 1` seconds around leap seconds.
+1) **Leap seconds**: Slots will last `SECONDS_PER_SLOT + 1` or `SECONDS_PER_SLOT - 1` seconds around leap seconds. This is automatically handled by [UNIX time](https://en.wikipedia.org/wiki/Unix_time).
 2) **Honest clocks**: Honest nodes are assumed to have clocks synchronized within `SECONDS_PER_SLOT` seconds of each other.
 3) **Eth1 data**: The large `ETH1_FOLLOW_DISTANCE` specified in the [honest validator document](https://github.com/ethereum/eth2.0-specs/blob/dev/specs/validator/0_beacon-chain-validator.md) should ensure that `state.latest_eth1_data` of the canonical Ethereum 2.0 chain remains consistent with the canonical Ethereum 1.0 chain. If not, emergency manual intervention will be required.
 4) **Manual forks**: Manual forks may arbitrarily change the fork choice rule but are expected to be enacted at epoch transitions, with the fork details reflected in `state.fork`.
+5) **Implementation**: The implementation found in this specification is constructed for ease of understanding rather than for optimization in computation, space, or any other resource. A number of optimized alternatives can be found [here](https://github.com/protolambda/lmd-ghost).
 
 ### Helpers
 
@@ -95,7 +96,13 @@ class Store(object):
 def get_genesis_store(genesis_state: BeaconState) -> Store:
     genesis_block = BeaconBlock(state_root=hash_tree_root(genesis_state))
     root = signing_root(genesis_block)
-    return Store(blocks={root: genesis_block}, states={root: genesis_state}, justified_root=root, finalized_root=root)
+    return Store(
+        blocks={root: genesis_block},
+        states={root: genesis_state},
+        time=genesis_state.genesis_time,
+        justified_root=root,
+        finalized_root=root,
+    )
 ```
 
 #### `get_ancestor`
@@ -150,16 +157,17 @@ def on_tick(store: Store, time: int) -> None:
 
 ```python
 def on_block(store: Store, block: BeaconBlock) -> None:
+    # Make a copy of the state to avoid mutability issues
+    parent_block = store.blocks[block.parent_root]
+    pre_state = store.states[RootSlot(signing_root(parent_block), parent_block.slot)].copy()
+    # Blocks cannot be in the future. If they are, their consideration must be delayed until the are in the past.
+    assert store.time >= pre_state.genesis_time + block.slot * SECONDS_PER_SLOT
     # Add new block to the store
     store.blocks[signing_root(block)] = block
     # Check block is a descendant of the finalized block
     assert get_ancestor(store, signing_root(block), store.blocks[store.finalized_root].slot) == store.finalized_root
     # Check that block is later than the finalized epoch slot
     assert blocks.slot > get_epoch_start_slot(store.finalized_epoch)
-    # Check block slot against Unix time
-    parent_block = store.blocks[block.parent_root]
-    pre_state = deepcopy(store.states[RootSlot(signing_root(parent_block), parent_block.slot)])
-    assert store.time >= pre_state.genesis_time + block.slot * SECONDS_PER_SLOT
     # Check the block is valid and compute the post-state
     state = state_transition(pre_state, block)
     # Add new state for this block to the store

test_libs/pyspec/eth2spec/test/test_fork_choice.py

@@ -2,7 +2,7 @@ from typing import List
 
 from eth2spec.utils.ssz.ssz_impl import signing_root, hash_tree_root
 
-from eth2spec.test.context import with_all_phases, spec_state_test
+from eth2spec.test.context import with_all_phases, with_state, bls_switch
 
 from eth2spec.test.helpers.block import build_empty_block_for_next_slot
 from eth2spec.test.helpers.attestations import get_valid_attestation
@@ -10,10 +10,10 @@ from eth2spec.test.helpers.state import next_slot
 
 
 @with_all_phases
-@spec_state_test
+@with_state
+@bls_switch
 def test_basic(spec, state):
     state.latest_block_header = spec.BeaconBlockHeader(body_root=hash_tree_root(spec.BeaconBlockBody()))
-    yield 'pre', state
 
     # Initialization
     store = spec.get_genesis_store(state)
@@ -36,17 +36,14 @@ def test_basic(spec, state):
 
     spec.on_block(store, block)
     assert store.blocks[signing_root(block)] == block
-    yield 'blocks', blocks, List[spec.BeaconBlock]
 
     # TODO: add tests for justified_root and finalized_root
-    yield 'post', state
 
 
 @with_all_phases
-@spec_state_test
+@with_state
+@bls_switch
 def test_on_attestation(spec, state):
-    yield 'pre', state
-
     store = spec.get_genesis_store(state)
     time = 100
     spec.on_tick(store, time)
@@ -54,7 +51,6 @@ def test_on_attestation(spec, state):
     next_slot(spec, state)
 
     attestation = get_valid_attestation(spec, state, slot=1)
-    yield 'attestation', attestation
     indexed_attestation = spec.convert_to_indexed(state, attestation)
     spec.on_attestation(store, attestation)
     assert (
@@ -64,5 +60,3 @@ def test_on_attestation(spec, state):
             root=attestation.data.target_root,
         )
     )
-
-    yield 'post', state

test_libs/pyspec/eth2spec/utils/ssz/ssz_typing.py

@@ -1,3 +1,4 @@
+import copy
 from types import GeneratorType
 from typing import (
     List,
@@ -151,6 +152,9 @@ class Container(object):
     def __hash__(self):
         return hash(self.hash_tree_root())
 
+    def copy(self):
+        return copy.deepcopy(self)
+
     @classmethod
     def get_fields_dict(cls):
         return dict(cls.__annotations__)