Merge pull request #1971 from ethereum/hwwhww/phase-1-fork-slot

Rework initial shard slot (`PHASE_1_FORK_SLOT`)

configs/README.md

@@ -15,7 +15,7 @@ Over time, the need to sync an older state may be deprecated.
 In this case, the prefix on the new constant may be removed, and the old constant will keep a special name before completely being removed.
 
 A previous iteration of forking made use of "timelines", but this collides with the definitions used in the spec (constants for special forking slots, etc.), and was not integrated sufficiently in any of the spec tools or implementations.
-Instead, the config essentially doubles as fork definition now, e.g. changing the value for `PHASE_1_GENESIS_SLOT` changes the fork.
+Instead, the config essentially doubles as fork definition now, e.g. changing the value for `PHASE_1_FORK_SLOT` changes the fork.
 
 Another reason to prefer forking through constants is the ability to program a forking moment based on context, instead of being limited to a static slot number.
 

configs/mainnet/phase1.yaml

@@ -5,7 +5,7 @@
 # ---------------------------------------------------------------
 PHASE_1_FORK_VERSION: 0x01000000
 # [STUB]
-PHASE_1_GENESIS_SLOT: 32
+PHASE_1_FORK_SLOT: 0
 INITIAL_ACTIVE_SHARDS: 64
 
 

configs/minimal/phase1.yaml

@@ -5,8 +5,8 @@
 # ---------------------------------------------------------------
 # [customized] for testnet distinction
 PHASE_1_FORK_VERSION: 0x01000001
-# [customized] for testing
-PHASE_1_GENESIS_SLOT: 8
+# [STUB]
+PHASE_1_FORK_SLOT: 0
 # [customized] reduced for testing
 INITIAL_ACTIVE_SHARDS: 2
 

specs/phase1/beacon-chain.md

@@ -760,20 +760,24 @@ def validate_attestation(state: BeaconState, attestation: Attestation) -> None:
     committee = get_beacon_committee(state, data.slot, data.index)
     assert len(attestation.aggregation_bits) == len(committee)
 
-    if attestation.data.target.epoch == get_current_epoch(state):
-        assert attestation.data.source == state.current_justified_checkpoint
+    if data.target.epoch == get_current_epoch(state):
+        assert data.source == state.current_justified_checkpoint
     else:
-        assert attestation.data.source == state.previous_justified_checkpoint
+        assert data.source == state.previous_justified_checkpoint
 
     # Type 1: on-time attestations
-    if is_on_time_attestation(state, attestation.data):
+    if is_on_time_attestation(state, data):
         # Correct parent block root
         assert data.beacon_block_root == get_block_root_at_slot(state, compute_previous_slot(state.slot))
         # Correct shard number
-        shard = compute_shard_from_committee_index(state, attestation.data.index, attestation.data.slot)
-        assert attestation.data.shard == shard
-        # On-time attestations should have a non-empty shard transition root
-        assert attestation.data.shard_transition_root != hash_tree_root(ShardTransition())
+        shard = compute_shard_from_committee_index(state, data.index, data.slot)
+        assert data.shard == shard
+        # NOTE: We currently set `PHASE_1_FORK_SLOT` to `GENESIS_SLOT` for test vectors.
+        if data.slot > GENESIS_SLOT:
+            # On-time attestations should have a non-empty shard transition root
+            assert data.shard_transition_root != hash_tree_root(ShardTransition())
+        else:
+            assert data.shard_transition_root == hash_tree_root(ShardTransition())
     # Type 2: no shard transition
     else:
         # Ensure delayed attestation
@@ -811,7 +815,7 @@ def process_attestation(state: BeaconState, attestation: Attestation) -> None:
 ```python
 def apply_shard_transition(state: BeaconState, shard: Shard, transition: ShardTransition) -> None:
     # TODO: only need to check it once when phase 1 starts
-    assert state.slot > PHASE_1_GENESIS_SLOT
+    assert state.slot > PHASE_1_FORK_SLOT
 
     # Correct data root count
     offset_slots = get_offset_slots(state, shard)
@@ -976,8 +980,11 @@ def verify_empty_shard_transition(state: BeaconState, shard_transitions: Sequenc
 def process_shard_transitions(state: BeaconState,
                               shard_transitions: Sequence[ShardTransition],
                               attestations: Sequence[Attestation]) -> None:
-    # Process crosslinks
-    process_crosslinks(state, shard_transitions, attestations)
+    # NOTE: We currently set `PHASE_1_FORK_SLOT` to `GENESIS_SLOT` for test vectors.
+    if compute_previous_slot(state.slot) > GENESIS_SLOT:
+        # Process crosslinks
+        process_crosslinks(state, shard_transitions, attestations)
+
     # Verify the empty proposal shard states
     assert verify_empty_shard_transition(state, shard_transitions)
 ```

specs/phase1/phase1-fork.md

@@ -35,18 +35,18 @@ Warning: this configuration is not definitive.
 | Name | Value |
 | - | - |
 | `PHASE_1_FORK_VERSION` | `Version('0x01000000')` |
-| `PHASE_1_GENESIS_SLOT` | `2**5` **TBD** |
+| `PHASE_1_FORK_SLOT` | `Slot(0)` **TBD** |
 | `INITIAL_ACTIVE_SHARDS` | `2**6` (= 64) |
 
 ## Fork to Phase 1
 
 ### Fork trigger
 
-TBD. Social consensus, along with state conditions such as epoch boundary, finality, deposits, active validator count, etc. may be part of the decision process to trigger the fork. For now we assume the condition will be triggered at slot `PHASE_1_GENESIS_SLOT`, where `PHASE_1_GENESIS_SLOT % SLOTS_PER_EPOCH == 0`.
+TBD. Social consensus, along with state conditions such as epoch boundary, finality, deposits, active validator count, etc. may be part of the decision process to trigger the fork. For now we assume the condition will be triggered at slot `PHASE_1_FORK_SLOT`, where `PHASE_1_FORK_SLOT % SLOTS_PER_EPOCH == 0`.
 
 ### Upgrading the state
 
-After `process_slots` of Phase 0 finishes, if `state.slot == PHASE_1_GENESIS_SLOT`, an irregular state change is made to upgrade to Phase 1.
+After `process_slots` of Phase 0 finishes, if `state.slot == PHASE_1_FORK_SLOT`, an irregular state change is made to upgrade to Phase 1.
 
 ```python
 def upgrade_to_phase1(pre: phase0.BeaconState) -> BeaconState:
@@ -102,7 +102,7 @@ def upgrade_to_phase1(pre: phase0.BeaconState) -> BeaconState:
         current_epoch_start_shard=Shard(0),
         shard_states=List[ShardState, MAX_SHARDS](
             ShardState(
-                slot=pre.slot,
+                slot=compute_previous_slot(pre.slot),
                 gasprice=MIN_GASPRICE,
                 latest_block_root=Root(),
             ) for i in range(INITIAL_ACTIVE_SHARDS)

specs/phase1/shard-fork-choice.md

@@ -48,7 +48,7 @@ def get_forkchoice_shard_store(anchor_state: BeaconState, shard: Shard) -> Shard
         shard=shard,
         signed_blocks={
             anchor_state.shard_states[shard].latest_block_root: SignedShardBlock(
-                message=ShardBlock(slot=anchor_state.slot, shard=shard)
+                message=ShardBlock(slot=compute_previous_slot(anchor_state.slot), shard=shard)
             )
         },
         block_states={anchor_state.shard_states[shard].latest_block_root: anchor_state.copy().shard_states[shard]},

specs/phase1/validator.md

@@ -31,7 +31,7 @@
     - [`FullAttestation`](#fullattestation)
     - [Timing](#timing)
     - [Attestation data](#attestation-data)
-      - [Head shard root](#head-shard-root)
+      - [Shard head root](#shard-head-root)
       - [Shard transition](#shard-transition)
     - [Construct attestation](#construct-attestation)
   - [Attestation Aggregation](#attestation-aggregation)
@@ -267,9 +267,9 @@ A validator should create and broadcast the `attestation` to the associated atte
 
 *Note*: We assume that the fork choice only follows branches with valid `offset_slots` with respect to the most recent beacon state shard transition for the queried shard.
 
-##### Head shard root
+##### Shard head root
 
-Set `attestation_data.shard_head_root = hash_tree_root(shard_head_block)`.
+If `attestation_data.slot == GENESIS_SLOT`, set `attestation_data.shard_head_root = Root()`. Otherwise, set `attestation_data.shard_head_root = hash_tree_root(shard_head_block)`.
 
 ##### Shard transition
 
@@ -310,6 +310,10 @@ def get_shard_transition_fields(
 def get_shard_transition(beacon_state: BeaconState,
                          shard: Shard,
                          shard_blocks: Sequence[SignedShardBlock]) -> ShardTransition:
+    # NOTE: We currently set `PHASE_1_FORK_SLOT` to `GENESIS_SLOT` for test vectors.
+    if beacon_state.slot == GENESIS_SLOT:
+        return ShardTransition()
+
     offset_slots = compute_offset_slots(
         get_latest_slot_for_shard(beacon_state, shard),
         Slot(beacon_state.slot + 1),

tests/core/pyspec/eth2spec/test/context.py

@@ -63,9 +63,6 @@ def _prepare_state(balances_fn: Callable[[Any], Sequence[int]], threshold_fn: Ca
         # TODO: instead of upgrading a test phase0 genesis state we can also write a phase1 state helper.
         # Decide based on performance/consistency results later.
         state = phases[PHASE1].upgrade_to_phase1(state)
-        # Shard state slot must lag behind BeaconState slot by at least 1
-        # Will handle this more elegantly with fork mechanics
-        spec.process_slots(state, state.slot + 1)
 
     return state
 

tests/core/pyspec/eth2spec/test/helpers/attestations.py

@@ -69,7 +69,7 @@ def build_attestation_data(spec, state, slot, index, shard=None, shard_transitio
         source_epoch = state.current_justified_checkpoint.epoch
         source_root = state.current_justified_checkpoint.root
 
-    attestation_data = spec.AttestationData(
+    data = spec.AttestationData(
         slot=slot,
         index=index,
         beacon_block_root=block_root,
@@ -79,23 +79,27 @@ def build_attestation_data(spec, state, slot, index, shard=None, shard_transitio
 
     if spec.fork == PHASE1:
         if shard is None:
-            shard = spec.compute_shard_from_committee_index(state, attestation_data.index, attestation_data.slot)
-        attestation_data.shard = shard
+            shard = spec.compute_shard_from_committee_index(state, data.index, data.slot)
+        data.shard = shard
 
         if shard_transition is not None:
             last_offset_index = len(shard_transition.shard_data_roots) - 1
-            attestation_data.shard_head_root = shard_transition.shard_states[last_offset_index].latest_block_root
-            attestation_data.shard_transition_root = shard_transition.hash_tree_root()
+            data.shard_head_root = shard_transition.shard_states[last_offset_index].latest_block_root
+            data.shard_transition_root = shard_transition.hash_tree_root()
         else:
             if on_time:
-                shard_transition = spec.get_shard_transition(state, shard, shard_blocks=[])
-                last_offset_index = len(shard_transition.shard_data_roots) - 1
-                attestation_data.shard_head_root = shard_transition.shard_states[last_offset_index].latest_block_root
-                attestation_data.shard_transition_root = shard_transition.hash_tree_root()
+                if data.slot == spec.GENESIS_SLOT:
+                    data.shard_head_root = spec.Root()
+                    data.shard_transition_root = spec.ShardTransition().hash_tree_root()
+                else:
+                    shard_transition = spec.get_shard_transition(state, shard, shard_blocks=[])
+                    last_offset_index = len(shard_transition.shard_data_roots) - 1
+                    data.shard_head_root = shard_transition.shard_states[last_offset_index].latest_block_root
+                    data.shard_transition_root = shard_transition.hash_tree_root()
             else:
-                attestation_data.shard_head_root = state.shard_states[shard].latest_block_root
-                attestation_data.shard_transition_root = spec.Root()
-    return attestation_data
+                data.shard_head_root = state.shard_states[shard].latest_block_root
+                data.shard_transition_root = spec.Root()
+    return data
 
 
 def get_valid_on_time_attestation(spec, state, slot=None, index=None, shard_transition=None, signed=False):

tests/core/pyspec/eth2spec/test/helpers/state.py

@@ -42,12 +42,10 @@ def transition_to_slot_via_block(spec, state, slot):
 
 def transition_to_valid_shard_slot(spec, state):
     """
-    Transition to slot `spec.PHASE_1_GENESIS_SLOT + 1` and fork at `spec.PHASE_1_GENESIS_SLOT`.
+    Transition to slot `spec.PHASE_1_FORK_SLOT + 1` and fork at `spec.PHASE_1_FORK_SLOT`.
     """
-    transition_to(spec, state, spec.PHASE_1_GENESIS_SLOT)
-    state = spec.upgrade_to_phase1(state)  # `upgrade_to_phase1` is a pure function
+    transition_to(spec, state, spec.PHASE_1_FORK_SLOT)
     next_slot(spec, state)
-    return state
 
 
 def next_epoch(spec, state):

tests/core/pyspec/eth2spec/test/phase0/block_processing/test_process_attester_slashing.py

@@ -1,6 +1,5 @@
 from eth2spec.test.context import (
-    PHASE0,
-    spec_state_test, expect_assertion_error, always_bls, with_all_phases, with_phases
+    spec_state_test, expect_assertion_error, always_bls, with_all_phases
 )
 from eth2spec.test.helpers.attestations import sign_indexed_attestation
 from eth2spec.test.helpers.attester_slashings import get_valid_attester_slashing, \
@@ -197,7 +196,7 @@ def test_participants_already_slashed(spec, state):
 # Some of the following tests are phase0 only: phase 1 lists participants with bitfields instead of index list.
 
 
-@with_phases([PHASE0])
+@with_all_phases
 @spec_state_test
 @always_bls
 def test_att1_high_index(spec, state):
@@ -210,7 +209,7 @@ def test_att1_high_index(spec, state):
     yield from run_attester_slashing_processing(spec, state, attester_slashing, False)
 
 
-@with_phases([PHASE0])
+@with_all_phases
 @spec_state_test
 @always_bls
 def test_att2_high_index(spec, state):
@@ -223,7 +222,7 @@ def test_att2_high_index(spec, state):
     yield from run_attester_slashing_processing(spec, state, attester_slashing, False)
 
 
-@with_phases([PHASE0])
+@with_all_phases
 @spec_state_test
 @always_bls
 def test_att1_empty_indices(spec, state):
@@ -235,7 +234,7 @@ def test_att1_empty_indices(spec, state):
     yield from run_attester_slashing_processing(spec, state, attester_slashing, False)
 
 
-@with_phases([PHASE0])
+@with_all_phases
 @spec_state_test
 @always_bls
 def test_att2_empty_indices(spec, state):
@@ -247,7 +246,7 @@ def test_att2_empty_indices(spec, state):
     yield from run_attester_slashing_processing(spec, state, attester_slashing, False)
 
 
-@with_phases([PHASE0])
+@with_all_phases
 @spec_state_test
 @always_bls
 def test_all_empty_indices(spec, state):
@@ -262,7 +261,7 @@ def test_all_empty_indices(spec, state):
     yield from run_attester_slashing_processing(spec, state, attester_slashing, False)
 
 
-@with_phases([PHASE0])
+@with_all_phases
 @spec_state_test
 @always_bls
 def test_att1_bad_extra_index(spec, state):
@@ -278,7 +277,7 @@ def test_att1_bad_extra_index(spec, state):
     yield from run_attester_slashing_processing(spec, state, attester_slashing, False)
 
 
-@with_phases([PHASE0])
+@with_all_phases
 @spec_state_test
 @always_bls
 def test_att1_bad_replaced_index(spec, state):
@@ -294,7 +293,7 @@ def test_att1_bad_replaced_index(spec, state):
     yield from run_attester_slashing_processing(spec, state, attester_slashing, False)
 
 
-@with_phases([PHASE0])
+@with_all_phases
 @spec_state_test
 @always_bls
 def test_att2_bad_extra_index(spec, state):
@@ -310,7 +309,7 @@ def test_att2_bad_extra_index(spec, state):
     yield from run_attester_slashing_processing(spec, state, attester_slashing, False)
 
 
-@with_phases([PHASE0])
+@with_all_phases
 @spec_state_test
 @always_bls
 def test_att2_bad_replaced_index(spec, state):
@@ -326,7 +325,7 @@ def test_att2_bad_replaced_index(spec, state):
     yield from run_attester_slashing_processing(spec, state, attester_slashing, False)
 
 
-@with_phases([PHASE0])
+@with_all_phases
 @spec_state_test
 @always_bls
 def test_att1_duplicate_index_normal_signed(spec, state):
@@ -346,7 +345,7 @@ def test_att1_duplicate_index_normal_signed(spec, state):
     yield from run_attester_slashing_processing(spec, state, attester_slashing, False)
 
 
-@with_phases([PHASE0])
+@with_all_phases
 @spec_state_test
 @always_bls
 def test_att2_duplicate_index_normal_signed(spec, state):
@@ -366,7 +365,7 @@ def test_att2_duplicate_index_normal_signed(spec, state):
     yield from run_attester_slashing_processing(spec, state, attester_slashing, False)
 
 
-@with_phases([PHASE0])
+@with_all_phases
 @spec_state_test
 @always_bls
 def test_att1_duplicate_index_double_signed(spec, state):
@@ -381,7 +380,7 @@ def test_att1_duplicate_index_double_signed(spec, state):
     yield from run_attester_slashing_processing(spec, state, attester_slashing, False)
 
 
-@with_phases([PHASE0])
+@with_all_phases
 @spec_state_test
 @always_bls
 def test_att2_duplicate_index_double_signed(spec, state):
@@ -396,7 +395,7 @@ def test_att2_duplicate_index_double_signed(spec, state):
     yield from run_attester_slashing_processing(spec, state, attester_slashing, False)
 
 
-@with_phases([PHASE0])
+@with_all_phases
 @spec_state_test
 def test_unsorted_att_1(spec, state):
     attester_slashing = get_valid_attester_slashing(spec, state, signed_1=False, signed_2=True)
@@ -409,7 +408,7 @@ def test_unsorted_att_1(spec, state):
     yield from run_attester_slashing_processing(spec, state, attester_slashing, False)
 
 
-@with_phases([PHASE0])
+@with_all_phases
 @spec_state_test
 def test_unsorted_att_2(spec, state):
     attester_slashing = get_valid_attester_slashing(spec, state, signed_1=True, signed_2=False)

tests/core/pyspec/eth2spec/test/phase0/epoch_processing/test_process_rewards_and_penalties.py

@@ -1,7 +1,6 @@
 from eth2spec.test.context import (
-    PHASE0,
     spec_state_test, spec_test,
-    with_all_phases, with_phases, single_phase,
+    with_all_phases, single_phase,
     with_custom_state,
     zero_activation_threshold,
     misc_balances, low_single_balance,
@@ -25,7 +24,7 @@ def run_process_rewards_and_penalties(spec, state):
     yield from run_epoch_processing_with(spec, state, 'process_rewards_and_penalties')
 
 
-@with_phases([PHASE0])
+@with_all_phases
 @spec_state_test
 def test_genesis_epoch_no_attestations_no_penalties(spec, state):
     pre_state = state.copy()
@@ -38,7 +37,7 @@ def test_genesis_epoch_no_attestations_no_penalties(spec, state):
         assert state.balances[index] == pre_state.balances[index]
 
 
-@with_phases([PHASE0])
+@with_all_phases
 @spec_state_test
 def test_genesis_epoch_full_attestations_no_rewards(spec, state):
     attestations = []