status-im
/
eth2.0-specs
mirror of https://github.com/status-im/eth2.0-specs.git
2
0
Fork 0
Code Issues Projects Releases Wiki Activity

Add notes about sync committee stability

This commit is contained in:
Alex Stokes 2021-05-07 10:06:44 -07:00
parent 86104ea361
commit 04a9595415
No known key found for this signature in database
GPG Key ID: 99B3D88FD6C55A69
1 changed files with 6 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
specs/altair/beacon-chain.md
View File

@ -277,6 +277,9 @@ def get_sync_committee_indices(state: BeaconState, epoch: Epoch) -> Sequence[Val
""" """
Return the sequence of sync committee indices (which may include duplicate indices) Return the sequence of sync committee indices (which may include duplicate indices)
for a given ``state`` and ``epoch``. for a given ``state`` and ``epoch``.
Note: This function is not stable during a sync committee period as
a validator's effective balance may change enough to affect the sampling.
""" """
MAX_RANDOM_BYTE = 2**8 - 1 MAX_RANDOM_BYTE = 2**8 - 1
base_epoch = Epoch((max(epoch // EPOCHS_PER_SYNC_COMMITTEE_PERIOD, 1) - 1) * EPOCHS_PER_SYNC_COMMITTEE_PERIOD) base_epoch = Epoch((max(epoch // EPOCHS_PER_SYNC_COMMITTEE_PERIOD, 1) - 1) * EPOCHS_PER_SYNC_COMMITTEE_PERIOD)
@ -310,6 +313,9 @@ def get_sync_committee(state: BeaconState, epoch: Epoch) -> SyncCommittee:
``SyncCommittee`` can also contain duplicate pubkeys, when ``get_sync_committee_indices`` ``SyncCommittee`` can also contain duplicate pubkeys, when ``get_sync_committee_indices``
returns duplicate indices. Implementations must take care when handling returns duplicate indices. Implementations must take care when handling
optimizations relating to aggregation and verification in the presence of duplicates. optimizations relating to aggregation and verification in the presence of duplicates.
Note: This function should only be called at sync committee period boundaries, as
``get_sync_committee_indices`` is not stable within a given period.
""" """
indices = get_sync_committee_indices(state, epoch) indices = get_sync_committee_indices(state, epoch)
pubkeys = [state.validators[index].pubkey for index in indices] pubkeys = [state.validators[index].pubkey for index in indices]