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[fix-recent_block_hashes] fix issue with recent_block_hashes when slots are skipped

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Danny Ryan 2018-10-04 12:43:30 -05:00
parent 9c255c3436
commit dc01cb0f4d
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1 changed files with 8 additions and 7 deletions
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specs/beacon-chain.md
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@ -141,7 +141,7 @@ fields = {
'pending_attestations': [AttestationRecord], 'pending_attestations': [AttestationRecord],
# Special objects that have not yet been processed # Special objects that have not yet been processed
'pending_specials': [SpecialObject], 'pending_specials': [SpecialObject],
# Most recent 2 * CYCLE_LENGTH block hashes, older to newer # recent block hashes needed to process attestations, older to newer
'recent_block_hashes': ['hash32'], 'recent_block_hashes': ['hash32'],
# RANDAO state # RANDAO state
'randao_mix': 'hash32' 'randao_mix': 'hash32'
@ -352,8 +352,8 @@ def get_shards_and_committees_for_slot(crystallized_state, slot):
return crystallized_state.shard_and_committee_for_slots[slot - earliest_slot_in_array] return crystallized_state.shard_and_committee_for_slots[slot - earliest_slot_in_array]
def get_block_hash(active_state, curblock, slot): def get_block_hash(active_state, curblock, slot):
earliest_slot_in_array = curblock.slot - CYCLE_LENGTH * 2 earliest_slot_in_array = curblock.slot - len(active_state.recent_block_hashes)
assert earliest_slot_in_array <= slot < earliest_slot_in_array + CYCLE_LENGTH * 2 assert earliest_slot_in_array <= slot < curblock.slot
return active_state.recent_block_hashes[slot - earliest_slot_in_array] return active_state.recent_block_hashes[slot - earliest_slot_in_array]
``` ```
@ -444,13 +444,13 @@ This procedure should be carried out every block.
First, set `recent_block_hashes` to the output of the following, where `parent_hash` is the hash of the immediate previous block (ie. must be equal to `ancestor_hashes[0]`): First, set `recent_block_hashes` to the output of the following, where `parent_hash` is the hash of the immediate previous block (ie. must be equal to `ancestor_hashes[0]`):
```python ```python
def get_new_recent_block_hashes(old_block_hashes, parent_slot, def append_to_recent_block_hashes(old_block_hashes, parent_slot,
current_slot, parent_hash): current_slot, parent_hash):
d = current_slot - parent_slot d = current_slot - parent_slot
return old_block_hashes[d:] + [parent_hash] * min(d, len(old_block_hashes)) return old_block_hashes + [parent_hash] * min(d, len(old_block_hashes))
``` ```
The output of `get_block_hash` should not change, except that it will no longer throw for `current_slot - 1`, and will now throw for `current_slot - CYCLE_LENGTH * 2 - 1`. Also, check that the block's `ancestor_hashes` array was correctly updated, using the following algorithm: The output of `get_block_hash` should not change, except that it will no longer throw for `current_slot - 1`. Also, check that the block's `ancestor_hashes` array was correctly updated, using the following algorithm:
```python ```python
def update_ancestor_hashes(parent_ancestor_hashes, parent_slot_number, parent_hash): def update_ancestor_hashes(parent_ancestor_hashes, parent_slot_number, parent_hash):
@ -542,6 +542,7 @@ For each `SpecialObject` `obj` in `active_state.pending_specials`:
* Set `crystallized_state.last_state_recalculation += CYCLE_LENGTH` * Set `crystallized_state.last_state_recalculation += CYCLE_LENGTH`
* Remove all attestation records older than slot `crystallized_state.last_state_recalculation` * Remove all attestation records older than slot `crystallized_state.last_state_recalculation`
* Empty the `active_state.pending_specials` list * Empty the `active_state.pending_specials` list
* Set `active_state.recent_block_hashes = active_state.recent_block_hashes[CYCLE_LENGTH:]`
* Set `shard_and_committee_for_slots[:CYCLE_LENGTH] = shard_and_committee_for_slots[CYCLE_LENGTH:]` * Set `shard_and_committee_for_slots[:CYCLE_LENGTH] = shard_and_committee_for_slots[CYCLE_LENGTH:]`
### Dynasty transition ### Dynasty transition