86 lines
3.2 KiB
Markdown
86 lines
3.2 KiB
Markdown
# Ethereum 2.0 Altair fork
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**Notice**: This document is a work-in-progress for researchers and implementers.
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## Table of contents
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<!-- START doctoc generated TOC please keep comment here to allow auto update -->
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<!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->
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- [Introduction](#introduction)
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- [Configuration](#configuration)
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- [Fork to Altair](#fork-to-altair)
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- [Fork trigger](#fork-trigger)
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- [Upgrading the state](#upgrading-the-state)
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<!-- END doctoc generated TOC please keep comment here to allow auto update -->
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## Introduction
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This document describes the process of the first upgrade of Ethereum 2.0: the Altair hard fork, introducing light client support and other improvements.
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## Configuration
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Warning: this configuration is not definitive.
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| Name | Value |
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| - | - |
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| `ALTAIR_FORK_VERSION` | `Version('0x01000000')` |
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| `ALTAIR_FORK_EPOCH` | `Epoch(18446744073709551615)` **TBD** |
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## Fork to Altair
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### Fork trigger
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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 epoch `ALTAIR_FORK_EPOCH`.
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### Upgrading the state
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After `process_slots` of Phase 0 finishes, if `state.slot % SLOTS_PER_EPOCH == 0` and `compute_epoch_at_slot(state.slot) == ALTAIR_FORK_EPOCH`, an irregular state change is made to upgrade to Altair.
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```python
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def upgrade_to_altair(pre: phase0.BeaconState) -> BeaconState:
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epoch = phase0.get_current_epoch(pre)
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post = BeaconState(
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# Versioning
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genesis_time=pre.genesis_time,
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genesis_validators_root=pre.genesis_validators_root,
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slot=pre.slot,
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fork=Fork(
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previous_version=pre.fork.current_version,
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current_version=ALTAIR_FORK_VERSION,
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epoch=epoch,
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),
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# History
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latest_block_header=pre.latest_block_header,
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block_roots=pre.block_roots,
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state_roots=pre.state_roots,
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historical_roots=pre.historical_roots,
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# Eth1
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eth1_data=pre.eth1_data,
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eth1_data_votes=pre.eth1_data_votes,
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eth1_deposit_index=pre.eth1_deposit_index,
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# Registry
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validators=pre.validators,
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balances=pre.balances,
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# Randomness
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randao_mixes=pre.randao_mixes,
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# Slashings
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slashings=pre.slashings,
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# Participation
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previous_epoch_participation=[ParticipationFlags(0b0000_0000) for _ in range(len(pre.validators))],
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current_epoch_participation=[ParticipationFlags(0b0000_0000) for _ in range(len(pre.validators))],
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# Finality
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justification_bits=pre.justification_bits,
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previous_justified_checkpoint=pre.previous_justified_checkpoint,
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current_justified_checkpoint=pre.current_justified_checkpoint,
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finalized_checkpoint=pre.finalized_checkpoint,
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# Inactivity
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inactivity_scores=[uint64(0) for _ in range(len(pre.validators))],
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)
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# Fill in sync committees
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post.current_sync_committee = get_sync_committee(post, get_current_epoch(post))
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post.next_sync_committee = get_sync_committee(post, get_current_epoch(post) + EPOCHS_PER_SYNC_COMMITTEE_PERIOD)
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return post
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```
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