84 lines
3.2 KiB
Markdown
84 lines
3.2 KiB
Markdown
# Ethereum 2.0 Light Client Support -- From Phase 0 to Light Client Patch
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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 Light-client patch](#fork-to-light-client-patch)
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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 moving from Phase 0 to Phase 1 of Ethereum 2.0.
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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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| `LIGHTCLIENT_PATCH_FORK_VERSION` | `Version('0x01000000')` |
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| `LIGHTCLIENT_PATCH_FORK_SLOT` | `Slot(0)` **TBD** |
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## Fork to Light-client patch
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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 slot `LIGHTCLIENT_PATCH_FORK_SLOT`, where `LIGHTCLIENT_PATCH_FORK_SLOT % SLOTS_PER_EPOCH == 0`.
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### Upgrading the state
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After `process_slots` of Phase 0 finishes, if `state.slot == LIGHTCLIENT_PATCH_FORK_SLOT`, an irregular state change is made to upgrade to light-client patch.
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```python
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def upgrade_to_lightclient_patch(pre: phase0.BeaconState) -> BeaconState:
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epoch = get_current_epoch(pre)
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post = BeaconState(
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genesis_time=pre.genesis_time,
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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=LIGHTCLIENT_PATCH_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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# Attestations
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# previous_epoch_attestations is cleared on upgrade.
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previous_epoch_attestations=List[PendingAttestation, MAX_ATTESTATIONS * SLOTS_PER_EPOCH](),
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# empty in pre state, since the upgrade is performed just after an epoch boundary.
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current_epoch_attestations=List[PendingAttestation, MAX_ATTESTATIONS * SLOTS_PER_EPOCH](),
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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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)
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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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