Inomurko/reorg block getter

[InoMurko]

Overview

I've observed two things:

:sys.get_state OMG.Watcher.BlockGetter
%OMG.Watcher.BlockGetter.Core{
  chain_status: :ok,
  config: %OMG.Watcher.BlockGetter.Core.Config{
    block_getter_loops_interval_ms: 500,
    block_getter_reorg_margin: 200,
    block_interval: 1000,
    child_chain_url: "http://childchain:80",
    maximum_block_withholding_time_ms: 54000000,
    maximum_number_of_pending_blocks: 4,
    maximum_number_of_unapplied_blocks: 50
  },
  events: [],
  last_applied_block: 241000,
  num_of_highest_block_being_downloaded: 241000,
  number_of_blocks_being_downloaded: 0,
  potential_block_withholdings: %{},
  synced_height: 10178703,
  unapplied_blocks: %{}
}
iex(watcher_info@127.0.0.1)14> :sys.get_state :depositor
{%OMG.EthereumEventListener.Core{
   cached: %{data: [], events_upper_bound: 10178693, request_max_size: 1000},
   ethereum_events_check_interval_ms: 8000,
   service_name: :depositor,
   synced_height: 10178693,
   synced_height_update_key: :last_depositor_eth_height
 },
 %{
   get_ethereum_events_callback: &OMG.Watcher.EthereumEventAggregator.deposit_created/2,
   process_events_callback: &OMG.State.deposit/1
 }}

So two services are syncing, but blockgetter is faster then depositor.
BlockGetter synced_height: 10178703
Depositor synced_height: 10178693

The consolidation PR #1376 introduced a behaviour where all services go through the same funnel to fetch ethereum logs while relying on :depositor reorg protection.

It was observed that :depositor and :block_getter do not have constraints with one another:

depositor: [finality_margin: deposit_finality_margin],
       block_getter: [
         waits_for: [depositor: :no_margin],
         finality_margin: 0
       ]

A following event could cause watcher to have issues:

• block was formed on height 10
• blockgetter gets that block + all other events (defined in OMG.Watcher.SyncSupervisor, EthereumEventAggregator, events)
• deposits or exits or whatever event happens after the block formation
• a reorg happens in the depositor reorg protection margin (10 blocks)

This would cause the ETS table of event aggregator to store same ethereum log on two different heights.

Changes

• BlockGetter has it's own reorg protection so we're letting him sync separately from ethereum event aggregator

Testing

Same tests apply.

[InoMurko]

this is actually a partial revert from:
https://github.com/omgnetwork/elixir-omg/pull/1376/files#diff-5fcd99569a2ce28c62745940476ced06L312

[InoMurko]

this is actually a partial revert from https://github.com/omgnetwork/elixir-omg/pull/1376/files#diff-fc70ee7361bc3bb591f254d40b95fcf8L158-L164

[boolafish]

shouldn't we also remove EthereumEventAggregator.block_submitted method function?

[InoMurko]

shouldn't we also remove EthereumEventAggregator.block_submitted method?

function! :))))

[InoMurko]

shouldn't we also remove EthereumEventAggregator.block_submitted method function?

done. thanks!