refactor: improve checkpoint-sync algorithm (#1277)

Author: avilagaston9

lib/lambda_ethereum_consensus/beacon/store_setup.ex

@@ -38,7 +38,7 @@ defmodule LambdaEthereumConsensus.Beacon.StoreSetup do
   end
 
   @doc """
-  Gets a {store, genesis_validators_root} tuple with the configured strategy.
+  Gets a store with the configured strategy.
   """
   @spec setup!() :: Store.t()
   def setup!(), do: setup!(get_strategy!())

lib/lambda_ethereum_consensus/beacon/sync_blocks.ex

@@ -8,7 +8,6 @@ defmodule LambdaEthereumConsensus.Beacon.SyncBlocks do
   alias LambdaEthereumConsensus.ForkChoice
   alias LambdaEthereumConsensus.Libp2pPort
   alias LambdaEthereumConsensus.P2P.BlockDownloader
-  alias LambdaEthereumConsensus.StateTransition.Misc
 
   @blocks_per_chunk 16
   @retries 50
@@ -23,9 +22,8 @@ defmodule LambdaEthereumConsensus.Beacon.SyncBlocks do
   """
   @spec run() :: non_neg_integer()
   def run() do
-    # Initial sleep for faster app start
-    checkpoint = ForkChoice.get_finalized_checkpoint()
-    initial_slot = Misc.compute_start_slot_at_epoch(checkpoint.epoch) + 1
+    %{head_slot: head_slot} = ForkChoice.get_current_status_message()
+    initial_slot = head_slot + 1
     last_slot = ForkChoice.get_current_chain_slot()
 
     # If we're around genesis, we consider ourselves synced

lib/lambda_ethereum_consensus/fork_choice/fork_choice.ex

@@ -176,7 +176,7 @@ defmodule LambdaEthereumConsensus.ForkChoice do
       Logger.info("Pruning states before slot #{new_finalized_epoch}")
 
       new_finalized_slot =
-        new_finalized_epoch * ChainSpec.get("SLOTS_PER_EPOCH")
+        Misc.compute_start_slot_at_epoch(new_finalized_epoch)
 
       Task.Supervisor.start_child(
         PruneStatesSupervisor,