fix: use last finalized block on startup

[jimjbrettj]

Changes

• When starting the syncing service we should be using the last finalized block that we have, not the best block that we have. This PR makes this change.
• After startup we are okay to go back to using the best block

Tests

go test -tags integration github.com/ChainSafe/gossamer

Issues

Primary Reviewer

@EclesioMeloJunior

[codecov]

Codecov Report

Attention: 7 lines in your changes are missing coverage. Please review.

Comparison is base (d1ca7aa) 50.51% compared to head (53a8579) 50.23%.
Report is 6 commits behind head on development.

❗ Current head 53a8579 differs from pull request most recent head 2d1561e. Consider uploading reports for the commit 2d1561e to get more accurate results

Additional details and impacted files

@@               Coverage Diff               @@
##           development    #3737      +/-   ##
===============================================
- Coverage        50.51%   50.23%   -0.29%     
===============================================
  Files              230      230              
  Lines            29006    29003       -3     
===============================================
- Hits             14653    14570      -83     
- Misses           12856    12935      +79     
- Partials          1497     1498       +1     

[EclesioMeloJunior]

Instead of using this flag property (isStartup) I would suggest to: inside the bootstrapSync method inserting the call to GetHighestFinalisedHeader before starting the for loop, which means that the process will start using the latest finalized header.

Also, I've suggested to transform currentSyncInformation method into isBootstrapSync where it doesn't need to return the block but only a bool indicating if we keep on bootstrap or change

func (cs *chainSync) bootstrapSync() {
  currentBlock, err := cs.blockState.GetHighestFinalisedHeader()
  if err != nil {
    panic("cannot find highest finalised header")
  }

  for {
    ...
    isBootstrap := cs.isBootstrapSync(currentBlock)
    
    if isBootstrap {
      cs.workerPool.useConnectedPeers()
      err = cs.requestMaxBlocksFrom(currentBlock, networkInitialSync)
      if err != nil {
        logger.Errorf("requesting max blocks from best block header: %s", err)
      }

      currentBlock, err = cs.blockState.BestBlockHeader()
      if err != nil {
        return nil, false, fmt.Errorf("getting best block header: %w", err)
      }
    } else {
      ...
    }
  }
}

func (cs *chainSync) isBootstrapSync(syncHeader *types.Header) bool {
  syncTarget := cs.peerViewSet.getTarget()
  return syncHeader.Number+network.MaxBlocksInResponse < syncTarget
}

[EclesioMeloJunior]

LGTM!

[github-actions]

🎉 This PR is included in version 0.9.0 🎉

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