Fix: stop the completed catchup service

Author: algonautshant

catchup/service.go

@@ -241,8 +241,10 @@ func (s *Service) fetchAndWrite(r basics.Round, prevFetchCompleteChan chan bool,
 
 		if err != nil {
 			if err == errLedgerAlreadyHasBlock {
-				// ledger already has the block, no need to request this block from anyone.
-				return true
+				// ledger already has the block, no need to request this block.
+				// only the agreement could have added this block into the ledger, catchup is complete
+				s.log.Infof("fetchAndWrite(%d): the block is already in the ledger. The catchup is complete", r)
+				return false
 			}
 			s.log.Debugf("fetchAndWrite(%v): Could not fetch: %v (attempt %d)", r, err, i)
 			peerSelector.rankPeer(psp, peerRankDownloadFailed)
@@ -353,8 +355,10 @@ func (s *Service) fetchAndWrite(r basics.Round, prevFetchCompleteChan chan bool,
 						s.log.Infof("fetchAndWrite(%d): no need to re-evaluate historical block", r)
 						return true
 					case ledgercore.BlockInLedgerError:
-						s.log.Infof("fetchAndWrite(%d): block already in ledger", r)
-						return true
+						// the block was added to the ledger from elsewhere after fetching it here
+						// only the agreement could have added this block into the ledger, catchup is complete
+						s.log.Infof("fetchAndWrite(%d): after fetching the block, it is already in the ledger. The catchup is complete", r)
+						return false
 					case protocol.Error:
 						if !s.protocolErrorLogged {
 							logging.Base().Errorf("fetchAndWrite(%v): unrecoverable protocol error detected: %v", r, err)
@@ -387,7 +391,7 @@ func (s *Service) pipelineCallback(r basics.Round, thisFetchComplete chan bool,
 		thisFetchComplete <- fetchResult
 
 		if !fetchResult {
-			s.log.Infof("failed to fetch block %v", r)
+			s.log.Infof("pipelineCallback(%d): did not fetch or write the block", r)
 			return 0
 		}
 		return r