Simplify compact loop error handling

Rather than restarting the outer loop on unhandled error, simmply break out of the inner loop on any error. We always want to update the compact and target rev, and do post-compact operations - so the only thing we really need to check the error for is logging and metrics.

Signed-off-by: Brad Davidson <[email protected]>

pkg/logstructured/sqllog/sql.go

@@ -113,7 +113,6 @@ func (s *SQLLog) compactor(interval time.Duration) {
 	targetCompactRev, _ := s.CurrentRevision(s.ctx)
 	logrus.Tracef("COMPACT starting compactRev=%d targetCompactRev=%d", compactRev, targetCompactRev)
 
-outer:
 	for {
 		select {
 		case <-s.ctx.Done():
@@ -127,12 +126,14 @@ outer:
 		// (several hundred ms) just for the database to execute the subquery to select the revisions to delete.
 
 		var (
+			resultLabel    string
 			iterCompactRev int64
 			compactedRev   int64
 			currentRev     int64
 			err            error
 		)
 
+		resultLabel = metrics.ResultSuccess
 		iterCompactRev = compactRev
 		compactedRev = compactRev
 
@@ -147,26 +148,25 @@ outer:
 
 			compactedRev, currentRev, err = s.compact(compactedRev, iterCompactRev)
 			if err != nil {
-				// ErrCompacted indicates that no further work is necessary - either compactRev changed since the
-				// last iteration because another client has compacted, or the requested revision has already been compacted.
-				if err == server.ErrCompacted {
-					break
-				}
-				logrus.Errorf("Compact failed: %v", err)
-				metrics.CompactTotal.WithLabelValues(metrics.ResultError).Inc()
-				continue outer
+				break
 			}
 		}
 
-		if err := s.postCompact(); err != nil {
-			logrus.Errorf("Post-compact operations failed: %v", err)
+		if perr := s.postCompact(); perr != nil {
+			logrus.Errorf("Post-compact operations failed: %v", perr)
 		}
 
 		// Record the final results for the outer loop
 		compactRev = compactedRev
 		targetCompactRev = currentRev
 
-		metrics.CompactTotal.WithLabelValues(metrics.ResultSuccess).Inc()
+		// ErrCompacted indicates that no further work is necessary - either compactRev changed since the
+		// last iteration because another client has compacted, or the requested revision has already been compacted.
+		if err != nil && err != server.ErrCompacted {
+			logrus.Errorf("Compact failed: %v", err)
+			resultLabel = metrics.ResultError
+		}
+		metrics.CompactTotal.WithLabelValues(resultLabel).Inc()
 	}
 }
 
@@ -206,7 +206,7 @@ func (s *SQLLog) compact(compactRev int64, targetCompactRev int64) (int64, int64
 
 	// Don't bother compacting to a revision that has already been compacted
 	if targetCompactRev <= compactRev {
-		logrus.Infof("COMPACT revision %d has already been compacted", targetCompactRev)
+		logrus.Tracef("COMPACT revision %d has already been compacted", targetCompactRev)
 		return dbCompactRev, currentRev, server.ErrCompacted
 	}