Merge pull request #800 from blevesearch/numsnapshots_config

making NumSnapshotsToKeep configurable

index/scorch/persister.go

@@ -633,14 +633,14 @@ func (s *Scorch) removeOldBoltSnapshots() (numRemoved int, err error) {
 		return 0, err
 	}
 
-	if len(persistedEpochs) <= NumSnapshotsToKeep {
+	if len(persistedEpochs) <= s.numSnapshotsToKeep {
 		// we need to keep everything
 		return 0, nil
 	}
 
 	// make a map of epochs to protect from deletion
-	protectedEpochs := make(map[uint64]struct{}, NumSnapshotsToKeep)
-	for _, epoch := range persistedEpochs[0:NumSnapshotsToKeep] {
+	protectedEpochs := make(map[uint64]struct{}, s.numSnapshotsToKeep)
+	for _, epoch := range persistedEpochs[0:s.numSnapshotsToKeep] {
 		protectedEpochs[epoch] = struct{}{}
 	}
 

index/scorch/scorch.go

@@ -57,6 +57,7 @@ type Scorch struct {
 	nextSnapshotEpoch    uint64
 	eligibleForRemoval   []uint64        // Index snapshot epochs that are safe to GC.
 	ineligibleForRemoval map[string]bool // Filenames that should not be GC'ed yet.
+	numSnapshotsToKeep   int
 
 	closeCh            chan struct{}
 	introductions      chan *segmentIntroduction
@@ -190,6 +191,17 @@ func (s *Scorch) openBolt() error {
 		}
 	}
 
+	s.numSnapshotsToKeep = NumSnapshotsToKeep
+	if v, ok := s.config["numSnapshotsToKeep"]; ok {
+		var t int
+		if t, err = parseToInteger(v); err != nil {
+			return fmt.Errorf("numSnapshotsToKeep parse err: %v", err)
+		}
+		if t > 0 {
+			s.numSnapshotsToKeep = t
+		}
+	}
+
 	return nil
 }
 
@@ -503,3 +515,15 @@ func (s *Scorch) unmarkIneligibleForRemoval(filename string) {
 func init() {
 	registry.RegisterIndexType(Name, NewScorch)
 }
+
+func parseToInteger(i interface{}) (int, error) {
+	switch v := i.(type) {
+	case float64:
+		return int(v), nil
+	case int:
+		return v, nil
+
+	default:
+		return 0, fmt.Errorf("expects int or float64 value")
+	}
+}