Add 'UpdateManyWithRetention' whisper function and migrate fill to us…

…e it

Fill must read and write data to exactly same archive.

For this purpose this commit intoroduce new function 'UpdateManyWithRetention'
that also gets 'desired' archive's retention.

Also migrate 'fillArchive' in fill package to use that function, instead of
plain 'UpdateMany'

Fixes jjneely#19

fill/fill.go

@@ -54,7 +54,7 @@ func fillArchive(srcWsp, dstWsp *whisper.Whisper, start, stop int) error {
 			}
 			tsStart += ts.Step()
 		}
-		dstWsp.UpdateMany(points)
+		dstWsp.UpdateManyWithRetention(points, v.MaxRetention())
 
 		stop = fromTime
 		if start >= stop {

whisper/whisper.go

@@ -369,14 +369,19 @@ func (whisper *Whisper) Update(value float64, timestamp int) (err error) {
 	return nil
 }
 
-func (whisper *Whisper) UpdateMany(points []*TimeSeriesPoint) {
+// UpdateManyWithRetention updates only archive with specified retention.
+// retention = -1 means "update all possible archives"
+func (whisper *Whisper) UpdateManyWithRetention(points []*TimeSeriesPoint, retention int) {
 	// sort the points, newest first
 	sort.Sort(timeSeriesPointsNewestFirst{points})
 
 	now := int(time.Now().Unix()) // TODO: danger of 2030 something overflow
 
 	var currentPoints []*TimeSeriesPoint
 	for _, archive := range whisper.archives {
+		if retention != -1 && retention != archive.MaxRetention() {
+			continue
+		}
 		currentPoints, points = extractPoints(points, now, archive.MaxRetention())
 		if len(currentPoints) == 0 {
 			continue
@@ -393,6 +398,10 @@ func (whisper *Whisper) UpdateMany(points []*TimeSeriesPoint) {
 	}
 }
 
+func (whisper *Whisper) UpdateMany(points []*TimeSeriesPoint) {
+	whisper.UpdateManyWithRetention(points, -1)
+}
+
 func (whisper *Whisper) archiveUpdateMany(archive *archiveInfo, points []*TimeSeriesPoint) {
 	alignedPoints := alignPoints(archive, points)
 	intervals, packedBlocks := packSequences(archive, alignedPoints)