From bcf6ff1c082fe82d7cbce299cc37bb9f347e2e66 Mon Sep 17 00:00:00 2001
From: Christian Schwarz <me@cschwarz.com>
Date: Sat, 29 Aug 2020 17:27:48 +0200
Subject: [PATCH] [#292] pruning: add func MustNewKeepGrid

---
 config/retentiongrid.go |  4 +--
 pruning/keep_grid.go    | 54 ++++++++++++++++++++++++++++++-----------
 2 files changed, 42 insertions(+), 16 deletions(-)

diff --git a/config/retentiongrid.go b/config/retentiongrid.go
index 95974d4..66d8c87 100644
--- a/config/retentiongrid.go
+++ b/config/retentiongrid.go
@@ -37,7 +37,7 @@ func (t *RetentionIntervalList) UnmarshalYAML(u func(interface{}, bool) error) (
 		return err
 	}
 
-	intervals, err := parseRetentionGridIntervalsString(in)
+	intervals, err := ParseRetentionIntervalSpec(in)
 	if err != nil {
 		return err
 	}
@@ -102,7 +102,7 @@ func parseRetentionGridIntervalString(e string) (intervals []RetentionInterval,
 
 }
 
-func parseRetentionGridIntervalsString(s string) (intervals []RetentionInterval, err error) {
+func ParseRetentionIntervalSpec(s string) (intervals []RetentionInterval, err error) {
 
 	ges := strings.Split(s, "|")
 	intervals = make([]RetentionInterval, 0, 7*len(ges))
diff --git a/pruning/keep_grid.go b/pruning/keep_grid.go
index 05d61d7..a62c9c9 100644
--- a/pruning/keep_grid.go
+++ b/pruning/keep_grid.go
@@ -30,35 +30,61 @@ func NewKeepGrid(in *config.PruneGrid) (p *KeepGrid, err error) {
 		return nil, errors.Wrap(err, "Regex is invalid")
 	}
 
+	return newKeepGrid(re, in.Grid)
+}
+
+func MustNewKeepGrid(regex, gridspec string) *KeepGrid {
+
+	ris, err := config.ParseRetentionIntervalSpec(gridspec)
+	if err != nil {
+		panic(err)
+	}
+
+	re := regexp.MustCompile(regex)
+
+	grid, err := newKeepGrid(re, ris)
+	if err != nil {
+		panic(err)
+	}
+	return grid
+}
+
+func newKeepGrid(re *regexp.Regexp, configIntervals []config.RetentionInterval) (*KeepGrid, error) {
+	if re == nil {
+		panic("re must not be nil")
+	}
+
+	if len(configIntervals) == 0 {
+		return nil, errors.New("retention grid must specify at least one interval")
+	}
+
+	intervals := make([]retentiongrid.Interval, len(configIntervals))
+	for i := range configIntervals {
+		intervals[i] = &configIntervals[i]
+	}
+
 	// Assert intervals are of increasing length (not necessarily required, but indicates config mistake)
 	lastDuration := time.Duration(0)
-	for i := range in.Grid {
+	for i := range intervals {
 
-		if in.Grid[i].Length() < lastDuration {
+		if intervals[i].Length() < lastDuration {
 			// If all intervals before were keep=all, this is ok
 			allPrevKeepCountAll := true
 			for j := i - 1; allPrevKeepCountAll && j >= 0; j-- {
-				allPrevKeepCountAll = in.Grid[j].KeepCount() == config.RetentionGridKeepCountAll
+				allPrevKeepCountAll = intervals[j].KeepCount() == config.RetentionGridKeepCountAll
 			}
 			if allPrevKeepCountAll {
 				goto isMonotonicIncrease
 			}
-			err = errors.New("retention grid interval length must be monotonically increasing")
-			return
+			return nil, errors.New("retention grid interval length must be monotonically increasing")
 		}
 	isMonotonicIncrease:
-		lastDuration = in.Grid[i].Length()
-
-	}
-
-	retentionIntervals := make([]retentiongrid.Interval, len(in.Grid))
-	for i := range in.Grid {
-		retentionIntervals[i] = &in.Grid[i]
+		lastDuration = intervals[i].Length()
 	}
 
 	return &KeepGrid{
-		retentiongrid.NewGrid(retentionIntervals),
-		re,
+		retentionGrid: retentiongrid.NewGrid(intervals),
+		re:            re,
 	}, nil
 }