[#292] pruning: grid: add all snapshots that do not match the regex to the rule's destroy list

Before this patch, multiple grids with disjoint regexes would result in
no snapshots being destroyed at all.

fixes #292

pruning/keep_grid.go

@@ -99,17 +99,21 @@ func (a retentionGridAdaptor) LessThan(b retentiongrid.Entry) bool {
 // Prune filters snapshots with the retention grid.
 func (p *KeepGrid) KeepRule(snaps []Snapshot) (destroyList []Snapshot) {
 
-	snaps = filterSnapList(snaps, func(snapshot Snapshot) bool {
+	matching, notMatching := partitionSnapList(snaps, func(snapshot Snapshot) bool {
 		return p.re.MatchString(snapshot.Name())
 	})
-	if len(snaps) == 0 {
-		return nil
+
+	// snaps that don't match the regex are not kept by this rule
+	destroyList = append(destroyList, notMatching...)
+
+	if len(matching) == 0 {
+		return destroyList
 	}
 
 	// Build adaptors for retention grid
 	adaptors := make([]retentiongrid.Entry, 0)
-	for i := range snaps {
-		adaptors = append(adaptors, retentionGridAdaptor{snaps[i]})
+	for i := range matching {
+		adaptors = append(adaptors, retentionGridAdaptor{matching[i]})
 	}
 
 	// determine 'now' edge
@@ -122,9 +126,8 @@ func (p *KeepGrid) KeepRule(snaps []Snapshot) (destroyList []Snapshot) {
 	_, removea := p.retentionGrid.FitEntries(now, adaptors)
 
 	// Revert adaptors
-	destroyList = make([]Snapshot, len(removea))
 	for i := range removea {
-		destroyList[i] = removea[i].(retentionGridAdaptor).Snapshot
+		destroyList = append(destroyList, removea[i].(retentionGridAdaptor).Snapshot)
 	}
 	return destroyList
 }

pruning/keep_helpers.go

@@ -10,6 +10,17 @@ func filterSnapList(snaps []Snapshot, predicate func(Snapshot) bool) []Snapshot
 	return r
 }
 
+func partitionSnapList(snaps []Snapshot, predicate func(Snapshot) bool) (sTrue, sFalse []Snapshot) {
+	for i := range snaps {
+		if predicate(snaps[i]) {
+			sTrue = append(sTrue, snaps[i])
+		} else {
+			sFalse = append(sFalse, snaps[i])
+		}
+	}
+	return
+}
+
 func shallowCopySnapList(snaps []Snapshot) []Snapshot {
 	c := make([]Snapshot, len(snaps))
 	copy(c, snaps)

pruning/pruning_test.go

@@ -75,6 +75,10 @@ func TestPruneSnapshots(t *testing.T) {
 		},
 	}
 
+	reltime := func(secs int64) time.Time {
+		return time.Unix(secs, 0)
+	}
+
 	tcs := map[string]testCase{
 		"simple": {
 			inputs: inputs["s1"],
@@ -121,6 +125,24 @@ func TestPruneSnapshots(t *testing.T) {
 			},
 			expDestroy: map[string]bool{},
 		},
+		"multiple_grids_with_disjoint_regexes": {
+			inputs: []Snapshot{
+				stubSnap{"p1_a", false, reltime(4)},
+				stubSnap{"p2_a", false, reltime(5)},
+				stubSnap{"p1_b", false, reltime(14)},
+				stubSnap{"p2_b", false, reltime(15)},
+				stubSnap{"p1_c", false, reltime(29)},
+				stubSnap{"p2_c", false, reltime(30)},
+			},
+			rules: []KeepRule{
+				MustNewKeepGrid("^p1_", `1x10s | 1x10s`),
+				MustNewKeepGrid("^p2_", `1x10s | 1x10s`),
+			},
+			expDestroy: map[string]bool{
+				"p1_a": true,
+				"p2_a": true,
+			},
+		},
 	}
 
 	testTable(tcs, t)