From 3a4e841c7318b861b067c6f5a1bbd21ebb17d4f6 Mon Sep 17 00:00:00 2001
From: Christian Schwarz <me@cschwarz.com>
Date: Sat, 29 Aug 2020 17:29:08 +0200
Subject: [PATCH] [#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    | 17 ++++++++++-------
 pruning/keep_helpers.go | 11 +++++++++++
 pruning/pruning_test.go | 22 ++++++++++++++++++++++
 3 files changed, 43 insertions(+), 7 deletions(-)

diff --git a/pruning/keep_grid.go b/pruning/keep_grid.go
index a62c9c9..2dffc07 100644
--- a/pruning/keep_grid.go
+++ b/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
 }
diff --git a/pruning/keep_helpers.go b/pruning/keep_helpers.go
index a756ce7..7c31d68 100644
--- a/pruning/keep_helpers.go
+++ b/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)
diff --git a/pruning/pruning_test.go b/pruning/pruning_test.go
index 0927333..9a33e7a 100644
--- a/pruning/pruning_test.go
+++ b/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)