[pkg/stanza] Take into account the ascending option when sorting by…

… mtime (open-telemetry#32820)

**Description:** <Describe what has changed.>
* Allow ascending sort when sorting by mtime

**Link to tracking Issue:** Closes open-telemetry#32792

**Testing:**
* Unit tests

.chloggen/feat_mtime-ascending-sort.yaml

@@ -0,0 +1,13 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: bug_fix
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: "pkg/stanza"
+
+# A brief description of the change. Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Allow sorting by ascending order when using the mtime sort_type.
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [32792]

pkg/stanza/fileconsumer/matcher/internal/filter/sort.go

@@ -142,7 +142,9 @@ func (t TopNOption) apply(items []*item) ([]*item, error) {
  return items[:t], nil
 }
 
-type mtimeSortOption struct{}
+type mtimeSortOption struct {
+ ascending bool
+}
 
 type mtimeItem struct {
  mtime time.Time
@@ -168,10 +170,20 @@ func (m mtimeSortOption) apply(items []*item) ([]*item, error) {
  })
  }
 
- sort.SliceStable(mtimeItems, func(i, j int) bool {
- // This checks if item i > j, in order to reverse the sort (most recently modified file is first in the list)
- return mtimeItems[i].mtime.After(mtimeItems[j].mtime)
- })
+ var lessFunc func(i, j int) bool
+ if m.ascending {
+ lessFunc = func(i, j int) bool {
+ // This checks if item i < j
+ return mtimeItems[i].mtime.Before(mtimeItems[j].mtime)
+ }
+ } else {
+ lessFunc = func(i, j int) bool {
+ // This checks if item i > j, in order to reverse the sort (most recently modified file is first in the list)
+ return mtimeItems[i].mtime.After(mtimeItems[j].mtime)
+ }
+ }
+
+ sort.SliceStable(mtimeItems, lessFunc)
 
  filteredValues := make([]*item, 0, len(items))
  for _, mtimeItem := range mtimeItems {
@@ -181,6 +193,8 @@ func (m mtimeSortOption) apply(items []*item) ([]*item, error) {
  return filteredValues, errs
 }
 
-func SortMtime() Option {
- return mtimeSortOption{}
+func SortMtime(ascending bool) Option {
+ return mtimeSortOption{
+ ascending: ascending,
+ }
 }

pkg/stanza/fileconsumer/matcher/internal/filter/sort_test.go

@@ -179,6 +179,7 @@ func TestMTimeFilter(t *testing.T) {
  name string
  files []string
  fileMTimes []time.Time
+ ascending bool
  expectedErr string
  expect []string
  }{
@@ -200,6 +201,20 @@ func TestMTimeFilter(t *testing.T) {
  fileMTimes: []time.Time{epoch, epoch.Add(time.Hour)},
  expect: []string{"b.log", "a.log"},
  },
+ {
+ name: "Multiple files in order, ascending sort",
+ files: []string{"a.log", "b.log"},
+ fileMTimes: []time.Time{epoch, epoch.Add(time.Hour)},
+ ascending: true,
+ expect: []string{"a.log", "b.log"},
+ },
+ {
+ name: "Multiple files out of order, ascending sort",
+ files: []string{"a.log", "b.log"},
+ fileMTimes: []time.Time{epoch.Add(time.Hour), epoch},
+ ascending: true,
+ expect: []string{"b.log", "a.log"},
+ },
  }
  for _, tc := range cases {
  t.Run(tc.name, func(t *testing.T) {
@@ -221,7 +236,7 @@ func TestMTimeFilter(t *testing.T) {
  items = append(items, it)
  }
 
- f := SortMtime()
+ f := SortMtime(tc.ascending)
  result, err := f.apply(items)
  if tc.expectedErr != "" {
  require.EqualError(t, err, tc.expectedErr)

pkg/stanza/fileconsumer/matcher/matcher.go

@@ -131,7 +131,7 @@ func New(c Criteria) (*Matcher, error) {
  if !mtimeSortTypeFeatureGate.IsEnabled() {
  return nil, fmt.Errorf("the %q feature gate must be enabled to use %q sort type", mtimeSortTypeFeatureGate.ID(), sortTypeMtime)
  }
- m.filterOpts = append(m.filterOpts, filter.SortMtime())
+ m.filterOpts = append(m.filterOpts, filter.SortMtime(sc.Ascending))
  default:
  return nil, fmt.Errorf("'sort_type' must be specified")
  }