add selector

selector/filter.go

@@ -0,0 +1,87 @@
+package selector
+
+import (
+	"time"
+
+	mdutil "github.com/go-gost/core/metadata/util"
+	"github.com/go-gost/core/selector"
+)
+
+type failFilter[T selector.Selectable] struct {
+	maxFails    int
+	failTimeout time.Duration
+}
+
+// FailFilter filters the dead objects.
+// An object is marked as dead if its failed count is greater than MaxFails.
+func FailFilter[T selector.Selectable](maxFails int, timeout time.Duration) selector.Filter[T] {
+	return &failFilter[T]{
+		maxFails:    maxFails,
+		failTimeout: timeout,
+	}
+}
+
+// Filter filters dead objects.
+func (f *failFilter[T]) Filter(vs ...T) []T {
+	if len(vs) <= 1 {
+		return vs
+	}
+	var l []T
+	for _, v := range vs {
+		maxFails := f.maxFails
+		failTimeout := f.failTimeout
+		if md := v.Metadata(); md != nil {
+			if md.IsExists(labelMaxFails) {
+				maxFails = mdutil.GetInt(md, labelMaxFails)
+			}
+			if md.IsExists(labelFailTimeout) {
+				failTimeout = mdutil.GetDuration(md, labelFailTimeout)
+			}
+		}
+		if maxFails <= 0 {
+			maxFails = 1
+		}
+		if failTimeout <= 0 {
+			failTimeout = DefaultFailTimeout
+		}
+
+		if marker := v.Marker(); marker != nil {
+			if marker.Count() < int64(maxFails) ||
+				time.Since(marker.Time()) >= failTimeout {
+				l = append(l, v)
+			}
+		} else {
+			l = append(l, v)
+		}
+	}
+	return l
+}
+
+type backupFilter[T selector.Selectable] struct{}
+
+// BackupFilter filters the backup objects.
+// An object is marked as backup if its metadata has backup flag.
+func BackupFilter[T selector.Selectable]() selector.Filter[T] {
+	return &backupFilter[T]{}
+}
+
+// Filter filters backup objects.
+func (f *backupFilter[T]) Filter(vs ...T) []T {
+	if len(vs) <= 1 {
+		return vs
+	}
+
+	var l, backups []T
+	for _, v := range vs {
+		if mdutil.GetBool(v.Metadata(), labelBackup) {
+			backups = append(backups, v)
+		} else {
+			l = append(l, v)
+		}
+	}
+
+	if len(l) == 0 {
+		return backups
+	}
+	return l
+}