Fix context.Canceled wrapping in compaction

We need to make sure that `tsdb_errors.NewMulti` handles the errors.Is()
calls properly, like it's done in grafana/dskit.

Also we need to check that `errors.Is(err, context.Canceled)`, not that
`err == context.Canceled`.

Signed-off-by: Oleg Zaytsev <mail@olegzaytsev.com>

tsdb/compact.go

@@ -471,7 +471,7 @@ func (c *LeveledCompactor) Compact(dest string, dirs []string, open []*Block) (u
 	}
 
 	errs := tsdb_errors.NewMulti(err)
-	if err != context.Canceled {
+	if !errors.Is(err, context.Canceled) {
 		for _, b := range bs {
 			if err := b.setCompactionFailed(); err != nil {
 				errs.Add(errors.Wrapf(err, "setting compaction failed for block: %s", b.Dir()))

tsdb/errors/errors.go

@@ -16,6 +16,7 @@ package errors
 
 import (
 	"bytes"
+	"errors"
 	"fmt"
 	"io"
 )
@@ -79,6 +80,19 @@ func (es nonNilMultiError) Error() string {
 	return buf.String()
 }
 
+// Is attempts to match the provided error against errors in the error list.
+//
+// This function allows errors.Is to traverse the values stored in the MultiError.
+// It returns true if any of the errors in the list match the target.
+func (es nonNilMultiError) Is(target error) bool {
+	for _, err := range es.errs {
+		if errors.Is(err, target) {
+			return true
+		}
+	}
+	return false
+}
+
 // CloseAll closes all given closers while recording error in MultiError.
 func CloseAll(cs []io.Closer) error {
 	errs := NewMulti()