prometheus/tsdb/errors/errors.go

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// Copyright 2016 The etcd Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package errors
import (
"bytes"
"fmt"
"io"
)
// multiError type allows combining multiple errors into one.
type multiError []error
// NewMulti returns multiError with provided errors added if not nil.
func NewMulti(errs ...error) multiError { // nolint:golint
m := multiError{}
m.Add(errs...)
return m
}
// Add adds single or many errors to the error list. Each error is added only if not nil.
// If the error is a nonNilMultiError type, the errors inside nonNilMultiError are added to the main multiError.
func (es *multiError) Add(errs ...error) {
for _, err := range errs {
if err == nil {
continue
}
if merr, ok := err.(nonNilMultiError); ok {
*es = append(*es, merr.errs...)
continue
}
*es = append(*es, err)
}
}
// Err returns the error list as an error or nil if it is empty.
func (es multiError) Err() error {
if len(es) == 0 {
return nil
}
return nonNilMultiError{errs: es}
}
// nonNilMultiError implements the error interface, and it represents
// multiError with at least one error inside it.
// This type is needed to make sure that nil is returned when no error is combined in multiError for err != nil
// check to work.
type nonNilMultiError struct {
errs multiError
}
// Error returns a concatenated string of the contained errors.
func (es nonNilMultiError) Error() string {
var buf bytes.Buffer
if len(es.errs) > 1 {
fmt.Fprintf(&buf, "%d errors: ", len(es.errs))
}
for i, err := range es.errs {
if i != 0 {
buf.WriteString("; ")
}
buf.WriteString(err.Error())
}
return buf.String()
}
// CloseAll closes all given closers while recording error in MultiError.
func CloseAll(cs []io.Closer) error {
errs := NewMulti()
for _, c := range cs {
errs.Add(c.Close())
}
return errs.Err()
}