ceph-csi/vendor/go.uber.org/multierr/error.go
Niels de Vos 91774fc936 rebase: vendor dependencies for Vault API
Uses github.com/libopenstorage/secrets to communicate with Vault. This
removes the need for maintaining our own limited Vault APIs.

By adding the new dependency, several other packages got updated in the
process. Unused indirect dependencies have been removed from go.mod.

Signed-off-by: Niels de Vos <ndevos@redhat.com>
2020-11-29 04:03:59 +00:00

402 lines
10 KiB
Go

// Copyright (c) 2017 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
// Package multierr allows combining one or more errors together.
//
// Overview
//
// Errors can be combined with the use of the Combine function.
//
// multierr.Combine(
// reader.Close(),
// writer.Close(),
// conn.Close(),
// )
//
// If only two errors are being combined, the Append function may be used
// instead.
//
// err = multierr.Combine(reader.Close(), writer.Close())
//
// This makes it possible to record resource cleanup failures from deferred
// blocks with the help of named return values.
//
// func sendRequest(req Request) (err error) {
// conn, err := openConnection()
// if err != nil {
// return err
// }
// defer func() {
// err = multierr.Append(err, conn.Close())
// }()
// // ...
// }
//
// The underlying list of errors for a returned error object may be retrieved
// with the Errors function.
//
// errors := multierr.Errors(err)
// if len(errors) > 0 {
// fmt.Println("The following errors occurred:")
// }
//
// Advanced Usage
//
// Errors returned by Combine and Append MAY implement the following
// interface.
//
// type errorGroup interface {
// // Returns a slice containing the underlying list of errors.
// //
// // This slice MUST NOT be modified by the caller.
// Errors() []error
// }
//
// Note that if you need access to list of errors behind a multierr error, you
// should prefer using the Errors function. That said, if you need cheap
// read-only access to the underlying errors slice, you can attempt to cast
// the error to this interface. You MUST handle the failure case gracefully
// because errors returned by Combine and Append are not guaranteed to
// implement this interface.
//
// var errors []error
// group, ok := err.(errorGroup)
// if ok {
// errors = group.Errors()
// } else {
// errors = []error{err}
// }
package multierr // import "go.uber.org/multierr"
import (
"bytes"
"fmt"
"io"
"strings"
"sync"
"go.uber.org/atomic"
)
var (
// Separator for single-line error messages.
_singlelineSeparator = []byte("; ")
_newline = []byte("\n")
// Prefix for multi-line messages
_multilinePrefix = []byte("the following errors occurred:")
// Prefix for the first and following lines of an item in a list of
// multi-line error messages.
//
// For example, if a single item is:
//
// foo
// bar
//
// It will become,
//
// - foo
// bar
_multilineSeparator = []byte("\n - ")
_multilineIndent = []byte(" ")
)
// _bufferPool is a pool of bytes.Buffers.
var _bufferPool = sync.Pool{
New: func() interface{} {
return &bytes.Buffer{}
},
}
type errorGroup interface {
Errors() []error
}
// Errors returns a slice containing zero or more errors that the supplied
// error is composed of. If the error is nil, the returned slice is empty.
//
// err := multierr.Append(r.Close(), w.Close())
// errors := multierr.Errors(err)
//
// If the error is not composed of other errors, the returned slice contains
// just the error that was passed in.
//
// Callers of this function are free to modify the returned slice.
func Errors(err error) []error {
if err == nil {
return nil
}
// Note that we're casting to multiError, not errorGroup. Our contract is
// that returned errors MAY implement errorGroup. Errors, however, only
// has special behavior for multierr-specific error objects.
//
// This behavior can be expanded in the future but I think it's prudent to
// start with as little as possible in terms of contract and possibility
// of misuse.
eg, ok := err.(*multiError)
if !ok {
return []error{err}
}
errors := eg.Errors()
result := make([]error, len(errors))
copy(result, errors)
return result
}
// multiError is an error that holds one or more errors.
//
// An instance of this is guaranteed to be non-empty and flattened. That is,
// none of the errors inside multiError are other multiErrors.
//
// multiError formats to a semi-colon delimited list of error messages with
// %v and with a more readable multi-line format with %+v.
type multiError struct {
copyNeeded atomic.Bool
errors []error
}
var _ errorGroup = (*multiError)(nil)
// Errors returns the list of underlying errors.
//
// This slice MUST NOT be modified.
func (merr *multiError) Errors() []error {
if merr == nil {
return nil
}
return merr.errors
}
func (merr *multiError) Error() string {
if merr == nil {
return ""
}
buff := _bufferPool.Get().(*bytes.Buffer)
buff.Reset()
merr.writeSingleline(buff)
result := buff.String()
_bufferPool.Put(buff)
return result
}
func (merr *multiError) Format(f fmt.State, c rune) {
if c == 'v' && f.Flag('+') {
merr.writeMultiline(f)
} else {
merr.writeSingleline(f)
}
}
func (merr *multiError) writeSingleline(w io.Writer) {
first := true
for _, item := range merr.errors {
if first {
first = false
} else {
w.Write(_singlelineSeparator)
}
io.WriteString(w, item.Error())
}
}
func (merr *multiError) writeMultiline(w io.Writer) {
w.Write(_multilinePrefix)
for _, item := range merr.errors {
w.Write(_multilineSeparator)
writePrefixLine(w, _multilineIndent, fmt.Sprintf("%+v", item))
}
}
// Writes s to the writer with the given prefix added before each line after
// the first.
func writePrefixLine(w io.Writer, prefix []byte, s string) {
first := true
for len(s) > 0 {
if first {
first = false
} else {
w.Write(prefix)
}
idx := strings.IndexByte(s, '\n')
if idx < 0 {
idx = len(s) - 1
}
io.WriteString(w, s[:idx+1])
s = s[idx+1:]
}
}
type inspectResult struct {
// Number of top-level non-nil errors
Count int
// Total number of errors including multiErrors
Capacity int
// Index of the first non-nil error in the list. Value is meaningless if
// Count is zero.
FirstErrorIdx int
// Whether the list contains at least one multiError
ContainsMultiError bool
}
// Inspects the given slice of errors so that we can efficiently allocate
// space for it.
func inspect(errors []error) (res inspectResult) {
first := true
for i, err := range errors {
if err == nil {
continue
}
res.Count++
if first {
first = false
res.FirstErrorIdx = i
}
if merr, ok := err.(*multiError); ok {
res.Capacity += len(merr.errors)
res.ContainsMultiError = true
} else {
res.Capacity++
}
}
return
}
// fromSlice converts the given list of errors into a single error.
func fromSlice(errors []error) error {
res := inspect(errors)
switch res.Count {
case 0:
return nil
case 1:
// only one non-nil entry
return errors[res.FirstErrorIdx]
case len(errors):
if !res.ContainsMultiError {
// already flat
return &multiError{errors: errors}
}
}
nonNilErrs := make([]error, 0, res.Capacity)
for _, err := range errors[res.FirstErrorIdx:] {
if err == nil {
continue
}
if nested, ok := err.(*multiError); ok {
nonNilErrs = append(nonNilErrs, nested.errors...)
} else {
nonNilErrs = append(nonNilErrs, err)
}
}
return &multiError{errors: nonNilErrs}
}
// Combine combines the passed errors into a single error.
//
// If zero arguments were passed or if all items are nil, a nil error is
// returned.
//
// Combine(nil, nil) // == nil
//
// If only a single error was passed, it is returned as-is.
//
// Combine(err) // == err
//
// Combine skips over nil arguments so this function may be used to combine
// together errors from operations that fail independently of each other.
//
// multierr.Combine(
// reader.Close(),
// writer.Close(),
// pipe.Close(),
// )
//
// If any of the passed errors is a multierr error, it will be flattened along
// with the other errors.
//
// multierr.Combine(multierr.Combine(err1, err2), err3)
// // is the same as
// multierr.Combine(err1, err2, err3)
//
// The returned error formats into a readable multi-line error message if
// formatted with %+v.
//
// fmt.Sprintf("%+v", multierr.Combine(err1, err2))
func Combine(errors ...error) error {
return fromSlice(errors)
}
// Append appends the given errors together. Either value may be nil.
//
// This function is a specialization of Combine for the common case where
// there are only two errors.
//
// err = multierr.Append(reader.Close(), writer.Close())
//
// The following pattern may also be used to record failure of deferred
// operations without losing information about the original error.
//
// func doSomething(..) (err error) {
// f := acquireResource()
// defer func() {
// err = multierr.Append(err, f.Close())
// }()
func Append(left error, right error) error {
switch {
case left == nil:
return right
case right == nil:
return left
}
if _, ok := right.(*multiError); !ok {
if l, ok := left.(*multiError); ok && !l.copyNeeded.Swap(true) {
// Common case where the error on the left is constantly being
// appended to.
errs := append(l.errors, right)
return &multiError{errors: errs}
} else if !ok {
// Both errors are single errors.
return &multiError{errors: []error{left, right}}
}
}
// Either right or both, left and right, are multiErrors. Rely on usual
// expensive logic.
errors := [2]error{left, right}
return fromSlice(errors[0:])
}