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authoruzhas <uzhas@ydb.tech>2023-11-16 16:04:50 +0300
committeruzhas <uzhas@ydb.tech>2023-11-16 17:46:46 +0300
commit46f0c0079bb50609d2eeb6586642bcf114fc5239 (patch)
tree84e4e4978d57fe5de321ba69bf9d0c290de60a66 /vendor/go.uber.org/multierr/error.go
parent73045e389397816cc2bdd6cd7818b4bce427b265 (diff)
downloadydb-46f0c0079bb50609d2eeb6586642bcf114fc5239.tar.gz
enable ya make for go projects
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+// Copyright (c) 2017-2023 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.Append(reader.Close(), writer.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:", errors)
+// }
+//
+// # Appending from a loop
+//
+// You sometimes need to append into an error from a loop.
+//
+// var err error
+// for _, item := range items {
+// err = multierr.Append(err, process(item))
+// }
+//
+// Cases like this may require knowledge of whether an individual instance
+// failed. This usually requires introduction of a new variable.
+//
+// var err error
+// for _, item := range items {
+// if perr := process(item); perr != nil {
+// log.Warn("skipping item", item)
+// err = multierr.Append(err, perr)
+// }
+// }
+//
+// multierr includes AppendInto to simplify cases like this.
+//
+// var err error
+// for _, item := range items {
+// if multierr.AppendInto(&err, process(item)) {
+// log.Warn("skipping item", item)
+// }
+// }
+//
+// This will append the error into the err variable, and return true if that
+// individual error was non-nil.
+//
+// See [AppendInto] for more information.
+//
+// # Deferred Functions
+//
+// Go makes it possible to modify the return value of a function in a defer
+// block if the function was using named returns. This makes it possible to
+// record resource cleanup failures from deferred blocks.
+//
+// func sendRequest(req Request) (err error) {
+// conn, err := openConnection()
+// if err != nil {
+// return err
+// }
+// defer func() {
+// err = multierr.Append(err, conn.Close())
+// }()
+// // ...
+// }
+//
+// multierr provides the Invoker type and AppendInvoke function to make cases
+// like the above simpler and obviate the need for a closure. The following is
+// roughly equivalent to the example above.
+//
+// func sendRequest(req Request) (err error) {
+// conn, err := openConnection()
+// if err != nil {
+// return err
+// }
+// defer multierr.AppendInvoke(&err, multierr.Close(conn))
+// // ...
+// }
+//
+// See [AppendInvoke] and [Invoker] for more information.
+//
+// NOTE: If you're modifying an error from inside a defer, you MUST use a named
+// return value for that function.
+//
+// # 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"
+ "errors"
+ "fmt"
+ "io"
+ "strings"
+ "sync"
+ "sync/atomic"
+)
+
+var (
+ // Separator for single-line error messages.
+ _singlelineSeparator = []byte("; ")
+
+ // 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, a nil slice is returned.
+//
+// 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 {
+ return extractErrors(err)
+}
+
+// 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
+}
+
+// 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
+}
+
+// Every compares every error in the given err against the given target error
+// using [errors.Is], and returns true only if every comparison returned true.
+func Every(err error, target error) bool {
+ for _, e := range extractErrors(err) {
+ if !errors.Is(e, target) {
+ return false
+ }
+ }
+ return true
+}
+
+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 {
+ // Don't pay to inspect small slices.
+ switch len(errors) {
+ case 0:
+ return nil
+ case 1:
+ return errors[0]
+ }
+
+ 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 {
+ // Error list is flat. Make a copy of it
+ // Otherwise "errors" escapes to the heap
+ // unconditionally for all other cases.
+ // This lets us optimize for the "no errors" case.
+ out := append(([]error)(nil), errors...)
+ return &multiError{errors: out}
+ }
+ }
+
+ 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())
+// }()
+//
+// Note that the variable MUST be a named return to append an error to it from
+// the defer statement. See also [AppendInvoke].
+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:])
+}
+
+// AppendInto appends an error into the destination of an error pointer and
+// returns whether the error being appended was non-nil.
+//
+// var err error
+// multierr.AppendInto(&err, r.Close())
+// multierr.AppendInto(&err, w.Close())
+//
+// The above is equivalent to,
+//
+// err := multierr.Append(r.Close(), w.Close())
+//
+// As AppendInto reports whether the provided error was non-nil, it may be
+// used to build a multierr error in a loop more ergonomically. For example:
+//
+// var err error
+// for line := range lines {
+// var item Item
+// if multierr.AppendInto(&err, parse(line, &item)) {
+// continue
+// }
+// items = append(items, item)
+// }
+//
+// Compare this with a version that relies solely on Append:
+//
+// var err error
+// for line := range lines {
+// var item Item
+// if parseErr := parse(line, &item); parseErr != nil {
+// err = multierr.Append(err, parseErr)
+// continue
+// }
+// items = append(items, item)
+// }
+func AppendInto(into *error, err error) (errored bool) {
+ if into == nil {
+ // We panic if 'into' is nil. This is not documented above
+ // because suggesting that the pointer must be non-nil may
+ // confuse users into thinking that the error that it points
+ // to must be non-nil.
+ panic("misuse of multierr.AppendInto: into pointer must not be nil")
+ }
+
+ if err == nil {
+ return false
+ }
+ *into = Append(*into, err)
+ return true
+}
+
+// Invoker is an operation that may fail with an error. Use it with
+// AppendInvoke to append the result of calling the function into an error.
+// This allows you to conveniently defer capture of failing operations.
+//
+// See also, [Close] and [Invoke].
+type Invoker interface {
+ Invoke() error
+}
+
+// Invoke wraps a function which may fail with an error to match the Invoker
+// interface. Use it to supply functions matching this signature to
+// AppendInvoke.
+//
+// For example,
+//
+// func processReader(r io.Reader) (err error) {
+// scanner := bufio.NewScanner(r)
+// defer multierr.AppendInvoke(&err, multierr.Invoke(scanner.Err))
+// for scanner.Scan() {
+// // ...
+// }
+// // ...
+// }
+//
+// In this example, the following line will construct the Invoker right away,
+// but defer the invocation of scanner.Err() until the function returns.
+//
+// defer multierr.AppendInvoke(&err, multierr.Invoke(scanner.Err))
+//
+// Note that the error you're appending to from the defer statement MUST be a
+// named return.
+type Invoke func() error
+
+// Invoke calls the supplied function and returns its result.
+func (i Invoke) Invoke() error { return i() }
+
+// Close builds an Invoker that closes the provided io.Closer. Use it with
+// AppendInvoke to close io.Closers and append their results into an error.
+//
+// For example,
+//
+// func processFile(path string) (err error) {
+// f, err := os.Open(path)
+// if err != nil {
+// return err
+// }
+// defer multierr.AppendInvoke(&err, multierr.Close(f))
+// return processReader(f)
+// }
+//
+// In this example, multierr.Close will construct the Invoker right away, but
+// defer the invocation of f.Close until the function returns.
+//
+// defer multierr.AppendInvoke(&err, multierr.Close(f))
+//
+// Note that the error you're appending to from the defer statement MUST be a
+// named return.
+func Close(closer io.Closer) Invoker {
+ return Invoke(closer.Close)
+}
+
+// AppendInvoke appends the result of calling the given Invoker into the
+// provided error pointer. Use it with named returns to safely defer
+// invocation of fallible operations until a function returns, and capture the
+// resulting errors.
+//
+// func doSomething(...) (err error) {
+// // ...
+// f, err := openFile(..)
+// if err != nil {
+// return err
+// }
+//
+// // multierr will call f.Close() when this function returns and
+// // if the operation fails, its append its error into the
+// // returned error.
+// defer multierr.AppendInvoke(&err, multierr.Close(f))
+//
+// scanner := bufio.NewScanner(f)
+// // Similarly, this scheduled scanner.Err to be called and
+// // inspected when the function returns and append its error
+// // into the returned error.
+// defer multierr.AppendInvoke(&err, multierr.Invoke(scanner.Err))
+//
+// // ...
+// }
+//
+// NOTE: If used with a defer, the error variable MUST be a named return.
+//
+// Without defer, AppendInvoke behaves exactly like AppendInto.
+//
+// err := // ...
+// multierr.AppendInvoke(&err, mutltierr.Invoke(foo))
+//
+// // ...is roughly equivalent to...
+//
+// err := // ...
+// multierr.AppendInto(&err, foo())
+//
+// The advantage of the indirection introduced by Invoker is to make it easy
+// to defer the invocation of a function. Without this indirection, the
+// invoked function will be evaluated at the time of the defer block rather
+// than when the function returns.
+//
+// // BAD: This is likely not what the caller intended. This will evaluate
+// // foo() right away and append its result into the error when the
+// // function returns.
+// defer multierr.AppendInto(&err, foo())
+//
+// // GOOD: This will defer invocation of foo unutil the function returns.
+// defer multierr.AppendInvoke(&err, multierr.Invoke(foo))
+//
+// multierr provides a few Invoker implementations out of the box for
+// convenience. See [Invoker] for more information.
+func AppendInvoke(into *error, invoker Invoker) {
+ AppendInto(into, invoker.Invoke())
+}
+
+// AppendFunc is a shorthand for [AppendInvoke].
+// It allows using function or method value directly
+// without having to wrap it into an [Invoker] interface.
+//
+// func doSomething(...) (err error) {
+// w, err := startWorker(...)
+// if err != nil {
+// return err
+// }
+//
+// // multierr will call w.Stop() when this function returns and
+// // if the operation fails, it appends its error into the
+// // returned error.
+// defer multierr.AppendFunc(&err, w.Stop)
+// }
+func AppendFunc(into *error, fn func() error) {
+ AppendInvoke(into, Invoke(fn))
+}