diff options
author | uzhas <uzhas@ydb.tech> | 2023-11-16 16:04:50 +0300 |
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committer | uzhas <uzhas@ydb.tech> | 2023-11-16 17:46:46 +0300 |
commit | 46f0c0079bb50609d2eeb6586642bcf114fc5239 (patch) | |
tree | 84e4e4978d57fe5de321ba69bf9d0c290de60a66 /vendor/go.uber.org/multierr/error.go | |
parent | 73045e389397816cc2bdd6cd7818b4bce427b265 (diff) | |
download | ydb-46f0c0079bb50609d2eeb6586642bcf114fc5239.tar.gz |
enable ya make for go projects
Diffstat (limited to 'vendor/go.uber.org/multierr/error.go')
-rw-r--r-- | vendor/go.uber.org/multierr/error.go | 646 |
1 files changed, 646 insertions, 0 deletions
diff --git a/vendor/go.uber.org/multierr/error.go b/vendor/go.uber.org/multierr/error.go new file mode 100644 index 0000000000..3a828b2dff --- /dev/null +++ b/vendor/go.uber.org/multierr/error.go @@ -0,0 +1,646 @@ +// 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)) +} |