README
¶
errors
为什么使用errors
- 基于github.com/pkg/errors扩展，基本无上手成本和迁移成本。
- 不会无限打印堆栈信息，有最大长度限制(5)。
导入包
import "git.qutoutiao.net/gopher/qms/pkg/errors"
如何使用
创建
errors.New("message")
errors.Newf("format", args...)
errors.Errorf("format", args...)
只追加堆栈信息
errors.WithStack(err)
只追加上下文
errors.WithMessage(err, "message")
errors.WithMessagef(err, "format", args...)
同时追加堆栈和上下文
errors.Wrap(err, "message")
errors.Wrapf(err, "format", args...)
获取堆栈信息[和qlog打通，不需要手动调用]
errors.Stack()
Cause递归检索最原始的error
switch err := errors.Cause(err).(type) {
case *MyError:
// handle specifically
default:
// unknown error
}
打印堆栈信息
qlog.WithError(err).Error("xxx")
qlog.WithField("error", err).Error("xxx")
qlog.WithFields(qlog.Fields{"error": err}).Error("xxx")
堆栈信息会显示在err.stack中，格式为file:line，对多显示5个。需要查看完整的调用链路请查看trace平台。
Documentation
¶
Overview ¶
Package errors provides simple error handling primitives.
The traditional error handling idiom in Go is roughly akin to
if err != nil {
return err
}
which when applied recursively up the call stack results in error reports without context or debugging information. The errors package allows programmers to add context to the failure path in their code in a way that does not destroy the original value of the error.
Adding context to an error ¶
The errors.Wrap function returns a new error that adds context to the original error by recording a stack trace at the point Wrap is called, together with the supplied message. For example
_, err := ioutil.ReadAll(r)
if err != nil {
return errors.Wrap(err, "read failed")
}
If additional control is required, the errors.WithStack and errors.WithMessage functions destructure errors.Wrap into its component operations: annotating an error with a stack trace and with a message, respectively.
Retrieving the cause of an error ¶
Using errors.Wrap constructs a stack of errors, adding context to the preceding error. Depending on the nature of the error it may be necessary to reverse the operation of errors.Wrap to retrieve the original error for inspection. Any error value which implements this interface
type causer interface {
Cause() error
}
can be inspected by errors.Cause. errors.Cause will recursively retrieve the topmost error that does not implement causer, which is assumed to be the original cause. For example:
switch err := errors.Cause(err).(type) {
case *MyError:
// handle specifically
default:
// unknown error
}
Although the causer interface is not exported by this package, it is considered a part of its stable public interface.
Formatted printing of errors ¶
All error values returned from this package implement fmt.Formatter and can be formatted by the fmt package. The following verbs are supported:
%s print the error. If the error has a Cause it will be
printed recursively.
%v see %s
%+v extended format. Each Frame of the error's StackTrace will
be printed in detail.
Retrieving the stack trace of an error or wrapper ¶
New, Errorf, Wrap, and Wrapf record a stack trace at the point they are invoked. This information can be retrieved with the following interface:
type stackTracer interface {
StackTrace() errors.StackTrace
}
The returned errors.StackTrace type is defined as
type StackTrace []Frame
The Frame type represents a call site in the stack trace. Frame supports the fmt.Formatter interface that can be used for printing information about the stack trace of this error. For example:
if err, ok := err.(stackTracer); ok {
for _, f := range err.StackTrace() {
fmt.Printf("%+s:%d", f)
}
}
Although the stackTracer interface is not exported by this package, it is considered a part of its stable public interface.
See the documentation for Frame.Format for more details.
Example (StackTrace) ¶
package main
import (
"fmt"
"github.com/star-table/startable-server/go-common/pkg/errors"
)
func fn() error {
e1 := errors.New("error")
e2 := errors.Wrap(e1, "inner")
e3 := errors.Wrap(e2, "middle")
return errors.Wrap(e3, "outer")
}
func main() {
type stackTracer interface {
StackTrace() errors.StackTrace
}
err, ok := errors.Cause(fn()).(stackTracer)
if !ok {
panic("oops, err does not implement stackTracer")
}
st := err.StackTrace()
fmt.Printf("%+v", st[0:2]) // top two frames
// Example output:
// github.com/pkg/errors_test.fn
// /home/dfc/src/github.com/pkg/errors/example_test.go:47
// github.com/pkg/errors_test.Example_stackTrace
// /home/dfc/src/github.com/pkg/errors/example_test.go:127
}
Index ¶
- Variables
- func Cause(err error) error
- func Errorf(format string, args ...interface{}) error
- func Ignore(err error) error
- func IsCircuitBreak(err error) bool
- func IsRateLimit(err error) bool
- func Msg(err error) []string
- func New(message string) error
- func Newf(format string, args ...interface{}) error
- func WithMessage(err error, message string) error
- func WithMessagef(err error, format string, args ...interface{}) error
- func WithStack(err error) error
- func WithStackLevel(err error, level log.Level) error
- func Wrap(err error, message string) error
- func WrapLevel(err error, level log.Level, message string) error
- func Wrapf(err error, format string, args ...interface{}) error
- func WrapfLevel(err error, level log.Level, format string, args ...interface{}) error
- type Frame
- type StackTrace
Examples ¶
Constants ¶
This section is empty.
Variables ¶
var ( ErrRateLimit = errors.New("rate limit triggered") ErrCircuitBreak = errors.New("circuit break triggered") )
Functions ¶
func Cause ¶
Cause returns the underlying cause of the error, if possible. An error value has a cause if it implements the following interface:
type causer interface {
Cause() error
}
If the error does not implement Cause, the original error will be returned. If the error is nil, nil will be returned without further investigation.
Example ¶
package main
import (
"fmt"
"github.com/star-table/startable-server/go-common/pkg/errors"
)
func fn() error {
e1 := errors.New("error")
e2 := errors.Wrap(e1, "inner")
e3 := errors.Wrap(e2, "middle")
return errors.Wrap(e3, "outer")
}
func main() {
err := fn()
fmt.Println(err)
fmt.Println(errors.Cause(err))
}
Output: outer: middle: inner: error error
Example (Printf) ¶
package main
import (
"fmt"
"github.com/star-table/startable-server/go-common/pkg/errors"
)
func main() {
err := errors.Wrap(func() error {
return func() error {
return errors.Errorf("hello %s", fmt.Sprintf("world"))
}()
}(), "failed")
fmt.Printf("%v", err)
}
Output: failed: hello world
func Errorf ¶
Errorf formats according to a format specifier and returns the string as a value that satisfies error. Errorf also records the stack trace at the point it was called.
Example (Extended) ¶
package main
import (
"fmt"
"github.com/star-table/startable-server/go-common/pkg/errors"
)
func main() {
err := errors.Errorf("whoops: %s", "foo")
fmt.Printf("%+v", err)
// Example output:
// whoops: foo
// github.com/pkg/errors_test.ExampleErrorf
// /home/dfc/src/github.com/pkg/errors/example_test.go:101
// testing.runExample
// /home/dfc/go/src/testing/example.go:114
// testing.RunExamples
// /home/dfc/go/src/testing/example.go:38
// testing.(*M).Run
// /home/dfc/go/src/testing/testing.go:744
// main.main
// /github.com/pkg/errors/_test/_testmain.go:102
// runtime.main
// /home/dfc/go/src/runtime/proc.go:183
// runtime.goexit
// /home/dfc/go/src/runtime/asm_amd64.s:2059
}
func IsCircuitBreak ¶
func IsRateLimit ¶
func New ¶
New returns an error with the supplied message. New also records the stack trace at the point it was called.
Example ¶
package main
import (
"fmt"
"github.com/star-table/startable-server/go-common/pkg/errors"
)
func main() {
err := errors.New("whoops")
fmt.Println(err)
}
Output: whoops
Example (Printf) ¶
package main
import (
"fmt"
"github.com/star-table/startable-server/go-common/pkg/errors"
)
func main() {
err := errors.New("whoops")
fmt.Printf("%+v", err)
// Example output:
// whoops
// github.com/pkg/errors_test.ExampleNew_printf
// /home/dfc/src/github.com/pkg/errors/example_test.go:17
// testing.runExample
// /home/dfc/go/src/testing/example.go:114
// testing.RunExamples
// /home/dfc/go/src/testing/example.go:38
// testing.(*M).Run
// /home/dfc/go/src/testing/testing.go:744
// main.main
// /github.com/pkg/errors/_test/_testmain.go:106
// runtime.main
// /home/dfc/go/src/runtime/proc.go:183
// runtime.goexit
// /home/dfc/go/src/runtime/asm_amd64.s:2059
}
func WithMessage ¶
WithMessage annotates err with a new message. If err is nil, WithMessage returns nil.
Example ¶
package main
import (
"fmt"
"github.com/star-table/startable-server/go-common/pkg/errors"
)
func main() {
cause := errors.New("whoops")
err := errors.WithMessage(cause, "oh noes")
fmt.Println(err)
}
Output: oh noes: whoops
func WithMessagef ¶
WithMessagef annotates err with the format specifier. If err is nil, WithMessagef returns nil.
func WithStack ¶
WithStack annotates err with a stack trace at the point WithStack was called. If err is nil, WithStack returns nil.
Example ¶
package main
import (
"fmt"
"github.com/star-table/startable-server/go-common/pkg/errors"
)
func main() {
cause := errors.New("whoops")
err := errors.WithStack(cause)
fmt.Println(err)
}
Output: whoops
Example (Printf) ¶
package main
import (
"fmt"
"github.com/star-table/startable-server/go-common/pkg/errors"
)
func main() {
cause := errors.New("whoops")
err := errors.WithStack(cause)
fmt.Printf("%+v", err)
// Example Output:
// whoops
// github.com/pkg/errors_test.ExampleWithStack_printf
// /home/fabstu/go/src/github.com/pkg/errors/example_test.go:55
// testing.runExample
// /usr/lib/go/src/testing/example.go:114
// testing.RunExamples
// /usr/lib/go/src/testing/example.go:38
// testing.(*M).Run
// /usr/lib/go/src/testing/testing.go:744
// main.main
// github.com/pkg/errors/_test/_testmain.go:106
// runtime.main
// /usr/lib/go/src/runtime/proc.go:183
// runtime.goexit
// /usr/lib/go/src/runtime/asm_amd64.s:2086
// github.com/pkg/errors_test.ExampleWithStack_printf
// /home/fabstu/go/src/github.com/pkg/errors/example_test.go:56
// testing.runExample
// /usr/lib/go/src/testing/example.go:114
// testing.RunExamples
// /usr/lib/go/src/testing/example.go:38
// testing.(*M).Run
// /usr/lib/go/src/testing/testing.go:744
// main.main
// github.com/pkg/errors/_test/_testmain.go:106
// runtime.main
// /usr/lib/go/src/runtime/proc.go:183
// runtime.goexit
// /usr/lib/go/src/runtime/asm_amd64.s:2086
}
func Wrap ¶
Wrap returns an error annotating err with a stack trace at the point Wrap is called, and the supplied message. If err is nil, Wrap returns nil.
Example ¶
package main
import (
"fmt"
"github.com/star-table/startable-server/go-common/pkg/errors"
)
func main() {
cause := errors.New("whoops")
err := errors.Wrap(cause, "oh noes")
fmt.Println(err)
}
Output: oh noes: whoops
Example (Extended) ¶
package main
import (
"fmt"
"github.com/star-table/startable-server/go-common/pkg/errors"
)
func fn() error {
e1 := errors.New("error")
e2 := errors.Wrap(e1, "inner")
e3 := errors.Wrap(e2, "middle")
return errors.Wrap(e3, "outer")
}
func main() {
err := fn()
fmt.Printf("%+v\n", err)
// Example output:
// error
// github.com/pkg/errors_test.fn
// /home/dfc/src/github.com/pkg/errors/example_test.go:47
// github.com/pkg/errors_test.ExampleCause_printf
// /home/dfc/src/github.com/pkg/errors/example_test.go:63
// testing.runExample
// /home/dfc/go/src/testing/example.go:114
// testing.RunExamples
// /home/dfc/go/src/testing/example.go:38
// testing.(*M).Run
// /home/dfc/go/src/testing/testing.go:744
// main.main
// /github.com/pkg/errors/_test/_testmain.go:104
// runtime.main
// /home/dfc/go/src/runtime/proc.go:183
// runtime.goexit
// /home/dfc/go/src/runtime/asm_amd64.s:2059
// github.com/pkg/errors_test.fn
// /home/dfc/src/github.com/pkg/errors/example_test.go:48: inner
// github.com/pkg/errors_test.fn
// /home/dfc/src/github.com/pkg/errors/example_test.go:49: middle
// github.com/pkg/errors_test.fn
// /home/dfc/src/github.com/pkg/errors/example_test.go:50: outer
}
func Wrapf ¶
Wrapf returns an error annotating err with a stack trace at the point Wrapf is called, and the format specifier. If err is nil, Wrapf returns nil.
Example ¶
package main
import (
"fmt"
"github.com/star-table/startable-server/go-common/pkg/errors"
)
func main() {
cause := errors.New("whoops")
err := errors.Wrapf(cause, "oh noes #%d", 2)
fmt.Println(err)
}
Output: oh noes #2: whoops
Types ¶
type Frame ¶
type Frame uintptr
Frame represents a program counter inside a stack frame.
func (Frame) Format ¶
Format formats the frame according to the fmt.Formatter interface.
%s source file %d source line %n function name %v equivalent to %s:%d
Format accepts flags that alter the printing of some verbs, as follows:
%+s function name and path of source file relative to the compile time
GOPATH separated by \n\t (<funcname>\n\t<path>)
%+v equivalent to %+s:%d
type StackTrace ¶
type StackTrace []Frame
StackTrace is stack of Frames from innermost (newest) to outermost (oldest).
func (StackTrace) Format ¶
func (st StackTrace) Format(s fmt.State, verb rune)
Format formats the stack of Frames according to the fmt.Formatter interface.
%s lists source files for each Frame in the stack %v lists the source file and line number for each Frame in the stack
Format accepts flags that alter the printing of some verbs, as follows:
%+v Prints filename, function, and line number for each Frame in the stack.
Source Files