VictoriaMetrics/vendor/github.com/go-kit/log/level/level.go

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package level
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import (
"errors"
"strings"
"github.com/go-kit/log"
)
// ErrInvalidLevelString is returned whenever an invalid string is passed to Parse.
var ErrInvalidLevelString = errors.New("invalid level string")
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// Error returns a logger that includes a Key/ErrorValue pair.
func Error(logger log.Logger) log.Logger {
return log.WithPrefix(logger, Key(), ErrorValue())
}
// Warn returns a logger that includes a Key/WarnValue pair.
func Warn(logger log.Logger) log.Logger {
return log.WithPrefix(logger, Key(), WarnValue())
}
// Info returns a logger that includes a Key/InfoValue pair.
func Info(logger log.Logger) log.Logger {
return log.WithPrefix(logger, Key(), InfoValue())
}
// Debug returns a logger that includes a Key/DebugValue pair.
func Debug(logger log.Logger) log.Logger {
return log.WithPrefix(logger, Key(), DebugValue())
}
// NewFilter wraps next and implements level filtering. See the commentary on
// the Option functions for a detailed description of how to configure levels.
// If no options are provided, all leveled log events created with Debug,
// Info, Warn or Error helper methods are squelched and non-leveled log
// events are passed to next unmodified.
func NewFilter(next log.Logger, options ...Option) log.Logger {
l := &logger{
next: next,
}
for _, option := range options {
option(l)
}
return l
}
type logger struct {
next log.Logger
allowed level
squelchNoLevel bool
errNotAllowed error
errNoLevel error
}
func (l *logger) Log(keyvals ...interface{}) error {
var hasLevel, levelAllowed bool
for i := 1; i < len(keyvals); i += 2 {
if v, ok := keyvals[i].(*levelValue); ok {
hasLevel = true
levelAllowed = l.allowed&v.level != 0
break
}
}
if !hasLevel && l.squelchNoLevel {
return l.errNoLevel
}
if hasLevel && !levelAllowed {
return l.errNotAllowed
}
return l.next.Log(keyvals...)
}
// Option sets a parameter for the leveled logger.
type Option func(*logger)
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// Allow the provided log level to pass.
func Allow(v Value) Option {
switch v {
case debugValue:
return AllowDebug()
case infoValue:
return AllowInfo()
case warnValue:
return AllowWarn()
case errorValue:
return AllowError()
default:
return AllowNone()
}
}
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// AllowAll is an alias for AllowDebug.
func AllowAll() Option {
return AllowDebug()
}
// AllowDebug allows error, warn, info and debug level log events to pass.
func AllowDebug() Option {
return allowed(levelError | levelWarn | levelInfo | levelDebug)
}
// AllowInfo allows error, warn and info level log events to pass.
func AllowInfo() Option {
return allowed(levelError | levelWarn | levelInfo)
}
// AllowWarn allows error and warn level log events to pass.
func AllowWarn() Option {
return allowed(levelError | levelWarn)
}
// AllowError allows only error level log events to pass.
func AllowError() Option {
return allowed(levelError)
}
// AllowNone allows no leveled log events to pass.
func AllowNone() Option {
return allowed(0)
}
func allowed(allowed level) Option {
return func(l *logger) { l.allowed = allowed }
}
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// Parse a string to its corresponding level value. Valid strings are "debug",
// "info", "warn", and "error". Strings are normalized via strings.TrimSpace and
// strings.ToLower.
func Parse(level string) (Value, error) {
switch strings.TrimSpace(strings.ToLower(level)) {
case debugValue.name:
return debugValue, nil
case infoValue.name:
return infoValue, nil
case warnValue.name:
return warnValue, nil
case errorValue.name:
return errorValue, nil
default:
return nil, ErrInvalidLevelString
}
}
// ParseDefault calls Parse and returns the default Value on error.
func ParseDefault(level string, def Value) Value {
v, err := Parse(level)
if err != nil {
return def
}
return v
}
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// ErrNotAllowed sets the error to return from Log when it squelches a log
// event disallowed by the configured Allow[Level] option. By default,
// ErrNotAllowed is nil; in this case the log event is squelched with no
// error.
func ErrNotAllowed(err error) Option {
return func(l *logger) { l.errNotAllowed = err }
}
// SquelchNoLevel instructs Log to squelch log events with no level, so that
// they don't proceed through to the wrapped logger. If SquelchNoLevel is set
// to true and a log event is squelched in this way, the error value
// configured with ErrNoLevel is returned to the caller.
func SquelchNoLevel(squelch bool) Option {
return func(l *logger) { l.squelchNoLevel = squelch }
}
// ErrNoLevel sets the error to return from Log when it squelches a log event
// with no level. By default, ErrNoLevel is nil; in this case the log event is
// squelched with no error.
func ErrNoLevel(err error) Option {
return func(l *logger) { l.errNoLevel = err }
}
// NewInjector wraps next and returns a logger that adds a Key/level pair to
// the beginning of log events that don't already contain a level. In effect,
// this gives a default level to logs without a level.
func NewInjector(next log.Logger, level Value) log.Logger {
return &injector{
next: next,
level: level,
}
}
type injector struct {
next log.Logger
level interface{}
}
func (l *injector) Log(keyvals ...interface{}) error {
for i := 1; i < len(keyvals); i += 2 {
if _, ok := keyvals[i].(*levelValue); ok {
return l.next.Log(keyvals...)
}
}
kvs := make([]interface{}, len(keyvals)+2)
kvs[0], kvs[1] = key, l.level
copy(kvs[2:], keyvals)
return l.next.Log(kvs...)
}
// Value is the interface that each of the canonical level values implement.
// It contains unexported methods that prevent types from other packages from
// implementing it and guaranteeing that NewFilter can distinguish the levels
// defined in this package from all other values.
type Value interface {
String() string
levelVal()
}
// Key returns the unique key added to log events by the loggers in this
// package.
func Key() interface{} { return key }
// ErrorValue returns the unique value added to log events by Error.
func ErrorValue() Value { return errorValue }
// WarnValue returns the unique value added to log events by Warn.
func WarnValue() Value { return warnValue }
// InfoValue returns the unique value added to log events by Info.
func InfoValue() Value { return infoValue }
// DebugValue returns the unique value added to log events by Debug.
func DebugValue() Value { return debugValue }
var (
// key is of type interface{} so that it allocates once during package
// initialization and avoids allocating every time the value is added to a
// []interface{} later.
key interface{} = "level"
errorValue = &levelValue{level: levelError, name: "error"}
warnValue = &levelValue{level: levelWarn, name: "warn"}
infoValue = &levelValue{level: levelInfo, name: "info"}
debugValue = &levelValue{level: levelDebug, name: "debug"}
)
type level byte
const (
levelDebug level = 1 << iota
levelInfo
levelWarn
levelError
)
type levelValue struct {
name string
level
}
func (v *levelValue) String() string { return v.name }
func (v *levelValue) levelVal() {}