2021-09-27 15:01:40 +00:00
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package level
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2022-05-20 11:48:16 +00:00
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import (
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"errors"
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"strings"
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"github.com/go-kit/log"
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)
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// ErrInvalidLevelString is returned whenever an invalid string is passed to Parse.
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var ErrInvalidLevelString = errors.New("invalid level string")
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2021-09-27 15:01:40 +00:00
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// Error returns a logger that includes a Key/ErrorValue pair.
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func Error(logger log.Logger) log.Logger {
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return log.WithPrefix(logger, Key(), ErrorValue())
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}
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// Warn returns a logger that includes a Key/WarnValue pair.
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func Warn(logger log.Logger) log.Logger {
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return log.WithPrefix(logger, Key(), WarnValue())
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}
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// Info returns a logger that includes a Key/InfoValue pair.
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func Info(logger log.Logger) log.Logger {
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return log.WithPrefix(logger, Key(), InfoValue())
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}
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// Debug returns a logger that includes a Key/DebugValue pair.
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func Debug(logger log.Logger) log.Logger {
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return log.WithPrefix(logger, Key(), DebugValue())
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}
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// NewFilter wraps next and implements level filtering. See the commentary on
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// the Option functions for a detailed description of how to configure levels.
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// If no options are provided, all leveled log events created with Debug,
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// Info, Warn or Error helper methods are squelched and non-leveled log
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// events are passed to next unmodified.
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func NewFilter(next log.Logger, options ...Option) log.Logger {
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l := &logger{
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next: next,
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}
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for _, option := range options {
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option(l)
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}
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return l
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}
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type logger struct {
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next log.Logger
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allowed level
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squelchNoLevel bool
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errNotAllowed error
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errNoLevel error
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}
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func (l *logger) Log(keyvals ...interface{}) error {
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var hasLevel, levelAllowed bool
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for i := 1; i < len(keyvals); i += 2 {
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if v, ok := keyvals[i].(*levelValue); ok {
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hasLevel = true
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levelAllowed = l.allowed&v.level != 0
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break
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}
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}
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if !hasLevel && l.squelchNoLevel {
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return l.errNoLevel
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}
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if hasLevel && !levelAllowed {
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return l.errNotAllowed
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}
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return l.next.Log(keyvals...)
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}
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// Option sets a parameter for the leveled logger.
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type Option func(*logger)
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2022-05-20 11:48:16 +00:00
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// Allow the provided log level to pass.
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func Allow(v Value) Option {
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switch v {
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case debugValue:
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return AllowDebug()
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case infoValue:
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return AllowInfo()
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case warnValue:
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return AllowWarn()
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case errorValue:
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return AllowError()
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default:
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return AllowNone()
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}
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}
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2021-09-27 15:01:40 +00:00
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// AllowAll is an alias for AllowDebug.
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func AllowAll() Option {
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return AllowDebug()
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}
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// AllowDebug allows error, warn, info and debug level log events to pass.
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func AllowDebug() Option {
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return allowed(levelError | levelWarn | levelInfo | levelDebug)
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}
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// AllowInfo allows error, warn and info level log events to pass.
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func AllowInfo() Option {
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return allowed(levelError | levelWarn | levelInfo)
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}
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// AllowWarn allows error and warn level log events to pass.
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func AllowWarn() Option {
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return allowed(levelError | levelWarn)
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}
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// AllowError allows only error level log events to pass.
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func AllowError() Option {
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return allowed(levelError)
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}
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// AllowNone allows no leveled log events to pass.
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func AllowNone() Option {
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return allowed(0)
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}
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func allowed(allowed level) Option {
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return func(l *logger) { l.allowed = allowed }
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}
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2022-05-20 11:48:16 +00:00
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// Parse a string to its corresponding level value. Valid strings are "debug",
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// "info", "warn", and "error". Strings are normalized via strings.TrimSpace and
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// strings.ToLower.
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func Parse(level string) (Value, error) {
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switch strings.TrimSpace(strings.ToLower(level)) {
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case debugValue.name:
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return debugValue, nil
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case infoValue.name:
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return infoValue, nil
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case warnValue.name:
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return warnValue, nil
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case errorValue.name:
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return errorValue, nil
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default:
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return nil, ErrInvalidLevelString
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}
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}
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// ParseDefault calls Parse and returns the default Value on error.
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func ParseDefault(level string, def Value) Value {
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v, err := Parse(level)
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if err != nil {
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return def
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}
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return v
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}
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2021-09-27 15:01:40 +00:00
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// ErrNotAllowed sets the error to return from Log when it squelches a log
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// event disallowed by the configured Allow[Level] option. By default,
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// ErrNotAllowed is nil; in this case the log event is squelched with no
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// error.
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func ErrNotAllowed(err error) Option {
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return func(l *logger) { l.errNotAllowed = err }
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}
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// SquelchNoLevel instructs Log to squelch log events with no level, so that
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// they don't proceed through to the wrapped logger. If SquelchNoLevel is set
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// to true and a log event is squelched in this way, the error value
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// configured with ErrNoLevel is returned to the caller.
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func SquelchNoLevel(squelch bool) Option {
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return func(l *logger) { l.squelchNoLevel = squelch }
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}
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// ErrNoLevel sets the error to return from Log when it squelches a log event
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// with no level. By default, ErrNoLevel is nil; in this case the log event is
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// squelched with no error.
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func ErrNoLevel(err error) Option {
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return func(l *logger) { l.errNoLevel = err }
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}
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// NewInjector wraps next and returns a logger that adds a Key/level pair to
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// the beginning of log events that don't already contain a level. In effect,
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// this gives a default level to logs without a level.
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func NewInjector(next log.Logger, level Value) log.Logger {
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return &injector{
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next: next,
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level: level,
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}
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}
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type injector struct {
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next log.Logger
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level interface{}
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}
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func (l *injector) Log(keyvals ...interface{}) error {
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for i := 1; i < len(keyvals); i += 2 {
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if _, ok := keyvals[i].(*levelValue); ok {
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return l.next.Log(keyvals...)
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}
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}
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kvs := make([]interface{}, len(keyvals)+2)
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kvs[0], kvs[1] = key, l.level
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copy(kvs[2:], keyvals)
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return l.next.Log(kvs...)
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}
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// Value is the interface that each of the canonical level values implement.
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// It contains unexported methods that prevent types from other packages from
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// implementing it and guaranteeing that NewFilter can distinguish the levels
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// defined in this package from all other values.
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type Value interface {
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String() string
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levelVal()
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}
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// Key returns the unique key added to log events by the loggers in this
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// package.
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func Key() interface{} { return key }
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// ErrorValue returns the unique value added to log events by Error.
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func ErrorValue() Value { return errorValue }
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// WarnValue returns the unique value added to log events by Warn.
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func WarnValue() Value { return warnValue }
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// InfoValue returns the unique value added to log events by Info.
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func InfoValue() Value { return infoValue }
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// DebugValue returns the unique value added to log events by Debug.
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func DebugValue() Value { return debugValue }
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var (
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// key is of type interface{} so that it allocates once during package
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// initialization and avoids allocating every time the value is added to a
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// []interface{} later.
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key interface{} = "level"
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errorValue = &levelValue{level: levelError, name: "error"}
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warnValue = &levelValue{level: levelWarn, name: "warn"}
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infoValue = &levelValue{level: levelInfo, name: "info"}
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debugValue = &levelValue{level: levelDebug, name: "debug"}
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)
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type level byte
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const (
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levelDebug level = 1 << iota
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levelInfo
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levelWarn
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levelError
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)
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type levelValue struct {
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name string
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level
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}
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func (v *levelValue) String() string { return v.name }
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func (v *levelValue) levelVal() {}
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