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vendor/github.com/go-kit/kit/log/levels/levels.go

@@ -0,0 +1,127 @@
+package levels
+
+import "github.com/go-kit/kit/log"
+
+// Levels provides a leveled logging wrapper around a logger. It has five
+// levels: debug, info, warning (warn), error, and critical (crit). If you
+// want a different set of levels, you can create your own levels type very
+// easily, and you can elide the configuration.
+type Levels struct {
+	ctx      *log.Context
+	levelKey string
+
+	// We have a choice between storing level values in string fields or
+	// making a separate context for each level. When using string fields the
+	// Log method must combine the base context, the level data, and the
+	// logged keyvals; but the With method only requires updating one context.
+	// If we instead keep a separate context for each level the Log method
+	// must only append the new keyvals; but the With method would have to
+	// update all five contexts.
+
+	// Roughly speaking, storing multiple contexts breaks even if the ratio of
+	// Log/With calls is more than the number of levels. We have chosen to
+	// make the With method cheap and the Log method a bit more costly because
+	// we do not expect most applications to Log more than five times for each
+	// call to With.
+
+	debugValue string
+	infoValue  string
+	warnValue  string
+	errorValue string
+	critValue  string
+}
+
+// New creates a new leveled logger, wrapping the passed logger.
+func New(logger log.Logger, options ...Option) Levels {
+	l := Levels{
+		ctx:      log.NewContext(logger),
+		levelKey: "level",
+
+		debugValue: "debug",
+		infoValue:  "info",
+		warnValue:  "warn",
+		errorValue: "error",
+		critValue:  "crit",
+	}
+	for _, option := range options {
+		option(&l)
+	}
+	return l
+}
+
+// With returns a new leveled logger that includes keyvals in all log events.
+func (l Levels) With(keyvals ...interface{}) Levels {
+	return Levels{
+		ctx:        l.ctx.With(keyvals...),
+		levelKey:   l.levelKey,
+		debugValue: l.debugValue,
+		infoValue:  l.infoValue,
+		warnValue:  l.warnValue,
+		errorValue: l.errorValue,
+		critValue:  l.critValue,
+	}
+}
+
+// Debug returns a debug level logger.
+func (l Levels) Debug() log.Logger {
+	return l.ctx.WithPrefix(l.levelKey, l.debugValue)
+}
+
+// Info returns an info level logger.
+func (l Levels) Info() log.Logger {
+	return l.ctx.WithPrefix(l.levelKey, l.infoValue)
+}
+
+// Warn returns a warning level logger.
+func (l Levels) Warn() log.Logger {
+	return l.ctx.WithPrefix(l.levelKey, l.warnValue)
+}
+
+// Error returns an error level logger.
+func (l Levels) Error() log.Logger {
+	return l.ctx.WithPrefix(l.levelKey, l.errorValue)
+}
+
+// Crit returns a critical level logger.
+func (l Levels) Crit() log.Logger {
+	return l.ctx.WithPrefix(l.levelKey, l.critValue)
+}
+
+// Option sets a parameter for leveled loggers.
+type Option func(*Levels)
+
+// Key sets the key for the field used to indicate log level. By default,
+// the key is "level".
+func Key(key string) Option {
+	return func(l *Levels) { l.levelKey = key }
+}
+
+// DebugValue sets the value for the field used to indicate the debug log
+// level. By default, the value is "debug".
+func DebugValue(value string) Option {
+	return func(l *Levels) { l.debugValue = value }
+}
+
+// InfoValue sets the value for the field used to indicate the info log level.
+// By default, the value is "info".
+func InfoValue(value string) Option {
+	return func(l *Levels) { l.infoValue = value }
+}
+
+// WarnValue sets the value for the field used to indicate the warning log
+// level. By default, the value is "warn".
+func WarnValue(value string) Option {
+	return func(l *Levels) { l.warnValue = value }
+}
+
+// ErrorValue sets the value for the field used to indicate the error log
+// level. By default, the value is "error".
+func ErrorValue(value string) Option {
+	return func(l *Levels) { l.errorValue = value }
+}
+
+// CritValue sets the value for the field used to indicate the critical log
+// level. By default, the value is "crit".
+func CritValue(value string) Option {
+	return func(l *Levels) { l.critValue = value }
+}