init

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

@@ -0,0 +1,22 @@
+// Package level implements leveled logging on top of Go kit's log package. To
+// use the level package, create a logger as per normal in your func main, and
+// wrap it with level.NewFilter.
+//
+//    var logger log.Logger
+//    logger = log.NewLogfmtLogger(os.Stderr)
+//    logger = level.NewFilter(logger, level.AllowInfo()) // <--
+//    logger = log.With(logger, "ts", log.DefaultTimestampUTC)
+//
+// Then, at the callsites, use one of the level.Debug, Info, Warn, or Error
+// helper methods to emit leveled log events.
+//
+//    logger.Log("foo", "bar") // as normal, no level
+//    level.Debug(logger).Log("request_id", reqID, "trace_data", trace.Get())
+//    if value > 100 {
+//        level.Error(logger).Log("value", value)
+//    }
+//
+// NewFilter allows precise control over what happens when a log event is
+// emitted without a level key, or if a squelched level is used. Check the
+// Option functions for details.
+package level

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

@@ -0,0 +1,205 @@
+package level
+
+import "github.com/go-kit/kit/log"
+
+// 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)
+
+// 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 }
+}
+
+// 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 Warn.
+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()      {}