Fix duplicated tags in InfluxDB

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

@@ -6,9 +6,9 @@ import (
 	"github.com/go-stack/stack"
 )
 
-// A Valuer generates a log value. When passed to Context.With in a value
-// element (odd indexes), it represents a dynamic value which is re-evaluated
-// with each log event.
+// A Valuer generates a log value. When passed to With or WithPrefix in a
+// value element (odd indexes), it represents a dynamic value which is re-
+// evaluated with each log event.
 type Valuer func() interface{}
 
 // bindValues replaces all value elements (odd indexes) containing a Valuer
@@ -32,22 +32,51 @@ func containsValuer(keyvals []interface{}) bool {
 	return false
 }
 
-// Timestamp returns a Valuer that invokes the underlying function when bound,
-// returning a time.Time. Users will probably want to use DefaultTimestamp or
-// DefaultTimestampUTC.
+// Timestamp returns a timestamp Valuer. It invokes the t function to get the
+// time; unless you are doing something tricky, pass time.Now.
+//
+// Most users will want to use DefaultTimestamp or DefaultTimestampUTC, which
+// are TimestampFormats that use the RFC3339Nano format.
 func Timestamp(t func() time.Time) Valuer {
 	return func() interface{} { return t() }
 }
 
-var (
-	// DefaultTimestamp is a Valuer that returns the current wallclock time,
-	// respecting time zones, when bound.
-	DefaultTimestamp Valuer = func() interface{} { return time.Now().Format(time.RFC3339) }
+// TimestampFormat returns a timestamp Valuer with a custom time format. It
+// invokes the t function to get the time to format; unless you are doing
+// something tricky, pass time.Now. The layout string is passed to
+// Time.Format.
+//
+// Most users will want to use DefaultTimestamp or DefaultTimestampUTC, which
+// are TimestampFormats that use the RFC3339Nano format.
+func TimestampFormat(t func() time.Time, layout string) Valuer {
+	return func() interface{} {
+		return timeFormat{
+			time:   t(),
+			layout: layout,
+		}
+	}
+}
 
-	// DefaultTimestampUTC is a Valuer that returns the current time in UTC
-	// when bound.
-	DefaultTimestampUTC Valuer = func() interface{} { return time.Now().UTC().Format(time.RFC3339) }
-)
+// A timeFormat represents an instant in time and a layout used when
+// marshaling to a text format.
+type timeFormat struct {
+	time   time.Time
+	layout string
+}
+
+func (tf timeFormat) String() string {
+	return tf.time.Format(tf.layout)
+}
+
+// MarshalText implements encoding.TextMarshaller.
+func (tf timeFormat) MarshalText() (text []byte, err error) {
+	// The following code adapted from the standard library time.Time.Format
+	// method. Using the same undocumented magic constant to extend the size
+	// of the buffer as seen there.
+	b := make([]byte, 0, len(tf.layout)+10)
+	b = tf.time.AppendFormat(b, tf.layout)
+	return b, nil
+}
 
 // Caller returns a Valuer that returns a file and line from a specified depth
 // in the callstack. Users will probably want to use DefaultCaller.
@@ -56,6 +85,17 @@ func Caller(depth int) Valuer {
 }
 
 var (
+	// DefaultTimestamp is a Valuer that returns the current wallclock time,
+	// respecting time zones, when bound.
+	DefaultTimestamp = TimestampFormat(time.Now, time.RFC3339Nano)
+
+	// DefaultTimestampUTC is a Valuer that returns the current time in UTC
+	// when bound.
+	DefaultTimestampUTC = TimestampFormat(
+		func() time.Time { return time.Now().UTC() },
+		time.RFC3339Nano,
+	)
+
 	// DefaultCaller is a Valuer that returns the file and line where the Log
 	// method was invoked. It can only be used with log.With.
 	DefaultCaller = Caller(3)