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111 lines
3.3 KiB
Go
111 lines
3.3 KiB
Go
package log
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import (
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"runtime"
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"strconv"
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"strings"
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"time"
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)
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// A Valuer generates a log value. When passed to With or WithPrefix in a
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// value element (odd indexes), it represents a dynamic value which is re-
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// evaluated with each log event.
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type Valuer func() interface{}
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// bindValues replaces all value elements (odd indexes) containing a Valuer
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// with their generated value.
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func bindValues(keyvals []interface{}) {
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for i := 1; i < len(keyvals); i += 2 {
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if v, ok := keyvals[i].(Valuer); ok {
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keyvals[i] = v()
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}
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}
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}
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// containsValuer returns true if any of the value elements (odd indexes)
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// contain a Valuer.
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func containsValuer(keyvals []interface{}) bool {
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for i := 1; i < len(keyvals); i += 2 {
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if _, ok := keyvals[i].(Valuer); ok {
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return true
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}
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}
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return false
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}
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// Timestamp returns a timestamp Valuer. It invokes the t function to get the
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// time; unless you are doing something tricky, pass time.Now.
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//
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// Most users will want to use DefaultTimestamp or DefaultTimestampUTC, which
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// are TimestampFormats that use the RFC3339Nano format.
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func Timestamp(t func() time.Time) Valuer {
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return func() interface{} { return t() }
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}
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// TimestampFormat returns a timestamp Valuer with a custom time format. It
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// invokes the t function to get the time to format; unless you are doing
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// something tricky, pass time.Now. The layout string is passed to
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// Time.Format.
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//
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// Most users will want to use DefaultTimestamp or DefaultTimestampUTC, which
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// are TimestampFormats that use the RFC3339Nano format.
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func TimestampFormat(t func() time.Time, layout string) Valuer {
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return func() interface{} {
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return timeFormat{
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time: t(),
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layout: layout,
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}
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}
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}
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// A timeFormat represents an instant in time and a layout used when
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// marshaling to a text format.
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type timeFormat struct {
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time time.Time
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layout string
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}
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func (tf timeFormat) String() string {
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return tf.time.Format(tf.layout)
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}
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// MarshalText implements encoding.TextMarshaller.
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func (tf timeFormat) MarshalText() (text []byte, err error) {
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// The following code adapted from the standard library time.Time.Format
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// method. Using the same undocumented magic constant to extend the size
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// of the buffer as seen there.
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b := make([]byte, 0, len(tf.layout)+10)
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b = tf.time.AppendFormat(b, tf.layout)
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return b, nil
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}
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// Caller returns a Valuer that returns a file and line from a specified depth
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// in the callstack. Users will probably want to use DefaultCaller.
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func Caller(depth int) Valuer {
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return func() interface{} {
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_, file, line, _ := runtime.Caller(depth)
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idx := strings.LastIndexByte(file, '/')
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// using idx+1 below handles both of following cases:
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// idx == -1 because no "/" was found, or
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// idx >= 0 and we want to start at the character after the found "/".
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return file[idx+1:] + ":" + strconv.Itoa(line)
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}
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}
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var (
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// DefaultTimestamp is a Valuer that returns the current wallclock time,
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// respecting time zones, when bound.
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DefaultTimestamp = TimestampFormat(time.Now, time.RFC3339Nano)
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// DefaultTimestampUTC is a Valuer that returns the current time in UTC
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// when bound.
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DefaultTimestampUTC = TimestampFormat(
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func() time.Time { return time.Now().UTC() },
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time.RFC3339Nano,
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)
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// DefaultCaller is a Valuer that returns the file and line where the Log
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// method was invoked. It can only be used with log.With.
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DefaultCaller = Caller(3)
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)
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