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

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package log
import (
"time"
"github.com/go-stack/stack"
)
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// 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.
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type Valuer func() interface{}
// bindValues replaces all value elements (odd indexes) containing a Valuer
// with their generated value.
func bindValues(keyvals []interface{}) {
for i := 1; i < len(keyvals); i += 2 {
if v, ok := keyvals[i].(Valuer); ok {
keyvals[i] = v()
}
}
}
// containsValuer returns true if any of the value elements (odd indexes)
// contain a Valuer.
func containsValuer(keyvals []interface{}) bool {
for i := 1; i < len(keyvals); i += 2 {
if _, ok := keyvals[i].(Valuer); ok {
return true
}
}
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.
func Timestamp(t func() time.Time) Valuer {
return func() interface{} { return t() }
}
// Caller returns a Valuer that returns a file and line from a specified depth
// in the callstack. Users will probably want to use DefaultCaller.
func Caller(depth int) Valuer {
return func() interface{} { return stack.Caller(depth) }
}
var (
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// DefaultTimestamp is a Valuer that returns the current wallclock time,
// respecting time zones, when bound.
DefaultTimestamp = Valuer(func() interface{} {
return time.Now().Format(time.RFC3339Nano)
})
// DefaultTimestampUTC is a Valuer that returns the current time in UTC
// when bound.
DefaultTimestampUTC = Valuer(func() interface{} {
return time.Now().UTC().Format(time.RFC3339Nano)
})
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// 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)
)