multi: add NewLogClosure in lnutils to avoid repetition

And replaces all usage of `logClosure` with `lnutils.LogClosure`.

lnwallet/chainfee/estimator.go

@@ -15,6 +15,7 @@ import (
 
 	"github.com/btcsuite/btcd/btcutil"
 	"github.com/btcsuite/btcd/rpcclient"
+	"github.com/lightningnetwork/lnd/lnutils"
 )
 
 const (
@@ -1004,7 +1005,7 @@ func (w *WebAPIEstimator) updateFeeEstimates() {
 		return
 	}
 
-	log.Debugf("Received response from source: %s", newLogClosure(
+	log.Debugf("Received response from source: %s", lnutils.NewLogClosure(
 		func() string {
 			resp, _ := json.Marshal(resp)
 			return string(resp)

lnwallet/chainfee/log.go

@@ -27,19 +27,3 @@ func DisableLog() {
 func UseLogger(logger btclog.Logger) {
 	log = logger
 }
-
-// logClosure is used to provide a closure over expensive logging operations so
-// don't have to be performed when the logging level doesn't warrant it.
-type logClosure func() string
-
-// String invokes the underlying function and returns the result.
-func (c logClosure) String() string {
-	return c()
-}
-
-// newLogClosure returns a new closure over a function that returns a string
-// which itself provides a Stringer interface so that it can be used with the
-// logging system.
-func newLogClosure(c func() string) logClosure {
-	return logClosure(c)
-}