memberlist.Logger Interface, More Flexible Logger Replacement

broadcast.go

@@ -57,7 +57,7 @@ func (m *Memberlist) encodeAndBroadcast(node string, msgType messageType, msg in
 func (m *Memberlist) encodeBroadcastNotify(node string, msgType messageType, msg interface{}, notify chan struct{}) {
 	buf, err := encode(msgType, msg)
 	if err != nil {
-		m.logger.Printf("[ERR] memberlist: Failed to encode message for broadcast: %s", err)
+		m.logger.Errorf("Failed to encode message for broadcast: %s", err)
 	} else {
 		m.queueBroadcast(node, buf.Bytes(), notify)
 	}

config.go

@@ -3,7 +3,6 @@ package memberlist
 import (
 	"fmt"
 	"io"
-	"log"
 	"net"
 	"os"
 	"strings"
@@ -209,7 +208,7 @@ type Config struct {
 	// this for the internal logger. If Logger is not set, it will fall back to the
 	// behavior for using LogOutput. You cannot specify both LogOutput and Logger
 	// at the same time.
-	Logger *log.Logger
+	Logger Logger
 
 	// Size of Memberlist's internal channel which handles UDP messages. The
 	// size of this determines the size of the queue which Memberlist will keep

integ_test.go

@@ -2,7 +2,6 @@ package memberlist
 
 import (
 	"fmt"
-	"log"
 	"os"
 	"testing"
 	"time"
@@ -42,7 +41,7 @@ func TestMemberlist_Integ(t *testing.T) {
 		c.GossipInterval = 20 * time.Millisecond
 		c.PushPullInterval = 200 * time.Millisecond
 		c.SecretKey = secret
-		c.Logger = log.New(os.Stderr, c.Name, log.LstdFlags)
+		c.Logger = newNamedLogger(os.Stderr, c.Name)
 
 		if i == 0 {
 			c.Events = &ChannelEventDelegate{eventCh}

logging.go

@@ -2,9 +2,57 @@ package memberlist
 
 import (
 	"fmt"
+	"io"
+	"log"
 	"net"
+	"os"
 )
 
+type Logger interface {
+	Debugf(format string, v ...interface{})
+	Infof(format string, v ...interface{})
+	Warnf(format string, v ...interface{})
+	Errorf(format string, v ...interface{})
+}
+
+type loggerImpl struct {
+	logger *log.Logger
+}
+
+func newLogger(output io.Writer) Logger {
+	return newNamedLogger(output, "")
+}
+
+func newNamedLogger(output io.Writer, name string) Logger {
+	return newNamedLoggerWithFlags(output, name, log.LstdFlags)
+}
+
+func newNamedLoggerWithFlags(output io.Writer, name string, flags int) Logger {
+	var logger *log.Logger
+	if output != nil {
+		logger = log.New(output, name, flags)
+	} else {
+		logger = log.New(os.Stderr, name, flags)
+	}
+	return &loggerImpl{logger}
+}
+
+func (l *loggerImpl) Debugf(format string, v ...interface{}) {
+	l.logger.Printf("[DEBUG] memberlist: "+format, v...)
+}
+
+func (l *loggerImpl) Infof(format string, v ...interface{}) {
+	l.logger.Printf("[INFO] memberlist: "+format, v...)
+}
+
+func (l *loggerImpl) Warnf(format string, v ...interface{}) {
+	l.logger.Printf("[WARN] memberlist: "+format, v...)
+}
+
+func (l *loggerImpl) Errorf(format string, v ...interface{}) {
+	l.logger.Printf("[ERROR] memberlist: "+format, v...)
+}
+
 func LogAddress(addr net.Addr) string {
 	if addr == nil {
 		return "from=<unknown address>"

memberlist.go

@@ -18,7 +18,6 @@ import (
 	"container/list"
 	"errors"
 	"fmt"
-	"log"
 	"net"
 	"os"
 	"strconv"
@@ -32,7 +31,7 @@ import (
 	"github.com/miekg/dns"
 )
 
-var errNodeNamesAreRequired = errors.New("memberlist: node names are required by configuration but one was not provided")
+var errNodeNamesAreRequired = errors.New("node names are required by configuration but one was not provided")
 
 type Memberlist struct {
 	sequenceNum uint32 // Local sequence number
@@ -76,7 +75,7 @@ type Memberlist struct {
 
 	broadcasts *TransmitLimitedQueue
 
-	logger *log.Logger
+	logger Logger
 }
 
 // BuildVsnArray creates the array of Vsn
@@ -127,7 +126,7 @@ func newMemberlist(conf *Config) (*Memberlist, error) {
 
 	logger := conf.Logger
 	if logger == nil {
-		logger = log.New(logDest, "", log.LstdFlags)
+		logger = newLogger(logDest)
 	}
 
 	// Set up a network transport by default if a custom one wasn't given
@@ -149,7 +148,7 @@ func newMemberlist(conf *Config) (*Memberlist, error) {
 					return nt, nil
 				}
 				if strings.Contains(err.Error(), "address already in use") {
-					logger.Printf("[DEBUG] memberlist: Got bind error: %v", err)
+					logger.Debugf("Got bind error: %v", err)
 					continue
 				}
 			}
@@ -176,14 +175,14 @@ func newMemberlist(conf *Config) (*Memberlist, error) {
 			port := nt.GetAutoBindPort()
 			conf.BindPort = port
 			conf.AdvertisePort = port
-			logger.Printf("[DEBUG] memberlist: Using dynamic bind port %d", port)
+			logger.Debugf("Using dynamic bind port %d", port)
 		}
 		transport = nt
 	}
 
 	nodeAwareTransport, ok := transport.(NodeAwareTransport)
 	if !ok {
-		logger.Printf("[DEBUG] memberlist: configured Transport is not a NodeAwareTransport and some features may not work as desired")
+		logger.Debugf("configured Transport is not a NodeAwareTransport and some features may not work as desired")
 		nodeAwareTransport = &shimNodeAwareTransport{transport}
 	}
 
@@ -254,7 +253,7 @@ func (m *Memberlist) Join(existing []string) (int, error) {
 		if err != nil {
 			err = fmt.Errorf("Failed to resolve %s: %v", exist, err)
 			errs = multierror.Append(errs, err)
-			m.logger.Printf("[WARN] memberlist: %v", err)
+			m.logger.Warnf("%v", err)
 			continue
 		}
 
@@ -264,7 +263,7 @@ func (m *Memberlist) Join(existing []string) (int, error) {
 			if err := m.pushPullNode(a, true); err != nil {
 				err = fmt.Errorf("Failed to join %s: %v", addr.ip, err)
 				errs = multierror.Append(errs, err)
-				m.logger.Printf("[DEBUG] memberlist: %v", err)
+				m.logger.Debugf("%v", err)
 				continue
 			}
 			numSuccess++
@@ -336,7 +335,7 @@ func (m *Memberlist) tcpLookupIP(host string, defaultPort uint16, nodeName strin
 			case (*dns.AAAA):
 				ips = append(ips, ipPort{ip: rr.AAAA, port: defaultPort, nodeName: nodeName})
 			case (*dns.CNAME):
-				m.logger.Printf("[DEBUG] memberlist: Ignoring CNAME RR in TCP-first answer for '%s'", host)
+				m.logger.Debugf("Ignoring CNAME RR in TCP-first answer for '%s'", host)
 			}
 		}
 		return ips, nil
@@ -384,7 +383,7 @@ func (m *Memberlist) resolveAddr(hostStr string) ([]ipPort, error) {
 	// way to query DNS, and we have a fallback below.
 	ips, err := m.tcpLookupIP(host, port, nodeName)
 	if err != nil {
-		m.logger.Printf("[DEBUG] memberlist: TCP-first lookup failed for '%s', falling back to UDP: %s", hostStr, err)
+		m.logger.Debugf("TCP-first lookup failed for '%s', falling back to UDP: %s", hostStr, err)
 	}
 	if len(ips) > 0 {
 		return ips, nil
@@ -427,7 +426,7 @@ func (m *Memberlist) setAlive() error {
 	}
 	_, publicIfs, err := sockaddr.IfByRFC("6890", ifAddrs)
 	if len(publicIfs) > 0 && !m.config.EncryptionEnabled() {
-		m.logger.Printf("[WARN] memberlist: Binding to public address without encryption!")
+		m.logger.Warnf("Binding to public address without encryption!")
 	}
 
 	// Set any metadata from the delegate.
@@ -639,7 +638,7 @@ func (m *Memberlist) Leave(timeout time.Duration) error {
 		state, ok := m.nodeMap[m.config.Name]
 		m.nodeLock.Unlock()
 		if !ok {
-			m.logger.Printf("[WARN] memberlist: Leave but we're not in the node map.")
+			m.logger.Warnf("Leave but we're not in the node map.")
 			return nil
 		}
 
@@ -718,7 +717,7 @@ func (m *Memberlist) Shutdown() error {
 	// completely torn down. If we kill the memberlist-side handlers
 	// those I/O handlers might get stuck.
 	if err := m.transport.Shutdown(); err != nil {
-		m.logger.Printf("[ERR] Failed to shutdown transport: %v", err)
+		m.logger.Errorf("Failed to shutdown transport: %v", err)
 	}
 
 	// Now tear down everything else.

memberlist_test.go

@@ -4,7 +4,6 @@ import (
 	"bytes"
 	"fmt"
 	"io/ioutil"
-	"log"
 	"net"
 	"os"
 	"reflect"
@@ -47,7 +46,7 @@ func testConfigNet(tb testing.TB, network byte) *Config {
 	config.Name = config.BindAddr
 	config.BindPort = 0 // choose free port
 	config.RequireNodeNames = true
-	config.Logger = log.New(os.Stderr, config.Name, log.LstdFlags)
+	config.Logger = newNamedLogger(os.Stderr, config.Name)
 	return config
 }
 
@@ -288,7 +287,7 @@ func TestCreate_keyringAndSecretKey(t *testing.T) {
 func TestCreate_invalidLoggerSettings(t *testing.T) {
 	c := DefaultLANConfig()
 	c.BindAddr = getBindAddr().String()
-	c.Logger = log.New(ioutil.Discard, "", log.LstdFlags)
+	c.Logger = newLogger(ioutil.Discard)
 	c.LogOutput = ioutil.Discard
 
 	m, err := Create(c)
@@ -1488,7 +1487,7 @@ func TestMemberlist_Join_IPv6(t *testing.T) {
 	c1.Name = "A"
 	c1.BindAddr = "[::1]"
 	c1.BindPort = 0 // choose free
-	c1.Logger = log.New(os.Stderr, c1.Name, log.LstdFlags)
+	c1.Logger = newNamedLogger(os.Stderr, c1.Name)
 
 	m1, err := Create(c1)
 	require.NoError(t, err)
@@ -1499,7 +1498,7 @@ func TestMemberlist_Join_IPv6(t *testing.T) {
 	c2.Name = "B"
 	c2.BindAddr = "[::1]"
 	c2.BindPort = 0 // choose free
-	c2.Logger = log.New(os.Stderr, c2.Name, log.LstdFlags)
+	c2.Logger = newNamedLogger(os.Stderr, c2.Name)
 
 	m2, err := Create(c2)
 	require.NoError(t, err)
@@ -1787,7 +1786,7 @@ func TestMemberlist_EncryptedGossipTransition(t *testing.T) {
 		// Set the gossip interval fast enough to get a reasonable test,
 		// but slow enough to avoid "sendto: operation not permitted"
 		conf.GossipInterval = 100 * time.Millisecond
-		conf.Logger = log.New(os.Stderr, shortName, log.LstdFlags)
+		conf.Logger = newNamedLogger(os.Stderr, shortName)
 
 		pretty[conf.Name] = shortName
 		return conf