core: add log listeners for k8s_event plugin (#5451)

add log listener interface
Signed-off-by: xh4n3 <xyn1016@gmail.com>

plugin/pkg/log/listener.go

+package log
+
+import (
+	"sync"
+)
+
+// Listener listens for all log prints of plugin loggers aka loggers with plugin name.
+// When a plugin logger gets called, it should first call the same method in the Listener object.
+// A usage example is, the external plugin k8s_event will replicate log prints to Kubernetes events.
+type Listener interface {
+	Name() string
+	Debug(plugin string, v ...interface{})
+	Debugf(plugin string, format string, v ...interface{})
+	Info(plugin string, v ...interface{})
+	Infof(plugin string, format string, v ...interface{})
+	Warning(plugin string, v ...interface{})
+	Warningf(plugin string, format string, v ...interface{})
+	Error(plugin string, v ...interface{})
+	Errorf(plugin string, format string, v ...interface{})
+	Fatal(plugin string, v ...interface{})
+	Fatalf(plugin string, format string, v ...interface{})
+}
+
+type listeners struct {
+	listeners []Listener
+	sync.RWMutex
+}
+
+var ls *listeners
+
+func init() {
+	ls = &listeners{}
+	ls.listeners = make([]Listener, 0)
+}
+
+// RegisterListener register a listener object.
+func RegisterListener(new Listener) error {
+	ls.Lock()
+	defer ls.Unlock()
+	for k, l := range ls.listeners {
+		if l.Name() == new.Name() {
+			ls.listeners[k] = new
+			return nil
+		}
+	}
+	ls.listeners = append(ls.listeners, new)
+	return nil
+}
+
+// DeregisterListener deregister a listener object.
+func DeregisterListener(old Listener) error {
+	ls.Lock()
+	defer ls.Unlock()
+	for k, l := range ls.listeners {
+		if l.Name() == old.Name() {
+			ls.listeners = append(ls.listeners[:k], ls.listeners[k+1:]...)
+			return nil
+		}
+	}
+	return nil
+}
+
+func (ls *listeners) debug(plugin string, v ...interface{}) {
+	ls.RLock()
+	for _, l := range ls.listeners {
+		l.Debug(plugin, v...)
+	}
+	ls.RUnlock()
+}
+
+func (ls *listeners) debugf(plugin string, format string, v ...interface{}) {
+	ls.RLock()
+	for _, l := range ls.listeners {
+		l.Debugf(plugin, format, v...)
+	}
+	ls.RUnlock()
+}
+
+func (ls *listeners) info(plugin string, v ...interface{}) {
+	ls.RLock()
+	for _, l := range ls.listeners {
+		l.Info(plugin, v...)
+	}
+	ls.RUnlock()
+
+}
+
+func (ls *listeners) infof(plugin string, format string, v ...interface{}) {
+	ls.RLock()
+	for _, l := range ls.listeners {
+		l.Infof(plugin, format, v...)
+	}
+	ls.RUnlock()
+}
+
+func (ls *listeners) warning(plugin string, v ...interface{}) {
+	ls.RLock()
+	for _, l := range ls.listeners {
+		l.Warning(plugin, v...)
+	}
+	ls.RUnlock()
+}
+
+func (ls *listeners) warningf(plugin string, format string, v ...interface{}) {
+	ls.RLock()
+	for _, l := range ls.listeners {
+		l.Warningf(plugin, format, v...)
+	}
+	ls.RUnlock()
+}
+
+func (ls *listeners) error(plugin string, v ...interface{}) {
+	ls.RLock()
+	for _, l := range ls.listeners {
+		l.Error(plugin, v...)
+	}
+	ls.RUnlock()
+}
+
+func (ls *listeners) errorf(plugin string, format string, v ...interface{}) {
+	ls.RLock()
+	for _, l := range ls.listeners {
+		l.Errorf(plugin, format, v...)
+	}
+	ls.RUnlock()
+}
+
+func (ls *listeners) fatal(plugin string, v ...interface{}) {
+	ls.RLock()
+	for _, l := range ls.listeners {
+		l.Fatal(plugin, v...)
+	}
+	ls.RUnlock()
+}
+
+func (ls *listeners) fatalf(plugin string, format string, v ...interface{}) {
+	ls.RLock()
+	for _, l := range ls.listeners {
+		l.Fatalf(plugin, format, v...)
+	}
+	ls.RUnlock()
+}

plugin/pkg/log/listener_test.go

+package log
+
+import (
+	"bytes"
+	golog "log"
+	"strings"
+	"testing"
+)
+
+func TestRegisterAndDeregisterListener(t *testing.T) {
+	for _, name := range []string{"listener1", "listener2", "listener1"} {
+		err := RegisterListener(NewMockListener(name))
+		if err != nil {
+			t.Errorf("RegsiterListener Error %s", err)
+		}
+	}
+	if len(ls.listeners) != 2 {
+		t.Errorf("Expected number of listeners to be %d, got %d", 2, len(ls.listeners))
+	}
+	for _, name := range []string{"listener1", "listener2"} {
+		err := DeregisterListener(NewMockListener(name))
+		if err != nil {
+			t.Errorf("DeregsiterListener Error %s", err)
+		}
+	}
+	if len(ls.listeners) != 0 {
+		t.Errorf("Expected number of listeners to be %d, got %d", 0, len(ls.listeners))
+	}
+}
+
+func TestSingleListenerMock(t *testing.T) {
+	listener1Name := "listener1"
+	listener1Output := info + listener1Name + " mocked info"
+	testListenersCalled(t, []string{listener1Name}, []string{listener1Output})
+}
+
+func TestMultipleListenerMock(t *testing.T) {
+	listener1Name := "listener1"
+	listener1Output := info + listener1Name + " mocked info"
+	listener2Name := "listener2"
+	listener2Output := info + listener2Name + " mocked info"
+	testListenersCalled(t, []string{listener1Name, listener2Name}, []string{listener1Output, listener2Output})
+}
+
+func testListenersCalled(t *testing.T, listenerNames []string, outputs []string) {
+	for _, name := range listenerNames {
+		err := RegisterListener(NewMockListener(name))
+		if err != nil {
+			t.Errorf("RegsiterListener Error %s", err)
+		}
+	}
+	var f bytes.Buffer
+	const ts = "test"
+	golog.SetOutput(&f)
+	lg := NewWithPlugin("testplugin")
+	lg.Info(ts)
+	for _, str := range outputs {
+		if x := f.String(); !strings.Contains(x, str) {
+			t.Errorf("Expected log to contain %s, got %s", str, x)
+		}
+	}
+	for _, name := range listenerNames {
+		err := DeregisterListener(NewMockListener(name))
+		if err != nil {
+			t.Errorf("DeregsiterListener Error %s", err)
+		}
+	}
+
+}
+
+type mockListener struct {
+	name string
+}
+
+func NewMockListener(name string) *mockListener {
+	return &mockListener{name: name}
+}
+
+func (l *mockListener) Name() string {
+	return l.name
+}
+
+func (l *mockListener) Debug(plugin string, v ...interface{}) {
+	log(debug, l.name+" mocked debug")
+}
+
+func (l *mockListener) Debugf(plugin string, format string, v ...interface{}) {
+	log(debug, l.name+" mocked debug")
+}
+
+func (l *mockListener) Info(plugin string, v ...interface{}) {
+	log(info, l.name+" mocked info")
+}
+
+func (l *mockListener) Infof(plugin string, format string, v ...interface{}) {
+	log(info, l.name+" mocked info")
+}
+
+func (l *mockListener) Warning(plugin string, v ...interface{}) {
+	log(warning, l.name+" mocked warning")
+}
+
+func (l *mockListener) Warningf(plugin string, format string, v ...interface{}) {
+	log(warning, l.name+" mocked warning")
+}
+
+func (l *mockListener) Error(plugin string, v ...interface{}) {
+	log(err, l.name+" mocked error")
+}
+
+func (l *mockListener) Errorf(plugin string, format string, v ...interface{}) {
+	log(err, l.name+" mocked error")
+}
+
+func (l *mockListener) Fatal(plugin string, v ...interface{}) {
+	log(fatal, l.name+" mocked fatal")
+}
+
+func (l *mockListener) Fatalf(plugin string, format string, v ...interface{}) {
+	log(fatal, l.name+" mocked fatal")
+}

plugin/pkg/log/plugin.go

@@ -27,6 +27,7 @@ func (p P) Debug(v ...interface{}) {
 	if !D.Value() {
 		return
 	}
+	ls.debug(p.plugin, v...)
 	p.log(debug, v...)
 }
 
@@ -35,29 +36,56 @@ func (p P) Debugf(format string, v ...interface{}) {
 	if !D.Value() {
 		return
 	}
+	ls.debugf(p.plugin, format, v...)
 	p.logf(debug, format, v...)
 }
 
 // Info logs as log.Info.
-func (p P) Info(v ...interface{}) { p.log(info, v...) }
+func (p P) Info(v ...interface{}) {
+	ls.info(p.plugin, v...)
+	p.log(info, v...)
+}
 
 // Infof logs as log.Infof.
-func (p P) Infof(format string, v ...interface{}) { p.logf(info, format, v...) }
+func (p P) Infof(format string, v ...interface{}) {
+	ls.infof(p.plugin, format, v...)
+	p.logf(info, format, v...)
+}
 
 // Warning logs as log.Warning.
-func (p P) Warning(v ...interface{}) { p.log(warning, v...) }
+func (p P) Warning(v ...interface{}) {
+	ls.warning(p.plugin, v...)
+	p.log(warning, v...)
+}
 
 // Warningf logs as log.Warningf.
-func (p P) Warningf(format string, v ...interface{}) { p.logf(warning, format, v...) }
+func (p P) Warningf(format string, v ...interface{}) {
+	ls.warningf(p.plugin, format, v...)
+	p.logf(warning, format, v...)
+}
 
 // Error logs as log.Error.
-func (p P) Error(v ...interface{}) { p.log(err, v...) }
+func (p P) Error(v ...interface{}) {
+	ls.error(p.plugin, v...)
+	p.log(err, v...)
+}
 
 // Errorf logs as log.Errorf.
-func (p P) Errorf(format string, v ...interface{}) { p.logf(err, format, v...) }
+func (p P) Errorf(format string, v ...interface{}) {
+	ls.errorf(p.plugin, format, v...)
+	p.logf(err, format, v...)
+}
 
 // Fatal logs as log.Fatal and calls os.Exit(1).
-func (p P) Fatal(v ...interface{}) { p.log(fatal, v...); os.Exit(1) }
+func (p P) Fatal(v ...interface{}) {
+	ls.fatal(p.plugin, v...)
+	p.log(fatal, v...)
+	os.Exit(1)
+}
 
 // Fatalf logs as log.Fatalf and calls os.Exit(1).
-func (p P) Fatalf(format string, v ...interface{}) { p.logf(fatal, format, v...); os.Exit(1) }
+func (p P) Fatalf(format string, v ...interface{}) {
+	ls.fatalf(p.plugin, format, v...)
+	p.logf(fatal, format, v...)
+	os.Exit(1)
+}