New package daemon/events

Signed-off-by: Alexander Morozov <lk4d4@docker.com>

daemon/events/events.go

@@ -0,0 +1,66 @@
+package events
+
+import (
+	"sync"
+	"time"
+
+	"github.com/docker/docker/pkg/jsonmessage"
+	"github.com/docker/docker/pkg/pubsub"
+)
+
+const eventsLimit = 64
+
+// Events is pubsub channel for *jsonmessage.JSONMessage
+type Events struct {
+	mu     sync.Mutex
+	events []*jsonmessage.JSONMessage
+	pub    *pubsub.Publisher
+}
+
+// New returns new *Events instance
+func New() *Events {
+	return &Events{
+		events: make([]*jsonmessage.JSONMessage, 0, eventsLimit),
+		pub:    pubsub.NewPublisher(100*time.Millisecond, 1024),
+	}
+}
+
+// Subscribe adds new listener to events, returns slice of 64 stored last events
+// channel in which you can expect new events in form of interface{}, so you
+// need type assertion.
+func (e *Events) Subscribe() ([]*jsonmessage.JSONMessage, chan interface{}) {
+	e.mu.Lock()
+	current := make([]*jsonmessage.JSONMessage, len(e.events))
+	copy(current, e.events)
+	l := e.pub.Subscribe()
+	e.mu.Unlock()
+	return current, l
+}
+
+// Evict evicts listener from pubsub
+func (e *Events) Evict(l chan interface{}) {
+	e.pub.Evict(l)
+}
+
+// Log broadcasts event to listeners. Each listener has 100 millisecond for
+// receiving event or it will be skipped.
+func (e *Events) Log(action, id, from string) {
+	go func() {
+		e.mu.Lock()
+		jm := &jsonmessage.JSONMessage{Status: action, ID: id, From: from, Time: time.Now().UTC().Unix()}
+		if len(e.events) == cap(e.events) {
+			// discard oldest event
+			copy(e.events, e.events[1:])
+			e.events[len(e.events)-1] = jm
+		} else {
+			e.events = append(e.events, jm)
+		}
+		e.mu.Unlock()
+		e.pub.Publish(jm)
+	}()
+}
+
+// SubscribersCount returns number of event listeners
+func (e *Events) SubscribersCount() int {
+	return e.pub.Len()
+}

daemon/events/events_test.go

@@ -0,0 +1,135 @@
+package events
+
+import (
+	"fmt"
+	"testing"
+	"time"
+
+	"github.com/docker/docker/pkg/jsonmessage"
+)
+
+func TestEventsLog(t *testing.T) {
+	e := New()
+	_, l1 := e.Subscribe()
+	_, l2 := e.Subscribe()
+	defer e.Evict(l1)
+	defer e.Evict(l2)
+	count := e.SubscribersCount()
+	if count != 2 {
+		t.Fatalf("Must be 2 subscribers, got %d", count)
+	}
+	e.Log("test", "cont", "image")
+	select {
+	case msg := <-l1:
+		jmsg, ok := msg.(*jsonmessage.JSONMessage)
+		if !ok {
+			t.Fatalf("Unexpected type %T", msg)
+		}
+		if len(e.events) != 1 {
+			t.Fatalf("Must be only one event, got %d", len(e.events))
+		}
+		if jmsg.Status != "test" {
+			t.Fatalf("Status should be test, got %s", jmsg.Status)
+		}
+		if jmsg.ID != "cont" {
+			t.Fatalf("ID should be cont, got %s", jmsg.ID)
+		}
+		if jmsg.From != "image" {
+			t.Fatalf("From should be image, got %s", jmsg.From)
+		}
+	case <-time.After(1 * time.Second):
+		t.Fatal("Timeout waiting for broadcasted message")
+	}
+	select {
+	case msg := <-l2:
+		jmsg, ok := msg.(*jsonmessage.JSONMessage)
+		if !ok {
+			t.Fatalf("Unexpected type %T", msg)
+		}
+		if len(e.events) != 1 {
+			t.Fatalf("Must be only one event, got %d", len(e.events))
+		}
+		if jmsg.Status != "test" {
+			t.Fatalf("Status should be test, got %s", jmsg.Status)
+		}
+		if jmsg.ID != "cont" {
+			t.Fatalf("ID should be cont, got %s", jmsg.ID)
+		}
+		if jmsg.From != "image" {
+			t.Fatalf("From should be image, got %s", jmsg.From)
+		}
+	case <-time.After(1 * time.Second):
+		t.Fatal("Timeout waiting for broadcasted message")
+	}
+}
+
+func TestEventsLogTimeout(t *testing.T) {
+	e := New()
+	_, l := e.Subscribe()
+	defer e.Evict(l)
+
+	c := make(chan struct{})
+	go func() {
+		e.Log("test", "cont", "image")
+		close(c)
+	}()
+
+	select {
+	case <-c:
+	case <-time.After(time.Second):
+		t.Fatal("Timeout publishing message")
+	}
+}
+
+func TestLogEvents(t *testing.T) {
+	e := New()
+
+	for i := 0; i < eventsLimit+16; i++ {
+		action := fmt.Sprintf("action_%d", i)
+		id := fmt.Sprintf("cont_%d", i)
+		from := fmt.Sprintf("image_%d", i)
+		e.Log(action, id, from)
+	}
+	time.Sleep(50 * time.Millisecond)
+	current, l := e.Subscribe()
+	for i := 0; i < 10; i++ {
+		num := i + eventsLimit + 16
+		action := fmt.Sprintf("action_%d", num)
+		id := fmt.Sprintf("cont_%d", num)
+		from := fmt.Sprintf("image_%d", num)
+		e.Log(action, id, from)
+	}
+	if len(e.events) != eventsLimit {
+		t.Fatalf("Must be %d events, got %d", eventsLimit, len(e.events))
+	}
+
+	var msgs []*jsonmessage.JSONMessage
+	for len(msgs) < 10 {
+		m := <-l
+		jm, ok := (m).(*jsonmessage.JSONMessage)
+		if !ok {
+			t.Fatalf("Unexpected type %T", m)
+		}
+		msgs = append(msgs, jm)
+	}
+	if len(current) != eventsLimit {
+		t.Fatalf("Must be %d events, got %d", eventsLimit, len(current))
+	}
+	first := current[0]
+	if first.Status != "action_16" {
+		t.Fatalf("First action is %s, must be action_16", first.Status)
+	}
+	last := current[len(current)-1]
+	if last.Status != "action_79" {
+		t.Fatalf("Last action is %s, must be action_79", last.Status)
+	}
+
+	firstC := msgs[0]
+	if firstC.Status != "action_80" {
+		t.Fatalf("First action is %s, must be action_80", firstC.Status)
+	}
+	lastC := msgs[len(msgs)-1]
+	if lastC.Status != "action_89" {
+		t.Fatalf("Last action is %s, must be action_89", lastC.Status)
+	}
+}