1. docker
  2. Commit 868f56e0839cb47223a7d988f21ae623d4ea9c6e
Browse code

New package daemon/events

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

Alexander Morozov authored on 2015/04/04 05:58:56
Showing 2 changed files
daemon/events/events.go
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+package events
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+
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+import (
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+	"sync"
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+	"time"
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+
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+	"github.com/docker/docker/pkg/jsonmessage"
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+	"github.com/docker/docker/pkg/pubsub"
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+)
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+
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+const eventsLimit = 64
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+
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+// Events is pubsub channel for *jsonmessage.JSONMessage
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+type Events struct {
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+	mu     sync.Mutex
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+	events []*jsonmessage.JSONMessage
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+	pub    *pubsub.Publisher
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+}
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+
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+// New returns new *Events instance
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+func New() *Events {
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+	return &Events{
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+		events: make([]*jsonmessage.JSONMessage, 0, eventsLimit),
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+		pub:    pubsub.NewPublisher(100*time.Millisecond, 1024),
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+	}
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+}
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+
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+// Subscribe adds new listener to events, returns slice of 64 stored last events
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+// channel in which you can expect new events in form of interface{}, so you
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+// need type assertion.
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+func (e *Events) Subscribe() ([]*jsonmessage.JSONMessage, chan interface{}) {
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+	e.mu.Lock()
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+	current := make([]*jsonmessage.JSONMessage, len(e.events))
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+	copy(current, e.events)
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+	l := e.pub.Subscribe()
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+	e.mu.Unlock()
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+	return current, l
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+}
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+
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+// Evict evicts listener from pubsub
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+func (e *Events) Evict(l chan interface{}) {
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+	e.pub.Evict(l)
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+}
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+
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+// Log broadcasts event to listeners. Each listener has 100 millisecond for
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+// receiving event or it will be skipped.
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+func (e *Events) Log(action, id, from string) {
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+	go func() {
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+		e.mu.Lock()
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+		jm := &jsonmessage.JSONMessage{Status: action, ID: id, From: from, Time: time.Now().UTC().Unix()}
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+		if len(e.events) == cap(e.events) {
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+			// discard oldest event
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+			copy(e.events, e.events[1:])
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+			e.events[len(e.events)-1] = jm
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+		} else {
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+			e.events = append(e.events, jm)
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+		}
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+		e.mu.Unlock()
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+		e.pub.Publish(jm)
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+	}()
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+}
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+
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+// SubscribersCount returns number of event listeners
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+func (e *Events) SubscribersCount() int {
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+	return e.pub.Len()
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+}
daemon/events/events_test.go
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+package events
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+
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+import (
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+	"fmt"
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+	"testing"
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+	"time"
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+
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+	"github.com/docker/docker/pkg/jsonmessage"
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+)
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+
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+func TestEventsLog(t *testing.T) {
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+	e := New()
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+	_, l1 := e.Subscribe()
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+	_, l2 := e.Subscribe()
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+	defer e.Evict(l1)
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+	defer e.Evict(l2)
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+	count := e.SubscribersCount()
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+	if count != 2 {
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+		t.Fatalf("Must be 2 subscribers, got %d", count)
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+	}
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+	e.Log("test", "cont", "image")
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+	select {
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+	case msg := <-l1:
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+		jmsg, ok := msg.(*jsonmessage.JSONMessage)
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+		if !ok {
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+			t.Fatalf("Unexpected type %T", msg)
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+		}
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+		if len(e.events) != 1 {
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+			t.Fatalf("Must be only one event, got %d", len(e.events))
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+		}
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+		if jmsg.Status != "test" {
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+			t.Fatalf("Status should be test, got %s", jmsg.Status)
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+		}
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+		if jmsg.ID != "cont" {
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+			t.Fatalf("ID should be cont, got %s", jmsg.ID)
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+		}
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+		if jmsg.From != "image" {
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+			t.Fatalf("From should be image, got %s", jmsg.From)
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+		}
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+	case <-time.After(1 * time.Second):
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+		t.Fatal("Timeout waiting for broadcasted message")
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+	}
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+	select {
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+	case msg := <-l2:
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+		jmsg, ok := msg.(*jsonmessage.JSONMessage)
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+		if !ok {
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+			t.Fatalf("Unexpected type %T", msg)
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+		}
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+		if len(e.events) != 1 {
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+			t.Fatalf("Must be only one event, got %d", len(e.events))
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+		}
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+		if jmsg.Status != "test" {
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+			t.Fatalf("Status should be test, got %s", jmsg.Status)
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+		}
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+		if jmsg.ID != "cont" {
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+			t.Fatalf("ID should be cont, got %s", jmsg.ID)
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+		}
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+		if jmsg.From != "image" {
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+			t.Fatalf("From should be image, got %s", jmsg.From)
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+		}
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+	case <-time.After(1 * time.Second):
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+		t.Fatal("Timeout waiting for broadcasted message")
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+	}
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+}
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+
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+func TestEventsLogTimeout(t *testing.T) {
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+	e := New()
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+	_, l := e.Subscribe()
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+	defer e.Evict(l)
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+
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+	c := make(chan struct{})
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+	go func() {
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+		e.Log("test", "cont", "image")
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+		close(c)
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+	}()
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+
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+	select {
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+	case <-c:
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+	case <-time.After(time.Second):
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+		t.Fatal("Timeout publishing message")
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+	}
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+}
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+
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+func TestLogEvents(t *testing.T) {
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+	e := New()
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+
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+	for i := 0; i < eventsLimit+16; i++ {
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+		action := fmt.Sprintf("action_%d", i)
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+		id := fmt.Sprintf("cont_%d", i)
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+		from := fmt.Sprintf("image_%d", i)
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+		e.Log(action, id, from)
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+	}
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+	time.Sleep(50 * time.Millisecond)
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+	current, l := e.Subscribe()
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+	for i := 0; i < 10; i++ {
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+		num := i + eventsLimit + 16
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+		action := fmt.Sprintf("action_%d", num)
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+		id := fmt.Sprintf("cont_%d", num)
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+		from := fmt.Sprintf("image_%d", num)
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+		e.Log(action, id, from)
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+	}
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+	if len(e.events) != eventsLimit {
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+		t.Fatalf("Must be %d events, got %d", eventsLimit, len(e.events))
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+	}
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+
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+	var msgs []*jsonmessage.JSONMessage
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+	for len(msgs) < 10 {
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+		m := <-l
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+		jm, ok := (m).(*jsonmessage.JSONMessage)
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+		if !ok {
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+			t.Fatalf("Unexpected type %T", m)
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+		}
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+		msgs = append(msgs, jm)
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+	}
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+	if len(current) != eventsLimit {
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+		t.Fatalf("Must be %d events, got %d", eventsLimit, len(current))
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+	}
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+	first := current[0]
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+	if first.Status != "action_16" {
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+		t.Fatalf("First action is %s, must be action_16", first.Status)
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+	}
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+	last := current[len(current)-1]
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+	if last.Status != "action_79" {
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+		t.Fatalf("Last action is %s, must be action_79", last.Status)
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+	}
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+
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+	firstC := msgs[0]
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+	if firstC.Status != "action_80" {
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+		t.Fatalf("First action is %s, must be action_80", firstC.Status)
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+	}
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+	lastC := msgs[len(msgs)-1]
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+	if lastC.Status != "action_89" {
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+		t.Fatalf("Last action is %s, must be action_89", lastC.Status)
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+	}
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+}