revid: added multiSender test to check that Write returns when active func return false in send retry

revid/senders_test.go

@@ -31,6 +31,7 @@ package revid
 import (
 	"errors"
 	"fmt"
+	"sync"
 	"testing"
 	"time"
 
@@ -355,19 +356,26 @@ func TestMultiSenderNotActiveNoRetry(t *testing.T) {
 		newDummyLoadSender(false),
 		newDummyLoadSender(false),
 	}
+
+	// This will allow us to simulate a change in running state of
+	// multiSender's 'owner'.
 	active := true
 	activeFunc := func() bool {
 		return active
 	}
+
 	ms, err := newMultiSender(senders, false, activeFunc)
 	if err != nil {
 		t.Fatalf("Unexpected error: %v", err)
 	}
 
+	// We will perform two writes. We expect the second write not to be complete,
+	// i.e. the senders should not send anything on this write.
 	ms.Write([]byte{0x00})
 	active = false
 	ms.Write([]byte{0x01})
 
+	// Check that the senders only sent data once.
 	for _, dest := range ms.senders {
 		if len(dest.(*dummyLoadSender).buf) != 1 {
 			t.Errorf("length of sender buf is not 1 as expected")
@@ -375,5 +383,60 @@ func TestMultiSenderNotActiveNoRetry(t *testing.T) {
 	}
 }
 
+// TestMultiSenderNotActiveRetry checks that we correctly returns from a call to
+// multiSender.Write when the active callback func return false during repeated
+// send retries.
+func TestMultiSenderNotActiveRetry(t *testing.T) {
+	senders := []loadSender{
+		newDummyLoadSender(false),
+	}
+
+	// Active will simulate the running state of the multiSender's 'owner'.
+	active := true
+
+	// We will run the ms.Write as routine so we need some sync.
+	var mu sync.Mutex
+
+	// After the write is running as a routine we will call this to change the
+	// running state of the 'owner'.
+	setActive := func(b bool) {
+		mu.Lock()
+		defer mu.Unlock()
+		active = b
+	}
+
+	// Once we use setActive to change the state of the fake owner, this will
+	// return false and we expect the ms.Write method to return from the continous
+	// send retry state.
+	activeFunc := func() bool {
+		mu.Lock()
+		defer mu.Unlock()
+		return active
+	}
+
+	ms, err := newMultiSender(senders, false, activeFunc)
+	if err != nil {
+		t.Fatalf("Unexpected error: %v", err)
+	}
+
+	// We run this in background so that we can change running state during the
+	// the write. We then expect done to be true after some period of time.
+	done := false
+	go func() {
+		ms.Write([]byte{0x00})
+		done = true
+	}()
+
+	// Wait for half a second and then change the active state.
+	time.Sleep(500 * time.Millisecond)
+	setActive(false)
+
+	// Wait half a second for the routine to return and check that done is true.
+	time.Sleep(500 * time.Millisecond)
+	if !done {
+		t.Fatal("multiSender.Write did not return as expected with active=false")
+	}
+}
+
 // TODO: test that send retry works
 // TODO: test that send fail works with no retry