fix: Check token bucket corner cases correctly.

Signed-off-by: John Calixto <jcalixto@vmware.com>

clientlibrary/worker/polling-shard-consumer.go

@@ -258,14 +258,16 @@ func (sc *PollingShardConsumer) checkCoolOffPeriod() (int, error) {
 	secondsPassed := currentTime.Sub(sc.lastCheckTime).Seconds()
 	sc.lastCheckTime = currentTime
 	sc.remBytes += int(secondsPassed * MaxBytesPerSecond)
-	transactionReadRate := float64(sc.bytesRead) / (secondsPassed * BytesToMbConversion)
 
 	if sc.remBytes > MaxBytes {
 		sc.remBytes = MaxBytes
 	}
-	if sc.remBytes <= sc.bytesRead || transactionReadRate > 2 {
+	if sc.remBytes < 1 {
 		// Wait until cool down period has passed to prevent ProvisionedThroughputExceededException
 		coolDown := sc.bytesRead / MaxBytesPerSecond
+		if sc.bytesRead%MaxBytesPerSecond > 0 {
+			coolDown++
+		}
 		return coolDown, maxBytesExceededError
 	} else {
 		sc.remBytes -= sc.bytesRead

clientlibrary/worker/polling-shard-consumer_test.go

@@ -86,6 +86,8 @@ func TestCallGetRecordsAPI(t *testing.T) {
 	// check that correct cool off period is taken for 10mb in 1 second
 	testTime := time.Now()
 	m4 := MockKinesisSubscriberGetter{}
+	ret4 := kinesis.GetRecordsOutput{Records: nil}
+	m4.On("GetRecords", mock.Anything, mock.Anything, mock.Anything).Return(&ret4, nil)
 	psc4 := PollingShardConsumer{
 		commonShardConsumer: commonShardConsumer{kc: &m4},
 		callsLeft:           2,
@@ -100,10 +102,10 @@ func TestCallGetRecordsAPI(t *testing.T) {
 		return testTime.Add(time.Second)
 	}
 	out4, checkSleepVal2, err4 := psc4.callGetRecordsAPI(&gri)
-	assert.Nil(t, out4)
-	assert.Equal(t, maxBytesExceededError, err4)
+	assert.Nil(t, err4)
+	assert.Equal(t, &ret4, out4)
 	m4.AssertExpectations(t)
-	if checkSleepVal2 != 5 {
+	if checkSleepVal2 != 0 {
 		t.Errorf("Incorrect Cool Off Period: %v", checkSleepVal2)
 	}
 
@@ -134,6 +136,8 @@ func TestCallGetRecordsAPI(t *testing.T) {
 	// check for correct cool off period with 8mb in .2 seconds with 6mb remaining
 	testTime3 := time.Now()
 	m6 := MockKinesisSubscriberGetter{}
+	ret6 := kinesis.GetRecordsOutput{Records: nil}
+	m6.On("GetRecords", mock.Anything, mock.Anything, mock.Anything).Return(&ret6, nil)
 	psc6 := PollingShardConsumer{
 		commonShardConsumer: commonShardConsumer{kc: &m6},
 		callsLeft:           2,
@@ -148,10 +152,10 @@ func TestCallGetRecordsAPI(t *testing.T) {
 		return testTime3.Add(time.Second / 5)
 	}
 	out6, checkSleepVal4, err6 := psc6.callGetRecordsAPI(&gri)
-	assert.Nil(t, out6)
-	assert.Equal(t, err6, maxBytesExceededError)
+	assert.Nil(t, err6)
+	assert.Equal(t, &ret6, out6)
 	m5.AssertExpectations(t)
-	if checkSleepVal4 != 4 {
+	if checkSleepVal4 != 0 {
 		t.Errorf("Incorrect Cool Off Period: %v", checkSleepVal4)
 	}
 
@@ -196,3 +200,156 @@ func (m *MockKinesisSubscriberGetter) GetShardIterator(ctx context.Context, para
 func (m *MockKinesisSubscriberGetter) SubscribeToShard(ctx context.Context, params *kinesis.SubscribeToShardInput, optFns ...func(*kinesis.Options)) (*kinesis.SubscribeToShardOutput, error) {
 	return nil, nil
 }
+
+func TestPollingShardConsumer_checkCoolOffPeriod(t *testing.T) {
+	refTime := time.Now()
+	type fields struct {
+		lastCheckTime time.Time
+		remBytes      int
+		bytesRead     int
+	}
+	tests := []struct {
+		name    string
+		fields  fields
+		timeNow time.Time
+		want    int
+		wantErr bool
+	}{
+		{
+			"zero time max bytes to spend",
+			fields{
+				time.Time{},
+				0,
+				0,
+			},
+			refTime,
+			0,
+			false,
+		},
+		{
+			"same second, bytes still left to spend",
+			fields{
+				refTime,
+				MaxBytesPerSecond,
+				MaxBytesPerSecond - 1,
+			},
+			refTime,
+			0,
+			false,
+		},
+		{
+			"same second, not many but some bytes still left to spend",
+			fields{
+				refTime,
+				8,
+				MaxBytesPerSecond,
+			},
+			refTime,
+			0,
+			false,
+		},
+		{
+			"same second, 1 byte still left to spend",
+			fields{
+				refTime,
+				1,
+				MaxBytesPerSecond,
+			},
+			refTime,
+			0,
+			false,
+		},
+		{
+			"next second, bytes still left to spend",
+			fields{
+				refTime,
+				42,
+				1024,
+			},
+			refTime.Add(1 * time.Second),
+			0,
+			false,
+		},
+		{
+			"same second, max bytes per second already spent",
+			fields{
+				refTime,
+				0,
+				MaxBytesPerSecond,
+			},
+			refTime,
+			1,
+			true,
+		},
+		{
+			"same second, more than max bytes per second already spent",
+			fields{
+				refTime,
+				0,
+				MaxBytesPerSecond + 1,
+			},
+			refTime,
+			2,
+			true,
+		},
+
+		// Kinesis prevents reading more than 10 MiB at once
+		{
+			"same second, 10 MiB read all at once",
+			fields{
+				refTime,
+				0,
+				10 * 1024 * 1024,
+			},
+			refTime,
+			6,
+			true,
+		},
+
+		{
+			"same second, 10 MB read all at once",
+			fields{
+				refTime,
+				0,
+				10 * 1000 * 1000,
+			},
+			refTime,
+			5,
+			true,
+		},
+		{
+			"5 seconds ago, 10 MB read all at once",
+			fields{
+				refTime,
+				0,
+				10 * 1000 * 1000,
+			},
+			refTime.Add(5 * time.Second),
+			0,
+			false,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			sc := &PollingShardConsumer{
+				lastCheckTime: tt.fields.lastCheckTime,
+				remBytes:      tt.fields.remBytes,
+				bytesRead:     tt.fields.bytesRead,
+			}
+			rateLimitTimeNow = func() time.Time {
+				return tt.timeNow
+			}
+			got, err := sc.checkCoolOffPeriod()
+			if (err != nil) != tt.wantErr {
+				t.Errorf("PollingShardConsumer.checkCoolOffPeriod() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if got != tt.want {
+				t.Errorf("PollingShardConsumer.checkCoolOffPeriod() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+
+	// restore original time.Now
+	rateLimitTimeNow = time.Now
+}