fix a deadlock bug along with unit tests

storage/memory/memory.go

@@ -183,6 +183,7 @@ func (self *InMemoryStorage) Samples(name string, numSamples int) ([]*info.Conta
 	var ok bool
 	self.lock.RLock()
 	if cstore, ok = self.containerStorageMap[name]; !ok {
+		self.lock.RUnlock()
 		return nil, fmt.Errorf("unable to find data for container %v", name)
 	}
 	self.lock.RUnlock()
@@ -195,6 +196,7 @@ func (self *InMemoryStorage) RecentStats(name string, numStats int) ([]*info.Con
 	var ok bool
 	self.lock.RLock()
 	if cstore, ok = self.containerStorageMap[name]; !ok {
+		self.lock.RUnlock()
 		return nil, fmt.Errorf("unable to find data for container %v", name)
 	}
 	self.lock.RUnlock()
@@ -207,6 +209,7 @@ func (self *InMemoryStorage) Percentiles(name string, cpuPercentiles, memPercent
 	var ok bool
 	self.lock.RLock()
 	if cstore, ok = self.containerStorageMap[name]; !ok {
+		self.lock.RUnlock()
 		return nil, fmt.Errorf("unable to find data for container %v", name)
 	}
 	self.lock.RUnlock()

storage/memory/memory_test.go

@@ -61,3 +61,15 @@ func TestRetrievePartialRecentStats(t *testing.T) {
 func TestRetrieveAllRecentStats(t *testing.T) {
 	runStorageTest(test.StorageDriverTestRetrieveAllRecentStats, t)
 }
+
+func TestNoRecentStats(t *testing.T) {
+	runStorageTest(test.StorageDriverTestNoRecentStats, t)
+}
+
+func TestNoSamples(t *testing.T) {
+	runStorageTest(test.StorageDriverTestNoSamples, t)
+}
+
+func TestPercentilesWithoutStats(t *testing.T) {
+	runStorageTest(test.StorageDriverTestPercentilesWithoutStats, t)
+}

storage/test/storagetests.go

@@ -319,3 +319,43 @@ func StorageDriverTestRetrieveAllRecentStats(driver storage.StorageDriver, t *te
 		}
 	}
 }
+
+func StorageDriverTestNoRecentStats(driver storage.StorageDriver, t *testing.T) {
+	defer driver.Close()
+	nonExistContainer := "somerandomecontainer"
+	stats, _ := driver.RecentStats(nonExistContainer, -1)
+	if len(stats) > 0 {
+		t.Errorf("RecentStats() returns %v stats on non exist container", len(stats))
+	}
+}
+
+func StorageDriverTestNoSamples(driver storage.StorageDriver, t *testing.T) {
+	defer driver.Close()
+	nonExistContainer := "somerandomecontainer"
+	samples, _ := driver.Samples(nonExistContainer, -1)
+	if len(samples) > 0 {
+		t.Errorf("Samples() returns %v samples on non exist container", len(samples))
+	}
+}
+
+func StorageDriverTestPercentilesWithoutStats(driver storage.StorageDriver, t *testing.T) {
+	defer driver.Close()
+	nonExistContainer := "somerandomecontainer"
+	percentiles, _ := driver.Percentiles(nonExistContainer, []int{50, 80}, []int{50, 80})
+	if percentiles == nil {
+		return
+	}
+	if percentiles.MaxMemoryUsage != 0 {
+		t.Errorf("Percentiles() reports max memory usage > 0 when there's no stats.")
+	}
+	for _, p := range percentiles.CpuUsagePercentiles {
+		if p.Value != 0 {
+			t.Errorf("Percentiles() reports cpu usage is %v when there's no stats.", p.Value)
+		}
+	}
+	for _, p := range percentiles.MemoryUsagePercentiles {
+		if p.Value != 0 {
+			t.Errorf("Percentiles() reports memory usage is %v when there's no stats.", p.Value)
+		}
+	}
+}