aggregate io r/w across all reported stats volumes

connector/collector/docker.go

@@ -114,10 +114,10 @@ func (c *Docker) ReadIO(stats *api.Stats) {
 	var read, write int64
 	for _, blk := range stats.BlkioStats.IOServiceBytesRecursive {
 		if blk.Op == "Read" {
-			read = int64(blk.Value)
+			read += int64(blk.Value)
 		}
 		if blk.Op == "Write" {
-			write = int64(blk.Value)
+			write += int64(blk.Value)
 		}
 	}
 	c.IOBytesRead, c.IOBytesWrite = read, write

connector/main.go

@@ -22,7 +22,7 @@ type Connector interface {
 	All() container.Containers
 	// Get returns a single container.Container by ID
 	Get(string) (*container.Container, bool)
-	// Wait waits for the underlying connection to be lost before returning
+	// Wait blocks until the underlying connection is lost
 	Wait() struct{}
 }