agent: add ConnStats

ammario · ammario · commit ea3c26f5637e · 2022-09-01T01:14:40.000Z
diff --git a/agent/stats.go b/agent/stats.go
@@ -0,0 +1,38 @@
+package agent
+
+import (
+	"net"
+	"time"
+)
+
+// ConnStats wraps a net.Conn with statistics.
+type ConnStats struct {
+	CreatedAt time.Time `json:"created_at,omitempty"`
+	Protocol  string    `json:"protocol,omitempty"`
+	RxBytes   uint64    `json:"rx_bytes,omitempty"`
+	TxBytes   uint64    `json:"tx_bytes,omitempty"`
+
+	net.Conn `json:"-"`
+}
+
+var _ net.Conn = new(ConnStats)
+
+func (c *ConnStats) Read(b []byte) (n int, err error) {
+	n, err = c.Conn.Read(b)
+	c.RxBytes += uint64(n)
+	return n, err
+}
+
+func (c *ConnStats) Write(b []byte) (n int, err error) {
+	n, err = c.Conn.Write(b)
+	c.TxBytes += uint64(n)
+	return n, err
+}
+
+var _ net.Conn = new(ConnStats)
+
+// Stats records the Agent's network connection statistics for use in
+// user-facing metrics and debugging.
+type Stats struct {
+	Conns []ConnStats `json:"conns,omitempty"`
+}
diff --git a/agent/stats_test.go b/agent/stats_test.go
@@ -0,0 +1,61 @@
+package agent_test
+
+import (
+	"io"
+	"net"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/coder/coder/agent"
+)
+
+func TestConnStats(t *testing.T) {
+	t.Parallel()
+
+	t.Run("Write", func(t *testing.T) {
+		t.Parallel()
+
+		c1, c2 := net.Pipe()
+
+		payload := []byte("dogs & cats")
+		statsConn := &agent.ConnStats{Conn: c1}
+
+		got := make(chan []byte)
+		go func() {
+			b, _ := io.ReadAll(c2)
+			got <- b
+		}()
+		n, err := statsConn.Write(payload)
+		require.NoError(t, err)
+		assert.Equal(t, len(payload), n)
+		statsConn.Close()
+
+		require.Equal(t, payload, <-got)
+
+		require.EqualValues(t, statsConn.TxBytes, len(payload))
+		require.EqualValues(t, statsConn.RxBytes, 0)
+	})
+
+	t.Run("Read", func(t *testing.T) {
+		t.Parallel()
+
+		c1, c2 := net.Pipe()
+
+		payload := []byte("cats & dogs")
+		statsConn := &agent.ConnStats{Conn: c1}
+
+		go func() {
+			c2.Write(payload)
+			c2.Close()
+		}()
+
+		got, err := io.ReadAll(statsConn)
+		require.NoError(t, err)
+		assert.Equal(t, len(payload), len(got))
+
+		require.EqualValues(t, statsConn.RxBytes, len(payload))
+		require.EqualValues(t, statsConn.TxBytes, 0)
+	})
+}
