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package topology
import (
"bytes"
"context"
"io"
"math"
"net"
"testing"
"time"
"github.com/stretchr/testify/assert"
"go.mongodb.org/mongo-driver/x/bsonx/bsoncore"
"go.mongodb.org/mongo-driver/x/mongo/driver"
"go.mongodb.org/mongo-driver/x/mongo/driver/drivertest"
"go.mongodb.org/mongo-driver/x/mongo/driver/operation"
)
func makeHelloReply() []byte {
doc := bsoncore.NewDocumentBuilder().AppendInt32("ok", 1).Build()
return drivertest.MakeReply(doc)
}
var _ net.Conn = &mockSlowConn{}
// mockSlowConn is a net.Conn that delays all calls to Read() by the given delay duration. After the
// delay, Read() reads the given response. Calls to Write() reset the read buffer, so subsequent
// Read() calls read from the beginning of the provided response.
type mockSlowConn struct {
reader *bytes.Reader
delay time.Duration
}
func newMockSlowConn(response []byte, delay time.Duration) *mockSlowConn {
return &mockSlowConn{
reader: bytes.NewReader(response),
delay: delay,
}
}
func (msc *mockSlowConn) Read(b []byte) (int, error) {
time.Sleep(msc.delay)
return msc.reader.Read(b)
}
func (msc *mockSlowConn) Write(b []byte) (int, error) {
_, err := msc.reader.Seek(0, io.SeekStart)
return len(b), err
}
func (*mockSlowConn) Close() error { return nil }
func (*mockSlowConn) LocalAddr() net.Addr { return nil }
func (*mockSlowConn) RemoteAddr() net.Addr { return nil }
func (*mockSlowConn) SetDeadline(_ time.Time) error { return nil }
func (*mockSlowConn) SetReadDeadline(_ time.Time) error { return nil }
func (*mockSlowConn) SetWriteDeadline(_ time.Time) error { return nil }
func TestRTTMonitor(t *testing.T) {
t.Run("measures the average and minimum RTT", func(t *testing.T) {
t.Parallel()
dialer := DialerFunc(func(_ context.Context, _, _ string) (net.Conn, error) {
return newMockSlowConn(makeHelloReply(), 10*time.Millisecond), nil
})
rtt := newRTTMonitor(&rttConfig{
interval: 10 * time.Millisecond,
createConnectionFn: func() (*connection, error) {
return newConnection("", WithDialer(func(Dialer) Dialer { return dialer }))
},
createOperationFn: func(conn driver.Connection) *operation.Hello {
return operation.NewHello().Deployment(driver.SingleConnectionDeployment{C: conn})
},
})
rtt.connect()
defer rtt.disconnect()
assert.Eventuallyf(
t,
func() bool { return rtt.getRTT() > 0 && rtt.getMinRTT() > 0 },
1*time.Second,
10*time.Millisecond,
"expected getRTT() and getMinRTT() to return positive durations within 1 second")
assert.True(
t,
rtt.getRTT() > 0,
"expected getRTT() to return a positive duration, got %v",
rtt.getRTT())
assert.True(
t,
rtt.getMinRTT() > 0,
"expected getMinRTT() to return a positive duration, got %v",
rtt.getMinRTT())
})
t.Run("creates the correct size samples slice", func(t *testing.T) {
t.Parallel()
cases := []struct {
desc string
interval time.Duration
wantSamplesLen int
}{
{
desc: "default",
interval: 10 * time.Second,
wantSamplesLen: 30,
},
{
desc: "min",
interval: 10 * time.Minute,
wantSamplesLen: 5,
},
{
desc: "max",
interval: 1 * time.Millisecond,
wantSamplesLen: 500,
},
}
for _, tc := range cases {
t.Run(tc.desc, func(t *testing.T) {
rtt := newRTTMonitor(&rttConfig{
interval: tc.interval,
minRTTWindow: 5 * time.Minute,
})
assert.Equal(t, tc.wantSamplesLen, len(rtt.samples), "expected samples length to match")
})
}
})
t.Run("can connect and disconnect repeatedly", func(t *testing.T) {
t.Parallel()
dialer := DialerFunc(func(_ context.Context, _, _ string) (net.Conn, error) {
return newMockSlowConn(makeHelloReply(), 10*time.Millisecond), nil
})
rtt := newRTTMonitor(&rttConfig{
interval: 10 * time.Second,
createConnectionFn: func() (*connection, error) {
return newConnection("", WithDialer(func(Dialer) Dialer {
return dialer
}))
},
createOperationFn: func(conn driver.Connection) *operation.Hello {
return operation.NewHello().Deployment(driver.SingleConnectionDeployment{C: conn})
},
})
for i := 0; i < 100; i++ {
rtt.connect()
rtt.disconnect()
}
})
t.Run("works after reset", func(t *testing.T) {
t.Parallel()
dialer := DialerFunc(func(_ context.Context, _, _ string) (net.Conn, error) {
return newMockSlowConn(makeHelloReply(), 10*time.Millisecond), nil
})
rtt := newRTTMonitor(&rttConfig{
interval: 10 * time.Millisecond,
createConnectionFn: func() (*connection, error) {
return newConnection("", WithDialer(func(Dialer) Dialer { return dialer }))
},
createOperationFn: func(conn driver.Connection) *operation.Hello {
return operation.NewHello().Deployment(driver.SingleConnectionDeployment{C: conn})
},
})
rtt.connect()
defer rtt.disconnect()
for i := 0; i < 3; i++ {
assert.Eventuallyf(
t,
func() bool { return rtt.getRTT() > 0 && rtt.getMinRTT() > 0 },
1*time.Second,
10*time.Millisecond,
"expected getRTT() and getMinRTT() to return positive durations within 1 second")
rtt.reset()
}
})
}
func TestMin(t *testing.T) {
cases := []struct {
desc string
samples []time.Duration
minSamples int
want time.Duration
}{
{
desc: "Should return the min for minSamples = 0",
samples: []time.Duration{1, 0, 0, 0},
minSamples: 0,
want: 1,
},
{
desc: "Should return 0 for fewer than minSamples samples",
samples: []time.Duration{1, 0, 0, 0},
minSamples: 2,
want: 0,
},
{
desc: "Should return 0 for empty samples slice",
samples: []time.Duration{},
minSamples: 0,
want: 0,
},
{
desc: "Should return 0 for no valid samples",
samples: []time.Duration{0, 0, 0},
minSamples: 0,
want: 0,
},
{
desc: "Should return max int64 if all samples are max int64",
samples: []time.Duration{math.MaxInt64, math.MaxInt64, math.MaxInt64},
minSamples: 0,
want: math.MaxInt64,
},
{
desc: "Should return the minimum if there are enough samples",
samples: []time.Duration{1 * time.Second, 100 * time.Millisecond, 150 * time.Millisecond, 0, 0, 0},
minSamples: 3,
want: 100 * time.Millisecond,
},
{
desc: "Should return 0 if there are are not enough samples",
samples: []time.Duration{1 * time.Second, 100 * time.Millisecond, 0, 0, 0, 0},
minSamples: 3,
want: 0,
},
}
for _, tc := range cases {
tc := tc
t.Run(tc.desc, func(t *testing.T) {
t.Parallel()
got := min(tc.samples, tc.minSamples)
assert.Equal(t, tc.want, got, "unexpected result from min()")
})
}
}
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