pgx/pgconn/internal/bgreader/bgreader_test.go at 3902e87ebe31e4d2fd0f2f2022959124523b195a · analytically/pgx · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
package bgreader_test

import (
	"bytes"
	"errors"
	"io"
	"math/rand/v2"
	"testing"
	"time"

	"github.com/jackc/pgx/v5/pgconn/internal/bgreader"
	"github.com/stretchr/testify/require"
)

func TestBGReaderReadWhenStopped(t *testing.T) {
	r := bytes.NewReader([]byte("foo bar baz"))
	bgr := bgreader.New(r)
	buf, err := io.ReadAll(bgr)
	require.NoError(t, err)
	require.Equal(t, []byte("foo bar baz"), buf)
}

func TestBGReaderReadWhenStarted(t *testing.T) {
	r := bytes.NewReader([]byte("foo bar baz"))
	bgr := bgreader.New(r)
	bgr.Start()
	buf, err := io.ReadAll(bgr)
	require.NoError(t, err)
	require.Equal(t, []byte("foo bar baz"), buf)
}

type mockReadFunc func(p []byte) (int, error)

type mockReader struct {
	readFuncs []mockReadFunc
}

func (r *mockReader) Read(p []byte) (int, error) {
	if len(r.readFuncs) == 0 {
		return 0, io.EOF
	}

	fn := r.readFuncs[0]
	r.readFuncs = r.readFuncs[1:]

	return fn(p)
}

func TestBGReaderReadWaitsForBackgroundRead(t *testing.T) {
	rr := &mockReader{
		readFuncs: []mockReadFunc{
			func(p []byte) (int, error) { time.Sleep(1 * time.Second); return copy(p, []byte("foo")), nil },
			func(p []byte) (int, error) { return copy(p, []byte("bar")), nil },
			func(p []byte) (int, error) { return copy(p, []byte("baz")), nil },
		},
	}
	bgr := bgreader.New(rr)
	bgr.Start()
	buf := make([]byte, 3)
	n, err := bgr.Read(buf)
	require.NoError(t, err)
	require.EqualValues(t, 3, n)
	require.Equal(t, []byte("foo"), buf)
}

func TestBGReaderErrorWhenStarted(t *testing.T) {
	rr := &mockReader{
		readFuncs: []mockReadFunc{
			func(p []byte) (int, error) { return copy(p, []byte("foo")), nil },
			func(p []byte) (int, error) { return copy(p, []byte("bar")), nil },
			func(p []byte) (int, error) { return copy(p, []byte("baz")), errors.New("oops") },
		},
	}

	bgr := bgreader.New(rr)
	bgr.Start()
	buf, err := io.ReadAll(bgr)
	require.Equal(t, []byte("foobarbaz"), buf)
	require.EqualError(t, err, "oops")
}

func TestBGReaderErrorWhenStopped(t *testing.T) {
	rr := &mockReader{
		readFuncs: []mockReadFunc{
			func(p []byte) (int, error) { return copy(p, []byte("foo")), nil },
			func(p []byte) (int, error) { return copy(p, []byte("bar")), nil },
			func(p []byte) (int, error) { return copy(p, []byte("baz")), errors.New("oops") },
		},
	}

	bgr := bgreader.New(rr)
	buf, err := io.ReadAll(bgr)
	require.Equal(t, []byte("foobarbaz"), buf)
	require.EqualError(t, err, "oops")
}

type numberReader struct {
	v   uint8
	rng *rand.Rand
}

func (nr *numberReader) Read(p []byte) (int, error) {
	n := nr.rng.IntN(len(p))
	for i := range n {
		p[i] = nr.v
		nr.v++
	}

	return n, nil
}

// TestBGReaderStress stress tests BGReader by reading a lot of bytes in random sizes while randomly starting and
// stopping the background worker from other goroutines.
func TestBGReaderStress(t *testing.T) {
	nr := &numberReader{rng: rand.New(rand.NewPCG(0, 0))}
	bgr := bgreader.New(nr)

	bytesRead := 0
	var expected uint8
	buf := make([]byte, 10_000)
	rng := rand.New(rand.NewPCG(0, 0))

	for bytesRead < 1_000_000 {
		randomNumber := rng.IntN(100)
		switch {
		case randomNumber < 10:
			go bgr.Start()
		case randomNumber < 20:
			go bgr.Stop()
		default:
			n, err := bgr.Read(buf)
			require.NoError(t, err)
			for i := range n {
				require.Equal(t, expected, buf[i])
				expected++
			}
			bytesRead += n
		}
	}
}