go-x/sync_test.go at main · tozd/go-x · 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
141
142
package x_test

import (
	"context"
	"testing"
	"time"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
	"golang.org/x/sync/errgroup"

	"gitlab.com/tozd/go/x"
)

func TestSyncVar(t *testing.T) {
	t.Parallel()

	v := x.NewSyncVar[int]()

	g := errgroup.Group{}
	g.Go(func() error {
		assert.Equal(t, 1, v.Load())
		return nil
	})
	g.Go(func() error {
		assert.Equal(t, 1, v.Load())
		return nil
	})
	g.Go(func() error {
		assert.Equal(t, 1, v.Load())
		return nil
	})
	errE := v.Store(1)
	require.NoError(t, errE, "% -+#.1v", errE)
	err := g.Wait()
	require.NoError(t, err)
	errE = v.Store(1)
	assert.ErrorIs(t, errE, x.ErrSyncVarAlreadyStored)
}

func TestSyncVarContext(t *testing.T) {
	t.Parallel()

	v := x.NewSyncVar[int]()

	g := errgroup.Group{}
	g.Go(func() error {
		v, err := v.LoadContext(t.Context())
		if assert.NoError(t, err) {
			assert.Equal(t, 1, v)
		}
		return nil
	})
	g.Go(func() error {
		v, err := v.LoadContext(t.Context())
		if assert.NoError(t, err) {
			assert.Equal(t, 1, v)
		}
		return nil
	})
	g.Go(func() error {
		v, err := v.LoadContext(t.Context())
		if assert.NoError(t, err) {
			assert.Equal(t, 1, v)
		}
		return nil
	})
	errE := v.Store(1)
	require.NoError(t, errE, "% -+#.1v", errE)
	err := g.Wait()
	require.NoError(t, err)
	errE = v.Store(1)
	assert.ErrorIs(t, errE, x.ErrSyncVarAlreadyStored)
}

func TestSyncVarEnsureWait(t *testing.T) {
	t.Parallel()

	v := x.NewSyncVar[int]()
	result := make(chan int, 1)

	go func() {
		result <- v.Load()
	}()

	// Give the goroutine time to start and block in Wait before Store is called.
	time.Sleep(10 * time.Millisecond)

	errE := v.Store(99)
	require.NoError(t, errE, "% -+#.1v", errE)

	assert.Equal(t, 99, <-result)
}

func TestSyncVarLoadAfterStore(t *testing.T) {
	t.Parallel()

	v := x.NewSyncVar[int]()

	errE := v.Store(42)
	require.NoError(t, errE, "% -+#.1v", errE)

	// Load after store should return immediately without blocking.
	val := v.Load()
	assert.Equal(t, 42, val)
}

func TestSyncVarContextCancel(t *testing.T) {
	t.Parallel()

	v := x.NewSyncVar[int]()

	ctx, cancel := context.WithCancel(t.Context())

	g := errgroup.Group{}
	g.Go(func() error {
		v, err := v.LoadContext(ctx)
		if assert.ErrorIs(t, err, context.Canceled) {
			assert.Equal(t, 0, v)
		}
		return nil
	})
	g.Go(func() error {
		v, err := v.LoadContext(ctx)
		if assert.ErrorIs(t, err, context.Canceled) {
			assert.Equal(t, 0, v)
		}
		return nil
	})
	g.Go(func() error {
		v, err := v.LoadContext(ctx)
		if assert.ErrorIs(t, err, context.Canceled) {
			assert.Equal(t, 0, v)
		}
		return nil
	})

	cancel()

	err := g.Wait()
	assert.NoError(t, err)
}