preamble_race_test.go RawHistoryFolder

1package sessionwire
2
3import (
4	"io"
5	"testing"
6
7	"github.com/stretchr/testify/require"
8
9	"github.com/bnema/vev/internal/protocol/wire"
10)
11
12// failingTransport fails every receive, so the lazy preamble settles quickly
13// while still writing the ceilings it negotiated.
14type failingTransport struct{}
15
16func (failingTransport) Send(wire.Envelope) error     { return nil }
17func (failingTransport) Recv() (wire.Envelope, error) { return wire.Envelope{}, io.EOF }
18func (failingTransport) Close() error                 { return nil }
19
20// TestCapabilitiesReadIsSafeDuringPreamble proves a caller may ask for
21// capabilities while another goroutine is establishing the preamble.
22//
23// The preamble is lazy: whoever first uses the connection runs it, and it
24// publishes the negotiated ceilings. A capabilities read does not go through
25// that once, so it needs the same lock the publication takes; without it the
26// read races with the write, which is exactly what a real offline composition
27// reported under the race detector.
28func TestCapabilitiesReadIsSafeDuringPreamble(t *testing.T) {
29	connection := NewClientConnection(failingTransport{})
30	require.NotNil(t, connection)
31
32	done := make(chan struct{})
33	go func() {
34		defer close(done)
35		_, _ = connection.ReceiveServer()
36	}()
37
38	// Read capabilities for the whole window in which the preamble publishes.
39	for {
40		select {
41		case <-done:
42			return
43		default:
44			_ = connection.Capabilities()
45		}
46	}
47}
48
49// TestServerCapabilitiesReadIsSafeDuringPreamble is the server-side twin: the
50// daemon-facing connection has the same lazy publication and the same unlocked
51// capabilities read.
52func TestServerCapabilitiesReadIsSafeDuringPreamble(t *testing.T) {
53	connection, ok := NewServerConnection(failingTransport{}).(*serverConnection)
54	require.True(t, ok)
55
56	done := make(chan struct{})
57	go func() {
58		defer close(done)
59		_, _ = connection.ReceiveClient()
60	}()
61
62	for {
63		select {
64		case <-done:
65			return
66		default:
67			_ = connection.Capabilities()
68		}
69	}
70}