bootstrapper: use atomics in nodelock (#2001)

bootstrapper/internal/nodelock/nodelock_test.go

@@ -0,0 +1,64 @@
+/*
+Copyright (c) Edgeless Systems GmbH
+
+SPDX-License-Identifier: AGPL-3.0-only
+*/
+
+package nodelock
+
+import (
+	"io"
+	"sync"
+	"sync/atomic"
+	"testing"
+
+	"github.com/edgelesssys/constellation/v2/internal/attestation/vtpm"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestTryLockOnce(t *testing.T) {
+	assert := assert.New(t)
+	tpm := spyDevice{}
+	lock := Lock{
+		tpm:    tpm.Opener(),
+		marker: stubMarker,
+	}
+	locked, err := lock.TryLockOnce(nil)
+	assert.NoError(err)
+	assert.True(locked)
+
+	wg := sync.WaitGroup{}
+	tryLock := func() {
+		defer wg.Done()
+		locked, err := lock.TryLockOnce(nil)
+		assert.NoError(err)
+		assert.False(locked)
+	}
+
+	for i := 0; i < 10; i++ {
+		wg.Add(1)
+		go tryLock()
+	}
+
+	wg.Wait()
+
+	assert.EqualValues(1, tpm.counter.Load())
+}
+
+type spyDevice struct {
+	counter atomic.Uint64
+}
+
+func (s *spyDevice) Opener() vtpm.TPMOpenFunc {
+	return func() (io.ReadWriteCloser, error) {
+		s.counter.Add(1)
+		return nil, nil
+	}
+}
+
+func stubMarker(openDevice func() (io.ReadWriteCloser, error), _ []byte) error {
+	// this only needs to invoke the openDevice function
+	// so that the spyTPM counter is incremented
+	_, _ = openDevice()
+	return nil
+}