Initial skeleton of in-memory locks

Signed-off-by: Matthew Heon <matthew.heon@gmail.com>

1 files changed, 84 insertions, 0 deletions

diff --git a/libpod/lock/locks_test.go b/libpod/lock/locks_test.go
new file mode 100644
index 000000000..b14d6e19a
--- /dev/null
+++ b/libpod/lock/locks_test.go
@@ -0,0 +1,84 @@
+package lock
+
+import (
+	"fmt"
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// All tests here are in the same process, which somewhat limits their utility
+// The big intent of this package it multiprocess locking, which is really hard
+// to test without actually having multiple processes...
+// We can at least verify that the locks work within the local process.
+
+// 4 * BITMAP_SIZE to ensure we have to traverse bitmaps
+const numLocks = 128
+
+// We need a test main to ensure that the SHM is created before the tests run
+func TestMain(m *testing.M) {
+	shmLock, err := CreateSHMLock(numLocks)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Error creating SHM for tests: %v\n", err)
+		os.Exit(-1)
+	}
+
+	// Close the SHM - every subsequent test will reopen
+	if err := shmLock.Close(); err != nil {
+		fmt.Fprintf(os.Stderr, "Error closing SHM locks: %v\n", err)
+		os.Exit(-1)
+	}
+
+	exitCode := m.Run()
+
+	// We need to remove the SHM segment to clean up after ourselves
+	os.RemoveAll("/dev/shm/libpod_lock")
+
+	os.Exit(exitCode)
+}
+
+
+func runLockTest(t *testing.T, testFunc func(*testing.T, *SHMLocks)) {
+	locks, err := OpenSHMLock(numLocks)
+	if err != nil {
+		t.Fatalf("Error opening locks: %v", err)
+	}
+	defer func() {
+		if err := locks.Close(); err != nil {
+			t.Fatalf("Error closing locks: %v", err)
+		}
+	}()
+
+	success := t.Run("locks", func (t *testing.T) {
+		testFunc(t, locks)
+	})
+	if !success {
+		t.Fail()
+	}
+}
+
+// Test that creating an SHM with a bad size fails
+func TestCreateNewSHMBadSize(t *testing.T) {
+	// Odd number, not a power of 2, should never be a word size on a system
+	_, err := CreateSHMLock(7)
+	assert.Error(t, err)
+}
+
+// Test allocating - lock - unlock - deallocate cycle, single lock
+func TestLockLifecycleSingleLock(t *testing.T) {
+	runLockTest(t, func(t *testing.T, locks *SHMLocks) {
+		sem, err := locks.AllocateSemaphore()
+		require.NoError(t, err)
+
+		err = locks.LockSemaphore(sem)
+		assert.NoError(t, err)
+
+		err = locks.UnlockSemaphore(sem)
+		assert.NoError(t, err)
+
+		err = locks.DeallocateSemaphore(sem)
+		assert.NoError(t, err)
+	})
+}