lua: Init with config and pool (#321)

* lua: Intial impl with config and pool

Signed-off-by: James Hillyerd <james@hillyerd.com>

pkg/extension/luahost/pool_test.go

@@ -0,0 +1,101 @@
+package luahost
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	lua "github.com/yuin/gopher-lua"
+	"github.com/yuin/gopher-lua/parse"
+)
+
+func makeEmptyPool() *statePool {
+	source := strings.NewReader("-- Empty source")
+
+	chunk, err := parse.Parse(source, "from string")
+	if err != nil {
+		panic(err)
+	}
+
+	proto, err := lua.Compile(chunk, "from string")
+	if err != nil {
+		panic(err)
+	}
+
+	return newStatePool(proto)
+}
+
+func TestPoolGetsDistinct(t *testing.T) {
+	pool := makeEmptyPool()
+
+	a, err := pool.getState()
+	require.NoError(t, err)
+	b, err := pool.getState()
+	require.NoError(t, err)
+
+	if a == b {
+		t.Error("Got pool a == b, expected distinct pools")
+	}
+}
+
+func TestPoolGrowsWithPuts(t *testing.T) {
+	pool := makeEmptyPool()
+
+	a, err := pool.getState()
+	require.NoError(t, err)
+	b, err := pool.getState()
+	require.NoError(t, err)
+	assert.Equal(t, 0, len(pool.states), "Wanted pool to be empty")
+
+	pool.putState(a)
+	pool.putState(b)
+
+	want := 2
+	if got := len(pool.states); got != want {
+		t.Errorf("len pool.states got %v, want %v", got, want)
+	}
+}
+
+// Closed LStates should not be added to the pool.
+func TestPoolPutDiscardsClosed(t *testing.T) {
+	pool := makeEmptyPool()
+
+	a, err := pool.getState()
+	require.NoError(t, err)
+	assert.Equal(t, 0, len(pool.states), "Wanted pool to be empty")
+
+	a.Close()
+	pool.putState(a)
+	assert.Equal(t, 0, len(pool.states), "Wanted pool to remain empty")
+}
+
+func TestPoolPutClearsStack(t *testing.T) {
+	pool := makeEmptyPool()
+
+	ls, err := pool.getState()
+	require.NoError(t, err)
+	assert.Equal(t, 0, len(pool.states), "Wanted pool to be empty")
+
+	// Setup stack.
+	ls.Push(lua.LNumber(4))
+	ls.Push(lua.LString("bacon"))
+	require.Equal(t, 2, ls.GetTop(), "Want stack to have two items")
+
+	// Return and verify stack cleared.
+	pool.putState(ls)
+	assert.Equal(t, 1, len(pool.states), "Wanted pool to have one item")
+	require.Equal(t, 0, ls.GetTop(), "Want stack to be empty")
+}
+
+func TestPoolSetsChannels(t *testing.T) {
+	pool := makeEmptyPool()
+	pool.createChannel("test_chan")
+
+	s, err := pool.getState()
+	require.NoError(t, err)
+
+	got := s.GetGlobal("test_chan")
+	assert.Equal(t, lua.LTChannel, got.Type(),
+		"Got global type %v, wanted LTChannel", got.Type().String())
+}