From 454689b8f6bec7f4d26d96e4806c8fbe480499e0 Mon Sep 17 00:00:00 2001
From: Edward Mack <ed@edwardmack.com>
Date: Mon, 25 Oct 2021 09:31:42 -0400
Subject: [PATCH] feat(lib/runtime/wasmer): implement
 ext_default_child_storage_storage_kill_version_3 (#1878)

---
 lib/runtime/wasmer/imports.go      | 64 ++++++++++++++++++++++++++----
 lib/runtime/wasmer/imports_test.go | 48 ++++++++++++++++++++++
 2 files changed, 104 insertions(+), 8 deletions(-)

diff --git a/lib/runtime/wasmer/imports.go b/lib/runtime/wasmer/imports.go
index 4be947a08d..584d5d26ba 100644
--- a/lib/runtime/wasmer/imports.go
+++ b/lib/runtime/wasmer/imports.go
@@ -1142,19 +1142,67 @@ func ext_default_child_storage_storage_kill_version_2(context unsafe.Pointer, ch
 	return 0
 }
 
-//export ext_default_child_storage_storage_kill_version_3
-func ext_default_child_storage_storage_kill_version_3(context unsafe.Pointer, childStorageKeySpan, _ C.int64_t) C.int64_t {
-	logger.Debug("[ext_default_child_storage_storage_kill_version_3] executing...")
-	logger.Warn("[ext_default_child_storage_storage_kill_version_3] somewhat unimplemented")
-	// TODO: need to use `limit` parameter (#1793)
+type noneRemain uint32
+type someRemain uint32
+
+func (noneRemain) Index() uint {
+	return 0
+}
+func (someRemain) Index() uint {
+	return 1
+}
 
+//export ext_default_child_storage_storage_kill_version_3
+func ext_default_child_storage_storage_kill_version_3(context unsafe.Pointer, childStorageKeySpan, lim C.int64_t) C.int64_t {
+	logger.Debug("executing...")
 	instanceContext := wasm.IntoInstanceContext(context)
 	ctx := instanceContext.Data().(*runtime.Context)
 	storage := ctx.Storage
-
 	childStorageKey := asMemorySlice(instanceContext, childStorageKeySpan)
-	storage.DeleteChild(childStorageKey)
-	return 0
+
+	limitBytes := asMemorySlice(instanceContext, lim)
+	buf := &bytes.Buffer{}
+	buf.Write(limitBytes)
+
+	limit, err := optional.NewBytes(true, nil).Decode(buf)
+	if err != nil {
+		logger.Warn("cannot generate limit", "error", err)
+	}
+
+	deleted, all, err := storage.DeleteChildLimit(childStorageKey, limit)
+	if err != nil {
+		logger.Warn("cannot get child storage", "error", err)
+		return C.int64_t(0)
+	}
+
+	vdt, err := scale.NewVaryingDataType(noneRemain(0), someRemain(0))
+	if err != nil {
+		logger.Warn("cannot create new varying data type", "error", err)
+	}
+
+	if all {
+		err = vdt.Set(noneRemain(deleted))
+	} else {
+		err = vdt.Set(someRemain(deleted))
+	}
+	if err != nil {
+		logger.Warn("cannot set varying data type", "error", err)
+		return C.int64_t(0)
+	}
+
+	encoded, err := scale.Marshal(vdt)
+	if err != nil {
+		logger.Warn("problem marshaling varying data type", "error", err)
+		return C.int64_t(0)
+	}
+
+	out, err := toWasmMemoryOptional(instanceContext, encoded)
+	if err != nil {
+		logger.Warn("failed to allocate", "error", err)
+		return 0
+	}
+
+	return C.int64_t(out)
 }
 
 //export ext_allocator_free_version_1
diff --git a/lib/runtime/wasmer/imports_test.go b/lib/runtime/wasmer/imports_test.go
index 27b286fb8b..831f309dee 100644
--- a/lib/runtime/wasmer/imports_test.go
+++ b/lib/runtime/wasmer/imports_test.go
@@ -1226,6 +1226,54 @@ func Test_ext_default_child_storage_storage_kill_version_2_limit_none(t *testing
 	require.Nil(t, child)
 }
 
+func Test_ext_default_child_storage_storage_kill_version_3(t *testing.T) {
+	inst := NewTestInstance(t, runtime.HOST_API_TEST_RUNTIME)
+
+	tr := trie.NewEmptyTrie()
+	tr.Put([]byte(`key2`), []byte(`value2`))
+	tr.Put([]byte(`key1`), []byte(`value1`))
+	tr.Put([]byte(`key3`), []byte(`value3`))
+	err := inst.ctx.Storage.SetChild(testChildKey, tr)
+	require.NoError(t, err)
+
+	testLimitBytes := make([]byte, 4)
+	binary.LittleEndian.PutUint32(testLimitBytes, uint32(2))
+	optLimit2 := optional.NewBytes(true, testLimitBytes)
+
+	testCases := []struct {
+		key      []byte
+		limit    *optional.Bytes
+		expected []byte
+		errMsg   string
+	}{
+		{key: []byte(`fakekey`), limit: optLimit2, expected: []byte{0, 0, 0, 0, 0}, errMsg: "Failed to call the `rtm_ext_default_child_storage_storage_kill_version_3` exported function."},
+		{key: testChildKey, limit: optLimit2, expected: []byte{1, 2, 0, 0, 0}},
+		{key: testChildKey, limit: nil, expected: []byte{0, 1, 0, 0, 0}},
+	}
+
+	for _, test := range testCases {
+		encChildKey, err := scale.Marshal(test.key)
+		require.NoError(t, err)
+		encOptLimit, err := test.limit.Encode()
+		require.NoError(t, err)
+		res, err := inst.Exec("rtm_ext_default_child_storage_storage_kill_version_3", append(encChildKey, encOptLimit...))
+		if test.errMsg != "" {
+			require.Error(t, err)
+			require.EqualError(t, err, test.errMsg)
+			continue
+		}
+
+		require.NoError(t, err)
+
+		buf := &bytes.Buffer{}
+		buf.Write(res)
+
+		read, err := new(optional.Bytes).Decode(buf)
+		require.NoError(t, err)
+		require.Equal(t, test.expected, read.Value())
+	}
+}
+
 func Test_ext_storage_append_version_1(t *testing.T) {
 	inst := NewTestInstance(t, runtime.HOST_API_TEST_RUNTIME)