From a53c14dc756b428991ed371c992f398d7f923462 Mon Sep 17 00:00:00 2001
From: David Aurelio <davidaurelio@fb.com>
Date: Fri, 19 Jul 2019 10:33:47 -0700
Subject: [PATCH] Add internal experiments API

Summary: Adds internal API that we can use to conduct experiments.

Reviewed By: SidharthGuglani

Differential Revision: D16340463

fbshipit-source-id: 07a8bb7dbc4a02c5c95f1ad29b18845ab43752cf
---
 tests/InternalTest.cpp          | 48 +++++++++++++++++++++++++++++++++
 yoga/internal/experiments-inl.h | 31 +++++++++++++++++++++
 yoga/internal/experiments.cpp   | 37 +++++++++++++++++++++++++
 yoga/internal/experiments.h     | 25 +++++++++++++++++
 4 files changed, 141 insertions(+)
 create mode 100644 tests/InternalTest.cpp
 create mode 100644 yoga/internal/experiments-inl.h
 create mode 100644 yoga/internal/experiments.cpp
 create mode 100644 yoga/internal/experiments.h

diff --git a/tests/InternalTest.cpp b/tests/InternalTest.cpp
new file mode 100644
index 00000000..8646aebc
--- /dev/null
+++ b/tests/InternalTest.cpp
@@ -0,0 +1,48 @@
+/*
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the LICENSE
+ * file in the root directory of this source tree.
+ */
+#include <gtest/gtest.h>
+#include <yoga/internal/experiments-inl.h>
+
+using namespace facebook::yoga::internal;
+
+struct YogaInternalTest : public testing::Test {
+  void SetUp() override;
+};
+
+TEST_F(YogaInternalTest, experiments_are_initially_disabled) {
+  ASSERT_EQ(isEnabled(Experiment::kDoubleMeasureCallbacks), false);
+}
+
+TEST_F(YogaInternalTest, experiments_are_can_be_enabled) {
+  enable(Experiment::kDoubleMeasureCallbacks);
+  ASSERT_EQ(isEnabled(Experiment::kDoubleMeasureCallbacks), true);
+}
+
+TEST_F(YogaInternalTest, experiments_are_can_be_disabled) {
+  enable(Experiment::kDoubleMeasureCallbacks);
+  disable(Experiment::kDoubleMeasureCallbacks);
+
+  ASSERT_EQ(isEnabled(Experiment::kDoubleMeasureCallbacks), false);
+}
+
+TEST_F(YogaInternalTest, experiments_are_can_be_toggled_on) {
+  disable(Experiment::kDoubleMeasureCallbacks);
+
+  ASSERT_EQ(toggle(Experiment::kDoubleMeasureCallbacks), false);
+  ASSERT_EQ(isEnabled(Experiment::kDoubleMeasureCallbacks), true);
+}
+
+TEST_F(YogaInternalTest, experiments_are_can_be_toggled_off) {
+  enable(Experiment::kDoubleMeasureCallbacks);
+
+  ASSERT_EQ(toggle(Experiment::kDoubleMeasureCallbacks), true);
+  ASSERT_EQ(isEnabled(Experiment::kDoubleMeasureCallbacks), false);
+}
+
+void YogaInternalTest::SetUp() {
+  disableAllExperiments();
+}
diff --git a/yoga/internal/experiments-inl.h b/yoga/internal/experiments-inl.h
new file mode 100644
index 00000000..ebbeccbc
--- /dev/null
+++ b/yoga/internal/experiments-inl.h
@@ -0,0 +1,31 @@
+/*
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the LICENSE
+ * file in the root directory of this source tree.
+ */
+#pragma once
+
+#include "experiments.h"
+
+#include <bitset>
+
+namespace facebook {
+namespace yoga {
+namespace internal {
+
+namespace detail {
+extern std::bitset<sizeof(int)> enabledExperiments;
+} // namespace detail
+
+inline bool isEnabled(Experiment experiment) {
+  return detail::enabledExperiments.test(static_cast<size_t>(experiment));
+}
+
+inline void disableAllExperiments() {
+  detail::enabledExperiments = 0;
+}
+
+} // namespace internal
+} // namespace yoga
+} // namespace facebook
diff --git a/yoga/internal/experiments.cpp b/yoga/internal/experiments.cpp
new file mode 100644
index 00000000..4b67eee5
--- /dev/null
+++ b/yoga/internal/experiments.cpp
@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the LICENSE
+ * file in the root directory of this source tree.
+ */
+#include "experiments.h"
+#include "experiments-inl.h"
+
+namespace facebook {
+namespace yoga {
+namespace internal {
+
+namespace detail {
+
+std::bitset<sizeof(int)> enabledExperiments = 0;
+
+} // namespace detail
+
+void enable(Experiment experiment) {
+  detail::enabledExperiments.set(static_cast<size_t>(experiment));
+}
+
+void disable(Experiment experiment) {
+  detail::enabledExperiments.reset(static_cast<size_t>(experiment));
+}
+
+bool toggle(Experiment experiment) {
+  auto bit = static_cast<size_t>(experiment);
+  auto previousState = detail::enabledExperiments.test(bit);
+  detail::enabledExperiments.flip(bit);
+  return previousState;
+}
+
+} // namespace internal
+} // namespace yoga
+} // namespace facebook
diff --git a/yoga/internal/experiments.h b/yoga/internal/experiments.h
new file mode 100644
index 00000000..7fd4cb37
--- /dev/null
+++ b/yoga/internal/experiments.h
@@ -0,0 +1,25 @@
+/*
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the LICENSE
+ * file in the root directory of this source tree.
+ */
+#pragma once
+
+#include <cstddef>
+
+namespace facebook {
+namespace yoga {
+namespace internal {
+
+enum struct Experiment : size_t {
+  kDoubleMeasureCallbacks,
+};
+
+void enable(Experiment);
+void disable(Experiment);
+bool toggle(Experiment);
+
+} // namespace internal
+} // namespace yoga
+} // namespace facebook