Add a skeleton for ArenaRef

Author: dconeybe

firestore/CMakeLists.txt

@@ -138,6 +138,8 @@ set(android_SRCS
     src/android/wrapper.h
     src/android/write_batch_android.cc
     src/android/write_batch_android.h
+    src/jni/arena_ref.cc
+    src/jni/arena_ref.h
     src/jni/array.h
     src/jni/array_list.cc
     src/jni/array_list.h

firestore/integration_test_internal/CMakeLists.txt

@@ -121,6 +121,7 @@ set(FIREBASE_INTEGRATION_TEST_PORTABLE_TEST_SRCS
 
 # These sources contain the actual tests that run on Android only.
 set(FIREBASE_INTEGRATION_TEST_ANDROID_TEST_SRCS
+    src/android/arena_ref_android_test.cc
     src/android/field_path_portable_test.cc
     src/android/firestore_integration_test_android_test.cc
     src/android/geo_point_android_test.cc

firestore/integration_test_internal/src/android/arena_ref_android_test.cc

@@ -0,0 +1,51 @@
+/*
+ * Copyright 2022 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "firestore/src/jni/arena_ref.h"
+
+#include "firestore_integration_test_android.h"
+
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+
+namespace firebase {
+namespace firestore {
+namespace jni {
+namespace {
+
+using ArenaRefTestAndroid = FirestoreAndroidIntegrationTest;
+
+TEST_F(ArenaRefTestAndroid, DefaultConstructorCreatesReferenceToNull) {
+  Env env;
+  ArenaRef arena_ref;
+  EXPECT_EQ(arena_ref.get(env).get(), nullptr);
+}
+
+TEST_F(ArenaRefTestAndroid, ConstructFromEnvAndObject) {
+  Env env;
+  Local<String> string = env.NewStringUtf("hello world");
+
+  ArenaRef arena_ref(env, string);
+
+  Local<String> stringRef2 = string;
+  string.clear();
+  EXPECT_TRUE(arena_ref.get(env).Equals(env, stringRef2));
+}
+
+}  // namespace
+}  // namespace jni
+}  // namespace firestore
+}  // namespace firebase

firestore/src/android/firestore_android.cc

@@ -59,6 +59,7 @@
 #include "firestore/src/common/hard_assert_common.h"
 #include "firestore/src/common/make_unique.h"
 #include "firestore/src/include/firebase/firestore.h"
+#include "firestore/src/jni/arena_ref.h"
 #include "firestore/src/jni/array.h"
 #include "firestore/src/jni/array_list.h"
 #include "firestore/src/jni/boolean.h"
@@ -314,6 +315,10 @@ bool FirestoreInternal::Initialize(App* app) {
     jni::Long::Initialize(loader);
     jni::Map::Initialize(loader);
 
+    // Initialize ArenaRef _after_ the other JNI classes because it relies on
+    // HashMap having already been initialized.
+    jni::ArenaRef::Initialize(env);
+
     InitializeFirestore(loader);
     InitializeFirestoreTasks(loader);
     InitializeUserCallbackExecutor(loader);

firestore/src/jni/arena_ref.cc

@@ -0,0 +1,69 @@
+/*
+ * Copyright 2022 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#include <atomic>
+
+#include "firestore/src/jni/arena_ref.h"
+
+#include "firestore/src/jni/hash_map.h"
+#include "firestore/src/jni/long.h"
+#include "firestore/src/jni/map.h"
+
+namespace firebase {
+namespace firestore {
+namespace jni {
+
+namespace {
+
+HashMap* gArenaRefHashMap = nullptr;
+
+int64_t GetNextArenaRefKey() {
+  static std::atomic<int64_t> next_key(1);
+  return next_key.fetch_add(1);
+}
+
+}
+
+ArenaRef::ArenaRef(Env& env, const Object& object) : key_(GetNextArenaRefKey()) {
+  gArenaRefHashMap->Put(env, key_object(env), object);
+}
+
+ArenaRef::~ArenaRef() {
+  if (key_ != 0) {
+    Env env;
+    gArenaRefHashMap->Remove(env, key_object(env));
+  }
+}
+
+Local<Long> ArenaRef::key_object(Env& env) const {
+  return Long::Create(env, key_);
+}
+
+void ArenaRef::Initialize(Env& env) {
+  if (gArenaRefHashMap) {
+    return;
+  }
+  Global<HashMap> hash_map(HashMap::Create(env));
+  jobject hash_map_jobject = hash_map.release();
+  gArenaRefHashMap = new HashMap(hash_map_jobject);
+}
+
+Local<Object> ArenaRef::get(Env& env) const {
+  return gArenaRefHashMap->Get(env, key_object(env));
+}
+
+}  // namespace jni
+}  // namespace firestore
+}  // namespace firebase

firestore/src/jni/arena_ref.h

@@ -0,0 +1,51 @@
+/*
+ * Copyright 2022 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#include <cstdlib>
+
+#include <jni.h>
+
+#include "firestore/src/jni/env.h"
+#include "firestore/src/jni/object.h"
+#include "firestore/src/jni/ownership.h"
+
+#ifndef FIREBASE_FIRESTORE_SRC_JNI_ARENA_REF_H_
+#define FIREBASE_FIRESTORE_SRC_JNI_ARENA_REF_H_
+
+namespace firebase {
+namespace firestore {
+namespace jni {
+
+class ArenaRef {
+ public:
+  ArenaRef() = default;
+  ArenaRef(Env&, const Object&);
+  ~ArenaRef();
+
+  static void Initialize(Env&);
+
+  Local<Object> get(Env&) const;
+
+ private:
+  Local<Long> key_object(Env&) const;
+
+  int64_t key_ = 0;
+};
+
+}  // namespace jni
+}  // namespace firestore
+}  // namespace firebase
+
+#endif  // FIREBASE_FIRESTORE_SRC_JNI_ARENA_REF_H_