| /* |
| * Copyright (C) 2017 The Android Open Source Project |
| * |
| * 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. |
| */ |
| |
| #ifndef LIBTEXTCLASSIFIER_UTIL_JAVA_SCOPED_GLOBAL_REF_H_ |
| #define LIBTEXTCLASSIFIER_UTIL_JAVA_SCOPED_GLOBAL_REF_H_ |
| |
| #include <jni.h> |
| #include <memory> |
| #include <type_traits> |
| |
| #include "util/base/logging.h" |
| |
| namespace libtextclassifier2 { |
| |
| // A deleter to be used with std::unique_ptr to delete JNI global references. |
| class GlobalRefDeleter { |
| public: |
| GlobalRefDeleter() : jvm_(nullptr) {} |
| |
| // Style guide violating implicit constructor so that the GlobalRefDeleter |
| // is implicitly constructed from the second argument to ScopedGlobalRef. |
| GlobalRefDeleter(JavaVM* jvm) : jvm_(jvm) {} // NOLINT(runtime/explicit) |
| |
| GlobalRefDeleter(const GlobalRefDeleter& orig) = default; |
| |
| // Copy assignment to allow move semantics in ScopedGlobalRef. |
| GlobalRefDeleter& operator=(const GlobalRefDeleter& rhs) { |
| TC_CHECK_EQ(jvm_, rhs.jvm_); |
| return *this; |
| } |
| |
| // The delete operator. |
| void operator()(jobject object) const { |
| JNIEnv* env; |
| if (object != nullptr && jvm_ != nullptr && |
| JNI_OK == |
| jvm_->GetEnv(reinterpret_cast<void**>(&env), JNI_VERSION_1_4)) { |
| env->DeleteGlobalRef(object); |
| } |
| } |
| |
| private: |
| // The jvm_ stashed to use for deletion. |
| JavaVM* const jvm_; |
| }; |
| |
| // A smart pointer that deletes a JNI global reference when it goes out |
| // of scope. Usage is: |
| // ScopedGlobalRef<jobject> scoped_global(env->JniFunction(), jvm); |
| template <typename T> |
| using ScopedGlobalRef = |
| std::unique_ptr<typename std::remove_pointer<T>::type, GlobalRefDeleter>; |
| |
| // A helper to create global references. |
| template <typename T> |
| ScopedGlobalRef<T> MakeGlobalRef(T object, JNIEnv* env, JavaVM* jvm) { |
| const jobject globalObject = env->NewGlobalRef(object); |
| return ScopedGlobalRef<T>(reinterpret_cast<T>(globalObject), jvm); |
| } |
| |
| } // namespace libtextclassifier2 |
| |
| #endif // LIBTEXTCLASSIFIER_UTIL_JAVA_SCOPED_GLOBAL_REF_H_ |