| /* |
| * 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_LOCAL_REF_H_ |
| #define LIBTEXTCLASSIFIER_UTIL_JAVA_SCOPED_LOCAL_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 local references. |
| class LocalRefDeleter { |
| public: |
| LocalRefDeleter() : env_(nullptr) {} |
| |
| // Style guide violating implicit constructor so that the LocalRefDeleter |
| // is implicitly constructed from the second argument to ScopedLocalRef. |
| LocalRefDeleter(JNIEnv* env) : env_(env) {} // NOLINT(runtime/explicit) |
| |
| LocalRefDeleter(const LocalRefDeleter& orig) = default; |
| |
| // Copy assignment to allow move semantics in ScopedLocalRef. |
| LocalRefDeleter& operator=(const LocalRefDeleter& rhs) { |
| // As the deleter and its state are thread-local, ensure the envs |
| // are consistent but do nothing. |
| TC_CHECK_EQ(env_, rhs.env_); |
| return *this; |
| } |
| |
| // The delete operator. |
| void operator()(jobject object) const { |
| if (env_) { |
| env_->DeleteLocalRef(object); |
| } |
| } |
| |
| private: |
| // The env_ stashed to use for deletion. Thread-local, don't share! |
| JNIEnv* const env_; |
| }; |
| |
| // A smart pointer that deletes a JNI local reference when it goes out |
| // of scope. Usage is: |
| // ScopedLocalRef<jobject> scoped_local(env->JniFunction(), env); |
| // |
| // Note that this class is not thread-safe since it caches JNIEnv in |
| // the deleter. Do not use the same jobject across different threads. |
| template <typename T> |
| using ScopedLocalRef = |
| std::unique_ptr<typename std::remove_pointer<T>::type, LocalRefDeleter>; |
| |
| } // namespace libtextclassifier2 |
| |
| #endif // LIBTEXTCLASSIFIER_UTIL_JAVA_SCOPED_LOCAL_REF_H_ |