/*
|
* Copyright (C) 2018 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_UTILS_JAVA_SCOPED_LOCAL_REF_H_
|
#define LIBTEXTCLASSIFIER_UTILS_JAVA_SCOPED_LOCAL_REF_H_
|
|
#include <jni.h>
|
#include <memory>
|
#include <type_traits>
|
|
#include "utils/base/logging.h"
|
|
namespace libtextclassifier3 {
|
|
// 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.
|
TC3_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 libtextclassifier3
|
|
#endif // LIBTEXTCLASSIFIER_UTILS_JAVA_SCOPED_LOCAL_REF_H_
|
