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jni_weak_ref.h
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jni_weak_ref.h
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// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef BASE_ANDROID_JNI_WEAK_REF_H_
#define BASE_ANDROID_JNI_WEAK_REF_H_
#include <jni.h>
#include "base/android/scoped_java_ref.h"
#include "base/base_export.h"
// Manages WeakGlobalRef lifecycle.
// This class is not thread-safe w.r.t. get() and reset(). Multiple threads may
// safely use get() concurrently, but if the user calls reset() (or of course,
// calls the destructor) they'll need to provide their own synchronization.
class BASE_EXPORT JavaObjectWeakGlobalRef {
public:
JavaObjectWeakGlobalRef();
JavaObjectWeakGlobalRef(const JavaObjectWeakGlobalRef& orig);
JavaObjectWeakGlobalRef(JavaObjectWeakGlobalRef&& orig) noexcept;
JavaObjectWeakGlobalRef(JNIEnv* env, jobject obj);
JavaObjectWeakGlobalRef(JNIEnv* env,
const base::android::JavaRef<jobject>& obj);
virtual ~JavaObjectWeakGlobalRef();
void operator=(const JavaObjectWeakGlobalRef& rhs);
void operator=(JavaObjectWeakGlobalRef&& rhs);
base::android::ScopedJavaLocalRef<jobject> get(JNIEnv* env) const;
// Returns true if the weak reference has not been initialized to point at
// an object (or ḣas had reset() called).
// Do not call this to test if the object referred to still exists! The weak
// reference remains initialized even if the target object has been collected.
bool is_uninitialized() const { return obj_ == nullptr; }
void reset();
private:
void Assign(const JavaObjectWeakGlobalRef& rhs);
jweak obj_;
};
// Get the real object stored in the weak reference returned as a
// ScopedJavaLocalRef.
BASE_EXPORT base::android::ScopedJavaLocalRef<jobject> GetRealObject(
JNIEnv* env, jweak obj);
#endif // BASE_ANDROID_JNI_WEAK_REF_H_