jni_weak_ref.h

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// Copyright 2013 The Flutter 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 FLUTTER_FML_PLATFORM_ANDROID_JNI_WEAK_REF_H_
#define FLUTTER_FML_PLATFORM_ANDROID_JNI_WEAK_REF_H_
 
#include <jni.h>
 
#include "flutter/fml/platform/android/scoped_java_ref.h"
 
namespace fml {
namespace jni {
 
// 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 JavaObjectWeakGlobalRef {
 public:
  JavaObjectWeakGlobalRef();
 
  JavaObjectWeakGlobalRef(const JavaObjectWeakGlobalRef& orig);
 
  JavaObjectWeakGlobalRef(JNIEnv* env, jobject obj);
 
  virtual ~JavaObjectWeakGlobalRef();
 
  void operator=(const JavaObjectWeakGlobalRef& rhs);
 
  ScopedJavaLocalRef<jobject> get(JNIEnv* env) const;
 
  bool is_empty() const { return obj_ == NULL; }
 
  void reset();
 
 private:
  void Assign(const JavaObjectWeakGlobalRef& rhs);
 
  jweak obj_;
};
 
// Get the real object stored in the weak reference returned as a
// ScopedJavaLocalRef.
ScopedJavaLocalRef<jobject> GetRealObject(JNIEnv* env, jweak obj);
 
}  // namespace jni
}  // namespace fml
 
#endif  // FLUTTER_FML_PLATFORM_ANDROID_JNI_WEAK_REF_H_