1 // Copyright 2014 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef BASE_ANDROID_JNI_WEAK_REF_H_ 6 #define BASE_ANDROID_JNI_WEAK_REF_H_ 7 8 #include <jni.h> 9 10 #include "base/android/scoped_java_ref.h" 11 #include "base/base_export.h" 12 13 // Manages WeakGlobalRef lifecycle. 14 // This class is not thread-safe w.r.t. get() and reset(). Multiple threads may 15 // safely use get() concurrently, but if the user calls reset() (or of course, 16 // calls the destructor) they'll need to provide their own synchronization. 17 class BASE_EXPORT JavaObjectWeakGlobalRef { 18 public: 19 JavaObjectWeakGlobalRef(); 20 JavaObjectWeakGlobalRef(const JavaObjectWeakGlobalRef& orig); 21 JavaObjectWeakGlobalRef(JavaObjectWeakGlobalRef&& orig); 22 JavaObjectWeakGlobalRef(JNIEnv* env, jobject obj); 23 JavaObjectWeakGlobalRef(JNIEnv* env, 24 const base::android::JavaRef<jobject>& obj); 25 virtual ~JavaObjectWeakGlobalRef(); 26 27 void operator=(const JavaObjectWeakGlobalRef& rhs); 28 void operator=(JavaObjectWeakGlobalRef&& rhs); 29 30 base::android::ScopedJavaLocalRef<jobject> get(JNIEnv* env) const; 31 32 // Returns true if the weak reference has not been initialized to point at 33 // an object (or as had reset() called). 34 // Do not call this to test if the object referred to still exists! The weak 35 // reference remains initialized even if the target object has been collected. 36 bool is_uninitialized() const { return obj_ == nullptr; } 37 38 void reset(); 39 40 private: 41 void Assign(const JavaObjectWeakGlobalRef& rhs); 42 43 jweak obj_; 44 }; 45 46 // Get the real object stored in the weak reference returned as a 47 // ScopedJavaLocalRef. 48 BASE_EXPORT base::android::ScopedJavaLocalRef<jobject> GetRealObject( 49 JNIEnv* env, jweak obj); 50 51 #endif // BASE_ANDROID_JNI_WEAK_REF_H_ 52
