text: // Copyright 2018 The Fuchsia 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 LIB_FIDL_CPP_INTERNAL_WEAK_STUB_CONTROLLER_H_
  #define LIB_FIDL_CPP_INTERNAL_WEAK_STUB_CONTROLLER_H_
  
  #include <stdint.h>
  
  namespace fidl {
  namespace internal {
  class StubController;
  
  // A weak reference to a |StubController|.
  //
  // Used to link a |PendingResponse| object with a |StubController|. When the
  // |StubController| is destroyed (or unbound from the underling channel), the
  // weak reference is invalidated, preventing outstanding |PendingResponse|
  // objects from referencing the |StubController|.
  class WeakStubController {
   public:
    // Creates a weak reference to a |StubController|.
    //
    // The created |WeakStubController| has a reference count of one, which means
    // the creator is responsible for calling |Release| exactly once.
    explicit WeakStubController(StubController* controller);
  
    // Increment the refernence count for this object.
    //
    // Each call to this method imposes a requirement to eventually call |Release|
    // exactly once.
    void AddRef();
  
    // Decrements the reference count for this object.
    //
    // When the reference count reaches zero, the object is destroyed.
    void Release();
  
    // Break the connection between this object and the |StubController|.
    //
    // After calling this method, |controller()| will return nullptr.
    void Invalidate();
  
    // The |StubController| to which this weak reference refers.
    //
    // After the weak reference has been invalidated, this method returns nullptr.
    StubController* controller() const { return controller_; }
  
   private:
    ~WeakStubController();
  
    uint32_t ref_count_;  // starts at one
    StubController* controller_;
  };
  
  }  // namespace internal
  }  // namespace fidl
  
  #endif  // LIB_FIDL_CPP_INTERNAL_WEAK_STUB_CONTROLLER_H_
  