| // 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> |
| |
| #include <zircon/assert.h> |
| #include <threads.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 final { |
| 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; |
| |
| private: |
| ~WeakStubController(); |
| |
| uint32_t ref_count_; // starts at one |
| StubController* controller_; |
| #if ZX_DEBUG_ASSERT_IMPLEMENTED |
| // thrd_current() needs to match the thread on which this instance was |
| // created, so that non-atomic ref_count_ updates work as intended. |
| bool IsCurrentThreadOk() const; |
| #endif |
| // If the WeakStubController constructor is release build, this field will be initialized to |
| // thrd_t{} by the constructor and stay that value until destruction. If debug build, this field |
| // remembers the construction thread. In a debug build, many of the methods will ZX_PANIC() if |
| // run on a thread other than the construction thread AND thread != thrd_t{}. By checking vs. |
| // thrd_t{}, a WeakStubController constructed by release code, but passed to a debug method, will |
| // avoid asserting. |
| thrd_t thread_; |
| }; |
| |
| } // namespace internal |
| } // namespace fidl |
| |
| #endif // LIB_FIDL_CPP_INTERNAL_WEAK_STUB_CONTROLLER_H_ |