shell/platform/fuchsia/dart-pkg/zircon/sdk_ext/handle.h

// 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_SHELL_PLATFORM_FUCHSIA_DART_PKG_ZIRCON_SDK_EXT_HANDLE_H_
#define FLUTTER_SHELL_PLATFORM_FUCHSIA_DART_PKG_ZIRCON_SDK_EXT_HANDLE_H_

#include <zircon/syscalls.h>

#include <optional>
#include <vector>

#include "flutter/fml/memory/ref_counted.h"
#include "handle_waiter.h"
#include "third_party/dart/runtime/include/dart_api.h"
#include "third_party/tonic/dart_library_natives.h"
#include "third_party/tonic/dart_wrappable.h"
#include "third_party/tonic/typed_data/dart_byte_data.h"

namespace zircon {
namespace dart {
/**
 * Handle is the native peer of a Dart object (Handle in dart:zircon)
 * that holds an zx_handle_t. It tracks active waiters on handle too.
 */
class Handle : public fml::RefCountedThreadSafe<Handle>,
               public tonic::DartWrappable {
  DEFINE_WRAPPERTYPEINFO();
  FML_FRIEND_REF_COUNTED_THREAD_SAFE(Handle);
  FML_FRIEND_MAKE_REF_COUNTED(Handle);

 public:
  ~Handle();

  static void RegisterNatives(tonic::DartLibraryNatives* natives);

  static fml::RefPtr<Handle> Create(zx_handle_t handle);
  static fml::RefPtr<Handle> Create(zx::handle handle) {
    return Create(handle.release());
  }

  static fml::RefPtr<Handle> Unwrap(Dart_Handle handle) {
    return fml::RefPtr<Handle>(
        tonic::DartConverter<zircon::dart::Handle*>::FromDart(handle));
  }

  static Dart_Handle CreateInvalid();

  zx_handle_t ReleaseHandle();

  bool is_valid() const { return handle_ != ZX_HANDLE_INVALID; }

  zx_handle_t handle() const { return handle_; }

  zx_koid_t koid() const {
    if (!cached_koid_.has_value()) {
      zx_info_handle_basic_t info;
      zx_status_t status = zx_object_get_info(
          handle_, ZX_INFO_HANDLE_BASIC, &info, sizeof(info), nullptr, nullptr);
      cached_koid_ = std::optional<zx_koid_t>(
          status == ZX_OK ? info.koid : ZX_KOID_INVALID);
    }
    return cached_koid_.value();
  }

  zx_status_t Close();

  fml::RefPtr<HandleWaiter> AsyncWait(zx_signals_t signals,
                                      Dart_Handle callback);

  void ReleaseWaiter(HandleWaiter* waiter);

  Dart_Handle Duplicate(uint32_t rights);

  Dart_Handle Replace(uint32_t rights);

 private:
  explicit Handle(zx_handle_t handle);

  void RetainDartWrappableReference() const override { AddRef(); }

  void ReleaseDartWrappableReference() const override { Release(); }

  zx_handle_t handle_;

  std::vector<HandleWaiter*> waiters_;

  // Cache koid. To guarantee proper cache invalidation, only one `Handle`
  // should own the `zx_handle_t` at a time and use of syscalls that invalidate
  // the handle should use `ReleaseHandle()`.
  mutable std::optional<zx_koid_t> cached_koid_;
};

}  // namespace dart
}  // namespace zircon

#endif  // FLUTTER_SHELL_PLATFORM_FUCHSIA_DART_PKG_ZIRCON_SDK_EXT_HANDLE_H_