diff options
Diffstat (limited to 'security/sandbox/chromium/base/sequenced_task_runner_helpers.h')
-rw-r--r-- | security/sandbox/chromium/base/sequenced_task_runner_helpers.h | 113 |
1 files changed, 113 insertions, 0 deletions
diff --git a/security/sandbox/chromium/base/sequenced_task_runner_helpers.h b/security/sandbox/chromium/base/sequenced_task_runner_helpers.h new file mode 100644 index 000000000..7980b46b6 --- /dev/null +++ b/security/sandbox/chromium/base/sequenced_task_runner_helpers.h @@ -0,0 +1,113 @@ +// Copyright (c) 2012 The Chromium 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 BASE_SEQUENCED_TASK_RUNNER_HELPERS_H_ +#define BASE_SEQUENCED_TASK_RUNNER_HELPERS_H_ + +#include "base/debug/alias.h" +#include "base/macros.h" + +// TODO(akalin): Investigate whether it's possible to just have +// SequencedTaskRunner use these helpers (instead of MessageLoop). +// Then we can just move these to sequenced_task_runner.h. + +namespace tracked_objects { +class Location; +} + +namespace base { + +namespace subtle { +template <class T, class R> class DeleteHelperInternal; +template <class T, class R> class ReleaseHelperInternal; +} + +// Template helpers which use function indirection to erase T from the +// function signature while still remembering it so we can call the +// correct destructor/release function. +// +// We use this trick so we don't need to include bind.h in a header +// file like sequenced_task_runner.h. We also wrap the helpers in a +// templated class to make it easier for users of DeleteSoon to +// declare the helper as a friend. +template <class T> +class DeleteHelper { + private: + template <class T2, class R> friend class subtle::DeleteHelperInternal; + + static void DoDelete(const void* object) { + delete reinterpret_cast<const T*>(object); + } + + DISALLOW_COPY_AND_ASSIGN(DeleteHelper); +}; + +template <class T> +class ReleaseHelper { + private: + template <class T2, class R> friend class subtle::ReleaseHelperInternal; + + static void DoRelease(const void* object) { + reinterpret_cast<const T*>(object)->Release(); + } + + DISALLOW_COPY_AND_ASSIGN(ReleaseHelper); +}; + +namespace subtle { + +// An internal SequencedTaskRunner-like class helper for DeleteHelper +// and ReleaseHelper. We don't want to expose the Do*() functions +// directly directly since the void* argument makes it possible to +// pass/ an object of the wrong type to delete. Instead, we force +// callers to go through these internal helpers for type +// safety. SequencedTaskRunner-like classes which expose DeleteSoon or +// ReleaseSoon methods should friend the appropriate helper and +// implement a corresponding *Internal method with the following +// signature: +// +// bool(const tracked_objects::Location&, +// void(*function)(const void*), +// void* object) +// +// An implementation of this function should simply create a +// base::Closure from (function, object) and return the result of +// posting the task. +template <class T, class ReturnType> +class DeleteHelperInternal { + public: + template <class SequencedTaskRunnerType> + static ReturnType DeleteViaSequencedTaskRunner( + SequencedTaskRunnerType* sequenced_task_runner, + const tracked_objects::Location& from_here, + const T* object) { + return sequenced_task_runner->DeleteSoonInternal( + from_here, &DeleteHelper<T>::DoDelete, object); + } + + private: + DISALLOW_COPY_AND_ASSIGN(DeleteHelperInternal); +}; + +template <class T, class ReturnType> +class ReleaseHelperInternal { + public: + template <class SequencedTaskRunnerType> + static ReturnType ReleaseViaSequencedTaskRunner( + SequencedTaskRunnerType* sequenced_task_runner, + const tracked_objects::Location& from_here, + const T* object) { + return sequenced_task_runner->ReleaseSoonInternal( + from_here, &ReleaseHelper<T>::DoRelease, object); + } + + private: + DISALLOW_COPY_AND_ASSIGN(ReleaseHelperInternal); +}; + +} // namespace subtle + +} // namespace base + +#endif // BASE_SEQUENCED_TASK_RUNNER_HELPERS_H_ |