74 lines
2.4 KiB
C++
74 lines
2.4 KiB
C++
// Copyright 2020 The Chromium Authors
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef BASE_WIN_COM_INIT_BALANCER_H_
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#define BASE_WIN_COM_INIT_BALANCER_H_
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#include <objidl.h>
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#include <winnt.h>
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#include <wrl/implements.h>
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#include "base/base_export.h"
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#include "base/threading/thread_checker.h"
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#include "base/win/windows_types.h"
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#include "third_party/abseil-cpp/absl/types/optional.h"
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namespace base {
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namespace win {
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namespace internal {
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// Implementation class of the IInitializeSpy Interface that prevents premature
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// uninitialization of the COM library, often caused by unbalanced
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// CoInitialize/CoUninitialize pairs. The use of this class is encouraged in
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// COM-supporting threads that execute third-party code.
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//
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// Disable() must be called before uninitializing the COM library in order to
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// revoke the registered spy and allow for the successful uninitialization of
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// the COM library.
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class BASE_EXPORT ComInitBalancer
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: public Microsoft::WRL::RuntimeClass<
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Microsoft::WRL::RuntimeClassFlags<Microsoft::WRL::ClassicCom>,
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IInitializeSpy> {
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public:
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// Constructs a COM initialize balancer. |co_init| defines the apartment's
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// concurrency model used by the balancer.
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explicit ComInitBalancer(DWORD co_init);
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ComInitBalancer(const ComInitBalancer&) = delete;
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ComInitBalancer& operator=(const ComInitBalancer&) = delete;
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~ComInitBalancer() override;
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// Disables balancer by revoking the registered spy and consequently
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// unblocking attempts to uninitialize the COM library.
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void Disable();
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DWORD GetReferenceCountForTesting() const;
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private:
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// IInitializeSpy:
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IFACEMETHODIMP PreInitialize(DWORD apartment_type,
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DWORD reference_count) override;
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IFACEMETHODIMP PostInitialize(HRESULT result,
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DWORD apartment_type,
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DWORD new_reference_count) override;
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IFACEMETHODIMP PreUninitialize(DWORD reference_count) override;
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IFACEMETHODIMP PostUninitialize(DWORD new_reference_count) override;
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const DWORD co_init_;
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// The current apartment reference count set after the completion of the last
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// call made to CoInitialize or CoUninitialize.
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DWORD reference_count_ = 0;
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absl::optional<ULARGE_INTEGER> spy_cookie_;
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THREAD_CHECKER(thread_checker_);
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};
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} // namespace internal
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} // namespace win
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} // namespace base
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#endif // BASE_WIN_COM_INIT_BALANCER_H_
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