77 lines
2.6 KiB
C
77 lines
2.6 KiB
C
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// Copyright 2012 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_SCOPED_COM_INITIALIZER_H_
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#define BASE_WIN_SCOPED_COM_INITIALIZER_H_
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#include <objbase.h>
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#include <wrl/client.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/com_init_balancer.h"
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#include "base/win/scoped_windows_thread_environment.h"
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namespace base {
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namespace win {
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// Initializes COM in the constructor (STA or MTA), and uninitializes COM in the
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// destructor.
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//
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// It is strongly encouraged to block premature uninitialization of the COM
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// libraries in threads that execute third-party code, as a way to protect
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// against unbalanced CoInitialize/CoUninitialize pairs.
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//
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// WARNING: This should only be used once per thread, ideally scoped to a
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// similar lifetime as the thread itself. You should not be using this in
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// random utility functions that make COM calls -- instead ensure these
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// functions are running on a COM-supporting thread!
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class BASE_EXPORT ScopedCOMInitializer : public ScopedWindowsThreadEnvironment {
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public:
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// Enum value provided to initialize the thread as an MTA instead of STA.
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enum SelectMTA { kMTA };
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// Enum values which enumerates uninitialization modes for the COM library.
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enum class Uninitialization {
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// Default value. Used in threads where no third-party code is executed.
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kAllow,
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// Blocks premature uninitialization of the COM libraries before going out
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// of scope. Used in threads where third-party code is executed.
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kBlockPremature,
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};
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// Constructors for STA initialization.
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explicit ScopedCOMInitializer(
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Uninitialization uninitialization = Uninitialization::kAllow);
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// Constructors for MTA initialization.
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explicit ScopedCOMInitializer(
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SelectMTA mta,
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Uninitialization uninitialization = Uninitialization::kAllow);
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ScopedCOMInitializer(const ScopedCOMInitializer&) = delete;
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ScopedCOMInitializer& operator=(const ScopedCOMInitializer&) = delete;
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~ScopedCOMInitializer() override;
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// ScopedWindowsThreadEnvironment:
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bool Succeeded() const override;
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// Used for testing. Returns the COM balancer's apartment thread ref count.
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DWORD GetCOMBalancerReferenceCountForTesting() const;
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private:
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void Initialize(COINIT init, Uninitialization uninitialization);
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HRESULT hr_ = S_OK;
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Microsoft::WRL::ComPtr<internal::ComInitBalancer> com_balancer_;
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THREAD_CHECKER(thread_checker_);
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};
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} // namespace win
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} // namespace base
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#endif // BASE_WIN_SCOPED_COM_INITIALIZER_H_
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