92 lines
3.9 KiB
C++
92 lines
3.9 KiB
C++
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// Copyright 2018 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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#include "base/threading/platform_thread_win.h"
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#include <windows.h>
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#include <array>
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#include "base/process/process.h"
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#include "base/win/windows_version.h"
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#include "testing/gmock/include/gmock/gmock.h"
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#include "testing/gtest/include/gtest/gtest.h"
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namespace base {
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// It has been observed that calling
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// :SetThreadPriority(THREAD_MODE_BACKGROUND_BEGIN) in an IDLE_PRIORITY_CLASS
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// process never affects the return value of ::GetThreadPriority() or
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// the base priority reported in Process Explorer. It does however
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// set the memory and I/O priorities to very low. This test confirms that
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// behavior which we suspect is a Windows kernel bug. If this test starts
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// failing, the mitigation for https://crbug.com/901483 in
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// PlatformThread::SetCurrentThreadType() should be revisited.
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TEST(PlatformThreadWinTest, SetBackgroundThreadModeFailsInIdlePriorityProcess) {
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PlatformThreadHandle::Handle thread_handle =
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PlatformThread::CurrentHandle().platform_handle();
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// ::GetThreadPriority() is NORMAL. Memory priority is NORMAL.
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// Note: There is no practical way to verify the I/O priority.
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EXPECT_EQ(::GetThreadPriority(thread_handle), THREAD_PRIORITY_NORMAL);
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internal::AssertMemoryPriority(thread_handle, MEMORY_PRIORITY_NORMAL);
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// Set the process priority to IDLE.
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// Note: Do not use Process::SetProcessBackgrounded() because it uses
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// PROCESS_MODE_BACKGROUND_BEGIN instead of IDLE_PRIORITY_CLASS when
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// the target is the current process.
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EXPECT_EQ(::GetPriorityClass(Process::Current().Handle()),
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static_cast<DWORD>(NORMAL_PRIORITY_CLASS));
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::SetPriorityClass(Process::Current().Handle(), IDLE_PRIORITY_CLASS);
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EXPECT_EQ(Process::Current().GetPriority(),
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static_cast<int>(IDLE_PRIORITY_CLASS));
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// GetThreadPriority() stays NORMAL. Memory priority stays NORMAL.
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EXPECT_EQ(::GetThreadPriority(thread_handle), THREAD_PRIORITY_NORMAL);
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internal::AssertMemoryPriority(thread_handle, MEMORY_PRIORITY_NORMAL);
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// Begin thread mode background.
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EXPECT_TRUE(::SetThreadPriority(thread_handle, THREAD_MODE_BACKGROUND_BEGIN));
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// On Win10+, GetThreadPriority() stays NORMAL and memory priority becomes
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// VERY_LOW.
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//
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// Note: this documents the aforementioned kernel bug. Ideally this would
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// *not* be the case.
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const int priority_after_thread_mode_background_begin =
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::GetThreadPriority(thread_handle);
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EXPECT_EQ(priority_after_thread_mode_background_begin,
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THREAD_PRIORITY_NORMAL);
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internal::AssertMemoryPriority(thread_handle, MEMORY_PRIORITY_VERY_LOW);
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PlatformThread::Sleep(base::Seconds(1));
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// After 1 second, GetThreadPriority() and memory priority don't change (this
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// refutes the hypothesis that it simply takes time before GetThreadPriority()
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// is updated after entering thread mode background).
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EXPECT_EQ(::GetThreadPriority(thread_handle),
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priority_after_thread_mode_background_begin);
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internal::AssertMemoryPriority(thread_handle, MEMORY_PRIORITY_VERY_LOW);
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// Set the process priority to NORMAL.
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::SetPriorityClass(Process::Current().Handle(), NORMAL_PRIORITY_CLASS);
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// GetThreadPriority() and memory priority don't change when the process
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// priority changes.
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EXPECT_EQ(::GetThreadPriority(thread_handle),
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priority_after_thread_mode_background_begin);
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internal::AssertMemoryPriority(thread_handle, MEMORY_PRIORITY_VERY_LOW);
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// End thread mode background.
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//
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// Note: at least "ending" the semi-enforced background mode works...
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EXPECT_TRUE(::SetThreadPriority(thread_handle, THREAD_MODE_BACKGROUND_END));
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// GetThreadPriority() stays/becomes NORMAL. Memory priority becomes NORMAL.
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EXPECT_EQ(::GetThreadPriority(thread_handle), THREAD_PRIORITY_NORMAL);
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internal::AssertMemoryPriority(thread_handle, MEMORY_PRIORITY_NORMAL);
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}
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} // namespace base
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