50 lines
1.5 KiB
Go
50 lines
1.5 KiB
Go
// Copyright (C) 2018 The Syncthing Authors.
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//
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// This Source Code Form is subject to the terms of the Mozilla Public
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// License, v. 2.0. If a copy of the MPL was not distributed with this file,
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// You can obtain one at https://mozilla.org/MPL/2.0/.
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package osutil
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import (
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"syscall"
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"github.com/pkg/errors"
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)
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const (
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// https://docs.microsoft.com/windows/win32/api/processthreadsapi/nf-processthreadsapi-setpriorityclass
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aboveNormalPriorityClass = 0x00008000
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belowNormalPriorityClass = 0x00004000
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highPriorityClass = 0x00000080
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idlePriorityClass = 0x00000040
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normalPriorityClass = 0x00000020
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processModeBackgroundBegin = 0x00100000
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processModeBackgroundEnd = 0x00200000
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realtimePriorityClass = 0x00000100
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)
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// SetLowPriority lowers the process CPU scheduling priority, and possibly
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// I/O priority depending on the platform and OS.
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func SetLowPriority() error {
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modkernel32 := syscall.NewLazyDLL("kernel32.dll")
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setPriorityClass := modkernel32.NewProc("SetPriorityClass")
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if err := setPriorityClass.Find(); err != nil {
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return errors.Wrap(err, "find proc")
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}
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handle, err := syscall.GetCurrentProcess()
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if err != nil {
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return errors.Wrap(err, "get process handler")
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}
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defer syscall.CloseHandle(handle)
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res, _, err := setPriorityClass.Call(uintptr(handle), belowNormalPriorityClass)
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if res != 0 {
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// "If the function succeeds, the return value is nonzero."
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return nil
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}
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return errors.Wrap(err, "set priority class") // wraps nil as nil
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}
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