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// *****************************************************************************
// * This file is part of the FreeFileSync project. It is distributed under *
// * GNU General Public License: https://www.gnu.org/licenses/gpl-3.0 *
// * Copyright (C) Zenju (zenju AT freefilesync DOT org) - All Rights Reserved *
// *****************************************************************************
#include "process_priority.h"
#include <sys/resource.h> //setpriority
using namespace zen;
namespace
{
#if 0
//https://linux.die.net/man/2/getpriority
//CPU priority from highest to lowest range: [-NZERO, NZERO -1] usually: [-20, 19]
enum //with values from CentOS 7
{
CPU_PRIO_VERYHIGH = -NZERO,
CPU_PRIO_HIGH = -5,
CPU_PRIO_NORMAL = 0,
CPU_PRIO_LOW = 5,
CPU_PRIO_VERYLOW = NZERO - 1,
};
int getCpuPriority() //throw SysError
{
errno = 0;
const int prio = getpriority(PRIO_PROCESS, 0 /* = the calling process */);
if (prio == -1 && errno != 0) //"can legitimately return the value -1"
THROW_LAST_SYS_ERROR("getpriority");
return prio;
}
//lowering is allowed, but increasing CPU prio requires admin rights >:(
void setCpuPriority(int prio) //throw SysError
{
if (setpriority(PRIO_PROCESS, 0 /* = the calling process */, prio) != 0)
THROW_LAST_SYS_ERROR("setpriority(" + numberTo<std::string>(prio) + ')');
}
#endif
//---------------------------------------------------------------------------------------------------
//- required functions ioprio_get/ioprio_set are not part of glibc: https://linux.die.net/man/2/ioprio_set
//- and probably never will: https://sourceware.org/bugzilla/show_bug.cgi?id=4464
//https://github.com/torvalds/linux/blob/master/include/uapi/linux/ioprio.h
#define IOPRIO_CLASS_SHIFT 13
#define IOPRIO_PRIO_VALUE(prioclass, priolevel) \
(((prioclass) << IOPRIO_CLASS_SHIFT) | (priolevel))
#define IOPRIO_NORM 4
enum
{
IOPRIO_WHO_PROCESS = 1,
IOPRIO_WHO_PGRP,
IOPRIO_WHO_USER,
};
enum
{
IOPRIO_CLASS_NONE = 0,
IOPRIO_CLASS_RT = 1,
IOPRIO_CLASS_BE = 2,
IOPRIO_CLASS_IDLE = 3,
};
int getIoPriority() //throw SysError
{
const int rv = ::syscall(SYS_ioprio_get, IOPRIO_WHO_PROCESS, ::getpid());
if (rv == -1)
THROW_LAST_SYS_ERROR("ioprio_get");
//fix Linux kernel fuck up: bogus system default value
if (rv == IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, IOPRIO_NORM))
return IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, IOPRIO_NORM);
return rv;
}
void setIoPriority(int ioPrio) //throw SysError
{
if (::syscall(SYS_ioprio_set, IOPRIO_WHO_PROCESS, ::getpid(), ioPrio) != 0)
THROW_LAST_SYS_ERROR("ioprio_set(0x" + printNumber<std::string>("%x", static_cast<unsigned int>(ioPrio)) + ')');
}
}
struct SetProcessPriority::Impl
{
std::optional<int> oldIoPrio;
};
SetProcessPriority::SetProcessPriority(ProcessPriority prio) : //throw FileError
pimpl_(new Impl)
{
if (prio == ProcessPriority::background)
try
{
pimpl_->oldIoPrio = getIoPriority(); //throw SysError
setIoPriority(IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, 6 /*0 (highest) to 7 (lowest)*/)); //throw SysError
//maybe even IOPRIO_PRIO_VALUE(IOPRIO_CLASS_IDLE, 0) ? nope: "only served when no one else is using the disk"
}
catch (const SysError& e) { throw FileError(_("Cannot change process I/O priorities."), e.toString()); }
}
SetProcessPriority::~SetProcessPriority()
{
if (pimpl_->oldIoPrio)
try
{
setIoPriority(*pimpl_->oldIoPrio); //throw SysError
}
catch (const SysError& e) { logExtraError(_("Cannot change process I/O priorities.") + L"\n\n" + e.toString()); }
}
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