/* * Copyright © 2012-2013 Canonical Ltd. * * This program is free software: you can redistribute it and/or modify it * under the terms of the GNU Lesser General Public License version 3, * as published by the Free Software Foundation. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public License * along with this program. If not, see . * * Authored by: Thomas Voß */ #ifndef CORE_POSIX_LINUX_PROC_PROCESS_OOM_ADJ_H_ #define CORE_POSIX_LINUX_PROC_PROCESS_OOM_ADJ_H_ #include namespace core { namespace posix { class Process; namespace linux { namespace proc { namespace process { /** * This file can be used to adjust the score used to select which process * should be killed in an out-of-memory (OOM) situation. The kernel uses this * value for a bit-shift operation of the process's oom_score value: valid * values are in the range -16 to +15, plus the special value -17, which disables * OOM-killing altogether for this process. A positive score increases the * likelihood of this process being killed by the OOM-killer; a negative score * decreases the likelihood. * * The default value for this file is 0; a new process inherits its parent's * oom_adj setting. A process must be privileged (CAP_SYS_RESOURCE) to update * this file. * * Since Linux 2.6.36, use of this file is deprecated in favor of * /proc/[pid]/oom_score_adj. */ struct CORE_POSIX_DLL_PUBLIC OomAdj { /** * @brief Returns the value that makes a process "invisible" to the oom killer. * @return Returns the value that makes a process "invisible" to the oom killer. */ static int disable_value(); /** * @brief Returns the minimum valid value. * @return The minimum valid value that the OomAdj can be set to. */ static int min_value(); /** * @brief Returns the maximum valid value. * @return The maximum valid value that the OomAdj can be set to. */ static int max_value(); /** * @brief is_valid checks whether the contained value is within the predefined bounds. * @return true iff min_value() <= value <= max_value(). */ inline bool is_valid() const { return (disable_value() <= value) && (value <= max_value()); } /** * @brief Current value. */ int value; }; /** * \brief Read the OomAdj value for a process instance. * \throws std::runtime_error in case of errors. * \param [in] process The process to read the score for. * \param [out] adj The destination to store the value in. */ CORE_POSIX_DLL_PUBLIC const posix::Process& operator>>(const posix::Process& process, OomAdj& adj); /** * \brief Write the OomAdj value for a process instance. * \throw std::runtime_error in case of errors and std::logic_error if score_adj.is_valid() returns false. * \param [in] process The process to write the score for. * \param [in] adj The new value to store. */ CORE_POSIX_DLL_PUBLIC const posix::Process& operator<<(const posix::Process& process, const OomAdj& adj); } } } } } #endif // CORE_POSIX_LINUX_PROC_PROCESS_OOM_ADJ_H_