be/src/util/cgroup-util.h

// Licensed to the Apache Software Foundation (ASF) under one
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// to you under the Apache License, Version 2.0 (the
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//   http://www.apache.org/licenses/LICENSE-2.0
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#pragma once

#include <cstdint>
#include <string>

#include "common/status.h"

namespace impala {

class CGroupUtil {
 public:
  /// Determines the CGroup memory limit from the current processes' cgroup.
  /// If the limit is more than INT64_MAX, INT64_MAX is returned (since that is
  /// effectively unlimited anyway). Does not take into account memory limits
  /// set on any ancestor CGroups. If is_v2 is provided: will return true when
  /// CGroup v2 is used, false otherwise.
  static Status FindCGroupMemLimit(int64_t* bytes, bool* is_v2 = nullptr);

  /// Returns a human-readable string with information about CGroups.
  static std::string DebugString();

 private:
  friend class CGroupInfo_ErrorHandling_Test;
  /// Finds the path of the cgroup of 'subsystem' for the current process.
  /// E.g. FindGlobalCGroup("memory") will return the memory cgroup
  /// that this process belongs to. This is a path relative to the system-wide root
  /// cgroup for 'subsystem'. Pass subsystem="" for CGroup V2 unified entries.
  static Status FindGlobalCGroup(const std::string& subsystem, std::string* path);

  /// Figures out the mapping of the cgroup root from the container's point of view to
  /// the full path relative to the system-wide cgroups outside of the container.
  /// E.g. /sys/fs/cgroup/memory/kubepods/burstable/pod-<long unique id> may be mounted at
  /// /sys/fs/cgroup/memory inside the container. In that case this function would return
  /// ("/sys/fs/cgroup/memory", "/kubepods/burstable/pod-<long unique id>"). CGroup v2
  /// uses a unified hierarchy, so the result will be the same for any value of
  /// 'subsystem'. If Status is Ok, returns whether the mount is for cgroup v1 or v2.
  static Status FindCGroupMounts(const std::string& subsystem,
      std::string* mount_path, std::string* system_path, bool* is_v2);
};
} // namespace impala