Class Counter

src/linux/cgroups.hpp:883–909

Counter is a primitive to listen on events of a given memory pressure level for a cgroup and keep track of the number of occurrence of that event. Use the public 'create' function to create a new counter; see 'value' for how to use.

// occurrence of that event. Use the public 'create' function to
// create a new counter; see 'value' for how to use.
class Counter
{
public:
  // Create a memory pressure counter for the given cgroup on the
  // specified level. This function assumes the given hierarchy and
  // cgroup are valid.
  static Try<process::Owned<Counter>> create(
      const std::string& hierarchy,
      const std::string& cgroup,
      Level level);

  virtual ~Counter();

  // Returns the current accumulated number of occurrences of the
  // pressure event. Returns a failure if any error occurs while
  // monitoring the pressure events, and any subsequent calls to
  // 'value' will return the same failure. In such case, the user
  // should consider creating a new Counter.
  process::Future<uint64_t> value() const;

private:
  Counter(const std::string& hierarchy,
          const std::string& cgroup,
          Level level);

  process::Owned<CounterProcess> process;
};

} // namespace pressure {