src/public/lib/clock_interfaces.h

// Copyright 2017 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef COBALT_SRC_PUBLIC_LIB_CLOCK_INTERFACES_H_
#define COBALT_SRC_PUBLIC_LIB_CLOCK_INTERFACES_H_

#include <chrono>
#include <iomanip>
#include <optional>
#include <queue>
#include <sstream>
#include <string>

namespace cobalt::util {

// Allows us to mock out a clock for tests.
class SystemClockInterface {
 public:
  virtual ~SystemClockInterface() = default;

  virtual std::chrono::system_clock::time_point now() = 0;
};

// Allows us to mock out a clock for tests.
class SteadyClockInterface {
 public:
  virtual ~SteadyClockInterface() = default;

  virtual std::chrono::steady_clock::time_point now() = 0;
};

// An abstract interface to a clock that refuses to provide the time if a quality condition is not
// satisfied; for example, if the clock has not been initialized from a trustworthy source.
class ValidatedClockInterface {
 public:
  virtual ~ValidatedClockInterface() = default;

  // Returns the current time if an accurate clock is avaliable or nullopt otherwise.
  virtual std::optional<std::chrono::system_clock::time_point> now() = 0;
};

}  // namespace cobalt::util

#endif  // COBALT_SRC_PUBLIC_LIB_CLOCK_INTERFACES_H_