log_time.h

/*
 * Copyright (C) 2005-2017 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#pragma once

#include <stdint.h>
#include <time.h>

/* struct log_time is a wire-format variant of struct timespec */
#define NS_PER_SEC 1000000000ULL
#define US_PER_SEC 1000000ULL
#define MS_PER_SEC 1000ULL

#define LOG_TIME_SEC(t) ((t)->tv_sec)
/* next power of two after NS_PER_SEC */
#define LOG_TIME_NSEC(t) ((t)->tv_nsec & (UINT32_MAX >> 2))

#ifdef __cplusplus

extern "C" {

struct log_time {
 public:
  uint32_t tv_sec = 0; /* good to Feb 5 2106 */
  uint32_t tv_nsec = 0;

  static constexpr timespec EPOCH = {0, 0};

  log_time() {}
  explicit log_time(const timespec& T)
      : tv_sec(static_cast<uint32_t>(T.tv_sec)), tv_nsec(static_cast<uint32_t>(T.tv_nsec)) {}
  explicit log_time(uint32_t sec, uint32_t nsec = 0)
      : tv_sec(sec), tv_nsec(nsec) {
  }
#ifdef __linux__
  explicit log_time(clockid_t id) {
    timespec T;
    clock_gettime(id, &T);
    tv_sec = static_cast<uint32_t>(T.tv_sec);
    tv_nsec = static_cast<uint32_t>(T.tv_nsec);
  }
#endif
  /* timespec */
  bool operator==(const timespec& T) const {
    return (tv_sec == static_cast<uint32_t>(T.tv_sec)) &&
           (tv_nsec == static_cast<uint32_t>(T.tv_nsec));
  }
  bool operator!=(const timespec& T) const {
    return !(*this == T);
  }
  bool operator<(const timespec& T) const {
    return (tv_sec < static_cast<uint32_t>(T.tv_sec)) ||
           ((tv_sec == static_cast<uint32_t>(T.tv_sec)) &&
            (tv_nsec < static_cast<uint32_t>(T.tv_nsec)));
  }
  bool operator>=(const timespec& T) const {
    return !(*this < T);
  }
  bool operator>(const timespec& T) const {
    return (tv_sec > static_cast<uint32_t>(T.tv_sec)) ||
           ((tv_sec == static_cast<uint32_t>(T.tv_sec)) &&
            (tv_nsec > static_cast<uint32_t>(T.tv_nsec)));
  }
  bool operator<=(const timespec& T) const {
    return !(*this > T);
  }

  /* log_time */
  bool operator==(const log_time& T) const {
    return (tv_sec == T.tv_sec) && (tv_nsec == T.tv_nsec);
  }
  bool operator!=(const log_time& T) const {
    return !(*this == T);
  }
  bool operator<(const log_time& T) const {
    return (tv_sec < T.tv_sec) ||
           ((tv_sec == T.tv_sec) && (tv_nsec < T.tv_nsec));
  }
  bool operator>=(const log_time& T) const {
    return !(*this < T);
  }
  bool operator>(const log_time& T) const {
    return (tv_sec > T.tv_sec) ||
           ((tv_sec == T.tv_sec) && (tv_nsec > T.tv_nsec));
  }
  bool operator<=(const log_time& T) const {
    return !(*this > T);
  }

  log_time operator-=(const log_time& T) {
    // No concept of negative time, clamp to EPOCH
    if (*this <= T) {
      return *this = log_time(EPOCH);
    }

    if (this->tv_nsec < T.tv_nsec) {
      --this->tv_sec;
      this->tv_nsec = NS_PER_SEC + this->tv_nsec - T.tv_nsec;
    } else {
      this->tv_nsec -= T.tv_nsec;
    }
    this->tv_sec -= T.tv_sec;

    return *this;
  }
  log_time operator-(const log_time& T) const {
    log_time local(*this);
    return local -= T;
  }
  log_time operator+=(const log_time& T) {
    this->tv_nsec += T.tv_nsec;
    if (this->tv_nsec >= NS_PER_SEC) {
      this->tv_nsec -= NS_PER_SEC;
      ++this->tv_sec;
    }
    this->tv_sec += T.tv_sec;

    return *this;
  }
  log_time operator+(const log_time& T) const {
    log_time local(*this);
    return local += T;
  }

  uint64_t nsec() const {
    return static_cast<uint64_t>(tv_sec) * NS_PER_SEC + tv_nsec;
  }
  uint64_t usec() const {
    return static_cast<uint64_t>(tv_sec) * US_PER_SEC +
           tv_nsec / (NS_PER_SEC / US_PER_SEC);
  }
  uint64_t msec() const {
    return static_cast<uint64_t>(tv_sec) * MS_PER_SEC +
           tv_nsec / (NS_PER_SEC / MS_PER_SEC);
  }

  /* Add %#q for the fraction of a second to the standard library functions */
  char* strptime(const char* s, const char* format);
} __attribute__((__packed__));
}

#else /* __cplusplus */

typedef struct log_time {
  uint32_t tv_sec;
  uint32_t tv_nsec;
} __attribute__((__packed__)) log_time;

#endif /* __cplusplus */