rocksdb/thrift/lib/cpp/concurrency/Util.h

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you 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.
 */

#ifndef _THRIFT_CONCURRENCY_UTIL_H_
#define _THRIFT_CONCURRENCY_UTIL_H_ 1

#include <assert.h>
#include <stddef.h>
#include <stdint.h>
#include <time.h>
#include <sys/time.h>

namespace apache { namespace thrift { namespace concurrency {

/**
 * Utility methods
 *
 * This class contains basic utility methods for converting time formats,
 * and other common platform-dependent concurrency operations.
 * It should not be included in API headers for other concurrency library
 * headers, since it will, by definition, pull in all sorts of horrid
 * platform dependent crap.  Rather it should be included directly in
 * concurrency library implementation source.
 *
 * @version $Id:$
 */
class Util {
 public:

  static const int64_t NS_PER_S = 1000000000LL;
  static const int64_t US_PER_S = 1000000LL;
  static const int64_t MS_PER_S = 1000LL;

  static const int64_t NS_PER_MS = NS_PER_S / MS_PER_S;
  static const int64_t NS_PER_US = NS_PER_S / US_PER_S;
  static const int64_t US_PER_MS = US_PER_S / MS_PER_S;

  /**
   * Converts millisecond timestamp into a timespec struct
   *
   * @param struct timespec& result
   * @param time or duration in milliseconds
   */
  static void toTimespec(struct timespec& result, int64_t value) {
    result.tv_sec = value / MS_PER_S; // ms to s
    result.tv_nsec = (value % MS_PER_S) * NS_PER_MS; // ms to ns
  }

  static void toTimeval(struct timeval& result, int64_t value) {
    result.tv_sec = value / MS_PER_S; // ms to s
    result.tv_usec = (value % MS_PER_S) * US_PER_MS; // ms to us
  }

  static const void toTicks(int64_t& result, int64_t secs, int64_t oldTicks,
                            int64_t oldTicksPerSec, int64_t newTicksPerSec) {
    result = secs * newTicksPerSec;
    result += oldTicks * newTicksPerSec / oldTicksPerSec;

    int64_t oldPerNew = oldTicksPerSec / newTicksPerSec;
    if (oldPerNew && ((oldTicks % oldPerNew) >= (oldPerNew / 2))) {
      ++result;
    }
  }
  /**
   * Converts struct timespec to arbitrary-sized ticks since epoch
   */
  static const void toTicks(int64_t& result,
                            const struct timespec& value,
                            int64_t ticksPerSec) {
    return toTicks(result, value.tv_sec, value.tv_nsec, NS_PER_S, ticksPerSec);
  }

  /**
   * Converts struct timeval to arbitrary-sized ticks since epoch
   */
  static const void toTicks(int64_t& result,
                            const struct timeval& value,
                            int64_t ticksPerSec) {
    return toTicks(result, value.tv_sec, value.tv_usec, US_PER_S, ticksPerSec);
  }

  /**
   * Converts struct timespec to milliseconds
   */
  static const void toMilliseconds(int64_t& result,
                                   const struct timespec& value) {
    return toTicks(result, value, MS_PER_S);
  }

  /**
   * Converts struct timeval to milliseconds
   */
  static const void toMilliseconds(int64_t& result,
                                   const struct timeval& value) {
    return toTicks(result, value, MS_PER_S);
  }

  /**
   * Converts struct timespec to microseconds
   */
  static const void toUsec(int64_t& result, const struct timespec& value) {
    return toTicks(result, value, US_PER_S);
  }

  /**
   * Converts struct timeval to microseconds
   */
  static const void toUsec(int64_t& result, const struct timeval& value) {
    return toTicks(result, value, US_PER_S);
  }

  /**
   * Get current time as a number of arbitrary-size ticks from epoch
   */
  static const int64_t currentTimeTicks(int64_t ticksPerSec);

  /**
   * Get current time as milliseconds from epoch
   */
  static const int64_t currentTime() { return currentTimeTicks(MS_PER_S); }

  /**
   * Get current time as micros from epoch
   */
  static const int64_t currentTimeUsec() { return currentTimeTicks(US_PER_S); }

  /**
   * Get monotonic time as a number of arbitrary-size ticks from some
   * unspecified starting point.
   *
   * This may fall back to the current time (potentially non-monotonic) on
   * systems that do not support monotonic time.
   */
  static const int64_t monotonicTimeTicks(int64_t ticksPerSec);

  /**
   * Get monotonic time as milliseconds.
   */
  static const int64_t monotonicTime() { return monotonicTimeTicks(MS_PER_S); }

  /**
   * Get current time as micros from epoch
   */
  static const int64_t monotonicTimeUsec() {
    return monotonicTimeTicks(US_PER_S);
  }
};

}}} // apache::thrift::concurrency

#endif // #ifndef _THRIFT_CONCURRENCY_UTIL_H_