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// Copyright (C) 2015 Internet Systems Consortium, Inc. ("ISC")
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
#ifndef STOPWATCH_H
#define STOPWATCH_H
#include <boost/noncopyable.hpp>
#include <boost/date_time/posix_time/posix_time.hpp>
namespace isc {
namespace util {
/// @brief Forward declaration to the @c Stopwatch implementation.
class StopwatchImpl;
/// @brief Utility class to measure code execution times.
///
/// The API of this class is based on the use cases of a stopwatch. It is
/// used to measure time spent executing portions of the code. The typical
/// use case for the @c Stopwatch is to measure the time spent invoking
/// callouts in hooks library. This provides means for diagnosing the
/// server's performance degradations when hooks libraries are in use.
///
/// This class exposes functions like @c start, @c stop and @c reset which
/// behave in the same way as a stopwatch used to measure time for sport
/// activities.
///
/// It is possible to measure the cumulative execution time by invoking
/// @c start and @c stop consecutively. The total measured time will be
/// a sum of durations between the invocations of respective starts and
/// stops.
class Stopwatch : boost::noncopyable {
public:
/// @brief Constructor.
///
/// @param autostart Indicates if the stopwatch should be initialized to
/// the "started" state. In this state the stopwatch is measuring the time
/// since it has been started (object has been constructed in this case.
/// If the parameter is set to false (default value), the
/// @c Stopwatch::start must be called to start time measurement.
Stopwatch(const bool autostart = true);
/// @brief Destructor.
///
/// Destroys the implementation instance.
~Stopwatch();
/// @brief Starts the stopwatch.
///
/// Sets the stopwatch to the "started" state. In this state the stopwatch
/// is measuring the duration since @c Stopwatch::start has been invoked.
///
//// This method is no-op if the stopwatch is already in the "started"
/// state.
void start();
/// @brief Stops the stopwatch.
///
/// Sets the stopwatch to the "stopped" state. The stopwatch stops the time
/// measurement and records the duration between the last stopwatch start
/// and the stop invocation. It also updates the total measured duration,
/// i.e. the sum of durations between all start/stop invocations. Both
/// values can be retrieved using @c Stopwatch::getLastDuration and
/// @c Stopwatch::getTotalDuration respectively, or their variants.
///
/// This method is no-op if the stopwatch is already in the "stopped" state.
void stop();
/// @brief Resets the stopwatch.
///
/// It resets the stopwatch to the initial state. In this state, the last
/// measured duration and the total duration is set to 0. The stopwatch
/// is set to the "stopped" state.
void reset();
/// @brief Retrieves last measured duration.
///
/// If the stopwatch is in the "stopped" state this method retrieves the
/// duration between the last start and stop. If the stopwatch is in the
/// "started" state, the retrieved duration is the duration between the
/// last start of the stopwatch and the current time.
boost::posix_time::time_duration getLastDuration() const;
/// @brief Retrieves total measured duration.
///
/// If the stopwatch is in the "stopped" state this method retrieves the
/// total duration between all starts and stops invoked during the
/// lifetime of the object or since the last reset. If the stopwatch is
/// in the "started" state, the returned is the sum of all durations
/// between respective starts and stops, and the duration since the
/// stopwatch has been last started and the current time.
boost::posix_time::time_duration getTotalDuration() const;
/// @brief Retrieves the last measured duration in milliseconds.
long getLastMilliseconds() const;
/// @brief Retrieves the total measured duration in milliseconds.
long getTotalMilliseconds() const;
/// @brief Retrieves the last measured duration in microseconds.
long getLastMicroseconds() const;
/// @brief Retrieves the total measured duration in microseconds.
long getTotalMicroseconds() const;
/// @brief Returns the last measured duration in the format directly
/// usable in log messages.
std::string logFormatLastDuration() const;
/// @brief Returns the total measured duration in the format directly
/// usable in the log messages.
std::string logFormatTotalDuration() const;
private:
/// @brief Pointer to the @c StopwatchImpl.
StopwatchImpl* impl_;
};
}
}
#endif // STOPWATCH_H
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