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diff --git a/src/lib/util/stopwatch.h b/src/lib/util/stopwatch.h
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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
+