apewer-dotnet/Apewer.Source/Externals/MySql.Data-6.10.9/MySqlClient/Common/LowResolutionStopwatch.cs

#if MYSQL_6_10

// Copyright (c) 2009, 2019, Oracle and/or its affiliates. All rights reserved.
//
// MySQL Connector/NET is licensed under the terms of the GPLv2
// <http://www.gnu.org/licenses/old-licenses/gpl-2.0.html>, like most 
// MySQL Connectors. There are special exceptions to the terms and 
// conditions of the GPLv2 as it is applied to this software, see the 
// FLOSS License Exception
// <http://www.mysql.com/about/legal/licensing/foss-exception.html>.
//
// This program is free software; you can redistribute it and/or modify 
// it under the terms of the GNU General Public License as published 
// by the Free Software Foundation; version 2 of the License.
//
// This program is distributed in the hope that it will be useful, but 
// WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 
// or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 
// for more details.
//
// You should have received a copy of the GNU General Public License along 
// with this program; if not, write to the Free Software Foundation, Inc., 
// 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA

using System;

namespace Externals.MySql.Data.Common
{
    /// <summary>
    /// This class is modeled after .NET Stopwatch. It provides better
    /// performance (no system calls).It is however less precise than
    /// .NET Stopwatch, measuring in milliseconds. It is adequate to use
    /// when high-precision is not required (e.g for measuring IO timeouts),
    /// but not for other tasks.
    /// </summary>
    internal class LowResolutionStopwatch
    {
        long _startTime;
        public static readonly long Frequency = 1000; // measure in milliseconds
        public static readonly bool IsHighResolution = false;

        public LowResolutionStopwatch()
        {
            ElapsedMilliseconds = 0;
        }
        public long ElapsedMilliseconds { get; private set; }

        public void Start()
        {
            _startTime = Environment.TickCount;
        }

        public void Stop()
        {
            long now = Environment.TickCount;
            long elapsed;

            // Calculate time different, handle possible overflow
            if (now < _startTime)
            {
                if (now < 0)
                    elapsed = 1 + ((long)Int32.MaxValue - _startTime) + (now - (long)Int32.MinValue);
                else
                    elapsed = Int32.MaxValue - _startTime + now;
            }
            else
                elapsed = now - _startTime;

            ElapsedMilliseconds += elapsed;
        }

        public void Reset()
        {
            ElapsedMilliseconds = 0;
            _startTime = 0;
        }

        public TimeSpan Elapsed => new TimeSpan(0, 0, 0, 0, (int)ElapsedMilliseconds);

        public static LowResolutionStopwatch StartNew()
        {
            LowResolutionStopwatch sw = new LowResolutionStopwatch();
            sw.Start();
            return sw;
        }

        public static long GetTimestamp()
        {
            return Environment.TickCount;
        }

        bool IsRunning()
        {
            return (_startTime != 0);
        }
    }
}

#endif