Watch.cs

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// Task.cs
//
// Copyright (c) 2008 Jérémie "Garuma" Laval
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
//
//

#if NET_4_0 || UNITY_5_3_OR_NEWER
using System;
using System.Reflection;

namespace System.Threading
{
    internal struct Watch
    {
        // Do not rely on Mono internals
        #if false
        static readonly MethodInfo GetTimeMonotonicMethodInfo = 
            typeof(DateTime).GetMethod("GetTimeMonotonic", BindingFlags.NonPublic | BindingFlags.Static);

        // Spicy Pixel: This appears to work on AOT too and is much faster than dynamic invoke.
        static readonly Func<long> GetTimeMonotonic = (Func<long>)Delegate.CreateDelegate(
            typeof(Func<long>), GetTimeMonotonicMethodInfo);
        #endif
        
        long startTicks;
        
        public static Watch StartNew ()
        {
            Watch watch = new Watch ();
            watch.Start ();
            return watch;
        }
        
        public void Start ()
        {
            startTicks = TicksNow ();
        }
        
        public void Stop ()
        {
            
        }
        
        public long ElapsedMilliseconds {
            get {
                return (TicksNow () - startTicks) / TimeSpan.TicksPerMillisecond;
            }
        }
        
        static long TicksNow ()
        {
            // Spicy Pixel: No access to internal Mono method except by reflection.
            //
            // Monotonic time cannot be set and represents a time in ticks since
            // some unspecified starting point. It avoids drift due to system
            // time updates (which DateTime.Now.Ticks does not).
            // 
            // return DateTime.GetTimeMonotonic ();
            return DateTime.Now.Ticks;
            // return Watch.GetTimeMonotonic();
        }
    }
}
#endif