Only update RFC 1123 once per second

Text only changes once per second; not fastest and allocates but moves
it out of hot path

Author: benaadams

experimental/ManagedRIOHttpServer/Program.cs

@@ -12,6 +12,10 @@ namespace ManagedRIOHttpServer
 {
     public sealed class Program
     {
+        // Number of 100ns ticks per time unit
+        private const long TicksPerMillisecond = 10000;
+        private const long TicksPerSecond = TicksPerMillisecond * 1000;
+
         static readonly string headersKeepAliveStr = "HTTP/1.1 200 OK\r\n" +
             "Content-Type: text/plain\r\n" +
             "Content-Length:13\r\n" +
@@ -106,6 +110,7 @@ static async Task ServeSocket(RIOTcpConnection socket)
 
                 var loop = 0;
                 var overflow = 0;
+                var lastSeconds = 0L;
                 // need to check for keep alive
 
                 while (true)
@@ -272,10 +277,15 @@ static async Task ServeSocket(RIOTcpConnection socket)
                         socket.SendCachedBad();
                         break;
                     }
-
-                    var date = DateTime.UtcNow.ToString("r");
-                    Encoding.UTF8.GetBytes(date, 0, dateBytes.Length, dateBytes, 0);
-
+                    
+                    var now = DateTime.UtcNow;
+                    var ticks = now.Ticks / TicksPerSecond;
+                    if (lastSeconds != ticks) {
+                        lastSeconds = ticks;
+                        var date = now.ToString("r");
+                        Encoding.ASCII.GetBytes(date, 0, dateBytes.Length, dateBytes, 0);
+                    }
+                    
                     for (var i = 1; i < count; i++)
                     {
                         socket.QueueSend(headerBuffer, false);
@@ -301,27 +311,30 @@ static async Task ServeSocket(RIOTcpConnection socket)
             }
         }
 
-
-        public static void LowerCaseSIMD(byte[] data)
-        {
-            var A = new Vector<byte>(65); // A
-            var Z = new Vector<byte>(90); // Z
+        //public static void LowerCaseSIMD(ArraySegment<byte> data)
+        //{
+        //    if (data.Offset + data.Count + Vector<byte>.Count < data.Array.Length)
+        //    {
+        //        throw new ArgumentOutOfRangeException("Nope");
+        //    }
+        //    var A = new Vector<byte>(65); // A
+        //    var Z = new Vector<byte>(90); // Z
 
-            for (var o = 0; o < data.Length - Vector<byte>.Count; o += Vector<byte>.Count)
-            {
-                var v = new Vector<byte>(data, o);
-
-                v = Vector.ConditionalSelect(
-                    Vector.BitwiseAnd(
-                        Vector.GreaterThanOrEqual(v, A),
-                        Vector.LessThanOrEqual(v, Z)
-                    ),
-                    Vector.BitwiseOr(new Vector<byte>(0x20), v), // 0010 0000
-                    v
-                );
-                v.CopyTo(data, o);
-            }
-        }
+        //    for (var o = data.Offset; o < data.Count - Vector<byte>.Count; o += Vector<byte>.Count)
+        //    {
+        //        var v = new Vector<byte>(data.Array, o);
+
+        //        v = Vector.ConditionalSelect(
+        //            Vector.BitwiseAnd(
+        //                Vector.GreaterThanOrEqual(v, A),
+        //                Vector.LessThanOrEqual(v, Z)
+        //            ),
+        //            Vector.BitwiseOr(new Vector<byte>(0x20), v), // 0010 0000
+        //            v
+        //        );
+        //        v.CopyTo(data.Array, o);
+        //    }
+        //}
     }
 
 }