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/* SPDX-License-Identifier: MIT
*
* Copyright (C) 2019-2021 WireGuard LLC. All Rights Reserved.
*/
using System;
using System.IO;
using System.IO.MemoryMappedFiles;
using System.Text;
using System.Collections.Generic;
using System.Threading;
using System.Runtime.CompilerServices;
namespace Tunnel
{
public class Ringlogger
{
private struct UnixTimestamp
{
private Int64 _ns;
public UnixTimestamp(Int64 ns) => _ns = ns;
public bool IsEmpty => _ns == 0;
public static UnixTimestamp Empty => new UnixTimestamp(0);
public static UnixTimestamp Now
{
get
{
var now = DateTimeOffset.UtcNow;
var ns = (now.Subtract(DateTimeOffset.FromUnixTimeSeconds(0)).Ticks * 100) % 1000000000;
return new UnixTimestamp(now.ToUnixTimeSeconds() * 1000000000 + ns);
}
}
public Int64 Nanoseconds => _ns;
public override string ToString()
{
return DateTimeOffset.FromUnixTimeSeconds(_ns / 1000000000).LocalDateTime.ToString("yyyy'-'MM'-'dd HH':'mm':'ss'.'") + ((_ns % 1000000000).ToString() + "00000").Substring(0, 6);
}
}
private struct Line
{
private const int maxLineLength = 512;
private const int offsetTimeNs = 0;
private const int offsetLine = 8;
private readonly MemoryMappedViewAccessor _view;
private readonly int _start;
public Line(MemoryMappedViewAccessor view, UInt32 index) => (_view, _start) = (view, (int)(Log.HeaderBytes + index * Bytes));
public static int Bytes => maxLineLength + offsetLine;
public UnixTimestamp Timestamp
{
get => new UnixTimestamp(_view.ReadInt64(_start + offsetTimeNs));
set => _view.Write(_start + offsetTimeNs, value.Nanoseconds);
}
public string Text
{
get
{
var textBytes = new byte[maxLineLength];
_view.ReadArray(_start + offsetLine, textBytes, 0, textBytes.Length);
var nullByte = Array.IndexOf<byte>(textBytes, 0);
if (nullByte <= 0)
return null;
return Encoding.UTF8.GetString(textBytes, 0, nullByte);
}
set
{
if (value == null)
{
_view.WriteArray(_start + offsetLine, new byte[maxLineLength], 0, maxLineLength);
return;
}
var textBytes = Encoding.UTF8.GetBytes(value);
var bytesToWrite = Math.Min(maxLineLength - 1, textBytes.Length);
_view.Write(_start + offsetLine + bytesToWrite, (byte)0);
_view.WriteArray(_start + offsetLine, textBytes, 0, bytesToWrite);
}
}
public override string ToString()
{
var time = Timestamp;
if (time.IsEmpty)
return null;
var text = Text;
if (text == null)
return null;
return string.Format("{0}: {1}", time, text);
}
}
private struct Log
{
private const UInt32 maxLines = 2048;
private const UInt32 magic = 0xbadbabe;
private const int offsetMagic = 0;
private const int offsetNextIndex = 4;
private const int offsetLines = 8;
private readonly MemoryMappedViewAccessor _view;
public Log(MemoryMappedViewAccessor view) => _view = view;
public static int HeaderBytes => offsetLines;
public static int Bytes => (int)(HeaderBytes + Line.Bytes * maxLines);
public UInt32 ExpectedMagic => magic;
public UInt32 Magic
{
get => _view.ReadUInt32(offsetMagic);
set => _view.Write(offsetMagic, value);
}
public UInt32 NextIndex
{
get => _view.ReadUInt32(offsetNextIndex);
set => _view.Write(offsetNextIndex, value);
}
public unsafe UInt32 InsertNextIndex()
{
byte* pointer = null;
_view.SafeMemoryMappedViewHandle.AcquirePointer(ref pointer);
var ret = (UInt32)Interlocked.Increment(ref Unsafe.AsRef<Int32>(pointer + offsetNextIndex));
_view.SafeMemoryMappedViewHandle.ReleasePointer();
return ret;
}
public UInt32 LineCount => maxLines;
public Line this[UInt32 i] => new Line(_view, i % maxLines);
public void Clear() => _view.WriteArray(0, new byte[Bytes], 0, Bytes);
}
private readonly Log _log;
private readonly string _tag;
public Ringlogger(string filename, string tag)
{
var file = File.Open(filename, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.ReadWrite | FileShare.Delete);
file.SetLength(Log.Bytes);
var mmap = MemoryMappedFile.CreateFromFile(file, null, 0, MemoryMappedFileAccess.ReadWrite, HandleInheritability.None, false);
var view = mmap.CreateViewAccessor(0, Log.Bytes, MemoryMappedFileAccess.ReadWrite);
_log = new Log(view);
if (_log.Magic != _log.ExpectedMagic)
{
_log.Clear();
_log.Magic = _log.ExpectedMagic;
}
_tag = tag;
}
public void Write(string line)
{
var time = UnixTimestamp.Now;
var entry = _log[_log.InsertNextIndex() - 1];
entry.Timestamp = UnixTimestamp.Empty;
entry.Text = null;
entry.Text = string.Format("[{0}] {1}", _tag, line.Trim());
entry.Timestamp = time;
}
public void WriteTo(TextWriter writer)
{
var start = _log.NextIndex;
for (UInt32 i = 0; i < _log.LineCount; ++i)
{
var entry = _log[i + start];
if (entry.Timestamp.IsEmpty)
continue;
var text = entry.ToString();
if (text == null)
continue;
writer.WriteLine(text);
}
}
public static readonly UInt32 CursorAll = UInt32.MaxValue;
public List<string> FollowFromCursor(ref UInt32 cursor)
{
var lines = new List<string>((int)_log.LineCount);
var i = cursor;
var all = cursor == CursorAll;
if (all)
i = _log.NextIndex;
for (UInt32 l = 0; l < _log.LineCount; ++l, ++i)
{
if (!all && i % _log.LineCount == _log.NextIndex % _log.LineCount)
break;
var entry = _log[i];
if (entry.Timestamp.IsEmpty)
{
if (all)
continue;
break;
}
cursor = (i + 1) % _log.LineCount;
var text = entry.ToString();
if (text == null)
continue;
lines.Add(text);
}
return lines;
}
}
}
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