[转]C#开发高性能Log Help类设计开发

项目中要在操作数据库的异常处理中加入写Log日志,对于商业上有要求,写log时对其它操作尽可能影响小,不能因为加入log导致耗时太多。在写入日志时利用Queue来管理,写日志有一个专门的backgroud线程来处理,如果没有日志要写,这个线程处于wait状态,这就有了线程的异步处理。
 

概述

项目中要在操作数据库的异常处理中加入写Log日志,对于商业上有要求,写log时对其它操作尽可能影响小,不能因为加入log导致耗时太多。

设计思想

在写入日志时利用Queue来管理,写日志有一个专门的backgroud线程来处理,如果没有日志要写,这个线程处于wait状态,这就有了线程的异步处理。

简单的实现方式

//<summary>
//Write Log
//<summary>
public static void WriteLog(string logFile, string msg)
{
    try
    {
        System.IO.StreamWriter sw = System.IO.File.AppendText(
                logPath + LogFilePrefix +" "+ logFile + " " +
                DateTime.Now.ToString("yyyyMMdd") + ".Log"
            );
        sw.WriteLine(DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss:  ") + msg);
        sw.Close();
    }
    catch (Exception)
    {

        throw;
    }
}

我们的设计图

而后我们在AddLogMessage时semaphore.Release()就能唤醒wait中的log 线程。

代码设计

/// <summary>
/// Author: spring yang
/// Create time:2012/3/30
/// Log Help class
/// </summary>
/// <remarks>High performance log class</remarks>
public class Log : IDisposable
{
    //Log Message queue
    private static Queue<LogMessage> _logMessages;

    //log save directory
    private static string _logDirectory;

    //log write file state
    private static bool _state;

    //log type
    private static LogType _logType;

    //log life time sign
    private static DateTime _timeSign;

    //log file stream writer
    private static StreamWriter _writer;

    /// <summary>
    /// Wait enqueue wirte log message semaphore will release
    /// </summary>
    private Semaphore _semaphore;

    /// <summary>
    /// Single instance
    /// </summary>
    private static Log _log;

    /// <summary>
    /// Gets a single instance
    /// </summary>
    public static Log LogInstance
    {
        get { return _log ?? (_log = new Log()); }
    }

    private object _lockObjeck;

    /// <summary>
    /// Initialize Log instance
    /// </summary>
    private void Initialize()
    {
        if (_logMessages == null)
        {   _state = true;
            string logPath = System.Configuration.ConfigurationManager.AppSettings["LogDirectory"];
            _logDirectory = string.IsNullOrEmpty(logPath) ? ".\\log\\" : logPath;
            if (!Directory.Exists(_logDirectory)) Directory.CreateDirectory(_logDirectory);
            _logType = LogType.Daily;
            _lockObjeck=new object();
            _semaphore = new Semaphore(0, int.MaxValue, Constants.LogSemaphoreName);
            _logMessages = new Queue<LogMessage>();
            var thread = new Thread(Work) {IsBackground = true};
            thread.Start();
        }
    }

    /// <summary>
    /// Create a log instance
    /// </summary>
    private Log()
    {
        Initialize();
    }

    /// <summary>
    /// Log save name type,default is daily
    /// </summary>
    public LogType LogType
    {
        get { return _logType; }
        set { _logType = value; }
    }

    /// <summary>
    /// Write Log file  work method
    /// </summary>
    private void Work()
    {
        while (true)
        {
            //Determine log queue have record need wirte
            if (_logMessages.Count > 0)
            {
                FileWriteMessage();
            }
            else
                if (WaitLogMessage()) break;
        }
    }

    /// <summary>
    /// Write message to log file
    /// </summary>
    private void FileWriteMessage()
    {
        LogMessage logMessage=null;
        lock (_lockObjeck)
        {
            if(_logMessages.Count>0)
            logMessage = _logMessages.Dequeue();
        }
        if (logMessage != null)
        {
            FileWrite(logMessage);
        }
    }

    /// <summary>
    /// The thread wait a log message
    /// </summary>
    /// <returns>is close or not</returns>
    private bool WaitLogMessage()
    {
        //determine log life time is true or false
        if (_state)
        {
            WaitHandle.WaitAny(new WaitHandle[] { _semaphore }, -1, false);
            return false;
        }
        FileClose();
        return true;
    }

    /// <summary>
    /// Gets file name by log type
    /// </summary>
    /// <returns>log file name</returns>
    private string GetFilename()
    {
        DateTime now = DateTime.Now;
        string format = "";
        switch (_logType)
        {
            case LogType.Daily:
                _timeSign = new DateTime(now.Year, now.Month, now.Day);
                _timeSign = _timeSign.AddDays(1);
                format = "yyyyMMdd'.log'";
                break;
            case LogType.Weekly:
                _timeSign = new DateTime(now.Year, now.Month, now.Day);
                _timeSign = _timeSign.AddDays(7);
                format = "yyyyMMdd'.log'";
                break;
            case LogType.Monthly:
                _timeSign = new DateTime(now.Year, now.Month, 1);
                _timeSign = _timeSign.AddMonths(1);
                format = "yyyyMM'.log'";
                break;
            case LogType.Annually:
                _timeSign = new DateTime(now.Year, 1, 1);
                _timeSign = _timeSign.AddYears(1);
                format = "yyyy'.log'";
                break;
        }
        return now.ToString(format);
    }

    /// <summary>
    /// Write log file message
    /// </summary>
    /// <param name="msg"></param>
    private void FileWrite(LogMessage msg)
    {
        try
        {
            if (_writer == null)
            {
                FileOpen();
            }
            else
            {
                //determine the log file is time sign
                if (DateTime.Now >= _timeSign)
                {
                    FileClose();
                    FileOpen();
                }
                _writer.WriteLine(Constants.LogMessageTime+msg.Datetime);
                _writer.WriteLine(Constants.LogMessageType+msg.Type);
                _writer.WriteLine(Constants.LogMessageContent+msg.Text);
                _writer.Flush();
            }
        }
        catch (Exception e)
        {
            Console.Out.Write(e);
        }
    }

    /// <summary>
    /// Open log file write log message
    /// </summary>
    private void FileOpen()
    {
        _writer = new StreamWriter(Path.Combine(_logDirectory, GetFilename()), true, Encoding.UTF8);
    }

    /// <summary>
    /// Close log file
    /// </summary>
    private void FileClose()
    {
        if (_writer != null)
        {
            _writer.Flush();
            _writer.Close();
            _writer.Dispose();
            _writer = null;
        }
    }

    /// <summary>
    /// Enqueue a new log message and release a semaphore
    /// </summary>
    /// <param name="msg">Log message</param>
    public void Write(LogMessage msg)
    {
        if (msg != null)
        {
            lock (_lockObjeck)
            {
                _logMessages.Enqueue(msg);
                _semaphore.Release();
            }
        }
    }

    /// <summary>
    /// Write message by message content and type
    /// </summary>
    /// <param name="text">log message</param>
    /// <param name="type">message type</param>
    public void Write(string text, MessageType type)
    {
        Write(new LogMessage(text, type));
    }

    /// <summary>
    /// Write Message by datetime and message content and type
    /// </summary>
    /// <param name="dateTime">datetime</param>
    /// <param name="text">message content</param>
    /// <param name="type">message type</param>
    public void Write(DateTime dateTime, string text, MessageType type)
    {
        Write(new LogMessage(dateTime, text, type));
    }

    /// <summary>
    /// Write message ty exception and message type
    /// </summary>
    /// <param name="e">exception</param>
    /// <param name="type">message type</param>
    public void Write(Exception e, MessageType type)
    {
        Write(new LogMessage(e.Message, type));
    }

    #region IDisposable member

    /// <summary>
    /// Dispose log
    /// </summary>
    public void Dispose()
    {
        _state = false;
    }

    #endregion
}

/// <summary>
/// Log Type
/// </summary>
/// <remarks>Create log by daily or weekly or monthly or annually</remarks>
public enum LogType
{
    /// <summary>
    /// Create log by daily
    /// </summary>
    Daily,

    /// <summary>
    /// Create log by weekly
    /// </summary>
    Weekly,

    /// <summary>
    /// Create log by monthly
    /// </summary>
    Monthly,

    /// <summary>
    /// Create log by annually
    /// </summary>
    Annually
}

/// <summary>
/// Log Message Class
/// </summary>
public class LogMessage
{

    /// <summary>
    /// Create Log message instance
    /// </summary>
    public LogMessage()
        : this("", MessageType.Unknown)
    {
    }

    /// <summary>
    /// Crete log message by message content and message type
    /// </summary>
    /// <param name="text">message content</param>
    /// <param name="messageType">message type</param>
    public LogMessage(string text, MessageType messageType)
        : this(DateTime.Now, text, messageType)
    {
    }

    /// <summary>
    /// Create log message by datetime and message content and message type
    /// </summary>
    /// <param name="dateTime">date time </param>
    /// <param name="text">message content</param>
    /// <param name="messageType">message type</param>
    public LogMessage(DateTime dateTime, string text, MessageType messageType)
    {
        Datetime = dateTime;
        Type = messageType;
        Text = text;
    }

    /// <summary>
    /// Gets or sets datetime
    /// </summary>
    public DateTime Datetime { get; set; }

    /// <summary>
    /// Gets or sets message content
    /// </summary>
    public string Text { get; set; }

    /// <summary>
    /// Gets or sets message type
    /// </summary>
    public MessageType Type { get; set; }

    /// <summary>
    /// Get Message to string
    /// </summary>
    /// <returns></returns>
    public new string ToString()
    {
        return Datetime.ToString(CultureInfo.InvariantCulture) + "\t" + Text + "\n";
    }
}

/// <summary>
/// Log Message Type enum
/// </summary>
public enum MessageType
{
    /// <summary>
    /// unknown type
    /// </summary>
    Unknown,

    /// <summary>
    /// information type
    /// </summary>
    Information,

    /// <summary>
    /// warning type
    /// </summary>
    Warning,

    /// <summary>
    /// error type
    /// </summary>
    Error,

    /// <summary>
    /// success type
    /// </summary>
    Success
}

Test Case：

public static void TestLog()
{
    Log.LogInstance.Write(  "Test Message",MessageType.Information);
    Log.LogInstance.Write("one",MessageType.Error);
    Log.LogInstance.Write("two", MessageType.Success);
    Log.LogInstance.Write("three", MessageType.Warning);
}

运行结果：

接受Mainz的建议，改了部分代码。