BackgroundWorker的&安培;定时器，只读取日志文件的新线路？ [英] BackgroundWorker & Timer, reading only new lines of a log file?

问题描述

我的应用程序写入日志文件（目前使用的 log4net的的）。我想设置一个计时器，并在后台工作，以读取日志文件并打印其内容到我的表格一定的控制，而它的写入。

我可以'T使用的 FileSystemWatcher的的类，因为似乎打破：有时事件改变了火灾，有时没有。它有一个非常低的汇聚率。

所以，我创建了一个定时器和一个FileSystemWatcher的。 。计时器的嘀的事件，在后台工作，它的工作。

现在的问题是： 如何阅读只有那些行因为工人的最后一次检查添加？的

 公共LogForm（）
 { 
的InitializeComponent（）; 
 logWatcherTimer.Start（）; 
} 
 
私人无效logWatcherTimer_Tick（对象发件人，EventArgs五）
 {
 FileInfo的登录=新的FileInfo（@C：\log.txt）; 
如果logWorker.RunWorkerAsync（日志）（logWorker.IsBusy！）; 
} 
 
私人无效logWorker_DoWork（对象发件人，DoWorkEventArgs E）
 {
 //读取上次检查只新线路。 
的FileInfo登录=（FileInfo的）e.Argument; 
 
 //这是最主要的问题！ 
} 
  

编辑：代码解决方案（也许是有更优雅的方式）：

 私人无效logWatherWorker_DoWork（对象发件人，DoWorkEventArgs E）
 {
 / / RETVAL 
字符串换行符=的String.Empty; 
的FileInfo登录=（FileInfo的）e.Argument; 
 
 //跳过如果日志文件没有改变
如果（lastLogLength == log.Length）回报; $ B使用
 $ B（StreamReader的流=新的StreamReader（log.FullName））
 {
 //设置位置到最后日志的大小和阅读
 //所有内容增加
 stream.BaseStream.Position = lastLogLength; 
换行符= stream.ReadToEnd（）; 
} 
 
 //保存上一段的轨迹记录长度
 lastLogLength = log.Length; 
 
 //将结果返回给工人，为
 //的形式
 e.Result =换行符消耗; 
} 
  

解决方案

查看和存储文件大小每次读取日志的时间，然后在该位置下次阅读时启动文本阅读器（或你使用任何）。

My application writes a log file (currently using log4net). I'd like to setup a timer and a background worker to read the log file and print its content into some control in my form, while it's being written.

I can't use the FileSystemWatcher class because seems broken: sometimes the event "changed" fires, sometimes do not. And it has an extremely low "pooling rate".

So I created a Timer and a FileSystemWatcher. On the "tick" event of the timer, the background worker does its job.

The question is: how to read only the lines that are added since the last check of the worker?

public LogForm()
{
    InitializeComponent();
    logWatcherTimer.Start();
}

private void logWatcherTimer_Tick(object sender, EventArgs e)
{
    FileInfo log = new FileInfo(@"C:\log.txt");
    if(!logWorker.IsBusy) logWorker.RunWorkerAsync(log);
}

private void logWorker_DoWork(object sender, DoWorkEventArgs e)
{
    // Read only new lines since last check.
    FileInfo log = (FileInfo) e.Argument;

   // Here is the main question!
}

EDIT: Code Solution (maybe there is a more elegant way?):

private void logWatherWorker_DoWork(object sender, DoWorkEventArgs e)
{
    // retval
    string newLines = string.Empty;
    FileInfo log = (FileInfo) e.Argument;

    // Just skip if log file hasn't changed
    if (lastLogLength == log.Length) return;

    using (StreamReader stream = new StreamReader(log.FullName))
    {
        // Set the position to the last log size and read
        // all the content added
        stream.BaseStream.Position = lastLogLength;
        newLines = stream.ReadToEnd();
    }

    // Keep track of the previuos log length
    lastLogLength = log.Length;

    // Assign the result back to the worker, to be
    // consumed by the form
    e.Result = newLines;
}

解决方案

Check and store the file size each time you read the log, then start your text reader (or whatever you're using) at that location the next time you read.

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