1

I have written the following method that essentially reads the newest lines out of a log file that is being written continuously by another thread. This code runs on a different thread and is driven by a timer (fires off every 5 seconds). It's very simple. Here's what it looks like:

void FileManager::ReadFile()
{
    std::vector<std::string> vecLines;
    std::string line;

    m_InputStream.clear();

    while (std::getline(m_InputStream, line))
    {
        vecLines.push_back(line);
    }

    if (! vecLines.empty())
    {
        OnFileUpdate(vecLines);
    }
}

My question, is this code safe? Basically, the algorithm I perform is that I open the input stream ahead of time and seek to the end of the file. Then when this method gets called, if there are any new lines to be read, then they will be read in here. If there are any new lines, then any interested clients of this class will be notified (via the OnFileUpdate() call).

user1040229
  • 491
  • 6
  • 18
  • 3
    Sounds like tail -f. Maybe check out the source code for comparison. – drum Jan 24 '13 at 23:41
  • You dont like message passing? (thread X:--Hey main thread, i wrote something, what are you gonna do about it? Main thread: --ok, i will send it to a function, keep the good work, until you die.) – Ricardo Ortega Magaña Jan 24 '13 at 23:43
  • Well, the writing side of the log file is beyond my control. I am creating a new thread in an application that will monitor the log file for certain conditions to be met (and I look at the updated lines to find out). – user1040229 Jan 24 '13 at 23:49
  • Related: http://stackoverflow.com/questions/2696976/implement-tail-f-in-c – Paul R Jan 24 '13 at 23:53

1 Answers1

0

This requires a thread pending in the background.

What I would do is create a class that handles ALL Of your error/event logging and looks something like the following. You could make everything static and then that way you could access it from multiple locations Pros: No additional File I/O No secondary thread Cons: Not multi-core safe without a lock

class EventLogger {
  public:
    EventLogger();
    ~EventLogger();
    void LogEvent(const std::string &event) {
      //Handle output to file here
      OnFileUpdate(event);
    }
  private: 
    void OnFileUpdate(const std::string &event) {
      //DoWorkHere
    }
}
jmoyerman
  • 21
  • 2