Re: Rolling files in C++

From:

"=?iso-8859-1?q?Erik_Wikstr=F6m?=" <eriwik@student.chalmers.se>

Newsgroups:

comp.lang.c++

Date:

20 Mar 2007 03:49:46 -0700

Message-ID:

<1174387786.441442.166850@n59g2000hsh.googlegroups.com>

On 20 Mar, 09:06, "farhadtarapore" <farhadtarap...@gmail.com> wrote:

I have a very large C++ application that has been converted into a
windows service. This application writes a lot of statements to the
console i.e. cout and cerr.
I have used
   std::ofstream out(coutFilePath.c_str (), ofstream::out |
ofstream::app);
    if(!out.is_open())
        throw std::runtime_error("Failed to open cout file");

    //Save the previous target before we redirect
    std::streambuf* orig_cout = std::cout.rdbuf( out.rdbuf());

....
... code that uses cout, calls lots of libraries, functions, etc...

....
....

    //Restore the cout to previous target
    std::cout.flush();
    std::cout.rdbuf(orig_cout);
    out.close();

//////////////////////////

My problem is this: The application cout file fills up very quickly. I
need some mechanism like a rolling file appender of Log4Cpp. How can I
implement a rolling file log in C++?

Don't know Log4Cpp but I assume that you want to rotate the logfiles.
There are several ways to do this, one would be to periodically check
how much data has been written to out (use tellp()) and if this
exceeds some value you close the file, rename it and then opens a new
file. Make sure that none is trying to write to the log when doing
this (if multithreaded). You could also shift files periodically
instead of based on size.

--
Erik Wikstr=F6m