[htdig-dev] Help required with "configure" - Porting Adjustable Logging Patch to 3.2

[Brian W. <bw...@st...>]

Hi,

I have been playing with my Adjustable Logging patch.
I now have it working for 3.2.0b3, but I am stuck on
the configure step. I have added the following to
configure.in:

AC_MSG_CHECKING(if fcntl can lock files?)
AC_TRY_COMPILE([#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>

struct flock flk;],
   [flk.l_type = F_RDLCK | F_WRLCK;
    flk.l_start = 0;
    flk.l_whence = SEEK_SET | SEEK_END;
    flk.l_len = 0;
    flk.l_pid = getpid();
    fcntl( 7, F_SETLKW | F_SETLK, &flk );],
   [AC_MSG_RESULT(yes);AC_DEFINE(__FILE_LOCKING__)],
   [AC_MSG_RESULT(no)])

This is producing a correct looking configure script
and it looks like it it is running OK, ( I am getting
the "Yes" and "No" responses as expected ) but I have
no idea how to propogate my AC_DEFINE down to the
C++ code.

Also, I decided to put all the file locking
stuff in a separate C++ class with an interface which
looks like this:

class LockedFile
{
public:

     LockedFile();

     // Destructor - will close the file if it hasn't
     // been closed already
     ~LockedFile();


     // This method opens a file, The path and mode parameters
     // are the same as those accepted by the standard fopen
     // function. It will return false if it fails to open
     // the file, in which case it will set the global
     // value errno as per the fopen function
     //
     // By deafult it will wait for the lock, but it can
     // be told to not wait

     int Open( const char* path, const char* mode, int waitForLock );
     int Open( const char* path, const char* mode );

     // This method will close the file if it hasn't been
     // closed already
     void Close();

     // This allows an object of this type to be used
     // at any point where a FILE* is expected
     operator FILE*();
};

which I have put in htlib/FileLocking.[h|cc], and
I have modified htlib/Makefile.am accordingly.

This means that all the evil mucking about
with #defines is limited to a single place, and the
functionality is available to anyone else who
needs it. If the file locking is not available, it
just calls "fopen".

Sample USage:

     #include "FileLocking.h"

     LockedFile lkdf;
     if ( lkdf.Open("/path/to/file", "w" ) )
     {
        fprintf( lkdf, "Hello Wordl\n" );
        lkdf.Close();
     }

Are there any problems with doing this? Are there
any conventions I should be following that I am not?

Regs

Brian


-------------------------
Brian White
Step Two Designs Pty Ltd
Knowledge Management Consultancy, SGML & XML
Phone: +612-93197901
Web:   http://www.steptwo.com.au/
Email: bw...@st...

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