call function once again after failure, without duplicate lines?

Question

I have what is probably an over-engineering question. I have some PHP code that logs messages to a file. We've been having a problem with the file having the wrong perms from time to time. While we're troubleshooting that, I am writing a work-around for that in the logging function, changing the unix perms and owners on the log file.

So my code looks like this:

function log($message) {
  if ( FALSE === file_put_contents(log_path(), $message) ) {
    chown(log_path(), 'apache');
    chgrp(log_path(), 'www-data');
    chown(log_path(), 0770);

    // now I'm repeating this line
    if ( FALSE === file_put_contents(log_path(), $message) ) {
      // log error to database
      db_log($message);
    }
  }
}

In the interest of DRY, can I somehow change the code to avoid repeating the line if ( FALSE === file_put_contents(log_path(), $message) ) {? Of course, I can't use recursion, because that would go on forever.

Answer 1

It's unnecessary, but if you want to dry this up:

function and_($now, $then) {
    return function($seed) use($now, $then) {
        return $now($seed) && $then($seed);
    };
}

function or_($now, $else) {
    return function($seed) use($now, $else) {
        return $now($seed) || $else($seed);
    };
}

function write_message($message) {
  return file_put_contents(log_path(), $message);
}

function fix_file($message) {
  chown(log_path(), 'apache');
  chgrp(log_path(), 'www-data');
  chown(log_path(), 0770);
  return TRUE;
}

function log_($message) {
    $log = or_('write_message', and_('fix_file', or_('write_message', 'db_log')));
    $log($message);
}

Answer 2

If you absolutely wanted to, you could do this:

function log($message)
{
  for($i = 0; $i < 2; ++$i)
  {
    if ( FALSE !== file_put_contents(log_path(), $message) )
    {
      return;
    }
    if($i == 0)
    {
      chown(log_path(), 'apache');
      chgrp(log_path(), 'www-data');
      chown(log_path(), 0770);
    }
    else
    {
      // log error to database
      db_log($message);
    }
  }
}

I don't like it, however... Just a simple function call? Well, it is OK. If it was a more complex code you had to execute before being able to make a decision, I'd write a separate function for this, returning true or false, and have it called twice, right as you did with the file_put_contents function.

Answer 3

A couple possibilities that haven't been mentioned:

1. If setting the permissions is always acceptable, always set the permissions, avoiding the first 'if' entirely. Especially since this is a workaround.
2. Check the permissions, setting them if necessary, then call file_put_contents(...). This has the added benefit of distinguishing a permissions error from a real error in the call to file_put_contents(...), which may help with debugging.