Handling file locks in PHP

By: Cory Christison Printer Friendly Format

While can do wonders if you need something to queue writing to a file while something else has access to it.

Here is my simple example:


<?php
  function write ($data, $file, $write_mode="w") {
    
$lock = $file . ".lock";
     // run the write fix, to 
stop any clashes that may occur
    
write_fix($lock);
     // create a new lock file after 
write_fix() for this writing session
    touch( $lock 
);
     // write to your file
    $open 
= fopen($file, $write_mode);
    fwrite($open, 
$data);
    fclose($open);
     // kill 
your current lock
    unlink($lock);
  }
  function write_fix ($lock_file) {
    while( 
file_exists($lock_file){
      // do something in 
here?
      // maybe sleep for a few 
microseconds
      // to maintain stability, if this 
is going to 
      // take a while ?? [just a 
suggestion]
    }
  }
?>

This method is not recommended for use with programs that will be needing a good few seconds to write to a file, as the while function will eat up alot of process cycles. However, this method does work, and is easy to implement. It also groups the writing functions into one easy to use function, making life easier.

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