Questions:
I’m trying to create a function (for purposes of logging)
append($path, $data)
that
- creates $file if it doesn’t exist and
- atomically appends $data to it.
It has to
- support high concurrency,
- support long strings and
- be as performant as possible.
So far the best attempt is:
function append($file, $data)
{
// Ensure $file exists. Just opening it with 'w' or 'a' might cause
// 1 process to clobber another's.
$fp = @fopen($file, 'x');
if ($fp)
fclose($fp);
// Append
$lock = strlen($data) > 4096; // assume PIPE_BUF is 4096 (Linux)
$fp = fopen($file, 'a');
if ($lock && !flock($fp, LOCK_EX))
throw new Exception('Cannot lock file: '.$file);
fwrite($fp, $data);
if ($lock)
flock($fp, LOCK_UN);
fclose($fp);
}
It works OK, but it seems to be a quite complex. Is there a cleaner (built-in?) way to do it?
How to&Answers:
PHP already has a built-in function to do this, file_put_contents(). The syntax is:
file_put_contents($filename, $data, FILE_APPEND);
Note that file_put_contents() will create the file if it does not already exist (as long as you have file system permissions to do so).
Answer：
using PHP’s internal function http://php.net/manual/en/function.file-put-contents.php
file_put_contents($file, $data, FILE_APPEND | LOCK_EX);
FILE_APPEND => flag to append the content to the end of the file
LOCK_EX => flag to prevent anyone else writing to the file at the same time (Available since PHP 5.1)
