FW: [PHP] - REPOST - Flock manual clarification please ;-)
| From: | Matt Friedman | Date: | Sun, 07 Apr 2002 23:56:17 +0000 |
| Subject: | FW: [PHP] - REPOST - Flock manual clarification please ;-) | ||
| Groups: | php.general | ||
| Request: | Send a blank email to php-general+get-91969@lists.php.net to get a copy of this message | ||
From the manual:
<snip>
Note: Because flock() requires a file pointer, you may have to use a
special lock file to protect access to a file that you intend to
truncate by opening it in write mode (with a "w" or "w+" argument to
fopen()).
</snip>
The manual indicates that you "may" need to use "a special lock file" if
you intend to open a file with "w" or "w+". I wrote some code to examine
this. (2 files) Each file locks a file after opening using "w" to do so.
Then, the file is locked using LOCK_EX. Subsequently executed, each file
appears to respect the lock applied by the other file. (Each file waits
for the lock to be released by the other) - So, I don't see this manual
entry applying in this case.
In regards to the <snip> above, under what circumstances might you have
to create a separate lock file? Is this an OS issue? Is it an issue when
concurrency is high? The manual says "you may have to"; I am looking for
some clarification as to when exactly you "may have to" follow the
<snip> advice.
Thanks as always,
Matt Friedman
Web Applications Developer
www.SpryNewMedia.com
--
PHP General Mailing List (http://www.php.net/)
To unsubscribe, visit: http://www.php.net/unsub.php