[Xerte-dev] Re: Lockfiles

[David Goodwin]

Oh, it also looks like you need to explicitly call flock($fp, LOCK_UN) afterwards.

The alternative is, I guess, having a field in the DB to store who is currently editing a file - presumably storing a session_id in a field.
The only problem with that is it would be possible on either a slow/busy/whatever webserver for two processes to think they had a "write" lock when in fact only one does, and you'd need some way of removing/detecting stale locks - so an LO isn't marked as being edited forever.

David


On 29 Feb 2012, at 00:34, David Goodwin wrote:

> 
> On 28 Feb 2012, at 23:50, Pat Lockley wrote:
> 
>> Stop concurrent access
>> 
> 
> $fp = fopen('/path/to/something.xml.lock', 'w');
> if(flock($fp, LOCK_EX, FALSE)) {
>     // we have an exclusive lock on someting.xml.lock; within the scope of this webserver.
> }
> else {
>    // someone else has access.
> }
> 
> See also http://php.net/flock  - note it's behaviour is slightly different on Windows, and it wouldn't scale past more than one web server.
> 
> 
> David.
> 
>> On 28 Feb 2012, at 23:45, David Goodwin <david at palepurple.co.uk> wrote:
>> 
>>> What do you mean by "lock an XML file down"
>>> 
>>> Are you trying to stop concurrent access to it, or something else?
>>> 
>>> David.
>>> 
>>> On 28 Feb 2012, at 22:26, Pat Lockley wrote:
>>> 
>>>> Hi all,
>>>> 
>>>> Thoughts on how to lock an XML file down?
>>>> 
>>>> I think it might be the session expiring, or the js might not fire properly. I am pretty sure the lockfile remove code doesn't use the session anymore.
>>>> 
>>>> 
>>>> 
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