Posted by ED on 10/25/06 10:45

"kelvin" <kelvin_gl@yahoo.com.cn> wrote in message
news:1161738745.665437.168230@b28g2000cwb.googlegroups.com...
> bob.chatman@gmail.com wrote:
>> are you talking about 2 users calling a page at the same time?
>
> Exactly.
>
> A little more information:
> The php page is actually called by PayPal IPN.
> It works just fine in most case.
> But a few times PayPal will call this page twice at the same time.
> And it causes bugs. Because the first time information hasn't been
> insert into the database, the second call happens.
> So I want to find a method to avoid this.
>
> Thank you a lot,
> Kelvin
>
>>
>> kelvin wrote:
>> > Hi,
>> >
>> > How to avoid one php page be called by 2 at the same time?
>> > How to lock a block of codes in php?
>> >
>> > something like
>> >
>> > mutex.Lock
>> > //...............
>> > One service one time
>> > //................
>> > mutex.Unlock
>> >
>> > Any way to do this?
>> >
>> > Thank you,
>> > Kelvin
>

Hi Kelvin,

I generally use a text file as a lock so:

$fp = @fopen("lock.txt", "w+"); //open lock file
if ($fp && (flock($fp, LOCK_EX))) {//place an exclusive lock on the file
//do stuff
@fclose($fp); //release Lock

cheers
ED

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