File Operations

[Cameron]

I am writing a project in PHP for Unix based systems and may need to
store data in files as apposed to an SQL server, I know there are many
problems that can arise out of using files in this way especially when
multiple users are concerned and would prefer not to use them at all,
but if I have to I could do with some suggestions about the best way to
avoid trashed files due to simultaneous writes.

I am aware of the flock() function and ignore_user_abort() but aren't
sure of the best way to implement them, and I also hear that
ignore_user_abort() doesn't work when PHP is running in safe mode.

Thanks for any help you can give.

~Cameron

[Jerry Sievers]

Cameron <devnull@foo-bar.invalid> writes:

> I am writing a project in PHP for Unix based systems and may need to
> store data in files as apposed to an SQL server, I know there are many
> problems that can arise out of using files in this way especially when
> multiple users are concerned and would prefer not to use them at all,
> but if I have to I could do with some suggestions about the best way to
> avoid trashed files due to simultaneous writes.
>
> I am aware of the flock() function and ignore_user_abort() but aren't

I haven't used flock in a while as I too go RDBMS whenever possible.

However, flock is usually adequate to avoid multiple file access. Use
it in a similar way as a DB transaction block.

open file
exclusive lock (you can either block here or spinn and retry)
read file
write file
release lock
close file

HTH



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