[Pm-utils] [patch commit] [000] POSIXification of pm-utils

[Victor Lowther]

On Jan 27, 2008 7:47 PM, Dan Nicholson <dbn.lists at gmail.com> wrote:
> On Jan 27, 2008 12:25 PM, Victor Lowther <victor.lowther at gmail.com> wrote:
> > Adds a generic locking mechanism built around directory creation/removal.
>
> The timeout support in spin_lock doesn't seem like it would work.
>
> +# spin waiting for the lock with optional timeout.
> +# return once we have it, or the timeout has expired
> +spin_lock()
> +{
> +       # $1 = directory to use as the lock directory
> +       # $2 = optional timeout
> +       local elapsed=0
> +       while ! try_lock $1; do
> +               sleep 1;
> +               [ "x$2" != "x" ] && [ $(( $elapsed == $2 )) -ne 0 ] && return 1
> +       done
> +}
>
> $elapsed never seems to be incremented. I also don't believe that you
> want to sleep before checking the timeout. This results in a `sleep 1'
> even if you haven't specified a timeout; i.e., you want to return
> immediately. Personally, I would write it like this (trying not to let
> too much personal style seep in):

You are correct -- I did not test that path, as nothing uses the
timeout functionaloty right now.

> spin_lock()
> {
>   local elapsed=0
>   local timeout=${2:-0}
>
>   while ! try_lock $1; do
>     [ $timeout -le $elapsed ] && return 1
>     elapsed=$(( $elapsed + 1 ))
>     sleep 1
>   done
> }
>
> What do you think?

Patch against my patch series attached.

> --
> Dan
>
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