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To: Dietmar Maurer <dietmar@proxmox.com>,
Proxmox Backup Server development discussion <pbs-devel@lists.proxmox.com>
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Subject: Re: [pbs-devel] [PATCH proxmox-backup] api2/tape/backup: wait
indefinitely for lock in scheduled backup jobs
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On 3/18/21 06:53, Dietmar Maurer wrote:
>> - // early check/lock before starting worker
>> - let drive_lock = lock_tape_device(&drive_config, &setup.drive)?;
>> + // for scheduled jobs we acquire the lock later in the worker
>> + let drive_lock = if schedule.is_some() {
>> + None
>> + } else {
>> + Some(lock_tape_device(&drive_config, &setup.drive)?)
>> + };
>
> What is the reason for the different locking times? Can't we always lock
> later in the worker?
>
yes we can, but for the non-scheduled backup, we only have one try
to lock and i did not want to start a task since that would generate
a task entry that was preventable by checking beforehand
On 3/18/21 07:04, Dietmar Maurer wrote:
>
>> + let (job_result, summary) = match try_block!({
>> + if schedule.is_some() {
>> + // for scheduled tape backup jobs, we wait
indefinitely for the lock
>> + task_log!(worker, "waiting for drive lock...");
>> + loop {
>> + if let Ok(lock) =
lock_tape_device(&drive_config, &setup.drive) {
>> + drive_lock = Some(lock);
>> + break;
>> + } // ignore errors
>
> I would prefer to add a timeout parameter to lock_tape_device() call.
> The question is if the lock call gets interrupted by task abort?
i did it this way, because an abort would not trigger if we are just
waiting on a lock, so i decided to try the lock in a loop with
the check_abort()? call below (so one can abort this)
we could ofc add a timeout parameter, but would not change
the code here (and currently has no real upside, since
we probably would not use different timeouts anyway?)
>
>> +
>> + worker.check_abort()?;
>> + }
>> + }
>> + set_tape_device_state(&setup.drive,
&worker.upid().to_string())?;