Re: about split the udev

[Kay Sievers <kay.sievers@vrfy.org>]

On Thu, Jan 22, 2004 at 01:27:45AM +0100, Kay Sievers wrote:
> On Wed, Jan 21, 2004 at 02:38:25PM +0100, Kay Sievers wrote:
> > On Thu, Jan 15, 2004 at 01:45:10PM -0800, Greg KH wrote:
> > > On Thu, Jan 15, 2004 at 10:36:25PM +0800, Ling, Xiaofeng wrote:
> > > > Hi, Greg
> > > >    I wrote a simple implementation for the two pieces 
> > > > of send and receive hotplug event, 
> > > > use a message queue and a list for the out of order
> > > >  hotplug event. It also has a timeout timer of 3 seconds.
> > > >  They are now separate program. the file nseq is the test script.
> > > >  Could you have a look to see wether it is feasible? 
> > > > If so, I'll continue to merge with udev.
> > > 
> > > Yes, very nice start.  Please continue on.
> > > 
> > > One minor comment, please stick with the kernel coding style when you
> > > are writing new code for udev.
> > 
> > I took the code from Xiaofeng, cleaned the whitespace, renamed some bits,
> > tweaked the debugging, added the udev exec and created a patch for the current tree.
> > 
> > It seems functional now, by simply executing our current udev (dirty hack).
> > It reorders the incoming events and if one is missing it delays the
> > execution of the following ones up to a maximum of 10 seconds.
> > 
> > Test script is included, but you can't mix hotplug sequence numbers and
> > test script numbers, it will result in waiting for the missing numbers :)
> 
> Hey, nobody want's to play with me?
> So here I'm chatting with myself :)
> 
> This is the next version with signal handling for resetting the expected
> signal number. I changed the behaviour of the timeout to skip all
> missing events at once and to proceed with the next event in the queue.
> 
> So it's now possible to use the test script at any time, cause it resets
> the daemon, if real hotplug event coming in later all missing nimbers will
> be skipped after a timeout of 10 seconds and the queued events are applied.


Here for the lazy one :)
Log from the test script which demonstrates the event reordering.
Event 5 is arriving before event 4, so 4 is queued until 5 is coming in,
then both are executed.
Events 8 and 9 are completely missing, so we wait for 10 seconds then go
ahead and exec the remaining events in the queue.

thanks,
Kay


   Jan 22 01:16:42 pim udev[17562]: dump_queue: next expected sequence 0

#in 1
   Jan 22 01:16:42 pim udev[17562]: process_queue: current sequence 1, expected sequence 0
#out 1
   Jan 22 01:16:42 pim udev[17562]: dump_msg: sequence 1, 'add', '/block/sda', 'block'
   Jan 22 01:16:42 pim udev[17562]: dump_queue: next expected sequence 2


#in 2
   Jan 22 01:16:42 pim udev[17562]: process_queue: current sequence 2, expected sequence 2
#out 2
   Jan 22 01:16:42 pim udev[17562]: dump_msg: sequence 2, 'add', '/block/sda', 'block'
   Jan 22 01:16:42 pim udev[17562]: dump_queue: next expected sequence 3


#in 3
   Jan 22 01:16:42 pim udev[17562]: process_queue: current sequence 3, expected sequence 3
#out 3
   Jan 22 01:16:42 pim udev[17562]: dump_msg: sequence 3, 'add', '/block/sda', 'block'
   Jan 22 01:16:42 pim udev[17562]: dump_queue: next expected sequence 4


#in 5
   Jan 22 01:16:42 pim udev[17562]: process_queue: current sequence 5, expected sequence 4
   Jan 22 01:16:42 pim udev[17562]: dump_queue: next expected sequence 4
#queue 5
   Jan 22 01:16:42 pim udev[17562]: dump_queue: queued sequence 5


#in 4
   Jan 22 01:16:42 pim udev[17562]: process_queue: current sequence 4, expected sequence 4
#out 4
   Jan 22 01:16:42 pim udev[17562]: dump_msg: sequence 4, 'add', '/block/sda', 'block'
   Jan 22 01:16:42 pim udev[17562]: dump_queue: next expected sequence 5
   Jan 22 01:16:42 pim udev[17562]: dump_queue: queued sequence 5 out queued 5
#out 5 (delayed)
   Jan 22 01:16:42 pim udev[17562]: dump_msg: sequence 5, 'add', '/block/sda', 'block'


#in 6
   Jan 22 01:16:42 pim udev[17562]: process_queue: current sequence 6, expected sequence 6
#out 6
   Jan 22 01:16:42 pim udev[17562]: dump_msg: sequence 6, 'add', '/block/sda', 'block'
   Jan 22 01:16:42 pim udev[17562]: dump_queue: next expected sequence 7


#in 7
   Jan 22 01:16:42 pim udev[17562]: process_queue: current sequence 7, expected sequence 7
#out 7
   Jan 22 01:16:42 pim udev[17562]: dump_msg: sequence 7, 'add', '/block/sda', 'block'
   Jan 22 01:16:42 pim udev[17562]: dump_queue: next expected sequence 8


#in 10
   Jan 22 01:16:42 pim udev[17562]: process_queue: current sequence 10, expected sequence 8
   Jan 22 01:16:42 pim udev[17562]: dump_queue: next expected sequence 8 queue 10
   Jan 22 01:16:42 pim udev[17562]: dump_queue: queued sequence 10


#in 11
   Jan 22 01:16:42 pim udev[17562]: process_queue: current sequence 11, expected sequence 8
   Jan 22 01:16:42 pim udev[17562]: dump_queue: next expected sequence 8 queue 11
   Jan 22 01:16:42 pim udev[17562]: dump_queue: queued sequence 10
   Jan 22 01:16:42 pim udev[17562]: dump_queue: queued sequence 11


#in 12
   Jan 22 01:16:42 pim udev[17562]: process_queue: current sequence 12, expected sequence 8
   Jan 22 01:16:42 pim udev[17562]: dump_queue: next expected sequence 8 queue 12
   Jan 22 01:16:42 pim udev[17562]: dump_queue: queued sequence 10
   Jan 22 01:16:42 pim udev[17562]: dump_queue: queued sequence 11
   Jan 22 01:16:42 pim udev[17562]: dump_queue: queued sequence 12


#in 13
   Jan 22 01:16:42 pim udev[17562]: process_queue: current sequence 13, expected sequence 8
   Jan 22 01:16:42 pim udev[17562]: dump_queue: next expected sequence 8 queue 13
   Jan 22 01:16:42 pim udev[17562]: dump_queue: queued sequence 10
   Jan 22 01:16:42 pim udev[17562]: dump_queue: queued sequence 11
   Jan 22 01:16:42 pim udev[17562]: dump_queue: queued sequence 12
   Jan 22 01:16:42 pim udev[17562]: dump_queue: queued sequence 13

#10 seconds timeout, skip missing events 8 and 9, proceed with queue
   Jan 22 01:16:52 pim udev[17562]: sig_alarmhandler: caught signal 14
   Jan 22 01:16:52 pim udev[17562]: sig_alarmhandler: timeout, event lost
   Jan 22 01:16:52 pim udev[17562]: process_queue: timeout reached, skip events 8 - 9
   Jan 22 01:16:52 pim udev[17562]: dump_queue: next expected sequence 10
   Jan 22 01:16:52 pim udev[17562]: dump_queue: queued sequence 10
   Jan 22 01:16:52 pim udev[17562]: dump_queue: queued sequence 11
   Jan 22 01:16:52 pim udev[17562]: dump_queue: queued sequence 12
   Jan 22 01:16:52 pim udev[17562]: dump_queue: queued sequence 13

#out 10 (delayed)
   Jan 22 01:16:52 pim udev[17562]: dump_msg: sequence 10, 'add', '/block/sda', 'block'
#out 11 (delayed)
   Jan 22 01:16:52 pim udev[17562]: dump_msg: sequence 11, 'add', '/block/sda', 'block'
#out 12 (delayed)
   Jan 22 01:16:52 pim udev[17562]: dump_msg: sequence 12, 'add', '/block/sda', 'block'
#out 13 (delayed)
   Jan 22 01:16:52 pim udev[17562]: dump_msg: sequence 13, 'add', '/block/sda', 'block'



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