testing of download from divecomputer needed

[Jef Driesen]

On 2015-01-13 08:49, Dirk Hohndel wrote:
> On Tue, Jan 13, 2015 at 08:25:50AM +0200, Willem Ferguson wrote:
>> I tested Uwatec Galileo Sol on Ubuntu 10.04 LTS
>> 
>> 1) Upload whole dc dive log ok.
>> 
>> 2) Second download:  I selected certain dives only from the download 
>> panel
>> (actually de-selected some dives)
>> Only the selected dives were transfered to dive list. ok.
>> 
>> 3) Upon CANCEL while downloading, it ignored the cancelation and still
>> continued to download the complete dc dive log. Probably not ok.
> 
> That's odd - I wonder if this is an issue of the backend not being able 
> to
> cancel. At least in my testing the cancel was delivered and we did 
> cancel
> successfully with a partial download. But I've only tried this using 
> the
> simulator (in that case a Suunto VyperAir, in case that matters).
> 
> I have no experience with the Uwatec Galileo backend and don't know if
> there's anything different there wrt canceling a download.

This is normal. Not all libdivecomputer backends support cancellation. 
Whether libdivecomputer will act upon the cancellation request or not 
also depends on the underlying communication protocol.

In a nutshell, libdivecomputer usually checks for a cancellation request 
before sending a command to the device. Thus, if the dives are 
downloaded with multiple smaller packets, then the cancellation will be 
almost instant. If they are downloaded all at once, with just one large 
request, then the cancellation won't even be noticed. Aborting the 
download while a transfer is still in progress, might have unexpected 
side effects. Therefore libdivecomputer plays on the safe side and won't 
do that.

The Uwatec Galileo is one example where all data is download at once.

Jef