Convenience vs. Speed: please!

[yuv]

TLDR: don't force my system to waste my time on discovery every time.

Thank you for this great idea and for generally contributing to an easier configuration of scanning, and apology if the technical details in this report are a bit sparse. This is first and foremost about user experience, and the principle:

1. Devices/network/configuration changes have a frequency of years: they happen rarely.
2. Scanning operations have a frequency of hours, sometimes even minutes: they happen multiple time each days. they happen more frequently than configuration changes.
3. Slowing the scanning operation by scanimage to do "automatic and manual device discovery and configuration" every time the user triggers a scan is a wasteful and bad default.

I don't know when the Ubuntu 22.04LTS system I am using as my daily driver upgraded, but at some point last week scanimage became painfully slow to start. Running it with SANE_DEBUG_DLL=5 scanimage -L revealed the culprit.

sudo apt purge sane-airscan fixed it, and restored my regular productive speed.

Can you please add a pairing mode to the "automatic and manual device discovery and configuration" feature?

default in /etc/sane.d/airscan.conf would be

[options]
discovery = pair

when discovery is set to pair, do the automatic and manual device discovery and configuration and

1. automatically add the newly discovered devices to [devices]
2. for devices already configured that are also newly discovered, prompt for user choices (keep config or replace it with autodiscovered config)
3. for devices already configured but not discovered during the pairing round, prompt for user choices (keep config or delete config)
4. then set discovery = disable

I can see how discovery = enable could be useful to some road warriors who fire up their laptops in different offices with different scanners every day, but the majority of users do not change their scanners/locations that frequently and when they do, they commute between a few fixed locations. If no UI asking to keep/replace config is possible, just do step 1 and 4 above and document in the manpage to set discovery = pair when a new scanner is added to the network or the existing scanners are unrecognized.

[alexpevzner]

Hi @yuv,

please notice that SANE backend neither have its own user interface to prompt user nor its own persistent storage.

You may disable automatic discovery and add all devices manually, with some help from airscan-discover utility,

But implementing whatever you propose is very hard.

Please notice also, I'm doing my best to make discovery as fast as possible, and depending on your hardvare it may be as fast as 1 second or so.

[ammgws]

Related so I will post this as reference for any others trying to speedup scanning.

I changed my config in /etc/sane/airscan.conf to

[devices]
"Brother MFC-L3780CDW series" = http://10.1.1.15:80/WebServices/ScannerService, WSD

[options]
discovery = disable

(I have a static IP set for the scanner so not an issue to hardcode it)

and now scanimage -L takes 3.4 seconds instead of 8.4 seconds.

Then I copied /etc/sane.d/dll.d/airscan to ~/.config/sane/dll.conf, and also copied /etc/sane/airscan.conf from above to ~/.config/sane. Running SANE_CONFIG_DIR=~/.config/sane/ scanimage -L, now it takes only 10ms. Scanning starts straight away.

[yuv]

thanks for the replies. And for the time measurement, @ammgws .

Steve Jobs is rumored to have dressed down a developer for not putting an extra hour to save a second in the login process. Because the code is written once, but run millions of times, and all the cumulated user-seconds make the one extra developer hour look... tiny small.

@alexpevzner : the UI is the configuration file. I (the user) interface/interact with your code via that file. Can't you open it in read/write mode instead of read mode? and write the result of the automatic detection into it? while over-writing discovery = disable may be a bit too far, just writing a commented line in the [devices] would tell the user they can trade-off the (in most cases unnecessary) flexibility for faster performance.

why changed it to a discussion? not going to do anything about this? I might as well keep installing manufacturer's drivers until this driver matures and becomes a competitive proposition.

In general, the goal for software should be to achieve automagically the 10ms that @ammgws achieved manually. Not to be over-dynamic. Obviously not all is in the purview of airscan. Optimization is a system-wide effort. In my line of work, paying a sysadmin to assign static IPs to office devices at the DHCP server and configure the desktops/laptops to start scanning within 10ms instead of 3 or 8 seconds is value for money.