bug#22921: 25.1.50; Wishlist: There should be a new URL interface

bug#22921: 25.1.50; Wishlist: There should be a new URL interface

[Lars Magne Ingebrigtsen]

The current interfaces to the URL library aren't very handy.  It's
`url-retrieve' and `url-retrieve-synchronously'.  The main problem is
that they're inconsistent and difficult to interact with.

For instance, most of the "inputs" to the functions are dynamically
bound specially variables like `url-request-method', and that sucks.
The buffers that are returned are inconsistent based on the URL
method -- HTTP buffers come with the headers first, while ftp buffers do
not.

So: `with-url-buffer'.

Typical usage would be

(with-url-buffer ("https://fsf.org"
                  :verbose t
                  :request-method "POST"
                  :timeout 10)
  (do-stuff-with-the-result-here))

That is, the callback is in the form.  There are no headers in the
buffer, and point is at point-min when the body is called.  Headers are
accessed with a new form like `(url-header "date")', and the headers are
available in a buffer-local variable called `url-headers'.

Upon completion of the body form, the buffer is killed, unless a
parameter :inhibit-kill-buffer is given.

Synchronous and asynchronous operation looks identical, but synchronous
operation happens when you say :synchronous t.

Implementation-wise, this happens with lexical bindings switched on, and
the body form is turned into a closure that's evaluated upon completion.

`with-url-buffer' will not support the exotic, never-actually-used
protocols like news:, irc:, imap:, etc, but only http:, https:, ftp:
and file:.



In GNU Emacs 25.1.50.23 (x86_64-unknown-linux-gnu, GTK+ Version 3.4.2)
 of 2016-03-06 built on stories
Repository revision: 20cc4182598c6c724f4556faf6bc322c9e58ad1d
Windowing system distributor 'The X.Org Foundation', version 11.0.11204000
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-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#37577: 27.0.50; GNU Emacs / eww inconsistent in showing images

[Unknown]

[-- Attachment #1: Type: text/plain, Size: 470 bytes --]


GNU Emacs seems to be inconsistent when showing images fetched via
http(s). Here is an example:

M-x eww

Paste in a URL of a webpage with many pictures, eg
https://moving-pictures.ingebrigtsen.no/2019/10/01/songs-from-the-second-floor-2/

Expected result is all images (eventually) load. Instead I see gray
boxes where the images should appear. This even after waiting 10
minutes. In Firefox I can get all images in seconds.

Here is what my Emacs window looks like:


[-- Attachment #2: emacs.png --]
[-- Type: image/png, Size: 63157 bytes --]

[-- Attachment #3: Type: text/plain, Size: 3881 bytes --]


It seems that the fewer images there are, the more likely they are to
appear. But it is very inconsistent, in my experience.

I don't expect Emacs to be optimized to fetch a lot of images
efficiently in the way, say, a dedicated web browser might be, but not
showing all images eventually, is suboptimimal.


In GNU Emacs 27.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.11)
 of 2019-09-21 built on tullinup
Repository revision: fea4a73300aa1da0a80548081874ced0c8df00f3
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12000000
System Description: Debian GNU/Linux bullseye/sid

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
Contacting host: moving-pictures.ingebrigtsen.no:443
Quit
Configured using:
 'configure --without-pop'

Configured features:
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ACL LIBSELINUX GNUTLS LIBXML2 FREETYPE HARFBUZZ M17N_FLT LIBOTF XFT ZLIB
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Important settings:
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Major mode: eww

Minor modes in effect:
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-- 
 "And all you can talk about is money and fairytales          Adam Sjøgren
  of eternal economic growth. How dare you!"             asjo@koldfront.dk

bug#37577: 27.0.50; GNU Emacs / eww inconsistent in showing images

[Lars Ingebrigtsen]

Adam Sjøgren <asjo@koldfront.dk> writes:

> Paste in a URL of a webpage with many pictures, eg
> https://moving-pictures.ingebrigtsen.no/2019/10/01/songs-from-the-second-floor-2/
>
> Expected result is all images (eventually) load. Instead I see gray
> boxes where the images should appear. This even after waiting 10
> minutes. In Firefox I can get all images in seconds.

shr (via url-queue) uses a very primitive timeout mechanism for
image-loading, and it aborts a lot of downloads prematurely.  And as you
say, the more images it's downloading in parallel, the more likely it is
that it drops the image.

This will work a lot better once the with-fetched-url branch has been
merged into Emacs, but that won't happen until Emacs 28, which is
probably still weeks away.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#37577: 27.0.50; GNU Emacs / eww inconsistent in showing images

[Unknown]

Lars writes:

> This will work a lot better once the with-fetched-url branch has been
> merged into Emacs, but that won't happen until Emacs 28, which is
> probably still weeks away.

Nice! I just merged the branch locally, and I am trying it out (after
resolving merge conflict semi-randomly).

It seems to work a lot better - there are still a couple of images
missing on long pages, but it's far from the around half I had before.

Thanks!

bug#37577: 27.0.50; GNU Emacs / eww inconsistent in showing images

[Lars Ingebrigtsen]

Adam Sjøgren <asjo@koldfront.dk> writes:

> It seems to work a lot better - there are still a couple of images
> missing on long pages, but it's far from the around half I had before.

Great; thanks for testing.

I've now merged this bug with bug#22921, which is the bug report about
the new URL interface.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#22921: 25.1.50; Wishlist: There should be a new URL interface

[Stefan Kangas]

Lars Magne Ingebrigtsen <larsi@gnus.org> writes:

> So: `with-url-buffer'.

What's the current status of your with-fetched-url branch?  Is it
ready to merge into master?  It would be nice to get it in so that we
can start playing around with it.

Best regards,
Stefan Kangas

bug#22921: 25.1.50; Wishlist: There should be a new URL interface

[Lars Ingebrigtsen]

Stefan Kangas <stefan@marxist.se> writes:

> Lars Magne Ingebrigtsen <larsi@gnus.org> writes:
>
>> So: `with-url-buffer'.
>
> What's the current status of your with-fetched-url branch?  Is it
> ready to merge into master?  It would be nice to get it in so that we
> can start playing around with it.

It should be (more or less) ready to go.  I've been meaning to merge it
ever since Emacs 28 started, but I haven't found time yet.

If I remember, there may be some quirks with certain auth schemes that
needs fixing, but that can be done after the merge.  But I need to block
out, say, a week where I can respond to bug reports in a speedy manner,
and I haven't found that week yet...

But it'll happen sometime within a month or to.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#37577: 27.0.50; GNU Emacs / eww inconsistent in showing images

[Stefan Kangas]

Lars Ingebrigtsen <larsi@gnus.org> writes:

>> What's the current status of your with-fetched-url branch?  Is it
>> ready to merge into master?  It would be nice to get it in so that we
>> can start playing around with it.
>
> It should be (more or less) ready to go.  I've been meaning to merge it
> ever since Emacs 28 started, but I haven't found time yet.

Hmm, maybe we can have it in Emacs 29?  :-)

bug#22921: bug#37577: 27.0.50; GNU Emacs / eww inconsistent in showing images

[Lars Ingebrigtsen]

Stefan Kangas <stefan@marxist.se> writes:

> Lars Ingebrigtsen <larsi@gnus.org> writes:
>
>>> What's the current status of your with-fetched-url branch?  Is it
>>> ready to merge into master?  It would be nice to get it in so that we
>>> can start playing around with it.
>>
>> It should be (more or less) ready to go.  I've been meaning to merge it
>> ever since Emacs 28 started, but I haven't found time yet.
>
> Hmm, maybe we can have it in Emacs 29?  :-)

:-)

It got put on the back burner because I started thinking about the proxy
stuff that url.el supports but I hadn't implemented for with-url yet.

Because I think that's the wrong level to do it.  Emacs should support a
general network proxy thing, that would allow all network connections to
be proxied.  (Or selectively.)

And the more I looked at this, the more apparently it became that Emacs'
network stuff should just be totally reimplemented, because it's so full
of...  oddnesses geared toward processes.  And processes and network
connections are very different things.

So it's a Big Project.  :-/

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no