The prologue to this post, and other posts in the series, is here.

Investigating commit b65d292f was fruitful but not for obvious reasons.

Dumping the symbols (nm -j server) before and after the commit showed large number of new equality (==) methods. From the diff:

1765a1772
> _*ActivityPub::Activity::Accept#==<Translation>:Bool
1920a1928
> _*ActivityPub::Activity::Add#==<Translation>:Bool
2062a2071
> _*ActivityPub::Activity::Announce#==<Translation>:Bool
2237a2247
> _*ActivityPub::Activity::Block#==<Translation>:Bool
    ...

The use, in a controller action, of the new Translation model seemingly triggered their generation. What was going on?

A long time ago I implemented a MVC model framework in the style of ActiveRecord (2de4a4b3) and it included a method for testing for equality. Note the method signature.

# Returns true if all properties are equal.
#
def ==(other : self)
  {% begin %}
    {% vs = @type.instance_vars.select(&.annotation(Persistent)) %}
    if
      {% for v in vs %}
        self.{{v}} == other.{{v}} &&
      {% end %}
      self.id == other.id
      true
    else
      false
    end
  {% end %}
end

The Reference class—the default parent for classes—defines two base implementations of this method:  one that tests for identity (not equality), with the signature def ==(other : self), and another that returns false, with the signature def ==(other). When I implemented my method, my assumption was: redefine the former for model classes and let the latter take care of everything else. This assumption was incorrect.

In circumstances that I still don't completely understand, the compiler will generate calls to the latter (the method that just returned false) when it "should have" been calling the former, and comparisons failed when they should have succeeded. I "fixed this" with commit effeaa26 that removed the type restriction and explicitly handled the type check. Everything worked!

The problem is Crystal creates a version of this method for every possible model comparison, specialized by both self and other. Most of the time the type check fails and the method returns false. But the rest of the code is still present.

The fix (re)adds a method specialization that returns false and lets the compiler handle the type check.

# Returns `false`.
#
def ==(other)
  false
end

Because this method just returns a constant value, the compiler gets rid of the method call, as well.

Interestingly, this change reduced the size of the Ktistec server executable by 4.0% when building without the --release flag but only 0.2% when building with it, so optimization does a good job at cleaning this up even without the change. 

#ktistec #crystallang

my content filters are getting a workout today...!

what's the union of all errors that a call like HTTP::Client.get(...) (in Crystal) might raise?

i typically rescue IO::Error (which gets hostname lookup and socket connection problems), OpenSSL::Error (which gets a few edge-case problems with SSL configuration on the other end), Compress::Deflate::Error and Compress::Gzip::Error (which gets a few even more edge-case configuration problems on the other end), and URI::Error.

what am i missing?

#crystallang

Ktistec release v2.4.4 fixes a few things in the prior release and introduces at least one killer feature!

Fixed

• Always get the attachments. (fixes #119)
• Don't run scripts until the server has been configured.

Changed

• ⭐️ Make the editor toolbar sticky.
• Clear the cached translator when the settings change.

I'm spending some cycles looking at the size of the server executable. You can read about my approach to reducing Crystal Language executable size and build time here.

#ktistec #fediverse #activitypub #crystallang

The prologue to this post is here.

Investigating commit e2327eea might be a bust.

I dumped the symbols before and after this change. The new symbols were all specializations of the core library Hash class introduced by adding JSON parsing support for the "language" property.

So what does that mean and why is this commit a dead end?

You can think of Crystal classes and methods as being implicitly generics. If you have a method foo with one parameter bar and call it with an Array, Crystal creates a version of that method specialized to handle an Array type as an argument. If you call it with a Hash, Crystal creates another version of that method specialized to handle a Hash type as an argument. If the method has 20 lines of code, you effectively get two copies of those 20 lines of code. There is no runtime polymorphic dispatch, which is one of the reasons Crystal is so fast. You can make all of this explicit with Crystal type restrictions, method overloading, and generics, of course, but you don't have to.

This path is a dead end (for now) because any improvements that I can see that I can make (replacing hash construction with a more fluent sequence of attribute assignments) will need to be made to other classes where this is a problem, and there are only a few of those, so the net potential for improvement seems small.

#ktistec #crystallang

After I release a new version of ktistec, I build the server commit-by-commit to see which commits increase the server executable size and build time the most. I do this because I’ve learned that small implementation details (inlined code, small methods, using blocks) can have large impacts on these numbers.

Here's the output:

Commit         Size          Time
======== ========== ======= ===== =======
248850b1   36426264          10.3
47268073   36425688  -0.00%  10.5  +1.60%
344de272   36425688  +0.00%  10.8  +3.24%
ef561f52   36425944  +0.00%  10.8  -0.08%
8ae2cbd4   36429128  +0.01%  10.8  -0.01%
3e425f3b   36429128  +0.00%  10.8  +0.22%
1487d903   36427704  -0.00%  11.0  +1.42%
935c9ceb   36427016  -0.00%  11.0  +0.14%
de37dc6a   36427016  +0.00%  10.9  -0.97%
a660a326   36427016  +0.00%  10.8  -1.12%
ff3d990e   36427016  +0.00%  10.8  +0.54%
5724a58d   36523192  +0.26%  11.0  +1.78%
7b5057d4   36523640  +0.00%  11.0  -0.44%
30ca6a3f   36541352  +0.05%  11.6  +5.73%
e2327eea   36671592  +0.36%  11.0  -5.36%
ad0d76eb   36671592  +0.00%  10.9  -0.48%
d388e74f   36671592  +0.00%  11.4  +4.59%
dacea7ad   36671592  +0.00%  11.0  -3.76%
03d5dfd8   36671592  +0.00%  10.8  -1.63%
79d9d89f   36671576  -0.00%  11.0  +1.82%
b65d292f   36792376  +0.33%  11.1  +0.95%
0ef53365   36808904  +0.04%  11.6  +4.88%
b3766e7b   36808904  +0.00%  11.1  -4.50%
56ba79ce   36825416  +0.04%  11.1  -0.50%
4824df58   36825736  +0.00%  11.1  +0.31%
c4705143   36837544  +0.03%  11.1  -0.03%
e3d37ef7   36837768  +0.00%  11.5  +3.52%
4509fa0d   36837768  +0.00%  11.0  -3.83%
0ff9237b   36837768  +0.00%  11.0  -0.55%

Overall, the server executable size increased by about 1.1% and the build time increased by about 6.8%. Maybe that's not too bad for a major feature, but let's dig in.

It's nice to see that three commits account for almost all of the increase in server executable size:

• 5724a58d Add `language` to `Object`.
  2 files +19  loc
• e2327eea Render `contentMap` on ActivityPub objects.
  2 files +17 -1 loc
• b65d292f Add translation actions to the objects controller.
  1 file +35 loc

But, compare 5724a58d to 8ae2cbd4 (Add `language` to `Account`). It added +22 loc but didn't increase the server executable size as much.

In any case, I'll look at e2327eea first. I'd like to understand why this relatively small change adds 130,240 bytes to the server executable size!

The follow ups are here, here, here, and here.

#ktistec #crystallang

Ktistec release v2.4.3 supports language translation.

Inspiration for this feature comes from Mastodon.

In order to enable translation, you need an API key for either DeepL or LibreTranslate. These are the only services Ktistec supports at this time.

Posts from properly configured accounts on supported servers, like Mastodon, include the content language. On posts like these, Ktistec will display a button to translate the content if the language differs from your language.

Unfortunately, not all Fediverse/ActivityPub servers explicitly support language (I mean, Ktistec didn't until just now). And not all users correctly set their posts' language, so ymmv... but it has been hugely useful for me.

I'm going to focus on site customization next (colors, etc.).

#ktistec #fediverse #activitypub #crystallang