I've been on the Fediverse since January 2017. I initially ran a single-user instance of Mastodon. In March 2020 I started to write Ktistec, my own implementation of an ActivityPub server in Crystal (a language with the ergonomics of Ruby but the speed of Go) because I wanted something more supportive of writing. This #introduction was written and published on Epiktistes, my Ktistec instance.

I'm an Engineer by training but now I run teams for companies in climate-tech.

I love #music, #sciencefiction and #fantasy literature (yes, I'm an R. A. Lafferty fan), attend fan conventions like #worldcon and #dragoncon, and do regular #weightlifting. I am also learning to play the #bagpipes, and I'm (re)learning #japanese.

The Ktistec executable is now ~24.7% smaller and build times are 28% faster.

I've been blogging about optimizations here, here, and here. This is the summary of the final outcome, with links to commits for the curious. I have one more post planned with a summary of my thoughts.

Here's my approach. Use nm to dump the symbols in a release build executable and then look for things that seem redundant. The first change and associated post below is a great example of what I mean—my original implementation led to the specialization of the #== method for every pairwise combination of model classes even though the result of the comparison was just false.

This might seem like a strange approach if you come from a compiled language where you mostly write all of the code yourself or invoke generics explicitly, but Crystal takes your code and does that for you. And it's not always obvious up front (to me, at least) what the final cost will be.

I've include counts of the lines added/removed because the point of this whole post is to say if you measure first and then optimize, a small change can have a big impact.

Here are the changes:

• Specialize model #==. (+7 -5)
  I talked about this here but didn't have the commit to link to. This change results in a large reduction in executable size on regular builds (~4.0%) and a small difference on release builds (~0.2%).
• Remove conversion to Hash. (+2 -2)
  This commit eliminates specialization of methods like __for_internal_use_only that get passed both named tuples and hashes by going all in with named tuples. It also eliminates instantiations of the Hash generic type itself for these cases. Reduces executable size by ~2.2%.
• Eliminate duplicate code in the executable. (+3 -3)
  This small change reduces the size of the executable by a further ~0.4% by eliminating redundant definitions of __for_internal_use_only entirely.
• Make InstanceMethods instance methods. (+1 -5)
  This was a goofy design I picked up somewhere. It's unnecessary. Changing this saves ~0.2% on release build executable size.
• Move the code for digging through JSON-LD. (+246 -281)
  It looks like a lot of lines of code changed here, but the large numbers are the result of moving code line-by-line from an included module to a utility class. Invoking these as methods on the utility class rather than as instance methods on each including class reduces the executable size by ~0.5%.
• Use map from base ActivityPub model classes. (+10 -2)
  map is a class method defined on each ActivityPub base model class. Each definition maps JSON-LD to a hash that is used to instantiate the class. Class methods defined on a base class are available on subclasses, as well. Calling the method on the subclass results in a copy of the method. This change reduces the executable size by ~5.8%.
• Move map into helper. (+104 -88)
  The map method does not depend on class/instance state. This change ensures that the mapping code is not duplicated even if a subclass's map method is accidentally again called. It looks like a lot of changes but this commit is mostly reorganization. It reduces executable size by ~0.4%.
• Replace classes with aliases. (+62 -148)
  Implementing ActivityPub's vocabulary with discrete model classes is expensive because every model class comes with machinery for type-specific CRUD operations. Enumerate aliases on each base model class (e.g. a "Service" is an "Actor"). This change reduces executable size by ~16.9%.

I'm off to optimize some queries now...

#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

The big feature in release v3.2.2 of Ktistec is pinned posts with support for the Mastodon Featured Posts collection. Federation works both ways—pin a post on Ktistec and it will show up as a pinned post on Mastodon and vice versa. When you refresh an actor profile, Ktistec also fetches and updates the actor's pinned posts. This is another small step in the direction of supporting all features that Mastodon-compatible client applications expect to access via the API. It's also useful in its own right.

The other major feature, which I posted a short video demonstrating here, is X-Ray Mode. X-Ray Mode is a developer and power-user tool for inspecting ActivityPub JSON-LD representations of actors, objects, and other content. Pressing Ctrl+Shift+X on any page displays the data behind the page—like an x-ray. You can:

• Cached Version: View the local JSON-LD representation stored in the Ktistec database
• Remote Version: Fetch and view the original JSON-LD representation from the source server
• Navigation: Click on any ActivityPub IRI to navigate to that object
• History: Use Alt+Left and Alt+Right to navigate through your viewing history

This feature is useful for debugging federation issues, understanding ActivityPub structures, and verifying how content is stored and represented.

Here's the full changelog for the release:

Added

• Support for pinned posts and the Mastodon "featured posts" collection.
• X-Ray Mode for viewing and navigating JSON-LD resource (actor, object, etc.) representations.
• Back links on thread pages for easier navigation. (fixes #1)
• License page for LibreJS compliance. (fixes #127)
• Highlighting of recently fetched hashtagged posts.

Changed

• Improved presentation of audio and video media.
• Refactored theming/styling implementation.

The next release will focus on smaller features and bug fixes.

Enjoy!

#ktistec #crystallang #activitypub #fediverse

Joining my first D&D 2024 campaign tonight. Leaning toward playing a Sorcerer. I haven't paid even the slightest bit of attention to the evolution of the new rules, so I'm interested to see how it feels...

#dnd #dnd2024

would a "more from this actor" button be helpful on #ktistec? the use case is 1) navigate to an actor you're thinking of following, 2) click on "more from this actor" to fetch ~10 additional, recent posts. is there another feature that would be more useful?

I've streamlined theme development in Ktistec. The theming system uses a hierarchy of CSS custom properties and fallbacks. Theme authors can customize a theme at multiple levels:

Base Colors Only

Define only base colors like --text-primary, --bg-primary, --bg-input, --semantic-primary, etc. Derived colors will auto-generate using color-mix formulas. For example:

:root { --semantic-primary: #ffa500; }

From this one line, theme-appropriate colors like --bg-accent-code, --anchor-color, etc. auto-generate.

Base Colors Plus Derived Colors

Define base colors and derived colors. Derived colors use custom values when defined. Undefined derived colors auto-generate. For example:

:root {
    --text-primary: #333;
    --text-primary-2: #ff0000;  /* red for this specific shade */
}

Given this theme, derived shades like --text-primary-1, --text-primary-3, and --text-primary-4 auto-generate. --text-primary-2 is red.

The simplest possible interesting theme redefines the primary semantic color. The single line above (in Base Colors Only) would result in the following, with button color, link color, disabled, selected, and hover states all derived automatically:

These changes will be in the upcoming release. Existing themes will continue to work, as is.

#ktistec #crystallang #activitypub #fediverse

Experimenting with x-ray mode for ktistec.

#ktistec #activitypub

Release v3.2.1 of Ktistec adds support for bookmarking posts. This was so immediately useful I don't know why it took me so long to get around to it!

Pinned/featured posts are in the works for the next release.

The full changelog:

Added

• Support for bookmarking posts.

Fixed

• Invalidate user's sessions after changing password.
• Ignore supplied languages that don't conform to expected format.

Changed

• Upgrade Kemal.

In other thoughts... I'd like to make followed hashtags more consumable. I follow ~10 hashtags and: 1) it's hard to tell what's new, 2) it feels like they arrive in large batches that are difficult to digest, and 3) the reading experience is meh.

#ktistec #fediverse #activitypub #crystallang