Roll back to JDK 21 for now, and make Java version configurable in the root build.gradle
The project has run into no less than three distinct show-stopping bugs in JDK22, across multiple vendors, and gradle still doesn't fully support it, meaning you need multiple JDK versions installed.
The changeset cleans up the query parsing logic in the query service. It gets rid of a lot of old and largely unmaintainable query-rewriting logic that was based on POS-tagging rules, and adds a new cleaner approach. Query parsing is also refactored, and the internal APIs are updated to remove unnecessary duplication of document-level data across each search term.
A new query segmentation model is introduced based on a dictionary of known n-grams, with tools for extracting this dictionary from Wikipedia data. The changeset introduces a new segmentation model file, which is downloaded with the usual run/setup.sh, as well as an updated term frequency model.
A new intermediate representation of the query is introduced, based on a DAG with predefined vertices initiating and terminating the graph. This is for the benefit of easily writing rules for generating alternative queries, e.g. using the new segmentation data.
The graph is converted to a basic LL(1) syntax loosely reminiscent of a regular expression, where e.g. "( wiby | marginalia | kagi ) ( search engine | searchengine )" expands to "wiby search engine", "wiby searchengine", "marginalia search engine", "marginalia searchengine", "kagi search engine" and "kagi searchengine".
This compiled query is passed to the index, which parses the expression, where it is used for execution of the search and ranking of the results.
Use SimpleBlockingThreadPool pool instead of Java's Workstealing Pool as the latter causes runaway memory consumption in some circumstances, while SimpleBlockingThreadPool uses a bounded queue and always pushes back against the supplier if it can't hold any more tasks.
Look, this will make the git history look funny, but trimming unnecessary depth from the source tree is a very necessary sanity-preserving measure when dealing with a super-modularized codebase like this one.
While it makes the project configuration a bit less conventional, it will save you several clicks every time you jump between modules. Which you'll do a lot, because it's *modul*ar. The src/main/java convention makes a lot of sense for a non-modular project though. This ain't that.
To avoid having to either hard-code or manually configure service addresses (possibly several dozen), and to reduce the project's dependency on docker to deal with routing and discovery, the option to use [Zookeeper](https://zookeeper.apache.org/) to manage services and discovery has been added.
A service registry interface was added, with a Zookeeper implementation and a basic implementation that only works on docker and hard-codes everything.
The last remaining REST service, the assistant-service, has been migrated to gRPC.
This also proved a good time to clear out primordial technical debt from the root of the codebase. The 'service-client' library has been taken behind the barn and given a last farewell. It's replaced by a small library for managing gRPC channels.
Since it's no longer used by anything, RxJava has been removed as a dependency from the project.
Although the current state seems reasonably stable, this is a work-in-progress commit.
The codebase used to have a monkey patched version of gson that made special optimizations for the unusually large JSON files that used to store e.g. crawl data.
Since JSON is no longer used in this fashion, the GSON fork is not needed anymore.
The production configuration assumes all content of interest is 7 bit ASCII, and makes a series of optimizations based on this. This assumption holds poorly in the wild.
Adding an **experimental** system property 'system.noFlattenUnicode', that when set to TRUE, will disable this behavior.
IMPORTANT!! The index needs to be re-constructed when this flag is changed, as different hash functions are selected for the keyword->identifier mappings.
Removed the need to have to run an external tool to pre-process the data in order to load stackexchange-style data into the search engine.
Removed the tool itself.
This stirred up some issues with the dependencies, that were due to both third-party:ing xz and importing it as a dependency. This has been fixed, and :third-party:xz was removed.
java.lang.Error:s were not handled properly, leading to mismatch in the bookkeeping of the FSMs. These are now caught, acted on, and re-thrown.
MqSynchronousInbox also no longer assumes all exceptions are InterruptedException.
Previously, in order to load encyclopedia data into the search engine, it was necessary to use the encyclopedia.marginalia.nu converter to first create a .db-file. This isn't very ergonomic, so parts of that code-base was lifted in as a 3rd party library, and conversion from .zim to .db is now done automatically.
The output file name is based on the original filename, plus a crc32 hash and a .db-ending, to ensure we can recycle the data on repeat loads.
This is not hooked into anything yet. The change also makes modifications to the parquet-floor library to support reading and writing of byte[] arrays. This is desirable since we may in the future want to support inputs that are not text-based, and codifying the assumption that each document is a string will definitely cause us grief down the line.
... also move some common configuration into the root build.gradle-file.
Support for JDK21 in lombok is a bit sketchy at the moment, but it seems to work. This upgrade is kind of important as the new index construction really benefits from Arena based lifecycle control over off-heap memory.
