add a sqlite history backend

[slingamn]

cc @felix @NyaaaWhatsUpDoc

1. This uses modernc.org/sqlite via the standard database/sql API
2. Performance is OK after I enabled WAL and synchronous(NORMAL)
3. The recommended setting here is still db.SetMaxOpenConns(1). I wasn't really confident in an alternative strategy? I've found sources saying that it can make sense to run multiple concurrent readers and a single writer, but the workload here is write-heavy so it could lead to starvation?
4. sqlite is compiled out by default, but I may reconsider (more discussion on figure out and document all build tag decisions #2348)

[NyaaaWhatsUpDoc]

it is possible to set maxOpenConns to higher than that :) just a few things to keep in mind, all of which we've documented fairly extensively in our gotosocial sqlite driver initialization here: https://codeberg.org/superseriousbusiness/gotosocial/src/commit/a2cbe8cf28d3271c52c6032cb9ea1841ea606ada/internal/db/bundb/driver_sqlite.go#L44

[slingamn]

@NyaaaWhatsUpDoc since I'm still using modernc.org/sqlite, what was the concurrency issue you experienced with it?

[slingamn]

Merging this because I have other stuff pipelined on top, but comments are still welcome

[NyaaaWhatsUpDoc]

@slingamn the issue is that the concurrent interrupt goroutine they use in their Query() and Exec() database/sql implementations can put their sqlite connection type into a bad state in which connections return "INTERRUPTED" forever and never recover. i've never been able to make a test case that reveals it in their repo, though i have tried. you can show it in gotosocial still though if you load our repo, remove the "replace modernc.org/sqlite" line in our go.mod to stop using my workaround, then run go run -tags='debug nowasm' ./cmd/gotosocial testrig start to start a test server, open up a web browser and spam refresh on "http://localhost:8080/@admin", you'll quickly see it come about in the logs.

you can find my 1 commit workaround for it here: https://gitlab.com/NyaaaWhatsUpDoc/sqlite/-/compare/master...workaround%2Fremove-concurrent-interrupt-calls?from_project_id=9241019

and as you can see from the tags here i've been maintaining additional ${version}-concurrency-workaround tags since 2024: https://gitlab.com/NyaaaWhatsUpDoc/sqlite/-/tags

you might want to keep an eye on https://github.com/ncruces/go-sqlite3, at the moment it relies on a WebAssembly runtime, but it's currently undergoing an underlying rewrite that uses transpiled WebAssembly to Go code as seen here which i've been helping a little with. in my opinion, the ncruces/go-sqlite3 code is a lot easier to reason with if you ever have issues to upstream fixes for, and doesn't use garbage-collector-opaque "uintptrs" all over the place like the transpiled modernc.org/sqlite does.

for the moment if you want i can submit a PR that switches you to my own fork without that issue? or i can just submit a PR when the WebAssembly-free release of https://github.com/ncruces/go-sqlite3 is ready :). or you can just stick with modernc.org/sqlite as it is too, obviously, these are all just my suggestions!

[slingamn]

Thanks! I am planning to release Ergo v2.18 with modernc.org/sqlite and a recommended max of 1 connection. I would definitely consider ncruces/go-sqlite-3 for v2.19, since it appears to be API-compatible with database/sql and also compatible at a file format level with all other sqlite implementations.