Use Harper readonly mode for Next.js builds

[cb1kenobi]

Next.js uses child processes to generate static pages. When those pages reference Harper data, it will try to load those databases and error with:

Error: IO error: While lock file: /Users/chris/harper/database/data/LOCK: Resource temporarily unavailable opening database /Users/chris/harper/database/data
    at openRocksDatabase (../harper/resources/databases.ts:162:22)
    at readRocksMetaDb (../harper/resources/databases.ts:407:16)
    at getDatabases (../harper/resources/databases.ts:247:6)
    at database (../harper/resources/databases.ts:734:2)
    at table (../harper/resources/databases.ts:899:20)
    at Object.<anonymous> (../harper/security/auth.ts:27:27)

Harper has a new READONLY environment variable that will allow a RocksDB database to be opened by another process in read-only mode allowing the static pages to be generated.

[kriszyp]

I believe we need to (somehow) flush all the databases so the new process can "see" all the data.

[cb1kenobi]

I believe we need to (somehow) flush all the databases so the new process can "see" all the data.

plugin.ts imports 'harper' and runs on the thread that has write access to the database, so does Harper have any public API that will flush all databases?

[kriszyp]

plugin.ts imports 'harper' and runs on the thread that has write access to the database, so does Harper have any public API that will flush all databases?

No, I think we will need to add one.

[Ethan-Arrowood]

I'm surprised this wasn't prefixed with like ROCKSDB_ or HARPER_, but thats an upstream thing so no concern here.

[cb1kenobi]

Good idea! Sit tight.

[Ethan-Arrowood]

looks like this needs to wait until Harper is updated (or flushDatabases is added to the types export?)

[cb1kenobi]

Yeah, this PR needs to wait a little bit.