Documentation

Fields

• _scrLock :: MVar ()

  The idea behind explicit locking here is to

  1. Allow maximum throughput for serving requests (v1graphql) (as each request reads the current schemacache)
  2. We don't want to process more than one request at any point of time which would modify the schema cache as such queries are expensive.

  Another option is to consider removing this lock in place of `_scrCache :: MVar ...` if it's okay or in fact correct to block during schema update in e.g. _wseGCtxMap. Vamshi says: It is theoretically possible to have a situation (in between building new schemacache and before writing it to the IORef) where we serve a request with a stale schemacache but I guess it is an okay trade-off to pay for a higher throughput (I remember doing a bunch of benchmarks to test this hypothesis).

• _scrCache :: IORef (RebuildableSchemaCache, SchemaCacheVer)
   
• _scrMetadataVersionGauge :: Gauge

  The gauge metric that tracks the current metadata version.

  Invariant: This gauge must be updated via updateMetadataVersionGauge whenever the _scrCache IORef is updated.