refactor(remove): schema cache load delay config

Remove internal schema cache load and relationship load sleep settings plus
the delay wrappers they enabled. Drop IO tests that depended on the removed
settings.

src/PostgREST/Config.hs

@@ -127,8 +127,6 @@ data AppConfig = AppConfig
   , configRoleSettings             :: RoleSettings
   , configRoleIsoLvl               :: RoleIsolationLvl
   , configInternalSCQuerySleep     :: Maybe Int32
-  , configInternalSCLoadSleep      :: Maybe Int32
-  , configInternalSCRelLoadSleep   :: Maybe Int32
   }
 
 data LogLevel = LogCrit | LogError | LogWarn | LogInfo | LogDebug
@@ -328,8 +326,6 @@ parser optPath env dbSettings roleSettings roleIsolationLvl =
     <*> pure roleSettings
     <*> pure roleIsolationLvl
     <*> optInt "internal-schema-cache-query-sleep"
-    <*> optInt "internal-schema-cache-load-sleep"
-    <*> optInt "internal-schema-cache-relationship-load-sleep"
   where
     parseErrorVerbosity :: C.Key -> C.Parser C.Config Verbosity
     parseErrorVerbosity k =

src/PostgREST/SchemaCache.hs

@@ -72,10 +72,9 @@ import PostgREST.SchemaCache.Table           (Column (..), ColumnMap,
 
 import qualified PostgREST.MediaType as MediaType
 
-import           Control.Arrow    ((&&&))
-import qualified Data.FuzzySet    as Fuzzy
+import           Control.Arrow ((&&&))
+import qualified Data.FuzzySet as Fuzzy
 import           Protolude
-import           System.IO.Unsafe (unsafePerformIO)
 
 type TablesFuzzyIndex = HM.HashMap Schema Fuzzy.FuzzySet
 
@@ -180,11 +179,9 @@ querySchemaCache conf@AppConfig{..} = do
   let tabsWViewsPks = addViewPrimaryKeys tabs keyDeps
       rels          = addInverseRels $ addM2MRels tabsWViewsPks $ addViewM2OAndO2ORels keyDeps m2oRels
 
-  -- Add delay in loading schema cache when internal-schema-cache-load-sleep config is set
-  return $ delayEval configInternalSCLoadSleep $ removeInternal schemas $ SchemaCache {
+  return $ removeInternal schemas $ SchemaCache {
       dbTables = tabsWViewsPks
-    -- Add delay in loading relationships when internal-schema-cache-relationship-load-sleep config is set
-    , dbRelationships = delayEval configInternalSCRelLoadSleep $ getOverrideRelationshipsMap rels cRels
+    , dbRelationships = getOverrideRelationshipsMap rels cRels
     , dbRoutines = funcs
     , dbRepresentations = reps
     , dbMediaHandlers = HM.union mHdlers initialMediaHandlers -- the custom handlers will override the initial ones
@@ -198,7 +195,6 @@ querySchemaCache conf@AppConfig{..} = do
     }
   where
     schemas = toList configDbSchemas
-    delayEval confDelay result = maybe result (unsafePerformIO . (($> result) . (threadDelay . (1000 *) . fromIntegral))) confDelay
     isLogDebug = configLogLevel == LogDebug
     sqlTimedStmt = sqlTimedStatement isLogDebug