MySQL: Initial connection and corresponding types

https://github.com/hasura/graphql-engine-mono/pull/1517

Co-authored-by: Sibi Prabakaran <737477+psibi@users.noreply.github.com>
Co-authored-by: Chris Done <11019+chrisdone@users.noreply.github.com>
Co-authored-by: Abby Sassel <3883855+sassela@users.noreply.github.com>
GitOrigin-RevId: e0f61664b33d8ca50f223ec7fb76c66940eabc89

server/graphql-engine.cabal

@@ -393,6 +393,9 @@ library
                      , Hasura.Backends.Postgres.Types.Table
                      , Hasura.Backends.Postgres.Types.CitusExtraTableMetadata
 
+                     , Hasura.Backends.MySQL.Types
+                     , Hasura.Backends.MySQL.Connection
+
                      -- Exposed for benchmark:
                      , Hasura.Cache.Bounded
                      , Hasura.Logging

server/src-lib/Hasura/Backends/MySQL/Connection.hs

@@ -0,0 +1,26 @@
+module Hasura.Backends.MySQL.Connection where
+
+
+import           Data.Pool                   (createPool)
+import qualified Data.Text                   as T
+import           Database.MySQL.Base
+import           Hasura.Backends.MySQL.Types
+import           Hasura.Base.Error
+import           Hasura.Prelude
+import           Hasura.RQL.Types.Common
+
+
+resolveSourceConfig :: (MonadIO m) =>
+  SourceName -> ConnSourceConfig -> m (Either QErr SourceConfig)
+resolveSourceConfig _name csc@ConnSourceConfig{..} =
+  let connectInfo =
+        defaultConnectInfo
+          { connectHost = T.unpack _cscHost
+          , connectPort = _cscPort
+          , connectUser = T.unpack _cscUser
+          , connectPassword = T.unpack _cscPassword
+          , connectDatabase = T.unpack  _cscDatabase
+          }
+   in runExceptT $
+        SourceConfig csc <$>
+          liftIO (createPool (connect connectInfo) close 1 (60 {-seconds-} * 60 {-minutes-}) 1)

server/src-lib/Hasura/Backends/MySQL/Types.hs

@@ -0,0 +1,54 @@
+{-# LANGUAGE DeriveAnyClass #-}
+{-# OPTIONS_GHC -fno-warn-orphans #-}
+
+
+module Hasura.Backends.MySQL.Types where
+
+
+import qualified Data.Aeson                             as J
+import qualified Data.Aeson.Casing                      as J
+import qualified Data.Aeson.TH                          as J
+import           Data.Hashable
+import           Data.Pool
+import           Data.Word                              (Word16)
+import           Database.MySQL.Base
+import           Hasura.Incremental.Internal.Dependency (Cacheable (..))
+import           Hasura.Prelude
+import           System.IO.Unsafe                       (unsafePerformIO)
+
+
+-- | Partial of Database.MySQL.Simple.ConnectInfo
+data ConnSourceConfig
+  = ConnSourceConfig
+    { _cscHost     :: !Text -- ^ Works with @127.0.0.1@ but not with @localhost@ for some reason
+    , _cscPort     :: !Word16
+    , _cscUser     :: !Text
+    , _cscPassword :: !Text
+    , _cscDatabase :: !Text
+    } deriving (Eq, Show, NFData, Generic, Hashable)
+$(J.deriveJSON (J.aesonDrop 4 J.snakeCase) {J.omitNothingFields = False} ''ConnSourceConfig)
+instance Arbitrary ConnSourceConfig where
+  arbitrary = genericArbitrary
+instance Cacheable Word16 where
+  unchanged _ = (==)
+deriving instance Cacheable ConnSourceConfig
+
+
+data SourceConfig
+  = SourceConfig
+    { scConfig         :: !ConnSourceConfig
+    , scConnectionPool :: !(Pool Connection)
+    } deriving (Eq, Generic, J.ToJSON)
+instance Arbitrary SourceConfig where
+  arbitrary = genericArbitrary
+instance J.ToJSON (Pool Connection) where
+  toJSON = const (J.String "_REDACTED_")
+instance Eq (Pool Connection) where
+  _ == _ = True
+instance Arbitrary (Pool Connection) where
+  arbitrary = pure . unsafePerformIO $
+    createPool (connect defaultConnectInfo) close 1 (60 {-seconds-} * 60 {-minutes-}) 1
+instance Cacheable SourceConfig where
+  unchanged _ = (==)
+
+