change timezone cache data structure from list to set

src/PostgREST/ApiRequest/Preferences.hs

@@ -16,13 +16,15 @@ module PostgREST.ApiRequest.Preferences
   , PreferRepresentation(..)
   , PreferResolution(..)
   , PreferTransaction(..)
+  , PreferTimezone(..)
   , fromHeaders
   , shouldCount
   , prefAppliedHeader
   ) where
 
 import qualified Data.ByteString.Char8     as BS
 import qualified Data.Map                  as Map
+import qualified Data.Set                  as S
 import qualified Network.HTTP.Types.Header as HTTP
 
 import PostgREST.Config.Database (TimezoneNames)
@@ -39,6 +41,7 @@ import Protolude
 -- >>> deriving instance Show PreferTransaction
 -- >>> deriving instance Show PreferMissing
 -- >>> deriving instance Show PreferHandling
+-- >>> deriving instance Show PreferTimezone
 -- >>> deriving instance Show Preferences
 
 -- | Preferences recognized by the application.
@@ -51,14 +54,14 @@ data Preferences
     , preferTransaction    :: Maybe PreferTransaction
     , preferMissing        :: Maybe PreferMissing
     , preferHandling       :: Maybe PreferHandling
-    , preferTimezone       :: Maybe ByteString
+    , preferTimezone       :: Maybe PreferTimezone
     , invalidPrefs         :: [ByteString]
     }
 
 -- |
 -- Parse HTTP headers based on RFC7240[1] to identify preferences.
 --
--- >>> let sc = ["America/Los_Angeles"]
+-- >>> let sc = S.fromList ["America/Los_Angeles"]
 --
 -- One header with comma-separated values can be used to set multiple preferences:
 -- >>> pPrint $ fromHeaders True sc [("Prefer", "resolution=ignore-duplicates, count=exact, timezone=America/Los_Angeles")]
@@ -70,7 +73,8 @@ data Preferences
 --     , preferTransaction = Nothing
 --     , preferMissing = Nothing
 --     , preferHandling = Nothing
---     , preferTimezone = Just "America/Los_Angeles"
+--     , preferTimezone = Just
+--         ( PreferTimezone "America/Los_Angeles" )
 --     , invalidPrefs = []
 --     }
 --
@@ -121,7 +125,7 @@ data Preferences
 --     }
 --
 fromHeaders :: Bool -> TimezoneNames -> [HTTP.Header] -> Preferences
-fromHeaders allowTxDbOverride tzNames headers =
+fromHeaders allowTxDbOverride acceptedTzNames headers =
   Preferences
     { preferResolution     = parsePrefs [MergeDuplicates, IgnoreDuplicates]
     , preferRepresentation = parsePrefs [Full, None, HeadersOnly]
@@ -131,24 +135,25 @@ fromHeaders allowTxDbOverride tzNames headers =
     , preferMissing        = parsePrefs [ApplyDefaults, ApplyNulls]
     , preferHandling       = parsePrefs [Strict, Lenient]
     , preferTimezone       = getTimezoneFromPrefs
-    , invalidPrefs         = filter (`notElem` acceptedPrefs) prefs
+    , invalidPrefs         = filter checkPrefs prefs
     }
   where
     mapToHeadVal :: ToHeaderValue a => [a] -> [ByteString]
     mapToHeadVal = map toHeaderValue
-    timezonePrefs = map ((<>) "timezone=" . encodeUtf8) tzNames
     acceptedPrefs = mapToHeadVal [MergeDuplicates, IgnoreDuplicates] ++
                     mapToHeadVal [Full, None, HeadersOnly] ++
                     mapToHeadVal [SingleObject] ++
                     mapToHeadVal [ExactCount, PlannedCount, EstimatedCount] ++
                     mapToHeadVal [Commit, Rollback] ++
                     mapToHeadVal [ApplyDefaults, ApplyNulls] ++
-                    mapToHeadVal [Strict, Lenient] ++ timezonePrefs
+                    mapToHeadVal [Strict, Lenient]
 
     prefHeaders = filter ((==) HTTP.hPrefer . fst) headers
     prefs = fmap BS.strip . concatMap (BS.split ',' . snd) $ prefHeaders
+
     hasTimezone p = BS.take 9 p == "timezone="
-    getTimezoneFromPrefs = listToMaybe [ BS.drop 9 p | p <- prefs, hasTimezone p && elem p timezonePrefs]
+    getTimezoneFromPrefs = listToMaybe [ PreferTimezone (BS.drop 9 p) | p <- prefs, hasTimezone p && S.member (BS.drop 9 p) acceptedTzNames]
+    checkPrefs p = p `notElem` acceptedPrefs && BS.drop 9 p `S.notMember` acceptedTzNames
 
     parsePrefs :: ToHeaderValue a => [a] -> Maybe a
     parsePrefs vals =
@@ -172,7 +177,7 @@ prefAppliedHeader Preferences {preferResolution, preferRepresentation, preferPar
       , toHeaderValue <$> preferCount
       , toHeaderValue <$> preferTransaction
       , toHeaderValue <$> preferHandling
-      , ("timezone=" <>) <$> preferTimezone
+      , toHeaderValue <$> preferTimezone
       ]
 
 -- |
@@ -265,3 +270,10 @@ data PreferHandling
 instance ToHeaderValue PreferHandling where
   toHeaderValue Strict  = "handling=strict"
   toHeaderValue Lenient = "handling=lenient"
+
+-- |
+-- Change timezone
+newtype PreferTimezone = PreferTimezone ByteString
+
+instance ToHeaderValue PreferTimezone where
+  toHeaderValue (PreferTimezone tz) = "timezone=" <> tz

src/PostgREST/Config/Database.hs

@@ -30,7 +30,7 @@ import Protolude
 
 type RoleSettings     = (HM.HashMap ByteString (HM.HashMap ByteString ByteString))
 type RoleIsolationLvl = HM.HashMap ByteString SQL.IsolationLevel
-type TimezoneNames    = [Text] -- cache timezone names for prefer timezone=
+type TimezoneNames    = Set ByteString -- cache timezone names for prefer timezone=
 
 toIsolationLevel :: (Eq a, IsString a) => a -> SQL.IsolationLevel
 toIsolationLevel a = case a of

src/PostgREST/Query.hs

@@ -33,6 +33,7 @@ import qualified PostgREST.SchemaCache        as SchemaCache
 
 import PostgREST.ApiRequest              (ApiRequest (..))
 import PostgREST.ApiRequest.Preferences  (PreferCount (..),
+                                          PreferTimezone (..),
                                           PreferTransaction (..),
                                           Preferences (..),
                                           shouldCount)
@@ -248,7 +249,7 @@ setPgLocals AppConfig{..} claims role roleSettings ApiRequest{..} = lift $
     roleSql = [setConfigWithConstantName ("role", role)]
     roleSettingsSql = setConfigWithDynamicName <$> roleSettings
     appSettingsSql = setConfigWithDynamicName <$> (join bimap toUtf8 <$> configAppSettings)
-    timezoneSql = maybe mempty (\tz -> [setConfigWithConstantName ("timezone", tz)]) $ preferTimezone iPreferences
+    timezoneSql = maybe mempty (\(PreferTimezone tz) -> [setConfigWithConstantName ("timezone", tz)]) $ preferTimezone iPreferences
     searchPathSql =
       let schemas = escapeIdentList (iSchema : configDbExtraSearchPath) in
       setConfigWithConstantName ("search_path", schemas)

src/PostgREST/SchemaCache.hs

@@ -1190,7 +1190,7 @@ timezones = SQL.Statement sql HE.noParams decodeTimezones
   where
     sql = "SELECT name FROM pg_timezone_names"
     decodeTimezones :: HD.Result TimezoneNames
-    decodeTimezones = HD.rowList $ column HD.text
+    decodeTimezones = S.fromList . map encodeUtf8 <$> HD.rowList (column HD.text)
 
 param :: HE.Value a -> HE.Params a
 param = HE.param . HE.nonNullable