From 7984fcd01c83995fa65422d7178b506131454243 Mon Sep 17 00:00:00 2001
From: fisx <mf@zerobuzz.net>
Date: Wed, 26 May 2021 17:14:32 +0200
Subject: [PATCH] Fix slow cassandra query. (#1530)

---
 services/galley/src/Galley/Data.hs         | 5 +++--
 services/galley/src/Galley/Data/Queries.hs | 3 ---
 2 files changed, 3 insertions(+), 5 deletions(-)

diff --git a/services/galley/src/Galley/Data.hs b/services/galley/src/Galley/Data.hs
index 126456b6bd5..5e446966696 100644
--- a/services/galley/src/Galley/Data.hs
+++ b/services/galley/src/Galley/Data.hs
@@ -148,6 +148,7 @@ import Imports hiding (Set, max)
 import System.Logger.Class (MonadLogger)
 import qualified System.Logger.Class as Log
 import UnliftIO (async, mapConcurrently, wait)
+import UnliftIO.Async (pooledMapConcurrentlyN)
 import Wire.API.Team.Member
 
 -- We use this newtype to highlight the fact that the 'Page' wrapped in here
@@ -310,9 +311,9 @@ userTeams u =
   map runIdentity
     <$> retry x1 (query Cql.selectUserTeams (params Quorum (Identity u)))
 
-usersTeams :: MonadClient m => [UserId] -> m (Map UserId TeamId)
+usersTeams :: (MonadUnliftIO m, MonadClient m) => [UserId] -> m (Map UserId TeamId)
 usersTeams uids = do
-  pairs <- retry x1 (query Cql.selectUsersTeams (params Quorum (Identity uids)))
+  pairs :: [(UserId, TeamId)] <- catMaybes <$> pooledMapConcurrentlyN 8 (\uid -> (uid,) <$$> oneUserTeam uid) uids
   pure $ foldl' (\m (k, v) -> Map.insert k v m) Map.empty pairs
 
 oneUserTeam :: MonadClient m => UserId -> m (Maybe TeamId)
diff --git a/services/galley/src/Galley/Data/Queries.hs b/services/galley/src/Galley/Data/Queries.hs
index bfe1b284b9d..00916aa20fe 100644
--- a/services/galley/src/Galley/Data/Queries.hs
+++ b/services/galley/src/Galley/Data/Queries.hs
@@ -135,9 +135,6 @@ selectUserTeamsIn = "select team from user_team where user = ? and team in ? ord
 selectUserTeamsFrom :: PrepQuery R (UserId, TeamId) (Identity TeamId)
 selectUserTeamsFrom = "select team from user_team where user = ? and team > ? order by team"
 
-selectUsersTeams :: PrepQuery R (Identity [UserId]) (UserId, TeamId)
-selectUsersTeams = "select user, team from user_team where user in ?"
-
 insertTeam :: PrepQuery W (TeamId, UserId, Text, Text, Maybe Text, TeamStatus, TeamBinding) ()
 insertTeam = "insert into team (team, creator, name, icon, icon_key, deleted, status, binding) values (?, ?, ?, ?, ?, false, ?, ?)"