Resolved #2

src/Control/Task/Scheduler/Query.hs

@@ -41,6 +41,7 @@ scheduleTaskQuery task = do
                 :* Set (param @2) `as` #payload
                 :* Default `as` #creation_time
                 :* Default `as` #started
+                :* Default `as` #failures
           )
           ( OnConflict
               (OnConstraint #pk_task_payload)
@@ -87,6 +88,7 @@ rescheduleTaskQuery payload = do
           #tasks
           ( Default `as` #creation_time
               :* Default `as` #started
+              :* Set (#failures + 1) `as` #failures
           )
           (param @1 .== #task .&& param @2 .== #payload)
   dbWrite (const $ return ()) $
@@ -112,6 +114,7 @@ pickTasksQuery tasks limitCount = do
           ( from (table #tasks)
               & where_ (#task `in_` (literal <$> tasks))
               & where_ (not_ . notNull $ #started)
+              & where_ (#failures .< 20)
               & orderBy [#creation_time & Asc]
               & limit limitCount
               & orderBy [#creation_time & Desc]

src/Server/Schema.hs

@@ -6,13 +6,15 @@ module Server.Schema
 where
 
 import Server.Schema.V1
+import Server.Schema.V2
 import Squeal.PostgreSQL
 
 type StaticPQ m = MonadPQ Schema m
 
-type Schema = SchemaV1
+type Schema = SchemaV2
 
 migration :: AlignedList (Migration (Terminally PQ IO)) (Public '[]) Schema
 migration =
   pureMigration schemaMigrationV1
+    :>> pureMigration schemaMigrationV2
     :>> Done

src/Server/Schema/V2.hs

@@ -0,0 +1,46 @@
+module Server.Schema.V2
+  ( SchemaV2,
+    schemaMigrationV2,
+  )
+where
+
+import Data.Aeson
+import Data.Int
+import Data.Submission
+import Data.Text (Text)
+import Data.Time
+import Server.Schema.V1
+import Squeal.PostgreSQL
+
+type SchemaV2 =
+  Public
+    '[ "tasks"
+         ::: 'Table
+               ( '[ "pk_task_payload" :=> 'PrimaryKey '["task", "payload"]
+                  ]
+                   :=> '[ "task" ::: 'NoDef :=> 'NotNull (PG Text),
+                          "payload" ::: 'NoDef :=> 'NotNull (PG (Jsonb Value)),
+                          "creation_time" ::: 'Def :=> 'NotNull (PG UTCTime),
+                          "started" ::: 'Def :=> 'NotNull (PG Bool),
+                          "failures" ::: 'Def :=> 'NotNull (PG Int32)
+                        ]
+               ),
+       "submissions"
+         ::: 'Table
+               ( '["pk_submission_repo_full_name_sha" :=> 'PrimaryKey '["repo_full_name", "sha"]]
+                   :=> '[ "user_name" ::: 'NoDef :=> 'NotNull (PG String),
+                          "repo_full_name" ::: 'NoDef :=> 'NotNull (PG String),
+                          "problem" ::: 'NoDef :=> 'NotNull (PG String),
+                          "sha" ::: 'NoDef :=> 'NotNull (PG String),
+                          "status" ::: 'NoDef :=> 'NotNull (PG (Jsonb SubmissionStatus))
+                        ]
+               )
+     ]
+
+schemaMigrationV2 :: Migration Definition SchemaV1 SchemaV2
+schemaMigrationV2 =
+  Migration
+    { name = "v2",
+      up = alterTable #tasks (addColumn #failures (default_ 0 $ notNullable int)),
+      down = alterTable #tasks (dropColumn #failures)
+    }