Refactor the /jobs endpoint

It also used the list-jobs function referred to in the last commit.
This refactor removes the use of list-jobs, cleans up the /jobs endpoint,
and addresses part of twosigma#617. /jobs no longer propagates UUID's
in the liberator context.

scheduler/src/cook/mesos/api.clj

@@ -839,6 +839,7 @@
 
 (defn fetch-job-map-from-entity
   [db framework-id job]
+  "Fetches a job map from a job entity"
   (timers/time!
     (timers/timer ["cook-mesos" "internal" "fetch-job-map"])
     (let [resources (util/job-ent->resources job)
@@ -891,6 +892,7 @@
               pool (assoc :pool (:pool/name pool))))))
 
 (defn fetch-job-map
+  "Fetches a job map from a UUID"
   [db framework-id job-uuid]
   (fetch-job-map-from-entity db framework-id (d/entity db [:job/uuid job-uuid])))
 
@@ -1118,23 +1120,18 @@
   [conn framework-id ctx]
   (mapv (partial fetch-job-map (db conn) framework-id) (::jobs ctx)))
 
-(defn render-jobs-for-response
-  [conn framework-id ctx]
-  (let [db (db conn)
-
-        fetch-group
-        (fn fetch-group [group-uuid]
-          (let [group (d/entity db [:group/uuid (UUID/fromString group-uuid)])]
-            {:uuid group-uuid
-             :name (:group/name group)}))
+(defn- fetch-group-for-response
+  [db group-uuid]
+  (let [group (d/entity db [:group/uuid (UUID/fromString group-uuid)])]
+    {:uuid group-uuid
+     :name (:group/name group)}))
 
-        fetch-job
-        (fn fetch-job [job-uuid]
-          (let [job (fetch-job-map db framework-id job-uuid)
-                groups (mapv fetch-group (:groups job))]
-            (assoc job :groups groups)))]
-
-    (mapv fetch-job (::jobs ctx))))
+(defn render-job-for-response
+  "Given a job entity, create the full response including job fields and group name and group UUID's"
+  [db framework-id job-entity]
+  (let [job (fetch-job-map-from-entity db framework-id job-entity)
+        groups (mapv #(fetch-group-for-response db %) (:groups job))]
+    (assoc job :groups groups)))
 
 (defn render-instances-for-response
   [conn framework-id ctx]
@@ -1260,7 +1257,7 @@
 (histograms/defhistogram [cook-mesos api list-request-param-limit])
 (histograms/defhistogram [cook-mesos api list-response-job-count])
 
-(defn list-jobents
+(defn list-jobs
   "Queries using the params from ctx and returns the jobs that were found as datomic entities."
   [db include-custom-executor? ctx]
   (timers/time!
@@ -1290,45 +1287,38 @@
       (histograms/update! list-response-job-count (count job-ents))
       job-ents)))
 
-(defn list-jobs
-  "Queries using the params from ctx and returns the job uuids that were found"
-  [db include-custom-executor? ctx]
-  (map :job/uuid (list-jobents db include-custom-executor? ctx)))
-
-(defn jobs-list-exist?
+(defn jobs-list->context
+  "Do a job query, add the resulting entites into the liberator context"
   [conn ctx]
-  [true {::jobs (list-jobs (d/db conn) true ctx)}])
-
-(defn read-jobs-handler
-  [conn is-authorized-fn resource-attrs]
-  (base-cook-handler
-    (merge {:allowed-methods [:get]
-            :malformed? (fn [ctx]
-                          (if (get-in ctx [:request :params :uuid])
-                            (job-request-malformed? ctx)
-                            (job-list-request-malformed? ctx)))
-            :allowed? (fn [ctx]
-                        (if (get-in ctx [:request :params :uuid])
-                          (job-request-allowed? conn is-authorized-fn ctx)
-                          (job-list-request-allowed? is-authorized-fn ctx)))
-            :exists? (fn [ctx]
-                       (if (get-in ctx [:request :params :uuid])
-                         (jobs-exist? conn ctx)
-                         (jobs-list-exist? conn ctx)))}
-           resource-attrs)))
+  [true {::job-entities (list-jobs (d/db conn) true ctx)}])
 
 (defn read-jobs-handler-multiple
   [conn framework-id is-authorized-fn]
-  (let [handle-ok (partial render-jobs-for-response conn framework-id)]
-    (read-jobs-handler conn is-authorized-fn {:handle-ok handle-ok})))
+  (let [db (d/db conn)
+        handle-ok
+        (fn handle-ok [ctx]
+          (mapv #(render-job-for-response db framework-id %) (::job-entities ctx)))]
+    (base-cook-handler
+      (merge {:allowed-methods [:get]
+              :malformed? job-list-request-malformed?
+              :allowed? (partial job-list-request-allowed? is-authorized-fn)
+              :exists? (partial jobs-list->context conn)
+              :handle-ok handle-ok}))))
 
 (defn read-jobs-handler-single
   [conn framework-id is-authorized-fn]
-  (let [handle-ok
+  (let [db (d/db conn)
+        handle-ok
         (fn handle-ok [ctx]
           (first
-            (render-jobs-for-response conn framework-id ctx)))]
-    (read-jobs-handler conn is-authorized-fn {:handle-ok handle-ok})))
+            (mapv #(render-job-for-response db framework-id (d/entity db [:job/uuid %]))
+                  (::jobs ctx))))]
+    (base-cook-handler
+      (merge {:allowed-methods [:get]
+              :malformed? job-request-malformed?
+              :allowed? (partial job-request-allowed? conn is-authorized-fn)
+              :exists? (partial jobs-exist? conn)}
+             {:handle-ok handle-ok}))))
 
 (defn instance-request-exists?
   [ctx]
@@ -2292,7 +2282,7 @@
     :handle-ok (fn [ctx]
                  (timers/time!
                    (timers/timer ["cook-scheduler" "handler" "list-endpoint-duration"])
-                   (let [job-ents (list-jobents db false ctx)]
+                   (let [job-ents (list-jobs db false ctx)]
                      (mapv (partial fetch-job-map-from-entity db framework-id) job-ents))))))
 
 ;;