Add information about requested task rank in the pipe

dispatcher/backend/src/common/schemas/orms.py

@@ -121,6 +121,7 @@ def get_schedule_name(task: dbm.RequestedTask) -> str:
     schedule_name = mf.Function(serialize=get_schedule_name)  # override base
     worker = mf.Function(serialize=get_worker_name)
     notification = mf.Dict()
+    rank = mf.Integer()
 
 
 class MostRecentTaskSchema(m.Schema):

dispatcher/backend/src/routes/requested_tasks/requested_task.py

@@ -300,6 +300,18 @@ def get(
         )
         resp = RequestedTaskFullSchema().dump(requested_task)
 
+        # also fetch all requested tasks IDs to compute estimated task rank ; this is
+        # only an estimation since logic to start tasks is more complex than simple
+        # sorting but it gives a good indicator of when the requested task might
+        # be expected to start (soon or in a long time) especially for zimit.kiwix.org
+        stmt = sa.select(
+            dbm.RequestedTask.id,
+        ).order_by(
+            dbm.RequestedTask.priority.desc(), dbm.RequestedTask.updated_at.asc()
+        )
+        requested_task_ids = session.execute(stmt).scalars().all()
+        resp["rank"] = requested_task_ids.index(requested_task_id)
+
         # exclude notification to not expose private information (privacy)
         # on anonymous requests and requests for users without schedules_update
         if not token or not token.get_permission("schedules", "update"):

dispatcher/backend/src/tests/integration/routes/conftest.py

@@ -269,10 +269,10 @@ def _make_requested_task(
         status=TaskStatus.requested,
         requested_by="someone",
         priority=0,
+        request_date=getnow(),
     ):
         events = [TaskStatus.requested]
-        now = getnow()
-        timestamp = {event: now for event in events}
+        timestamp = {event: request_date for event in events}
         events = [make_event(event, timestamp[event]) for event in events]
 
         config = {
@@ -291,7 +291,7 @@ def _make_requested_task(
             requested_task = dbm.RequestedTask(
                 status=status,
                 timestamp=timestamp,
-                updated_at=now,
+                updated_at=request_date,
                 events=events,
                 requested_by=requested_by,
                 priority=priority,
@@ -336,6 +336,33 @@ def requested_tasks(make_requested_task):
     return tasks
 
 
+@pytest.fixture(scope="module")
+def requested_tasks_2(make_requested_task):
+    return [
+        make_requested_task(
+            schedule_name="recipe1",
+            request_date=getnow() - datetime.timedelta(minutes=5),
+        ),
+        make_requested_task(
+            schedule_name="recipe2",
+            request_date=getnow() - datetime.timedelta(minutes=4),
+        ),
+        make_requested_task(
+            schedule_name="recipe3",
+            request_date=getnow() - datetime.timedelta(minutes=10),
+        ),
+        make_requested_task(
+            schedule_name="recipe4",
+            request_date=getnow() - datetime.timedelta(minutes=3),
+            priority=5,
+        ),
+        make_requested_task(
+            schedule_name="recipe5",
+            request_date=getnow() - datetime.timedelta(minutes=1),
+        ),
+    ]
+
+
 @pytest.fixture(scope="module")
 def requested_task(make_requested_task):
     return make_requested_task()

dispatcher/backend/src/tests/integration/routes/requested_tasks/test_requested_task.py

@@ -179,6 +179,32 @@ def test_get(self, client, requested_task, access_token, authenticated):
         else:
             assert data["notification"] is None
 
+    @pytest.mark.parametrize(
+        "recipename, expected_rank",
+        [
+            pytest.param("recipe1", 2, id="recipe1"),
+            pytest.param("recipe2", 3, id="recipe2"),
+            pytest.param("recipe3", 1, id="recipe3"),
+            pytest.param("recipe4", 0, id="recipe4"),
+            pytest.param("recipe5", 4, id="recipe5"),
+        ],
+    )
+    def test_get_requested_task_rank_ok(
+        self, client, requested_tasks_2, recipename, expected_rank
+    ):
+        requested_task = [
+            requested_task
+            for requested_task in requested_tasks_2
+            if requested_task["schedule_name"] == recipename
+        ][0]
+        url = f'/requested-tasks/{requested_task["_id"]}'
+        headers = {"Content-Type": "application/json"}
+        response = client.get(url, headers=headers)
+        assert response.status_code == 200
+
+        data = json.loads(response.data)
+        assert data["rank"] == expected_rank
+
 
 class TestRequestedTaskCreate:
     @pytest.fixture()