Refactoring use_cache attribute on Worker classes

arkindex_worker/worker/__init__.py

@@ -36,8 +36,8 @@ class ElementsWorker(
     EntityMixin,
     MetaDataMixin,
 ):
-    def __init__(self, description="Arkindex Elements Worker", use_cache=False):
-        super().__init__(description, use_cache)
+    def __init__(self, description="Arkindex Elements Worker", support_cache=False):
+        super().__init__(description, support_cache)
 
         # Add report concerning elements
         self.report = Reporter("unknown worker")

arkindex_worker/worker/base.py

@@ -33,7 +33,7 @@ def _is_500_error(exc):
 
 
 class BaseWorker(object):
-    def __init__(self, description="Arkindex Base Worker", use_cache=False):
+    def __init__(self, description="Arkindex Base Worker", support_cache=False):
         self.parser = argparse.ArgumentParser(description=description)
 
         # Setup workdir either in Ponos environment or on host's home
@@ -56,7 +56,10 @@ class BaseWorker(object):
 
         logger.info(f"Worker will use {self.work_dir} as working directory")
 
-        self.use_cache = use_cache
+        self.support_cache = support_cache
+        # use_cache will be updated in configure() if the cache is supported and if there
+        # is at least one available sqlite database either given or in the parent tasks
+        self.use_cache = False
 
     @property
     def is_read_only(self):
@@ -133,22 +136,24 @@ class BaseWorker(object):
         # Load all required secrets
         self.secrets = {name: self.load_secret(name) for name in required_secrets}
 
-        if self.args.database is not None:
+        task_id = os.environ.get("PONOS_TASK")
+        task = None
+        if self.support_cache and self.args.database is not None:
             self.use_cache = True
+        elif self.support_cache and task_id:
+            task = self.request("RetrieveTaskFromAgent", id=task_id)
+            self.use_cache = len(task["parents"]) > 0
 
-        task_id = os.environ.get("PONOS_TASK")
-        if self.use_cache is True:
+        if self.use_cache:
             if self.args.database is not None:
                 assert os.path.isfile(
                     self.args.database
                 ), f"Database in {self.args.database} does not exist"
                 self.cache_path = self.args.database
-            elif task_id:
+            else:
                 cache_dir = os.path.join(os.environ.get("PONOS_DATA", "/data"), task_id)
                 assert os.path.isdir(cache_dir), f"Missing task cache in {cache_dir}"
                 self.cache_path = os.path.join(cache_dir, "db.sqlite")
-            else:
-                self.cache_path = os.path.join(os.getcwd(), "db.sqlite")
 
             init_cache_db(self.cache_path)
             create_tables()
@@ -156,8 +161,7 @@ class BaseWorker(object):
             logger.debug("Cache is disabled")
 
         # Merging parents caches (if there are any) in the current task local cache, unless the database got overridden
-        if self.use_cache and self.args.database is None and task_id is not None:
-            task = self.request("RetrieveTaskFromAgent", id=task_id)
+        if self.use_cache and self.args.database is None and task:
             merge_parents_cache(
                 task["parents"],
                 self.cache_path,

tests/conftest.py

@@ -177,7 +177,7 @@ def mock_base_worker_with_cache(mocker, monkeypatch, mock_worker_version_api):
     """Build a BaseWorker using SQLite cache, also mocking a PONOS_TASK"""
     monkeypatch.setattr(sys, "argv", ["worker"])
 
-    worker = BaseWorker(use_cache=True)
+    worker = BaseWorker(support_cache=True)
     monkeypatch.setenv("PONOS_TASK", "my_task")
     return worker
 
@@ -188,7 +188,7 @@ def mock_elements_worker_with_cache(monkeypatch, mock_worker_version_api):
     monkeypatch.setattr(sys, "argv", ["worker"])
     monkeypatch.setenv("ARKINDEX_CORPUS_ID", "11111111-1111-1111-1111-111111111111")
 
-    worker = ElementsWorker(use_cache=True)
+    worker = ElementsWorker(support_cache=True)
     worker.configure()
     return worker
 

tests/test_base_worker.py

@@ -29,7 +29,7 @@ def test_init_default_xdg_data_home(monkeypatch):
 
 
 def test_init_with_local_cache(monkeypatch):
-    worker = BaseWorker(use_cache=True)
+    worker = BaseWorker(support_cache=True)
 
     assert worker.work_dir == os.path.expanduser("~/.local/share/arkindex")
     assert worker.worker_version_id == "12341234-1234-1234-1234-123412341234"