task label example improved

Author: Johannes Otepka

docs/source/examples/basic_task_label.py

@@ -1,4 +1,12 @@
-"""Basic task label example"""
+"""Basic task label example
+
+Labels can be used for identifying or semantically grouping tasks. Using the $glob operator
+relevant task records can be queried from the Task Database.
+
+Authors
+-------
+* ottointhesky
+"""
 
 import ipyparallel as ipp
 
@@ -18,13 +26,17 @@ def wait(t):
     return time.time() - tic
 
 
+count = 5  # number of tasks per method
+
 # use load balanced view
 bview = rc.load_balanced_view()
 ar_list_b1 = [
-    bview.set_flags(label=f"mylabel_map_{i:02}").map_async(wait, [2]) for i in range(10)
+    bview.set_flags(label=f"bview_map_{i:02}").map_async(wait, [2])
+    for i in range(count)
 ]
 ar_list_b2 = [
-    bview.set_flags(label=f"mylabel_map_{i:02}").apply_async(wait, 2) for i in range(10)
+    bview.set_flags(label=f"bview_apply_{i:02}").apply_async(wait, 2)
+    for i in range(count)
 ]
 bview.wait(ar_list_b1)
 bview.wait(ar_list_b2)
@@ -33,19 +45,36 @@ def wait(t):
 # use direct view
 dview = rc[:]
 ar_list_d1 = [
-    dview.set_flags(label=f"mylabel_map_{i + 10:02}").apply_async(wait, 2)
-    for i in range(10)
+    dview.set_flags(label=f"dview_map_{i + 10:02}").map_async(wait, [2])
+    for i in range(count)
 ]
 ar_list_d2 = [
-    dview.set_flags(label=f"mylabel_map_{i + 10:02}").map_async(wait, [2])
-    for i in range(10)
+    dview.set_flags(label=f"dview_apply_{i + 10:02}").apply_async(wait, 2)
+    for i in range(count)
 ]
 dview.wait(ar_list_d1)
 dview.wait(ar_list_d2)
 
+
+def print_records(titel, data):
+    print(f"{titel} ({len(data)} records)")
+    for d in data:
+        print(
+            f"\tmsg_id={d['msg_id']}; label={d['label']}; engine_uuid={d['engine_uuid']}"
+        )
+
+
+query_keys = ['msg_id', 'label', 'engine_uuid']
+
 # query database
-data = rc.db_query({'label': {"$nin": ""}}, keys=['msg_id', 'label', 'engine_uuid'])
-for d in data:
-    print(f"msg_id={d['msg_id']}; label={d['label']}; engine_uuid={d['engine_uuid']}")
+data = rc.db_query({'label': {"$nin": ""}}, keys=query_keys)
+print_records("all entries with labels", data)
+
+data = rc.db_query({'label': {"$glob": "dview_*"}}, keys=query_keys)
+print_records("all dview label entries", data)
+
+data = rc.db_query({'label': {"$glob": "*_map_*"}}, keys=query_keys)
+print_records("all map label entries", data)
 
+# stop cluster
 cluster.stop_cluster_sync()