openage.util.threading: fixed concurrent_chain

used to fail when given zero generators

openage/convert/driver.py

@@ -159,8 +159,6 @@ def convert_metadata(args):
 
 def convert_media(args):
     """ Converts the media part """
-    info("converting media")
-
     ignored_suffixes = set()
     if args.flag("no_sounds"):
         ignored_suffixes.add('.wav')
@@ -177,6 +175,11 @@ def convert_media(args):
 
     yield len(files_to_convert)
 
+    if not files_to_convert:
+        return
+
+    info("converting media")
+
     jobs = getattr(args, "jobs", None)
     with SLPConverterPool(args.palette, jobs) as slp_converter:
         args.slp_converter = slp_converter

openage/util/threading.py

@@ -38,7 +38,7 @@ def concurrent_chain(generators, jobs=None):
             pool.submit(generator_to_queue, generator, queue)
             running_generator_count += 1
 
-        while True:
+        while running_generator_count > 0:
             event_type, value = queue.get()
 
             if event_type == GeneratorEvent.VALUE:
@@ -48,8 +48,6 @@ def concurrent_chain(generators, jobs=None):
                 raise value
             elif event_type == GeneratorEvent.STOP_ITERATION:
                 running_generator_count -= 1
-                if running_generator_count == 0:
-                    return
 
 
 class ClosableQueue(Queue):
@@ -122,6 +120,8 @@ def errorgen():
         yield "errorgen"
         raise ValueError()
 
+    assert_value(list(concurrent_chain([], 2)), [])
+
     assert_value(list(concurrent_chain([range(10)], 2)), list(range(10)))
 
     assert_value(