Move queue logic out of parallel_execute()

Signed-off-by: Aanand Prasad <aanand.prasad@gmail.com>

compose/parallel.py

@@ -32,22 +32,13 @@ def parallel_execute(objects, func, get_name, msg, get_deps=None):
     for obj in objects:
         writer.initialize(get_name(obj))
 
-    q = setup_queue(objects, func, get_deps)
+    events = parallel_execute_stream(objects, func, get_deps)
 
-    done = 0
     errors = {}
     results = []
     error_to_reraise = None
 
-    while done < len(objects):
-        try:
-            obj, result, exception = q.get(timeout=1)
-        except Empty:
-            continue
-        # See https://github.com/docker/compose/issues/189
-        except thread.error:
-            raise ShutdownException()
-
+    for obj, result, exception in events:
         if exception is None:
             writer.write(get_name(obj), 'done')
             results.append(result)
@@ -59,7 +50,6 @@ def parallel_execute(objects, func, get_name, msg, get_deps=None):
         else:
             errors[get_name(obj)] = exception
             error_to_reraise = exception
-        done += 1
 
     for obj_name, error in errors.items():
         stream.write("\nERROR: for {}  {}\n".format(obj_name, error))
@@ -74,7 +64,7 @@ def _no_deps(x):
     return []
 
 
-def setup_queue(objects, func, get_deps):
+def parallel_execute_stream(objects, func, get_deps):
     if get_deps is None:
         get_deps = _no_deps
 
@@ -85,7 +75,17 @@ def setup_queue(objects, func, get_deps):
     t.daemon = True
     t.start()
 
-    return output
+    done = 0
+
+    while done < len(objects):
+        try:
+            yield output.get(timeout=1)
+            done += 1
+        except Empty:
+            continue
+        # See https://github.com/docker/compose/issues/189
+        except thread.error:
+            raise ShutdownException()
 
 
 def queue_producer(obj, func, results):