Add support for repeated keys in TaskRequest.

appengine/swarming/message_conversion.py

Index: appengine/swarming/message_conversion.py
diff --git a/appengine/swarming/message_conversion.py b/appengine/swarming/message_conversion.py
index 1c299d1bda1bfece36a4262f95658f89a57248df..bee7ad3b4fc898aa746ee041200b14ef08ec4619 100644
--- a/appengine/swarming/message_conversion.py
+++ b/appengine/swarming/message_conversion.py
@@ -25,13 +25,17 @@ from server import task_result
 ### Private API.
 
 
-def _string_pairs_from_dict(dictionary):
+def _string_pairs_from_list_of_tuples(dictionary):
   return [
     swarming_rpcs.StringPair(key=k, value=v)
-    for k, v in sorted((dictionary or {}).iteritems())
+    for k, v in sorted((dictionary or []))
   ]
 
 
+def _string_pairs_from_dict(dictionary):
+  return _string_pairs_from_list_of_tuples((dictionary or {}).iteritems())
+
+
 def _string_list_pairs_from_dict(dictionary):
   return [
     swarming_rpcs.StringListPair(key=k, value=v)
@@ -125,7 +129,7 @@ def task_request_to_rpc(entity):
       caches=[_ndb_to_rpc(swarming_rpcs.CacheEntry, c) for c in props.caches],
       cipd_input=cipd_input,
       secret_bytes='<REDACTED>' if props.has_secret_bytes else None,
-      dimensions=_string_pairs_from_dict(props.dimensions),
+      dimensions=_string_pairs_from_list_of_tuples(props.dimensions),
       env=_string_pairs_from_dict(props.env),
       inputs_ref=inputs_ref)
 
@@ -171,8 +175,11 @@ def new_task_request_from_rpc(msg, now):
   if props.secret_bytes:
     secret_bytes = task_request.SecretBytes(secret_bytes=props.secret_bytes)
 
-  if len(set(i.key for i in props.dimensions)) != len(props.dimensions):
-    raise ValueError('same dimension key cannot be specified twice')
+  # keys with ':' would corrupt the data. Rest of validation is done in
+  # TaskProperties.
+  if any(':' in i.key for i in props.dimensions):
+    raise ValueError('dimension key cannot contain ":"')
+  # Repeated keys would be lost. Rest of validation is done in TaskProperties.
   if len(set(i.key for i in props.env)) != len(props.env):
     raise ValueError('same environment variable key cannot be specified twice')
 
@@ -186,8 +193,8 @@ def new_task_request_from_rpc(msg, now):
       has_secret_bytes=secret_bytes is not None,
       secret_bytes=None, # ignore this, it's handled out of band
       dimensions=None,
-      dimensions_dict={i.key: i.value for i in props.dimensions},
-      dimensions_flat=[],
+      dimensions_flat=sorted(
+          u'%s:%s' % (i.key, i.value) for i in props.dimensions),
       env={i.key: i.value for i in props.env},
       inputs_ref=inputs_ref)