ref(controller): prefer dict view objects

Deis requires Python 2.7, so code can use dict views:
https://docs.python.org/2/library/stdtypes.html#dictionary-view-objects

This is more efficient than the copying involved with items()
and related traditional dict view methods.

Author: mboersma

controller/api/models.py

@@ -84,7 +84,7 @@ def validate_id_is_docker_compatible(value):
 def validate_app_structure(value):
     """Error if the dict values aren't ints >= 0."""
     try:
-        if any(int(v) < 0 for v in value.itervalues()):
+        if any(int(v) < 0 for v in value.viewvalues()):
             raise ValueError("Must be greater than or equal to zero")
     except ValueError, err:
         raise ValidationError(err)
@@ -665,7 +665,7 @@ def save(self, **kwargs):
                     new_data = {}
                 data.update(new_data)
                 # remove config keys if we provided a null value
-                [data.pop(k) for k, v in new_data.items() if v is None]
+                [data.pop(k) for k, v in new_data.viewitems() if v is None]
                 setattr(self, attr, data)
         except Config.DoesNotExist:
             pass

controller/api/serializers.py

@@ -141,7 +141,7 @@ class Meta:
         model = models.Config
 
     def validate_memory(self, value):
-        for k, v in value.items():
+        for k, v in value.viewitems():
             if v is None:  # use NoneType to unset a value
                 continue
             if not re.match(PROCTYPE_MATCH, k):
@@ -152,15 +152,15 @@ def validate_memory(self, value):
         return value
 
     def validate_cpu(self, value):
-        for k, v in value.items():
+        for k, v in value.viewitems():
             if v is None:  # use NoneType to unset a value
                 continue
             if not re.match(PROCTYPE_MATCH, k):
                 raise serializers.ValidationError("Process types can only contain [a-z]")
             shares = re.match(CPUSHARE_MATCH, str(v))
             if not shares:
                 raise serializers.ValidationError("CPU shares must be an integer")
-            for v in shares.groupdict().values():
+            for v in shares.groupdict().viewvalues():
                 try:
                     i = int(v)
                 except ValueError:
@@ -170,7 +170,7 @@ def validate_cpu(self, value):
         return value
 
     def validate_tags(self, value):
-        for k, v in value.items():
+        for k, v in value.viewitems():
             if v is None:  # use NoneType to unset a value
                 continue
             if not re.match(TAGKEY_MATCH, k):

controller/api/views.py

@@ -134,7 +134,7 @@ def scale(self, request, **kwargs):
         new_structure = {}
         app = self.get_object()
         try:
-            for target, count in request.data.items():
+            for target, count in request.data.viewitems():
                 new_structure[target] = int(count)
             models.validate_app_structure(new_structure)
             app.scale(request.user, new_structure)

controller/registry/private.py

@@ -90,7 +90,7 @@ def _api_call(endpoint, data=None, headers={}, cookies=None, request_type='GET')
     base_headers = {'user-agent': 'docker/1.0.0'}
     r = None
     if len(headers) > 0:
-        for header, value in headers.iteritems():
+        for header, value in headers.viewitems():
             base_headers[header] = value
     if request_type == 'GET':
         r = requests.get(endpoint, headers=base_headers)
@@ -170,7 +170,7 @@ def _construct_env(env, config):
             v = config.pop(k)
         new_env.append("{}={}".format(encode(k), encode(v)))
     # add other config ENV items
-    for k, v in config.items():
+    for k, v in config.viewitems():
         new_env.append("{}={}".format(encode(k), encode(v)))
     return new_env
 

controller/scheduler/fleet.py

@@ -153,7 +153,7 @@ def _create_container(self, name, image, command, unit, **kwargs):
         # prepare tags only if one was provided
         tags = kwargs.get('tags', {})
         if tags:
-            tagset = ' '.join(['"{}={}"'.format(k, v) for k, v in tags.items()])
+            tagset = ' '.join(['"{}={}"'.format(k, v) for k, v in tags.viewitems()])
             unit.append({"section": "X-Fleet", "name": "MachineMetadata",
                          "value": tagset})
         # post unit to fleet

controller/scheduler/swarm.py

@@ -123,7 +123,7 @@ def _get_hostname(self, application_name):
 
     def _get_portbindings(self, image):
         dictports = self.docker_cli.inspect_image(image)['ContainerConfig']['ExposedPorts']
-        for port, mapping in dictports.items():
+        for port, mapping in dictports.viewitems():
             dictports[port] = None
         return dictports