move gerrit querying loop somewhere more reusable

Change-Id: Ib41e49fe1e94af56d2a3fef892b55c4526e4f31d
Signed-off-by: Doug Hellmann <doug@doughellmann.com>

goal_tools/gerrit.py

@@ -94,6 +94,14 @@ class Review:
         self._id = id
         self._data = data
 
+    @property
+    def id(self):
+        return self._id
+
+    @property
+    def raw_change(self):
+        return self._data
+
     @property
     def url(self):
         return GERRIT_API_URL + self._id + '/'
@@ -262,3 +270,36 @@ class ReviewFactory:
         response = Review(review_id, data)
         cache_review(review_id, data, self._cache)
         return response
+
+    def query(self, query_string):
+        "Generator for changes matching the query criteria."
+        batch_size = 200
+        offset = 0
+        while True:
+            changes = query_gerrit(
+                'changes/',
+                params={
+                    'n': str(batch_size),
+                    'start': offset,
+                    'q': query_string,
+                    'o': QUERY_OPTIONS,
+                },
+            )
+            LOG.debug('%d changes', len(changes))
+
+            for change in changes:
+                review = Review(
+                    change['_number'],
+                    change,
+                )
+                cache_review(
+                    review.id,
+                    review.raw_change,
+                    self._cache,
+                )
+                yield review
+
+            if changes and changes[-1].get('_more_changes', False):
+                offset += batch_size
+            else:
+                break

goal_tools/who_helped/changes.py

@@ -56,43 +56,18 @@ class QueryChanges(command.Command):
 
         cache = self.app._load_cache_file(preload=False)
 
-        offset = 0
-        while True:
-            changes = gerrit.query_gerrit(
-                'changes/',
-                params={
-                    'n': '100',
-                    'start': offset,
-                    'q': parsed_args.query_string,
-                    'o': gerrit.QUERY_OPTIONS,
-                },
-            )
-            LOG.debug('%d changes', len(changes))
+        factory = gerrit.ReviewFactory(cache)
 
-            for change in changes:
-                review = gerrit.Review(
-                    change['_number'],
-                    change,
+        review_source = factory.query(parsed_args.query_string)
+        for review in review_source:
+            team_name = team_data.get_repo_owner(review.project)
+            if not parsed_args.include_unofficial and not team_name:
+                LOG.debug(
+                    'filtered out %s based on repo governance status',
+                    review.project,
                 )
-                team_name = team_data.get_repo_owner(review.project)
-                if not parsed_args.include_unofficial and not team_name:
-                    LOG.debug(
-                        'filtered out %s based on repo governance status',
-                        change['project'],
-                    )
-                    continue
-
-                gerrit.cache_review(
-                    change['_number'],
-                    change,
-                    cache,
-                )
-                review_ids.append(change['_number'])
-
-            if changes and changes[-1].get('_more_changes', False):
-                offset += 100
-            else:
-                break
+                continue
+            review_ids.append(review.id)
 
         with open(parsed_args.review_list, 'w', encoding='utf-8') as f:
             f.write('# QUERY: {}\n'.format(