Don't query branch protection on pull request events

The pull request based events already have the information if the
target branch is protected. Hence we don't need to re-query this
information again.

Change-Id: I547db8090e13f1103918ce9c5f33002e9a42fcef

zuul/connection/__init__.py

@@ -247,7 +247,8 @@ class CachedBranchConnection(BaseConnection):
         self._project_branch_cache_exclude_unprotected.pop(project.name, None)
         self._project_branch_cache_include_unprotected.pop(project.name, None)
 
-    def checkBranchCache(self, project_name: str, event) -> None:
+    def checkBranchCache(self, project_name: str, event,
+                         protected: bool = None) -> None:
         """Clear the cache for a project when a branch event is processed
 
         This method must be called when a branch event is processed: if the
@@ -258,9 +259,13 @@ class CachedBranchConnection(BaseConnection):
             The project name.
         :params event:
             The event, inherit from `zuul.model.TriggerEvent` class.
+        :params protected:
+            If defined the caller already knows if the branch is protected
+            so the query can be skipped.
         """
-        protected = self.isBranchProtected(project_name, event.branch,
-                                           zuul_event_id=event)
+        if protected is None:
+            protected = self.isBranchProtected(project_name, event.branch,
+                                               zuul_event_id=event)
         if protected is not None:
 
             # If the branch appears in the exclude_unprotected cache but

zuul/driver/github/githubconnection.py

@@ -435,12 +435,14 @@ class GithubEventProcessor(object):
                 event.zuul_event_id = self.delivery
                 event.timestamp = self.ts
                 project = self.connection.source.getProject(event.project_name)
+                change = None
                 if event.change_number:
-                    self.connection._getChange(project,
-                                               event.change_number,
-                                               event.patch_number,
-                                               refresh=True,
-                                               event=event)
+                    change = self.connection._getChange(
+                        project,
+                        event.change_number,
+                        event.patch_number,
+                        refresh=True,
+                        event=event)
                     self.log.debug("Refreshed change %s,%s",
                                    event.change_number, event.patch_number)
 
@@ -448,7 +450,14 @@ class GithubEventProcessor(object):
                 # unprotected branches, we might need to check whether the
                 # branch is now protected.
                 if hasattr(event, "branch") and event.branch:
-                    self.connection.checkBranchCache(project.name, event)
+                    protected = None
+                    if change:
+                        # PR based events already have the information if the
+                        # target branch is protected so take the information
+                        # from there.
+                        protected = change.branch_protected
+                    self.connection.checkBranchCache(project.name, event,
+                                                     protected=protected)
 
             event.project_hostname = self.connection.canonical_hostname
             self.event = event
@@ -1484,6 +1493,7 @@ class GithubConnection(CachedBranchConnection):
         change.required_contexts = set(
             canmerge_data['requiredStatusCheckContexts']
         )
+        change.branch_protected = canmerge_data['protected']
 
     def getGitUrl(self, project: Project):
         if self.git_ssh_key:

zuul/driver/github/githubmodel.py

@@ -42,6 +42,7 @@ class PullRequest(Change):
         self.review_decision = None
         self.required_contexts = set()
         self.contexts = set()
+        self.branch_protected = False
 
     @property
     def status(self):

zuul/driver/github/graphql/__init__.py

@@ -107,8 +107,10 @@ class GraphQLClient:
                 'requiresApprovingReviews')
             result['requiresCodeOwnerReviews'] = matching_rule.get(
                 'requiresCodeOwnerReviews')
+            result['protected'] = True
         else:
             result['requiredStatusCheckContexts'] = []
+            result['protected'] = False
 
         # Check for draft
         pull_request = nested_get(repository, 'pullRequest')