BERTE-561 skip the merge through the queue when not needed (#158)

Author: tcarmet

CHANGELOG

@@ -1,6 +1,10 @@
 # Change Log
 All notable changes to this project will be documented in this file.
 
+## [3.11.0] - 2024-01-26
+# Added
+- Support of merging a PR and skip the queue when it is not needed.
+
 ## [3.10.0] - 2023-11-14
 # Added
 - Support of tags created with `v` prefix.

bert_e/settings.py

@@ -184,6 +184,8 @@ class Meta:
     quiet = fields.Bool(required=False, load_default=False)
     disable_queues = fields.Bool(required=False, load_default=False)
     use_queues = fields.Bool(required=False, load_default=True)
+    skip_queue_when_not_needed = fields.Bool(
+        required=False, load_default=False)
     cmd_line_options = fields.List(fields.Str(), load_default=[])
 
     client_id = fields.Str(required=False, load_default='')

bert_e/tests/test_bert_e.py

@@ -7690,6 +7690,41 @@ def test_job_rebuild_queues_without_hotfix(self):
             self.assertFalse(self.gitrepo.remote_branch_exists(branch),
                              "branch %s shouldn't exist" % branch)
 
+    def test_no_need_queuing(self):
+        """Expect Bert-E to skip the queue when there is no need to queue."""
+
+        # Two PRs created at the same time
+        # At the moment they were created they are both up to date with the
+        # destination branch
+        self.init_berte(
+            options=self.bypass_all, skip_queue_when_not_needed=True)
+        first_pr = self.create_pr('feature/TEST-1', 'development/4.3')
+        second_pr = self.create_pr('feature/TEST-2', 'development/4.3')
+        # The first PR is ready to merge, and is expected to merge directly
+        # without going through the queue.
+        self.process_pr_job(first_pr, 'SuccessMessage')
+        # When the second PR is merged we expect it to go through the queue
+        # as it is no longer up to date with the destination branch.
+        self.process_pr_job(second_pr, 'Queued')
+        # At this point the repository should now contain queue branches.
+        # We force the merge to get everything setup according for the next
+        # scenario.
+        self.process_job(ForceMergeQueuesJob(bert_e=self.berte), 'Merged')
+        # We expect the PR to be merged so there should be nothing left to do.
+        self.process_pr_job(second_pr, 'NothingToDo')
+        # We get the local repo setup for a third PR that should be up to
+        # date with the latest changes.
+        self.gitrepo.cmd('git checkout development/4.3')
+        self.gitrepo.cmd('git branch --set-upstream-to=origin/development/4.3')
+        self.gitrepo.cmd('git pull')
+        third_pr = self.create_pr('feature/TEST-3', 'development/4.3')
+        fourth_pr = self.create_pr('feature/TEST-4', 'development/4.3')
+        # Just like the first PR, we expect this one to be merged directly.
+        self.process_pr_job(third_pr, 'SuccessMessage')
+        # Now we want to know if when the queue is a bit late is Bert-E
+        # capable of reeastablishing the Queue in order, and queue PR number 4.
+        self.process_pr_job(fourth_pr, 'Queued')
+
     def test_bypass_prefixes(self):
         self.init_berte()
         pr = self.create_pr('documentation/stuff', 'development/4.3')

bert_e/workflow/gitwaterflow/__init__.py

@@ -207,10 +207,14 @@ def _handle_pull_request(job: PullRequestJob):
     # check for conflicts), and all builds were green, and we reached
     # this point without an error, then all conditions are met to enter
     # the queue.
-    if job.settings.use_queue:
-        # validate current state of queues
+    queues = queueing.build_queue_collection(job) if job.settings.use_queue \
+        else None
+
+    # If we need to go through the queue, we need to check if we can
+    # merge the integration branches right away, or if we need to add
+    # the pull request to the queue.
+    if queueing.is_needed(job, wbranches, queues):
         try:
-            queues = queueing.build_queue_collection(job)
             queues.validate()
         except messages.IncoherentQueues as err:
             raise messages.QueueOutOfOrder(
@@ -224,8 +228,14 @@ def _handle_pull_request(job: PullRequestJob):
             issue=job.git.src_branch.jira_issue_key,
             author=job.pull_request.author_display_name,
             active_options=job.active_options)
-
     else:
+        # If we don't need to go through the queue, we can merge the
+        # integration branches right away.
+        # But if the bot is configured with the 'use_queue' option, we
+        # still need to delete the queue to ensure that we don't raise
+        # IncoherentQueues in the next runs.
+        if queues is not None:
+            queues.delete()
         merge_integration_branches(job, wbranches)
         job.bert_e.add_merged_pr(job.pull_request.id)
         job.git.cascade.validate()

bert_e/workflow/gitwaterflow/branches.py

@@ -743,6 +743,18 @@ def has_version_queued_prs(self, version):
         return (self._queues.get(version, {}).get(QueueIntegrationBranch)
                 is not None)
 
+    def delete(self):
+        """Delete the queues entirely."""
+
+        for branch in self._queues.values():
+            queue: QueueBranch = branch[QueueBranch]
+            queue.dst_branch.checkout()
+            queue.remove(do_push=True)
+            queue_integration: QueueIntegrationBranch | None = branch.get(
+                QueueIntegrationBranch)
+            if queue_integration:
+                queue_integration.remove(do_push=True)
+
 
 class BranchCascade(object):
     def __init__(self):

bert_e/workflow/gitwaterflow/queueing.py

@@ -18,16 +18,17 @@
 
 from bert_e import exceptions
 from bert_e.job import handler as job_handler
-from bert_e.job import QueuesJob
+from bert_e.job import QueuesJob, PullRequestJob
 from bert_e.lib import git
 
 from ..git_utils import clone_git_repo, consecutive_merge, robust_merge, push
 from ..pr_utils import send_comment
-from .branches import (BranchCascade, DevelopmentBranch, IntegrationBranch,
-                       QueueBranch, QueueIntegrationBranch,
-                       branch_factory, build_queue_collection)
+from .branches import (BranchCascade, DevelopmentBranch, GWFBranch,
+                       IntegrationBranch, QueueBranch, QueueCollection,
+                       QueueIntegrationBranch, branch_factory,
+                       build_queue_collection)
 from .integration import get_integration_branches
-
+from typing import List
 LOG = logging.getLogger(__name__)
 
 
@@ -207,3 +208,38 @@ def close_queued_pull_request(job, pr_id, cascade):
         except git.RemoveFailedException:
             # not critical
             pass
+
+
+def is_needed(
+        job: PullRequestJob,
+        wbranches: List[GWFBranch],
+        queues: QueueCollection | None):
+    """Determine if queuing is required to merge the given PR.
+
+    Queuing a pull request should only be done if:
+    - The PR or the integration branches are not up to date
+      with the destination branch.
+    - Other PRs are already in the queue.
+
+    Returns:
+    - True if the PR should be queued.
+    - False otherwise.
+    """
+
+    if queues is None or job.settings.use_queue is False:
+        return False
+
+    if (job.settings.skip_queue_when_not_needed is False or
+            already_in_queue(job, wbranches) or
+            len(queues.queued_prs) > 0):
+        return True
+
+    if not job.git.src_branch.includes_commit(
+            job.git.dst_branch.get_latest_commit()):
+        return True
+    # Check if the wbranches all contain the commits in the dst branches
+    for branch, dst_branch in zip(wbranches, job.git.cascade.dst_branches):
+        if not branch.includes_commit(dst_branch.get_latest_commit()):
+            return True
+
+    return False