[GITEA] avoid superfluous synchronized pull_request run when opening a PR (#2236)

* Split TestPullRequest out of AddTestPullRequestTask
* Before scheduling the task, AddTestPullRequestTask stores the max
  index of the repository
* When the task runs, it does not take into account pull requests that
  have an index higher than the recorded max index

When AddTestPullRequestTask is called with isSync == true, it is the
direct consequence of a new commit being pushed. Forgejo knows nothing
of this new commit yet. If a PR is created later and its head
references the new commit, it will have an index that is higher and
must not be taken into account. It would be acting and triggering a
notification for a PR based on an event that happened before it
existed.

Refs: https://codeberg.org/forgejo/forgejo/issues/2009
Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/2236
Reviewed-by: Gusted <gusted@noreply.codeberg.org>
Co-authored-by: Earl Warren <contact@earl-warren.org>
Co-committed-by: Earl Warren <contact@earl-warren.org>

models/issues/issue_index.go

@@ -9,6 +9,14 @@ import (
 	"code.gitea.io/gitea/models/db"
 )
 
+func GetMaxIssueIndexForRepo(ctx context.Context, repoID int64) (int64, error) {
+	var max int64
+	if _, err := db.GetEngine(ctx).Select("MAX(`index`)").Table("issue").Where("repo_id=?", repoID).Get(&max); err != nil {
+		return 0, err
+	}
+	return max, nil
+}
+
 // RecalculateIssueIndexForRepo create issue_index for repo if not exist and
 // update it based on highest index of existing issues assigned to a repo
 func RecalculateIssueIndexForRepo(ctx context.Context, repoID int64) error {
@@ -18,8 +26,8 @@ func RecalculateIssueIndexForRepo(ctx context.Context, repoID int64) error {
 	}
 	defer committer.Close()
 
-	var max int64
-	if _, err = db.GetEngine(ctx).Select(" MAX(`index`)").Table("issue").Where("repo_id=?", repoID).Get(&max); err != nil {
+	max, err := GetMaxIssueIndexForRepo(ctx, repoID)
+	if err != nil {
 		return err
 	}
 

models/issues/issue_index_test.go

@@ -0,0 +1,38 @@
+// Copyright 2024 The Forgejo Authors
+// SPDX-License-Identifier: MIT
+
+package issues_test
+
+import (
+	"testing"
+
+	"code.gitea.io/gitea/models/db"
+	issues_model "code.gitea.io/gitea/models/issues"
+	repo_model "code.gitea.io/gitea/models/repo"
+	"code.gitea.io/gitea/models/unittest"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestGetMaxIssueIndexForRepo(t *testing.T) {
+	assert.NoError(t, unittest.PrepareTestDatabase())
+
+	repo := unittest.AssertExistsAndLoadBean(t, &repo_model.Repository{ID: 1})
+
+	maxPR, err := issues_model.GetMaxIssueIndexForRepo(db.DefaultContext, repo.ID)
+	assert.NoError(t, err)
+
+	issue := testCreateIssue(t, repo.ID, repo.OwnerID, "title1", "content1", false)
+	assert.Greater(t, issue.Index, maxPR)
+
+	maxPR, err = issues_model.GetMaxIssueIndexForRepo(db.DefaultContext, repo.ID)
+	assert.NoError(t, err)
+
+	pull := testCreateIssue(t, repo.ID, repo.OwnerID, "title2", "content2", true)
+	assert.Greater(t, pull.Index, maxPR)
+
+	maxPR, err = issues_model.GetMaxIssueIndexForRepo(db.DefaultContext, repo.ID)
+	assert.NoError(t, err)
+
+	assert.Equal(t, maxPR, pull.Index)
+}

models/issues/pull_list.go

@@ -50,6 +50,14 @@ func listPullRequestStatement(ctx context.Context, baseRepoID int64, opts *PullR
 	return sess, nil
 }
 
+func GetUnmergedPullRequestsByHeadInfoMax(ctx context.Context, repoID, maxIndex int64, branch string) ([]*PullRequest, error) {
+	prs := make([]*PullRequest, 0, 2)
+	sess := db.GetEngine(ctx).
+		Join("INNER", "issue", "issue.id = `pull_request`.issue_id").
+		Where("`pull_request`.head_repo_id = ? AND `pull_request`.head_branch = ? AND `pull_request`.has_merged = ? AND `issue`.is_closed = ? AND `pull_request`.flow = ? AND `issue`.`index` <= ?", repoID, branch, false, false, PullRequestFlowGithub, maxIndex)
+	return prs, sess.Find(&prs)
+}
+
 // GetUnmergedPullRequestsByHeadInfo returns all pull requests that are open and has not been merged
 func GetUnmergedPullRequestsByHeadInfo(ctx context.Context, repoID int64, branch string) ([]*PullRequest, error) {
 	prs := make([]*PullRequest, 0, 2)

models/issues/pull_test.go

@@ -4,6 +4,7 @@
 package issues_test
 
 import (
+	"fmt"
 	"testing"
 
 	"code.gitea.io/gitea/models/db"
@@ -158,6 +159,91 @@ func TestGetUnmergedPullRequestsByHeadInfo(t *testing.T) {
 	}
 }
 
+func TestGetUnmergedPullRequestsByHeadInfoMax(t *testing.T) {
+	assert.NoError(t, unittest.PrepareTestDatabase())
+
+	repoID := int64(1)
+	maxPR := int64(0)
+	prs, err := issues_model.GetUnmergedPullRequestsByHeadInfoMax(db.DefaultContext, repoID, maxPR, "branch2")
+	assert.NoError(t, err)
+	assert.Len(t, prs, 0)
+	maxPR, err = issues_model.GetMaxIssueIndexForRepo(db.DefaultContext, repoID)
+	assert.NoError(t, err)
+	prs, err = issues_model.GetUnmergedPullRequestsByHeadInfoMax(db.DefaultContext, repoID, maxPR, "branch2")
+	assert.NoError(t, err)
+	assert.Len(t, prs, 1)
+	for _, pr := range prs {
+		assert.Equal(t, int64(1), pr.HeadRepoID)
+		assert.Equal(t, "branch2", pr.HeadBranch)
+	}
+	pr := prs[0]
+
+	for _, testCase := range []struct {
+		table   string
+		field   string
+		id      int64
+		match   any
+		nomatch any
+	}{
+		{
+			table:   "issue",
+			field:   "is_closed",
+			id:      pr.IssueID,
+			match:   false,
+			nomatch: true,
+		},
+		{
+			table:   "pull_request",
+			field:   "flow",
+			id:      pr.ID,
+			match:   issues_model.PullRequestFlowGithub,
+			nomatch: issues_model.PullRequestFlowAGit,
+		},
+		{
+			table:   "pull_request",
+			field:   "head_repo_id",
+			id:      pr.ID,
+			match:   pr.HeadRepoID,
+			nomatch: 0,
+		},
+		{
+			table:   "pull_request",
+			field:   "head_branch",
+			id:      pr.ID,
+			match:   pr.HeadBranch,
+			nomatch: "something else",
+		},
+		{
+			table:   "pull_request",
+			field:   "has_merged",
+			id:      pr.ID,
+			match:   false,
+			nomatch: true,
+		},
+	} {
+		t.Run(testCase.field, func(t *testing.T) {
+			update := fmt.Sprintf("UPDATE `%s` SET `%s` = ? WHERE `id` = ?", testCase.table, testCase.field)
+
+			// expect no match
+			_, err = db.GetEngine(db.DefaultContext).Exec(update, testCase.nomatch, testCase.id)
+			assert.NoError(t, err)
+			prs, err = issues_model.GetUnmergedPullRequestsByHeadInfoMax(db.DefaultContext, repoID, maxPR, "branch2")
+			assert.NoError(t, err)
+			assert.Len(t, prs, 0)
+
+			// expect one match
+			_, err = db.GetEngine(db.DefaultContext).Exec(update, testCase.match, testCase.id)
+			assert.NoError(t, err)
+			prs, err = issues_model.GetUnmergedPullRequestsByHeadInfoMax(db.DefaultContext, repoID, maxPR, "branch2")
+			assert.NoError(t, err)
+			assert.Len(t, prs, 1)
+
+			// identical to the known PR
+			assert.Equal(t, pr.ID, prs[0].ID)
+		})
+	}
+}
+
 func TestGetUnmergedPullRequestsByBaseInfo(t *testing.T) {
 	assert.NoError(t, unittest.PrepareTestDatabase())
 	prs, err := issues_model.GetUnmergedPullRequestsByBaseInfo(db.DefaultContext, 1, "master")

services/pull/merge.go

@@ -181,7 +181,7 @@ func Merge(ctx context.Context, pr *issues_model.PullRequest, doer *user_model.U
 	}
 
 	defer func() {
-		go AddTestPullRequestTask(doer, pr.BaseRepo.ID, pr.BaseBranch, false, "", "")
+		AddTestPullRequestTask(ctx, doer, pr.BaseRepo.ID, pr.BaseBranch, false, "", "")
 	}()
 
 	pr.MergedCommitID, err = doMergeAndPush(ctx, pr, doer, mergeStyle, expectedHeadCommitID, message)

services/pull/pull.go

@@ -287,22 +287,39 @@ func checkForInvalidation(ctx context.Context, requests issues_model.PullRequest
 
 // AddTestPullRequestTask adds new test tasks by given head/base repository and head/base branch,
 // and generate new patch for testing as needed.
-func AddTestPullRequestTask(doer *user_model.User, repoID int64, branch string, isSync bool, oldCommitID, newCommitID string) {
-	log.Trace("AddTestPullRequestTask [head_repo_id: %d, head_branch: %s]: finding pull requests", repoID, branch)
-	graceful.GetManager().RunWithShutdownContext(func(ctx context.Context) {
+func AddTestPullRequestTask(ctx context.Context, doer *user_model.User, repoID int64, branch string, isSync bool, oldCommitID, newCommitID string) {
+	// When TestPullRequest runs it must ignore any PR with an index > maxPR because they
+	// would have been created after the goroutine started. They are in the future.
+	// This guards the following race:
+	// * commit A is pushed
+	// * goroutine starts but does not run TestPullRequest yet
+	// * a pull request with commit A as the head is created
+	// * goroutine continues and runs TestPullRequest
+	maxPR, err := issues_model.GetMaxIssueIndexForRepo(ctx, repoID)
+	if err != nil {
+		log.Error("AddTestPullRequestTask GetMaxIssueIndexForRepo(%d): %v", repoID, err)
+		return
+	}
+	log.Trace("AddTestPullRequestTask [head_repo_id: %d, head_branch: %s]: only pull requests with index <= %d will be considered", repoID, branch, maxPR)
+	go graceful.GetManager().RunWithShutdownContext(func(ctx context.Context) {
 		// There is no sensible way to shut this down ":-("
 		// If you don't let it run all the way then you will lose data
-		// TODO: graceful: AddTestPullRequestTask needs to become a queue!
+		// TODO: graceful: TestPullRequest needs to become a queue!
 
+		TestPullRequest(ctx, doer, repoID, maxPR, branch, isSync, oldCommitID, newCommitID)
+	})
+}
+
+func TestPullRequest(ctx context.Context, doer *user_model.User, repoID, maxPR int64, branch string, isSync bool, oldCommitID, newCommitID string) {
 	// GetUnmergedPullRequestsByHeadInfo() only return open and unmerged PR.
-		prs, err := issues_model.GetUnmergedPullRequestsByHeadInfo(ctx, repoID, branch)
+	prs, err := issues_model.GetUnmergedPullRequestsByHeadInfoMax(ctx, repoID, maxPR, branch)
 	if err != nil {
 		log.Error("Find pull requests [head_repo_id: %d, head_branch: %s]: %v", repoID, branch, err)
 		return
 	}
 
 	for _, pr := range prs {
-			log.Trace("Updating PR[%d]: composing new test task", pr.ID)
+		log.Trace("Updating PR[id=%d,index=%d]: composing new test task", pr.ID, pr.Index)
 		if pr.Flow == issues_model.PullRequestFlowGithub {
 			if err := PushToBaseRepo(ctx, pr); err != nil {
 				log.Error("PushToBaseRepo: %v", err)
@@ -371,7 +388,7 @@ func AddTestPullRequestTask(doer *user_model.User, repoID int64, branch string,
 		}
 	}
 
-		log.Trace("AddTestPullRequestTask [base_repo_id: %d, base_branch: %s]: finding pull requests", repoID, branch)
+	log.Trace("TestPullRequest [base_repo_id: %d, base_branch: %s]: finding pull requests", repoID, branch)
 	prs, err = issues_model.GetUnmergedPullRequestsByBaseInfo(ctx, repoID, branch)
 	if err != nil {
 		log.Error("Find pull requests [base_repo_id: %d, base_branch: %s]: %v", repoID, branch, err)
@@ -393,7 +410,6 @@ func AddTestPullRequestTask(doer *user_model.User, repoID int64, branch string,
 		}
 		AddToTaskQueue(ctx, pr)
 	}
-	})
 }
 
 // checkIfPRContentChanged checks if diff to target branch has changed by push

services/pull/update.go

@@ -36,7 +36,7 @@ func Update(ctx context.Context, pr *issues_model.PullRequest, doer *user_model.
 
 	if rebase {
 		defer func() {
-			go AddTestPullRequestTask(doer, pr.BaseRepo.ID, pr.BaseBranch, false, "", "")
+			AddTestPullRequestTask(ctx, doer, pr.BaseRepo.ID, pr.BaseBranch, false, "", "")
 		}()
 
 		return updateHeadByRebaseOnToBase(ctx, pr, doer, message)
@@ -75,7 +75,7 @@ func Update(ctx context.Context, pr *issues_model.PullRequest, doer *user_model.
 	_, err = doMergeAndPush(ctx, reversePR, doer, repo_model.MergeStyleMerge, "", message)
 
 	defer func() {
-		go AddTestPullRequestTask(doer, reversePR.HeadRepo.ID, reversePR.HeadBranch, false, "", "")
+		AddTestPullRequestTask(ctx, doer, reversePR.HeadRepo.ID, reversePR.HeadBranch, false, "", "")
 	}()
 
 	return err

services/repository/push.go

@@ -171,7 +171,7 @@ func pushUpdates(optsList []*repo_module.PushUpdateOptions) error {
 			branch := opts.RefFullName.BranchName()
 			if !opts.IsDelRef() {
 				log.Trace("TriggerTask '%s/%s' by %s", repo.Name, branch, pusher.Name)
-				go pull_service.AddTestPullRequestTask(pusher, repo.ID, branch, true, opts.OldCommitID, opts.NewCommitID)
+				pull_service.AddTestPullRequestTask(ctx, pusher, repo.ID, branch, true, opts.OldCommitID, opts.NewCommitID)
 
 				newCommit, err := gitRepo.GetCommit(opts.NewCommitID)
 				if err != nil {

tests/integration/pull_request_task_test.go

@@ -0,0 +1,86 @@
+// Copyright 2024 The Forgejo Authors
+// SPDX-License-Identifier: MIT
+
+package integration
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	issues_model "code.gitea.io/gitea/models/issues"
+	repo_model "code.gitea.io/gitea/models/repo"
+	"code.gitea.io/gitea/models/unittest"
+	user_model "code.gitea.io/gitea/models/user"
+	"code.gitea.io/gitea/modules/git"
+	"code.gitea.io/gitea/modules/log"
+	repo_module "code.gitea.io/gitea/modules/repository"
+	"code.gitea.io/gitea/modules/test"
+	pull_service "code.gitea.io/gitea/services/pull"
+	repo_service "code.gitea.io/gitea/services/repository"
+	"code.gitea.io/gitea/tests"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestPullRequestSynchronized(t *testing.T) {
+	defer tests.PrepareTestEnv(t)()
+
+	// unmerged pull request of user2/repo1 from branch2 to master
+	pull := unittest.AssertExistsAndLoadBean(t, &issues_model.PullRequest{ID: 2})
+	// tip of tests/gitea-repositories-meta/user2/repo1 branch2
+	pull.HeadCommitID = "985f0301dba5e7b34be866819cd15ad3d8f508ee"
+
+	require.Equal(t, pull.HeadRepoID, pull.BaseRepoID)
+	repo := unittest.AssertExistsAndLoadBean(t, &repo_model.Repository{ID: pull.HeadRepoID})
+	owner := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: repo.OwnerID})
+
+	t.Run("AddTestPullRequestTask", func(t *testing.T) {
+		logChecker, cleanup := test.NewLogChecker(log.DEFAULT, log.TRACE)
+		logChecker.Filter("Updating PR").StopMark("TestPullRequest ")
+		defer cleanup()
+
+		opt := &repo_module.PushUpdateOptions{
+			PusherID:     owner.ID,
+			PusherName:   owner.Name,
+			RepoUserName: owner.Name,
+			RepoName:     repo.Name,
+			RefFullName:  git.RefName("refs/heads/branch2"),
+			OldCommitID:  pull.HeadCommitID,
+			NewCommitID:  pull.HeadCommitID,
+		}
+		require.NoError(t, repo_service.PushUpdate(opt))
+		logFiltered, logStopped := logChecker.Check(5 * time.Second)
+		assert.True(t, logStopped)
+		assert.True(t, logFiltered[0])
+	})
+
+	for _, testCase := range []struct {
+		name     string
+		maxPR    int64
+		expected bool
+	}{
+		{
+			name:     "TestPullRequest process PR",
+			maxPR:    pull.Index,
+			expected: true,
+		},
+		{
+			name:     "TestPullRequest skip PR",
+			maxPR:    pull.Index - 1,
+			expected: false,
+		},
+	} {
+		t.Run(testCase.name, func(t *testing.T) {
+			logChecker, cleanup := test.NewLogChecker(log.DEFAULT, log.TRACE)
+			logChecker.Filter("Updating PR").StopMark("TestPullRequest ")
+			defer cleanup()
+
+			pull_service.TestPullRequest(context.Background(), owner, repo.ID, testCase.maxPR, "branch2", true, pull.HeadCommitID, pull.HeadCommitID)
+			logFiltered, logStopped := logChecker.Check(5 * time.Second)
+			assert.True(t, logStopped)
+			assert.Equal(t, testCase.expected, logFiltered[0])
+		})
+	}
+}