Cache PullRequest Divergence (#10914)

* Cache PullRequest Divergence

* only re-calc divergence if AddTestPullRequestTask() is exec

* migrate already open pulls

* finalize

* take care of closed&not-merged+deleted-branch pull requests

* fix nil pointer exeption

Signed-off-by: 6543 <6543@obermui.de>

* try this

* no error its a warn

* init gitea-repositories-meta

* dont use gitDivergence type

* CI.restart()

* CI.restart()

* CI.restart()

* CI.restart()

* check IsUserAllowedToUpdate independend from CommitsBehind

3 files changed, 88 insertions, 0 deletions

diff --git a/models/migrations/migrations.go b/models/migrations/migrations.go
index cad7f05f15..e1d46236a9 100644
--- a/models/migrations/migrations.go
+++ b/models/migrations/migrations.go
@@ -204,6 +204,8 @@ var migrations = []Migration{
 	NewMigration("Refix merge base for merged pull requests", refixMergeBase),
 	// v135 -> 136
 	NewMigration("Add OrgID column to Labels table", addOrgIDLabelColumn),
+	// v136 -> 137
+	NewMigration("Add CommitsAhead and CommitsBehind Column to PullRequest Table", addCommitDivergenceToPulls),
 }
 
 // GetCurrentDBVersion returns the current db version
diff --git a/models/migrations/v136.go b/models/migrations/v136.go
new file mode 100644
index 0000000000..115861f344
--- /dev/null
+++ b/models/migrations/v136.go
@@ -0,0 +1,69 @@
+// Copyright 2020 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package migrations
+
+import (
+	"fmt"
+
+	"code.gitea.io/gitea/models"
+	"code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/modules/setting"
+	pull_service "code.gitea.io/gitea/services/pull"
+
+	"xorm.io/xorm"
+)
+
+func addCommitDivergenceToPulls(x *xorm.Engine) error {
+
+	if err := x.Sync2(new(models.PullRequest)); err != nil {
+		return fmt.Errorf("Sync2: %v", err)
+	}
+
+	var last int
+	batchSize := setting.Database.IterateBufferSize
+	sess := x.NewSession()
+	defer sess.Close()
+	for {
+		if err := sess.Begin(); err != nil {
+			return err
+		}
+		var results = make([]*models.PullRequest, 0, batchSize)
+		err := sess.Where("has_merged = ?", false).OrderBy("id").Limit(batchSize, last).Find(&results)
+		if err != nil {
+			return err
+		}
+		if len(results) == 0 {
+			break
+		}
+		last += len(results)
+
+		for _, pr := range results {
+			divergence, err := pull_service.GetDiverging(pr)
+			if err != nil {
+				if err = pr.LoadIssue(); err != nil {
+					return fmt.Errorf("pr.LoadIssue()[%d]: %v", pr.ID, err)
+				}
+				if !pr.Issue.IsClosed {
+					return fmt.Errorf("GetDiverging: %v", err)
+				}
+				log.Warn("Could not recalculate Divergence for pull: %d", pr.ID)
+				pr.CommitsAhead = 0
+				pr.CommitsBehind = 0
+			}
+			if divergence != nil {
+				pr.CommitsAhead = divergence.Ahead
+				pr.CommitsBehind = divergence.Behind
+			}
+			if _, err = sess.ID(pr.ID).Cols("commits_ahead", "commits_behind").Update(pr); err != nil {
+				return fmt.Errorf("Update Cols: %v", err)
+			}
+		}
+
+		if err := sess.Commit(); err != nil {
+			return err
+		}
+	}
+	return nil
+}
diff --git a/models/pull.go b/models/pull.go
index 055f9bbc6e..9f1f485266 100644
--- a/models/pull.go
+++ b/models/pull.go
@@ -42,6 +42,8 @@ type PullRequest struct {
 	Type            PullRequestType
 	Status          PullRequestStatus
 	ConflictedFiles []string `xorm:"TEXT JSON"`
+	CommitsAhead    int
+	CommitsBehind   int
 
 	IssueID int64  `xorm:"INDEX"`
 	Issue   *Issue `xorm:"-"`
@@ -615,6 +617,21 @@ func (pr *PullRequest) GetWorkInProgressPrefix() string {
 	return ""
 }
 
+// UpdateCommitDivergence update Divergence of a pull request
+func (pr *PullRequest) UpdateCommitDivergence(ahead, behind int) error {
+	return pr.updateCommitDivergence(x, ahead, behind)
+}
+
+func (pr *PullRequest) updateCommitDivergence(e Engine, ahead, behind int) error {
+	if pr.ID == 0 {
+		return fmt.Errorf("pull ID is 0")
+	}
+	pr.CommitsAhead = ahead
+	pr.CommitsBehind = behind
+	_, err := e.ID(pr.ID).Cols("commits_ahead", "commits_behind").Update(pr)
+	return err
+}
+
 // IsSameRepo returns true if base repo and head repo is the same
 func (pr *PullRequest) IsSameRepo() bool {
 	return pr.BaseRepoID == pr.HeadRepoID