summaryrefslogtreecommitdiffstats
path: root/models/db/index.go
diff options
context:
space:
mode:
Diffstat (limited to '')
-rw-r--r--models/db/index.go148
1 files changed, 148 insertions, 0 deletions
diff --git a/models/db/index.go b/models/db/index.go
new file mode 100644
index 0000000..259ddd6
--- /dev/null
+++ b/models/db/index.go
@@ -0,0 +1,148 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package db
+
+import (
+ "context"
+ "errors"
+ "fmt"
+ "strconv"
+
+ "code.gitea.io/gitea/modules/setting"
+)
+
+// ResourceIndex represents a resource index which could be used as issue/release and others
+// We can create different tables i.e. issue_index, release_index, etc.
+type ResourceIndex struct {
+ GroupID int64 `xorm:"pk"`
+ MaxIndex int64 `xorm:"index"`
+}
+
+var (
+ // ErrResouceOutdated represents an error when request resource outdated
+ ErrResouceOutdated = errors.New("resource outdated")
+ // ErrGetResourceIndexFailed represents an error when resource index retries 3 times
+ ErrGetResourceIndexFailed = errors.New("get resource index failed")
+)
+
+// SyncMaxResourceIndex sync the max index with the resource
+func SyncMaxResourceIndex(ctx context.Context, tableName string, groupID, maxIndex int64) (err error) {
+ e := GetEngine(ctx)
+
+ // try to update the max_index and acquire the write-lock for the record
+ res, err := e.Exec(fmt.Sprintf("UPDATE %s SET max_index=? WHERE group_id=? AND max_index<?", tableName), maxIndex, groupID, maxIndex)
+ if err != nil {
+ return err
+ }
+ affected, err := res.RowsAffected()
+ if err != nil {
+ return err
+ }
+ if affected == 0 {
+ // if nothing is updated, the record might not exist or might be larger, it's safe to try to insert it again and then check whether the record exists
+ _, errIns := e.Exec(fmt.Sprintf("INSERT INTO %s (group_id, max_index) VALUES (?, ?)", tableName), groupID, maxIndex)
+ var savedIdx int64
+ has, err := e.SQL(fmt.Sprintf("SELECT max_index FROM %s WHERE group_id=?", tableName), groupID).Get(&savedIdx)
+ if err != nil {
+ return err
+ }
+ // if the record still doesn't exist, there must be some errors (insert error)
+ if !has {
+ if errIns == nil {
+ return errors.New("impossible error when SyncMaxResourceIndex, insert succeeded but no record is saved")
+ }
+ return errIns
+ }
+ }
+ return nil
+}
+
+func postgresGetNextResourceIndex(ctx context.Context, tableName string, groupID int64) (int64, error) {
+ res, err := GetEngine(ctx).Query(fmt.Sprintf("INSERT INTO %s (group_id, max_index) "+
+ "VALUES (?,1) ON CONFLICT (group_id) DO UPDATE SET max_index = %s.max_index+1 RETURNING max_index",
+ tableName, tableName), groupID)
+ if err != nil {
+ return 0, err
+ }
+ if len(res) == 0 {
+ return 0, ErrGetResourceIndexFailed
+ }
+ return strconv.ParseInt(string(res[0]["max_index"]), 10, 64)
+}
+
+func mysqlGetNextResourceIndex(ctx context.Context, tableName string, groupID int64) (int64, error) {
+ if _, err := GetEngine(ctx).Exec(fmt.Sprintf("INSERT INTO %s (group_id, max_index) "+
+ "VALUES (?,1) ON DUPLICATE KEY UPDATE max_index = max_index+1",
+ tableName), groupID); err != nil {
+ return 0, err
+ }
+
+ var idx int64
+ _, err := GetEngine(ctx).SQL(fmt.Sprintf("SELECT max_index FROM %s WHERE group_id = ?", tableName), groupID).Get(&idx)
+ if err != nil {
+ return 0, err
+ }
+ if idx == 0 {
+ return 0, errors.New("cannot get the correct index")
+ }
+ return idx, nil
+}
+
+// GetNextResourceIndex generates a resource index, it must run in the same transaction where the resource is created
+func GetNextResourceIndex(ctx context.Context, tableName string, groupID int64) (int64, error) {
+ switch {
+ case setting.Database.Type.IsPostgreSQL():
+ return postgresGetNextResourceIndex(ctx, tableName, groupID)
+ case setting.Database.Type.IsMySQL():
+ return mysqlGetNextResourceIndex(ctx, tableName, groupID)
+ }
+
+ e := GetEngine(ctx)
+
+ // try to update the max_index to next value, and acquire the write-lock for the record
+ res, err := e.Exec(fmt.Sprintf("UPDATE %s SET max_index=max_index+1 WHERE group_id=?", tableName), groupID)
+ if err != nil {
+ return 0, err
+ }
+ affected, err := res.RowsAffected()
+ if err != nil {
+ return 0, err
+ }
+ if affected == 0 {
+ // this slow path is only for the first time of creating a resource index
+ _, errIns := e.Exec(fmt.Sprintf("INSERT INTO %s (group_id, max_index) VALUES (?, 0)", tableName), groupID)
+ res, err = e.Exec(fmt.Sprintf("UPDATE %s SET max_index=max_index+1 WHERE group_id=?", tableName), groupID)
+ if err != nil {
+ return 0, err
+ }
+ affected, err = res.RowsAffected()
+ if err != nil {
+ return 0, err
+ }
+ // if the update still can not update any records, the record must not exist and there must be some errors (insert error)
+ if affected == 0 {
+ if errIns == nil {
+ return 0, errors.New("impossible error when GetNextResourceIndex, insert and update both succeeded but no record is updated")
+ }
+ return 0, errIns
+ }
+ }
+
+ // now, the new index is in database (protected by the transaction and write-lock)
+ var newIdx int64
+ has, err := e.SQL(fmt.Sprintf("SELECT max_index FROM %s WHERE group_id=?", tableName), groupID).Get(&newIdx)
+ if err != nil {
+ return 0, err
+ }
+ if !has {
+ return 0, errors.New("impossible error when GetNextResourceIndex, upsert succeeded but no record can be selected")
+ }
+ return newIdx, nil
+}
+
+// DeleteResourceIndex delete resource index
+func DeleteResourceIndex(ctx context.Context, tableName string, groupID int64) error {
+ _, err := Exec(ctx, fmt.Sprintf("DELETE FROM %s WHERE group_id=?", tableName), groupID)
+ return err
+}