fix: avoid race condition when running AutoMigrate concurrently

cmd/woj/woj.go

@@ -37,10 +37,10 @@ func main() {
 			Action:  wrap(appServer.RunServer),
 		},
 		{
-			Name:    "init",
+			Name:    "migrate",
-			Aliases: []string{"i"},
+			Aliases: []string{"m"},
-			Usage:   "init database",
+			Usage:   "migrate database",
-			Action:  wrap(appServer.RunServerInit),
+			Action:  wrap(appServer.RunServerMigrate),
 		},
 		{
 			Name:    "runner",

internal/app/server/server.go

@@ -23,7 +23,7 @@ import (
 	"time"
 )
 
-func RunServerInit(i *do.Injector) error {
+func RunServerMigrate(i *do.Injector) error {
 	slog := do.MustInvoke[log.Service](i).GetLogger("app.server")
 
 	// Migrate and shutdown database

internal/repo/db/pg.go

@@ -7,11 +7,13 @@ import (
 	"git.0x7f.app/WOJ/woj-server/internal/misc/config"
 	"git.0x7f.app/WOJ/woj-server/internal/misc/log"
 	"git.0x7f.app/WOJ/woj-server/internal/model"
+	"git.0x7f.app/WOJ/woj-server/pkg/utils"
 	"github.com/samber/do"
 	"go.uber.org/zap"
 	"gorm.io/driver/postgres"
 	"gorm.io/gorm"
 	"gorm.io/gorm/schema"
+	"hash/fnv"
 	"moul.io/zapgorm2"
 	"time"
 )
@@ -108,11 +110,34 @@ func (s *service) setup(conf *model.Config) {
 func (s *service) migrateDatabase() {
 	s.log.Info("Auto Migrating database...")
 
+	// Running AutoMigrate concurrently on the same model fails with various race conditions
+	// https://github.com/go-gorm/gorm/pull/6680
+	// https://github.com/go-gorm/postgres/pull/224
+
+	// Obtain a lock to prevent concurrent AutoMigrate
+
+	lockID := func(s string) int64 {
+		h := fnv.New64a()
+		_, err := h.Write([]byte(s))
+		return utils.If(err != nil, int64(0x4242AA55), int64(h.Sum64()))
+	}("gorm:migrator")
+
+	s.err = s.db.Exec("SELECT pg_advisory_lock(?)", lockID).Error
+	if s.err != nil {
+		s.log.Error("Failed to obtain lock", zap.Error(s.err))
+		return
+	}
+
 	_ = s.db.AutoMigrate(&model.User{})
 	_ = s.db.AutoMigrate(&model.Problem{})
 	_ = s.db.AutoMigrate(&model.ProblemVersion{})
 	_ = s.db.AutoMigrate(&model.Submission{})
 	_ = s.db.AutoMigrate(&model.Status{})
+
+	s.err = s.db.Exec("SELECT pg_advisory_unlock(?)", lockID).Error
+	if s.err != nil {
+		s.log.Error("Failed to release lock", zap.Error(s.err))
+	}
 }
 
 func (s *service) checkAlive(retry int) (*sql.DB, error) {