🐛 Support reused connection for better performance. (#753)

Fixes: https://issues.redhat.com/browse/MTA-4007

---------

Signed-off-by: Jeff Ortel <jortel@redhat.com>

Makefile

@@ -141,6 +141,9 @@ endif
 test:
 	go test -count=1 -v $(shell go list ./... | grep -v "hub/test")
 
+test-db:
+	go test -count=1 -timeout=6h -v ./database...
+
 # Run Hub REST API tests.
 test-api:
 	HUB_BASE_URL=$(HUB_BASE_URL) go test -count=1 -p=1 -v -failfast ./test/api/...

database/db_test.go

@@ -6,13 +6,48 @@ import (
 	"testing"
 	"time"
 
+	"github.com/konveyor/tackle2-hub/api"
 	"github.com/konveyor/tackle2-hub/model"
 	"gorm.io/gorm"
 	"k8s.io/utils/env"
 )
 
 var N, _ = env.GetInt("TEST_CONCURRENT", 10)
 
+func TestDriver(t *testing.T) {
+	pid := os.Getpid()
+	Settings.DB.Path = fmt.Sprintf("/tmp/driver-%d.db", pid)
+	defer func() {
+		_ = os.Remove(Settings.DB.Path)
+	}()
+	db, err := Open(true)
+	if err != nil {
+		panic(err)
+	}
+	key := "driver"
+	m := &model.Setting{Key: key, Value: "Test"}
+	// insert.
+	err = db.Create(m).Error
+	if err != nil {
+		panic(err)
+	}
+	// update
+	err = db.Save(m).Error
+	if err != nil {
+		panic(err)
+	}
+	// select
+	err = db.First(m, m.ID).Error
+	if err != nil {
+		panic(err)
+	}
+	// delete
+	err = db.Delete(m).Error
+	if err != nil {
+		panic(err)
+	}
+}
+
 func TestConcurrent(t *testing.T) {
 	pid := os.Getpid()
 	Settings.DB.Path = fmt.Sprintf("/tmp/concurrent-%d.db", pid)
@@ -23,12 +58,35 @@ func TestConcurrent(t *testing.T) {
 	if err != nil {
 		panic(err)
 	}
+
+	type A struct {
+		model.Model
+	}
+
+	type B struct {
+		N int
+		model.Model
+		A   A
+		AID uint
+	}
+	err = db.Migrator().AutoMigrate(&A{}, &B{})
+	if err != nil {
+		panic(err)
+	}
+
+	a := A{}
+	err = db.Create(&a).Error
+	if err != nil {
+		panic(err)
+	}
+
 	dq := make(chan int, N)
 	for w := 0; w < N; w++ {
 		go func(id int) {
 			fmt.Printf("Started %d\n", id)
-			for n := 0; n < N*10; n++ {
-				m := &model.Setting{Key: fmt.Sprintf("key-%d-%d", id, n), Value: n}
+			for n := 0; n < N*100; n++ {
+				m := &B{N: n, A: a}
+				m.CreateUser = "Test"
 				fmt.Printf("(%.4d) CREATE: %.4d\n", id, n)
 				uErr := db.Create(m).Error
 				if uErr != nil {
@@ -45,6 +103,20 @@ func TestConcurrent(t *testing.T) {
 						panic(uErr)
 					}
 				}
+				for i := 0; i < 10; i++ {
+					fmt.Printf("(%.4d) LIST: %.4d/%.4d\n", id, n, i)
+					page := api.Page{}
+					cursor := api.Cursor{}
+					mx := B{}
+					dbx := db.Model(mx)
+					dbx = dbx.Joins("A")
+					dbx = dbx.Limit(10)
+					cursor.With(dbx, page)
+					for cursor.Next(&mx) {
+						time.Sleep(time.Millisecond + 10)
+						fmt.Printf("(%.4d) NEXT: %.4d/%.4d ID=%d\n", id, n, i, mx.ID)
+					}
+				}
 				for i := 0; i < 4; i++ {
 					uErr = db.Transaction(func(tx *gorm.DB) (err error) {
 						time.Sleep(time.Millisecond * 10)