Load balance policy

We can indicate a special load balance policy when we create engine group. There are 5 load balances on xorm. They are RandomPolicy, WeightRandomPolicy, RoundRobinPolicy, WeightRoundRobinPolicy and LeastConnPolicy. You can also implement yourself policy according GroupPolicy interface.

RandomPolicy

1. import (
2. _ "github.com/lib/pq"
3. "xorm.io/xorm"
4. )

6. var eg *xorm.EngineGroup

8. func main() {
9. conns := []string{
10. "postgres://postgres:[email protected]:5432/test?sslmode=disable;",
11. "postgres://postgres:[email protected]:5432/test1?sslmode=disable;",
12. "postgres://postgres:[email protected]:5432/test2?sslmode=disable",
13. }

15. var err error
16. eg, err = xorm.NewEngineGroup("postgres", conns, xorm.RandomPolicy())
17. }

WeightRandomPolicy

1. import (
2. _ "github.com/lib/pq"
3. "xorm.io/xorm"
4. )

6. var eg *xorm.EngineGroup

8. func main() {
9. conns := []string{
10. "postgres://postgres:[email protected]:5432/test?sslmode=disable;",
11. "postgres://postgres:[email protected]:5432/test1?sslmode=disable;",
12. "postgres://postgres:[email protected]:5432/test2?sslmode=disable",
13. }

15. var err error
16. // set the weights
17. eg, err = xorm.NewEngineGroup("postgres", conns, xorm.WeightRandomPolicy([]int{2, 3}))
18. }

RoundRobinPolicy

1. import (
2. _ "github.com/lib/pq"
3. "xorm.io/xorm"
4. )

6. var eg *xorm.EngineGroup

8. func main() {
9. conns := []string{
10. "postgres://postgres:[email protected]:5432/test?sslmode=disable;",
11. "postgres://postgres:[email protected]:5432/test1?sslmode=disable;",
12. "postgres://postgres:[email protected]:5432/test2?sslmode=disable",
13. }

15. var err error
16. eg, err = xorm.NewEngineGroup("postgres", conns, xorm.RoundRobinPolicy())
17. }

WeightRoundRobinPolicy

1. import (
2. _ "github.com/lib/pq"
3. "xorm.io/xorm"
4. )

6. var eg *xorm.EngineGroup

8. func main() {
9. conns := []string{
10. "postgres://postgres:[email protected]:5432/test?sslmode=disable;",
11. "postgres://postgres:[email protected]:5432/test1?sslmode=disable;",
12. "postgres://postgres:[email protected]:5432/test2?sslmode=disable",
13. }

15. var err error
16. // set the weights
17. eg, err = xorm.NewEngineGroup("postgres", conns, xorm.WeightRoundRobinPolicy([]int{2, 3}))
18. }

LeastConnPolicy

1. import (
2. _ "github.com/lib/pq"
3. "xorm.io/xorm"
4. )

6. var eg *xorm.EngineGroup

8. func main() {
9. conns := []string{
10. "postgres://postgres:[email protected]:5432/test?sslmode=disable;",
11. "postgres://postgres:[email protected]:5432/test1?sslmode=disable;",
12. "postgres://postgres:[email protected]:5432/test2?sslmode=disable",
13. }

15. var err error
16. eg, err = xorm.NewEngineGroup("postgres", conns, xorm.LeastConnPolicy())
17. }

Customerize Policy

You can also implement yourself policy according GroupPolicy interface.

1. type GroupPolicy interface {
2. Slave(*EngineGroup) *Engine
3. }