parseDSN: support connection pool settings (#1082) (#1084)

* parseDSN: support connection pool settings (#1082)

* add unit test

---------

Co-authored-by: Kuba Kaflik <kuba.kaflik@clickhouse.com>

clickhouse_options.go

@@ -266,6 +266,24 @@ func (o *Options) fromDSN(in string) error {
 			case "round_robin":
 				o.ConnOpenStrategy = ConnOpenRoundRobin
 			}
+		case "max_open_conns":
+			maxOpenConns, err := strconv.Atoi(params.Get(v))
+			if err != nil {
+				return errors.Wrap(err, "max_open_conns invalid value")
+			}
+			o.MaxOpenConns = maxOpenConns
+		case "max_idle_conns":
+			maxIdleConns, err := strconv.Atoi(params.Get(v))
+			if err != nil {
+				return errors.Wrap(err, "max_idle_conns invalid value")
+			}
+			o.MaxIdleConns = maxIdleConns
+		case "conn_max_lifetime":
+			connMaxLifetime, err := time.ParseDuration(params.Get(v))
+			if err != nil {
+				return errors.Wrap(err, "conn_max_lifetime invalid value")
+			}
+			o.ConnMaxLifetime = connMaxLifetime
 		case "username":
 			o.Auth.Username = params.Get(v)
 		case "password":

clickhouse_options_test.go

@@ -20,6 +20,7 @@ package clickhouse
 import (
 	"crypto/tls"
 	"testing"
+	"time"
 
 	"github.com/stretchr/testify/assert"
 )
@@ -449,6 +450,23 @@ func TestParseDSN(t *testing.T) {
 			},
 			"",
 		},
+		{
+			"client connection pool settings",
+			"clickhouse://127.0.0.1/test_database?max_open_conns=-1&max_idle_conns=0&conn_max_lifetime=1h",
+			&Options{
+				Protocol:        Native,
+				MaxOpenConns:    -1,
+				MaxIdleConns:    0,
+				ConnMaxLifetime: time.Hour,
+				Addr:            []string{"127.0.0.1"},
+				Settings:        Settings{},
+				Auth: Auth{
+					Database: "test_database",
+				},
+				scheme: "clickhouse",
+			},
+			"",
+		},
 	}
 
 	for _, testCase := range testCases {