Add keepalives support

conn.go

@@ -1068,6 +1068,8 @@ func isDriverSetting(key string) bool {
 		return true
 	case "fallback_application_name":
 		return true
+	case "keepalives", "keepalives_interval":
+		return true
 	case "connect_timeout":
 		return true
 	case "disable_prepared_binary_result":

connector.go

@@ -5,8 +5,11 @@ import (
 	"database/sql/driver"
 	"errors"
 	"fmt"
+	"net"
 	"os"
+	"strconv"
 	"strings"
+	"time"
 )
 
 // Connector represents a fixed configuration for the pq driver with a given
@@ -107,9 +110,41 @@ func NewConnector(dsn string) (*Connector, error) {
 	}
 
 	// SSL is not necessary or supported over UNIX domain sockets
-	if network, _ := network(o); network == "unix" {
+	ntw, _ := network(o)
+	if ntw == "unix" {
 		o["sslmode"] = "disable"
 	}
 
-	return &Connector{opts: o, dialer: defaultDialer{}}, nil
+	var d net.Dialer
+	if ntw == "tcp" {
+		d.KeepAlive, err = keepalive(o)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	return &Connector{opts: o, dialer: defaultDialer{d}}, nil
+}
+
+// keepalive returns the interval between keep-alive probes controlled by keepalives_interval.
+// If zero, keep-alive probes are sent with a default value (see net.Dialer).
+// If negative, keep-alive probes are disabled.
+//
+// The keepalives parameter controls whether client-side TCP keepalives are used.
+// The default value is 1, meaning on, but you can change this to 0, meaning off, if keepalives are not wanted.
+func keepalive(o values) (time.Duration, error) {
+	v, ok := o["keepalives"]
+	if v == "0" {
+		return -1, nil
+	}
+
+	if v, ok = o["keepalives_interval"]; !ok {
+		return 0, nil
+	}
+
+	keepintvl, err := strconv.ParseInt(v, 10, 0)
+	if err != nil {
+		return 0, fmt.Errorf("invalid value for parameter keepalives_interval: %w", err)
+	}
+	return time.Duration(keepintvl) * time.Second, nil
 }

connector_test.go

@@ -6,7 +6,10 @@ import (
 	"context"
 	"database/sql"
 	"database/sql/driver"
+	"errors"
+	"strconv"
 	"testing"
+	"time"
 )
 
 func TestNewConnector_WorksWithOpenDB(t *testing.T) {
@@ -65,3 +68,70 @@ func TestNewConnector_Driver(t *testing.T) {
 	}
 	txn.Rollback()
 }
+
+func TestNewConnectorKeepalive(t *testing.T) {
+	c, err := NewConnector("keepalives=1 keepalives_interval=10")
+	if err != nil {
+		t.Fatal(err)
+	}
+	db := sql.OpenDB(c)
+	defer db.Close()
+	// database/sql might not call our Open at all unless we do something with
+	// the connection
+	txn, err := db.Begin()
+	if err != nil {
+		t.Fatal(err)
+	}
+	txn.Rollback()
+
+	d, _ := c.dialer.(defaultDialer)
+	want := 10 * time.Second
+	if want != d.d.KeepAlive {
+		t.Fatalf("expected: %v, got: %v", want, d.d.KeepAlive)
+	}
+}
+
+func TestKeepalive(t *testing.T) {
+	var tt = map[string]struct {
+		input values
+		want  time.Duration
+	}{
+		"keepalives on":                 {values{"keepalives": "1"}, 0},
+		"keepalives on by default":      {nil, 0},
+		"keepalives off":                {values{"keepalives": "0"}, -1},
+		"keepalives_interval 5 seconds": {values{"keepalives_interval": "5"}, 5 * time.Second},
+		"keepalives_interval default":   {values{"keepalives_interval": "0"}, 0},
+		"keepalives_interval off":       {values{"keepalives_interval": "-1"}, -1 * time.Second},
+	}
+
+	for name, tc := range tt {
+		t.Run(name, func(t *testing.T) {
+			got, err := keepalive(tc.input)
+			if err != nil {
+				t.Fatal(err)
+			}
+			if tc.want != got {
+				t.Fatalf("expected: %v, got: %v", tc.want, got)
+			}
+		})
+	}
+}
+
+func TestKeepaliveError(t *testing.T) {
+	var tt = map[string]struct {
+		input values
+		want  error
+	}{
+		"keepalives_interval whitespace": {values{"keepalives_interval": " "}, strconv.ErrSyntax},
+		"keepalives_interval float":      {values{"keepalives_interval": "1.1"}, strconv.ErrSyntax},
+	}
+
+	for name, tc := range tt {
+		t.Run(name, func(t *testing.T) {
+			_, err := keepalive(tc.input)
+			if !errors.Is(err, tc.want) {
+				t.Fatalf("expected: %v, got: %v", tc.want, err)
+			}
+		})
+	}
+}

doc.go

@@ -51,6 +51,12 @@ supported:
 	* sslmode - Whether or not to use SSL (default is require, this is not
 	  the default for libpq)
 	* fallback_application_name - An application_name to fall back to if one isn't provided.
+	* keepalives - Whether or not to use client-side TCP keepalives
+	  (the default value is 1, meaning on, but you can change this to 0, meaning off)
+	* keepalives_interval - The number of seconds after which a TCP keepalive message
+	  that is not acknowledged by the server should be retransmitted.
+	  If zero or not specified, keep-alive probes are sent with a default value (see net.Dialer).
+	  If negative, keep-alive probes are disabled.
 	* connect_timeout - Maximum wait for connection, in seconds. Zero or
 	  not specified means wait indefinitely.
 	* sslcert - Cert file location. The file must contain PEM encoded data.