database/sql: allow OpenConnector in a driver.Driver interface

While driver.Connector was previously added to allow non-string
connection arguments and access to the context, most users of
the sql package will continue to rely on a string DSN.

Allow drivers to implement a string DSN to Connector interface
that both allows a single parsing of the string DSN and uses
the Connector interface which passes available context to
the driver dialer.

Fixes #22713

Change-Id: Ia0b862262f4c4670effe2538d0d6d43733fea18d
Reviewed-on: https://go-review.googlesource.com/77550
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>

1 files changed, 8 insertions, 0 deletions

diff --git a/src/database/sql/sql.go b/src/database/sql/sql.go
index 30b4ad3609..1192eaae26 100644
--- a/src/database/sql/sql.go
+++ b/src/database/sql/sql.go
@@ -662,6 +662,14 @@ func Open(driverName, dataSourceName string) (*DB, error) {
 		return nil, fmt.Errorf("sql: unknown driver %q (forgotten import?)", driverName)
 	}
 
+	if driverCtx, ok := driveri.(driver.DriverContext); ok {
+		connector, err := driverCtx.OpenConnector(dataSourceName)
+		if err != nil {
+			return nil, err
+		}
+		return OpenDB(connector), nil
+	}
+
 	return OpenDB(dsnConnector{dsn: dataSourceName, driver: driveri}), nil
 }