instrumentDriver() register wrapped driver per driver instead of per connection

[sio4]

The function instrumentDriver() registers a custom SQL driver with sql.Register() and it uses a decorated driver name as something like instrumented-sql-driver-sqlite3 which is based on the driver name but actually it used wrapper options per connection. So if there are two or more connections with the same driver, only one wrapped driver will be registered with the wrapper option of the first successful connection.

The purpose of the wrapped driver is to support logging, tracing, etc. and those actions can be applied to each connection with different settings.

pop/connection_instrumented.go

Line 17 in d146f1b

func instrumentDriver(deets *ConnectionDetails, defaultDriverName string) (driverName, dialect string, err error) {

See this and the following comments for more details.

Related Issues or PRs

• Support SQL instrumentation with Open Census, Open Tracing, AWS Xray, Google Stack Driver #599
• fix: add lock to registering instrumented drivers #722

[zepatrik]

I guess one option to consider would be to not register the instrumented drivers in the first place. After looking a bit through the code, it would be easily possible to just not register them. There is only two usages of sql.Open:

1. pop/dialect_sqlite.go

   Line 355 in d146f1b

   db, err := sql.Open(nameSQLite3, ":memory:?cache=newSQLiteDriver_temporary")

   I think this is just a helper to determine whether the sqlite driver is registered

2. pop/connection_instrumented.go

   Line 86 in d146f1b

   con, err := sql.Open(driverName, dsn)

   which is the single point of opening a driver in the first place

Instead of using sql.Open, it would be possible to just get the driver, potentially wrap it, and then use sql.OpenDB instead (essentially re-implement what sql.Open does, with the driver as a parameter).