internal/database: wrap OpenCensus sql driver

The datbase/sql package provides a way to get at the underlying driver's
connection. We will need that feature to access pgx's fast CopyFrom
method.

Unfortunately, we do not use the pgx driver directly. Instead, we wrap
it in an OpenCensus driver for tracing and metrics. And that
OpenCensus driver's connection does not allow us to dig into _it_ to
retrieve the pgx connection that it wraps.

Hence this dance: we must write our own driver and connection
implementations.  The driver return the connection, and the connection
holds both the underlying (pgx) connection and the OpenCensus
connection, to which it delegates.

This CL is a no-op; everything behaves as before. But it lays the
groundwork for a subsequent CL that will use pgx's CopyFrom.

Change-Id: I5bf308aa23f07f20d1f6410ebb04cd6b9a5e0922
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/304630
Trust: Jonathan Amsterdam <jba@google.com>
Run-TryBot: Jonathan Amsterdam <jba@google.com>
TryBot-Result: kokoro <noreply+kokoro@google.com>
Reviewed-by: Julie Qiu <julie@golang.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/cmd/internal/cmdconfig/cmdconfig.go b/cmd/internal/cmdconfig/cmdconfig.go
index e9d915b6..9600f925 100644
--- a/cmd/internal/cmdconfig/cmdconfig.go
+++ b/cmd/internal/cmdconfig/cmdconfig.go
@@ -98,8 +98,8 @@ func ExperimentGetter(ctx context.Context, cfg *config.Config) middleware.Experi
 func OpenDB(ctx context.Context, cfg *config.Config, bypassLicenseCheck bool) (_ *postgres.DB, err error) {
 	defer derrors.Wrap(&err, "cmdconfig.OpenDB(ctx, cfg)")
 
-	// Wrap the postgres driver with OpenCensus instrumentation.
-	ocDriver, err := ocsql.Register(cfg.DBDriver, ocsql.WithAllTraceOptions())
+	// Wrap the postgres driver with our own wrapper, which adds OpenCensus instrumentation.
+	ocDriver, err := database.RegisterOCWrapper(cfg.DBDriver, ocsql.WithAllTraceOptions())
 	if err != nil {
 		return nil, fmt.Errorf("unable to register the ocsql driver: %v", err)
 	}