sqlds - Allow ctx mod (#127)

* adds QueryDataMutator hook

* adds checkhealth pre-hook

* checkhealthmutator

Author: shelldandy

datasource.go

@@ -98,6 +98,10 @@ func (ds *SQLDatasource) QueryData(ctx context.Context, req *backend.QueryDataRe
 
 	wg.Add(len(req.Queries))
 
+	if queryDataMutator, ok := ds.driver().(QueryDataMutator); ok {
+		ctx, req = queryDataMutator.MutateQueryData(ctx, req)
+	}
+
 	// Execute each query and store the results by query RefID
 	for _, q := range req.Queries {
 		go func(query backend.DataQuery) {
@@ -243,6 +247,9 @@ func (ds *SQLDatasource) handleQuery(ctx context.Context, req backend.DataQuery,
 
 // CheckHealth pings the connected SQL database
 func (ds *SQLDatasource) CheckHealth(ctx context.Context, req *backend.CheckHealthRequest) (*backend.CheckHealthResult, error) {
+	if checkHealthMutator, ok := ds.driver().(CheckHealthMutator); ok {
+		ctx, req = checkHealthMutator.MutateCheckHealth(ctx, req)
+	}
 	healthChecker := &HealthChecker{
 		Connector: ds.connector,
 		Metrics:   ds.metrics.WithEndpoint(EndpointHealth),

driver.go

@@ -42,6 +42,19 @@ type Connection interface {
 	QueryContext(ctx context.Context, query string, args ...interface{}) (*sql.Rows, error)
 }
 
+// QueryDataMutator  is an additional interface that could be implemented by driver.
+// This adds ability to the driver to optionally mutate the query before it's run
+// with the QueryDataRequest.
+type QueryDataMutator interface {
+	MutateQueryData(ctx context.Context, req *backend.QueryDataRequest) (context.Context, *backend.QueryDataRequest)
+}
+
+// CheckHealthMutator  is an additional interface that could be implemented by driver.
+// This adds ability to the driver to optionally mutate the CheckHealth before it's run
+type CheckHealthMutator interface {
+	MutateCheckHealth(ctx context.Context, req *backend.CheckHealthRequest) (context.Context, *backend.CheckHealthRequest)
+}
+
 // QueryMutator is an additional interface that could be implemented by driver.
 // This adds ability to the driver it can mutate query before run.
 type QueryMutator interface {