Adds function to wrap a driver.Conn directly (#25)

- Adds function to wrap a driver.Conn directly
- Readme example of wrapping a driver.Conn
- Updated readme with vanity import url

Author: basvanbeek

README.md

@@ -1,14 +1,18 @@
 # ocsql
 
-[![Go Report Card](https://goreportcard.com/badge/github.com/opencensus-integrations/ocsql)](https://goreportcard.com/report/github.com/opencensus-integrations/ocsql)
-[![GoDoc](https://godoc.org/github.com/opencensus-integrations/ocsql?status.svg)](https://godoc.org/github.com/opencensus-integrations/ocsql)
+[![Go Report Card](https://goreportcard.com/badge/contrib.go.opencensus.io/integrations/ocsql)](https://goreportcard.com/report/contrib.go.opencensus.io/integrations/ocsql)
+[![GoDoc](https://godoc.org/contrib.go.opencensus.io/integrations/ocsql?status.svg)](https://godoc.org/contrib.go.opencensus.io/integrations/ocsql)
 [![Sourcegraph](https://sourcegraph.com/github.com/opencensus-integrations/ocsql/-/badge.svg)](https://sourcegraph.com/github.com/opencensus-integrations/ocsql?badge)
 
 OpenCensus SQL database driver wrapper.
 
 Add an ocsql wrapper to your existing database code to instrument the
 interactions with the database.
 
+## installation
+
+go get -u contrib.go.opencensus.io/integrations/ocsql
+
 ## initialize
 
 To use ocsql with your application, register an ocsql wrapper of a database
@@ -18,7 +22,7 @@ Example:
 ```go
 import (
     _ "github.com/mattn/go-sqlite3"
-    "github.com/opencensus-integrations/ocsql"
+    "contrib.go.opencensus.io/integrations/ocsql"
 )
 
 var (
@@ -45,7 +49,7 @@ Example:
 ```go
 import (
     sqlite3 "github.com/mattn/go-sqlite3"
-    "github.com/opencensus-integrations/ocsql"
+    "contrib.go.opencensus.io/integrations/ocsql"
 )
 
 var (
@@ -64,6 +68,22 @@ sql.Register("ocsql-sqlite3", driver)
 db, err = sql.Open("ocsql-sqlite3", "resource.db")
 ```
 
+Projects providing their own abstractions on top of database/sql/driver can also
+wrap an existing driver.Conn interface directly with ocsql.
+
+Example:
+```go
+import "contrib.go.opencensus.io/integrations/ocsql"
+
+func GetConn(...) driver.Conn {
+    // create custom driver.Conn
+    conn := initializeConn(...)
+
+    // wrap with ocsql
+    return ocsql.WrapConn(conn, ocsql.WithAllTraceOptions())    
+}
+```
+
 ## jmoiron/sqlx
 
 If using the `sqlx` library with named queries you will need to use the

driver.go

@@ -89,6 +89,7 @@ func Wrap(d driver.Driver, options ...TraceOption) driver.Driver {
 	return wrapDriver(d, o)
 }
 
+// Open implements driver.Driver
 func (d ocDriver) Open(name string) (driver.Conn, error) {
 	c, err := d.parent.Open(name)
 	if err != nil {
@@ -97,6 +98,15 @@ func (d ocDriver) Open(name string) (driver.Conn, error) {
 	return wrapConn(c, d.options), nil
 }
 
+// WrapConn allows an existing driver.Conn to be wrapped by ocsql.
+func WrapConn(c driver.Conn, options ...TraceOption) driver.Conn {
+	o := TraceOptions{}
+	for _, option := range options {
+		option(&o)
+	}
+	return wrapConn(c, o)
+}
+
 // ocConn implements driver.Conn
 type ocConn struct {
 	parent  driver.Conn