Merge pull request #423 from hmmftg/master

hide DBOutput to decrease complexity

dbms/output.go

@@ -1,27 +1,91 @@
 package dbms
 
 import (
+	"context"
 	"database/sql"
-	go_ora "github.com/sijms/go-ora/v2"
+	"fmt"
 	"io"
+
+	go_ora "github.com/sijms/go-ora/v2"
 )
 
 type DBOutput struct {
 	bufferSize int
 	conn       *sql.DB
 }
 
+const (
+	MaxBufferSize = 0x7FFF
+	MinBufferSize = 2000
+	KeyInContext  = "GO-ORA.DBMS_OUTPUT"
+)
+
+// enable oracle output for current session
+// param:
+//
+//	ctx: context of goroutine used in large apps
+//	     for main: context.Background()
+//	     for rest apis:
+//	       http.Request.Context()
+//	       gin.Context
+//	       fiber.Ctx.Context()
+//	       ...
+func EnableOutput(ctx context.Context, conn *sql.DB) error {
+	out, err := NewOutput(conn, MaxBufferSize)
+	if err != nil {
+		return err
+	}
+	context.WithValue(ctx, KeyInContext, out)
+	return nil
+}
+
+// disable oracle output for current session
+func DisableOutput(ctx context.Context) error {
+	out := ctx.Value(KeyInContext)
+	if out == nil {
+		return fmt.Errorf("invalid context")
+	}
+	err := out.(*DBOutput).Close()
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+// get oracle output for current session
+func GetOutput(ctx context.Context) (string, error) {
+	out := ctx.Value(KeyInContext)
+	if out == nil {
+		return "", fmt.Errorf("invalid context")
+	}
+	output, err := out.(*DBOutput).GetOutput()
+	if err != nil {
+		return "", err
+	}
+	return output, nil
+}
+
+// print oracle output into StringWriter for current session
+func PrintOutput(ctx context.Context, w io.StringWriter) error {
+	output, err := GetOutput(ctx)
+	if err != nil {
+		return err
+	}
+	_, err = w.WriteString(output)
+	return err
+}
+
 func NewOutput(conn *sql.DB, bufferSize int) (*DBOutput, error) {
 	output := &DBOutput{
 		bufferSize: bufferSize,
 		conn:       conn,
 	}
 	sqlText := `begin dbms_output.enable(:1); end;`
-	if output.bufferSize > 0x7FFF {
-		output.bufferSize = 0x7FFF
+	if output.bufferSize > MaxBufferSize {
+		output.bufferSize = MaxBufferSize
 	}
-	if output.bufferSize < 2000 {
-		output.bufferSize = 2000
+	if output.bufferSize < MinBufferSize {
+		output.bufferSize = MinBufferSize
 	}
 	_, err := output.conn.Exec(sqlText, bufferSize)
 	return output, err
@@ -55,7 +119,7 @@ end;`
 		state  int
 		output string
 	)
-	_, err := db_out.conn.Exec(sqlText, 0x7FFF, go_ora.Out{Dest: &state},
+	_, err := db_out.conn.Exec(sqlText, MaxBufferSize, go_ora.Out{Dest: &state},
 		go_ora.Out{Dest: &output, Size: db_out.bufferSize})
 	return output, err
 }

examples/dbms_output/main.go

@@ -1,11 +1,13 @@
 package main
 
 import (
+	"context"
 	"database/sql"
 	"fmt"
+	"os"
+
 	"github.com/sijms/go-ora/dbms"
 	_ "github.com/sijms/go-ora/v2"
-	"os"
 )
 
 func exec_simple_conn(conn *sql.DB, texts ...string) error {
@@ -18,53 +20,99 @@ func exec_simple_conn(conn *sql.DB, texts ...string) error {
 	}
 	return err
 }
-func main() {
-	conn, err := sql.Open("oracle", os.Getenv("DSN"))
+
+func addOutput(conn *sql.DB, data string) error {
+	return exec_simple_conn(conn, fmt.Sprintf(`--sql
+		BEGIN
+			DBMS_OUTPUT.PUT_LINE('%s');
+		END;
+	`, data))
+}
+
+func withoutContext(conn *sql.DB) {
+	output, err := dbms.NewOutput(conn, 0x7FFF)
 	if err != nil {
-		fmt.Println("error in connection: ", err)
+		fmt.Println("can't init DBMS_OUTPUT: ", err)
 		return
 	}
 	defer func() {
-		err = conn.Close()
+		err = output.Close()
 		if err != nil {
-			fmt.Println("error in close: ", err)
+			fmt.Println("can't end dbms_output: ", err)
 		}
 	}()
-	output, err := dbms.NewOutput(conn, 0x7FFF)
+	err = addOutput(conn, "test1")
+	if err != nil {
+		fmt.Println("can't write output: ", err)
+		return
+	}
+	line, err := output.GetOutput()
+	if err != nil {
+		fmt.Println("can't get output: ", err)
+		return
+	}
+	fmt.Print(line)
+	err = addOutput(conn, "test2")
+	if err != nil {
+		fmt.Println("can't write output: ", err)
+		return
+	}
+	err = output.Print(os.Stdout)
+	if err != nil {
+		fmt.Println("can't print: ", err)
+		return
+	}
+}
+
+func withContext(conn *sql.DB, ctx context.Context) {
+	err := dbms.EnableOutput(ctx, conn)
 	if err != nil {
 		fmt.Println("can't init DBMS_OUTPUT: ", err)
 		return
 	}
 	defer func() {
-		err = output.Close()
+		err = dbms.DisableOutput(ctx)
 		if err != nil {
 			fmt.Println("can't end dbms_output: ", err)
 		}
 	}()
-	err = exec_simple_conn(conn, `BEGIN
-DBMS_OUTPUT.PUT_LINE('this is a test');
-END;`)
+	err = addOutput(conn, "test1")
 	if err != nil {
 		fmt.Println("can't write output: ", err)
 		return
 	}
-	line, err := output.GetOutput()
+	output, err := dbms.GetOutput(ctx)
 	if err != nil {
 		fmt.Println("can't get output: ", err)
 		return
 	}
-	fmt.Print(line)
-	err = exec_simple_conn(conn, `BEGIN
-DBMS_OUTPUT.PUT_LINE('this is a test2');
-END;`)
+	fmt.Print(output)
+	err = addOutput(conn, "test2")
 	if err != nil {
 		fmt.Println("can't write output: ", err)
 		return
 	}
-	err = output.Print(os.Stdout)
+	err = dbms.PrintOutput(ctx, os.Stdout)
 	if err != nil {
-		fmt.Println("can't print: ", err)
+		fmt.Println("can't print output: ", err)
 		return
 	}
+}
+
+func main() {
+	conn, err := sql.Open("oracle", os.Getenv("DSN"))
+	if err != nil {
+		fmt.Println("error in connection: ", err)
+		return
+	}
+	defer func() {
+		err = conn.Close()
+		if err != nil {
+			fmt.Println("error in close: ", err)
+		}
+	}()
 
+	withoutContext(conn)
+	ctx := context.Background()
+	withContext(conn, ctx)
 }