Merge pull request #530 from navytux/y/no-go-if-notneeded

Don't spawn interrupt goroutine if we know that context cannot be canceled

sqlite3.go

@@ -1124,9 +1124,10 @@ func (s *SQLiteStmt) query(ctx context.Context, args []namedValue) (driver.Rows,
 		done:     make(chan struct{}),
 	}
 
+	if ctxdone := ctx.Done(); ctxdone != nil {
 		go func(db *C.sqlite3) {
 			select {
-		case <-ctx.Done():
+			case <-ctxdone:
 				select {
 				case <-rows.done:
 				default:
@@ -1136,6 +1137,7 @@ func (s *SQLiteStmt) query(ctx context.Context, args []namedValue) (driver.Rows,
 			case <-rows.done:
 			}
 		}(s.c.db)
+	}
 
 	return rows, nil
 }
@@ -1169,12 +1171,13 @@ func (s *SQLiteStmt) exec(ctx context.Context, args []namedValue) (driver.Result
 		return nil, err
 	}
 
+	if ctxdone := ctx.Done(); ctxdone != nil {
 		done := make(chan struct{})
 		defer close(done)
 		go func(db *C.sqlite3) {
 			select {
 			case <-done:
-		case <-ctx.Done():
+			case <-ctxdone:
 				select {
 				case <-done:
 				default:
@@ -1182,6 +1185,7 @@ func (s *SQLiteStmt) exec(ctx context.Context, args []namedValue) (driver.Result
 				}
 			}
 		}(s.c.db)
+	}
 
 	var rowid, changes C.longlong
 	rv := C._sqlite3_step(s.s, &rowid, &changes)