Asynchronously opens this for reading and writing.
For more details, see open_readwrite which is the synchronous version of this call.
When the operation is finished, callback will be called. You can then call
open_readwrite_async.end to get the result of the operation.
| this |
input File |
| io_priority |
the I/O priority of the request |
| cancellable |
optional Cancellable object, null to ignore |
| callback |
a AsyncReadyCallback to call when the request is satisfied |
| user_data |
the data to pass to callback function |