IOStream#
Added in version 2.22.
Superclasses: Object
Subclasses: FileIOStream
, SimpleIOStream
, SocketConnection
, TlsConnection
GIOStream
represents an object that has both read and write streams.
Generally the two streams act as separate input and output streams,
but they share some common resources and state. For instance, for
seekable streams, both streams may use the same position.
Examples of GIOStream
objects are SocketConnection
, which represents
a two-way network connection; and FileIOStream
, which represents a
file handle opened in read-write mode.
To do the actual reading and writing you need to get the substreams
with get_input_stream
and
get_output_stream
.
The GIOStream
object owns the input and the output streams, not the other
way around, so keeping the substreams alive will not keep the GIOStream
object alive. If the GIOStream
object is freed it will be closed, thus
closing the substreams, so even if the substreams stay alive they will
always return G_IO_ERROR_CLOSED
for all operations.
To close a stream use close
which will close the common
stream object and also the individual substreams. You can also close
the substreams themselves. In most cases this only marks the
substream as closed, so further I/O on it fails but common state in the
GIOStream
may still be open. However, some streams may support
‘half-closed’ states where one direction of the stream is actually shut down.
Operations on GIOStream
’s cannot be started while another operation on the
GIOStream
or its substreams is in progress. Specifically, an application can
read from the InputStream
and write to the
OutputStream
simultaneously (either in separate threads, or as
asynchronous operations in the same thread), but an application cannot start
any GIOStream
operation while there is a GIOStream
, GInputStream
or
GOutputStream
operation in progress, and an application can’t start any
GInputStream
or GOutputStream
operation while there is a GIOStream
operation in progress.
This is a product of individual stream operations being associated with a
given MainContext
(the thread-default context at the time the
operation was started), rather than entire streams being associated with a
single GMainContext
.
GIO may run operations on GIOStream
’s from other (worker) threads, and this
may be exposed to application code in the behaviour of wrapper streams, such
as BufferedInputStream
or TlsConnection
. With such
wrapper APIs, application code may only run operations on the base (wrapped)
stream when the wrapper stream is idle. Note that the semantics of such
operations may not be well-defined due to the state the wrapper stream leaves
the base stream in (though they are guaranteed not to crash).
Methods#
- class IOStream
-
- close(cancellable: Cancellable | None = None) bool #
Closes the stream, releasing resources related to it. This will also close the individual input and output streams, if they are not already closed.
Once the stream is closed, all other operations will return
CLOSED
. Closing a stream multiple times will not return an error.Closing a stream will automatically flush any outstanding buffers in the stream.
Streams will be automatically closed when the last reference is dropped, but you might want to call this function to make sure resources are released as early as possible.
Some streams might keep the backing store of the stream (e.g. a file descriptor) open after the stream is closed. See the documentation for the individual stream for details.
On failure the first error that happened will be reported, but the close operation will finish as much as possible. A stream that failed to close will still return
CLOSED
for all operations. Still, it is important to check and report the error to the user, otherwise there might be a loss of data as all data might not be written.If
cancellable
is not NULL, then the operation can be cancelled by triggering the cancellable object from another thread. If the operation was cancelled, the errorCANCELLED
will be returned. Cancelling a close will still leave the stream closed, but some streams can use a faster close that doesn’t block to e.g. check errors.The default implementation of this method just calls close on the individual input/output streams.
Added in version 2.22.
- Parameters:
cancellable – optional
Cancellable
object,None
to ignore
- close_async(io_priority: int, cancellable: Cancellable | None = None, callback: Callable[[...], None] | None = None, *user_data: Any) None #
Requests an asynchronous close of the stream, releasing resources related to it. When the operation is finished
callback
will be called. You can then callclose_finish()
to get the result of the operation.For behaviour details see
close()
.The asynchronous methods have a default fallback that uses threads to implement asynchronicity, so they are optional for inheriting classes. However, if you override one you must override all.
Added in version 2.22.
- Parameters:
io_priority – the io priority of the request
cancellable – optional cancellable object
callback – a
AsyncReadyCallback
to call when the request is satisfieduser_data – the data to pass to callback function
- close_finish(result: AsyncResult) bool #
Closes a stream.
Added in version 2.22.
- Parameters:
result – a
AsyncResult
- get_input_stream() InputStream #
Gets the input stream for this object. This is used for reading.
Added in version 2.22.
- get_output_stream() OutputStream #
Gets the output stream for this object. This is used for writing.
Added in version 2.22.
- set_pending() bool #
Sets
stream
to have actions pending. If the pending flag is already set orstream
is closed, it will returnFalse
and seterror
.Added in version 2.22.
- splice_async(stream2: IOStream, flags: IOStreamSpliceFlags, io_priority: int, cancellable: Cancellable | None = None, callback: Callable[[...], None] | None = None, *user_data: Any) None #
Asynchronously splice the output stream of
stream1
to the input stream ofstream2
, and splice the output stream ofstream2
to the input stream ofstream1
.When the operation is finished
callback
will be called. You can then callsplice_finish()
to get the result of the operation.Added in version 2.28.
- Parameters:
stream2 – a
IOStream
.flags – a set of
IOStreamSpliceFlags
.io_priority – the io priority of the request.
cancellable – optional
Cancellable
object,None
to ignore.callback – a
AsyncReadyCallback
to call when the request is satisfieduser_data – the data to pass to callback function
- splice_finish(result: AsyncResult) bool #
Finishes an asynchronous io stream splice operation.
Added in version 2.28.
- Parameters:
result – a
AsyncResult
.
Properties#
- class IOStream
-
- props.input_stream: InputStream#
The type of the None singleton.
Added in version 2.22.
- props.output_stream: OutputStream#
The type of the None singleton.
Added in version 2.22.
Virtual Methods#
- class IOStream
- do_close_async(io_priority: int, cancellable: Cancellable | None = None, callback: Callable[[...], None] | None = None, *user_data: Any) None #
Requests an asynchronous close of the stream, releasing resources related to it. When the operation is finished
callback
will be called. You can then callclose_finish()
to get the result of the operation.For behaviour details see
close()
.The asynchronous methods have a default fallback that uses threads to implement asynchronicity, so they are optional for inheriting classes. However, if you override one you must override all.
Added in version 2.22.
- Parameters:
io_priority – the io priority of the request
cancellable – optional cancellable object
callback – a
AsyncReadyCallback
to call when the request is satisfieduser_data – the data to pass to callback function
- do_close_finish(result: AsyncResult) bool #
Closes a stream.
Added in version 2.22.
- Parameters:
result – a
AsyncResult
- do_close_fn(cancellable: Cancellable | None = None) bool #
The type of the None singleton.
- Parameters:
cancellable
- do_get_input_stream() InputStream #
Gets the input stream for this object. This is used for reading.
Added in version 2.22.
- do_get_output_stream() OutputStream #
Gets the output stream for this object. This is used for writing.
Added in version 2.22.