class: IOStream

[50:7] extends: object

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 [class@Gio.SocketConnection], which represents a two-way network connection; and [class@Gio.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 [method@Gio.IOStream.get_input_stream] and [method@Gio.IOStream.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 [method@Gio.IOStream.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 GIOStreams cannot be started while another operation on the GIOStream or its substreams is in progress. Specifically, an application can read from the [class@Gio.InputStream] and write to the [class@Gio.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 [type@GLib.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 GIOStreams from other (worker) threads, and this may be exposed to application code in the behaviour of wrapper streams, such as [class@Gio.BufferedInputStream] or [class@Gio.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).

Members

• handleObj
• lib
• retainedCallbacks
• signalHandlerNames
• signalSetterHandlers

Methods

• IOStream (Handle = null)

  Creates a new IOStream by wrapping a native handle or another wrapper.

  • @p Handle is the native handle or another wrapper whose handle to adopt.

• toNativeHandle (Source)

  Normalizes a constructor argument into a raw pointer carrier. Accepts a raw NativeHandle, a raw NativeBuffer returned from fn.call(...), another generated wrapper exposing handle(), or null. Returns null when the argument carries no pointer.

  • @p Source is the raw handle, raw buffer, wrapper, or null.
  • @r A raw pointer carrier or null when no pointer is present.

• getLib ()

  Returns the opened native library for this generated wrapper.

  • @r The opened native library.

• handle ()

  Returns the wrapped NativeHandle.

  • @r The wrapped NativeHandle.

• isNull ()

  Returns true when the wrapped handle is null.

  • @r A bool.

• describe ()

  Returns a small string for debugging generated wrappers.

  • @r A string.

• asObject ()

  Wraps this handle as Object.

  • @r A Object object.

• clear_pending ()

  Clears the pending flag on @stream.

  • @r None.

• close (object cancellable)

  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 %G_IO_ERROR_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 %G_IO_ERROR_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 error %G_IO_ERROR_CANCELLED 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.
  • @p cancellable is optional #GCancellable object, %NULL to ignore.

• close_finish (object result)

  Closes a stream.

  • @p result is a #GAsyncResult.

• get_input_stream ()

  Gets the input stream for this object. This is used for reading.

• get_output_stream ()

  Gets the output stream for this object. This is used for writing.

• has_pending ()

  Checks if a stream has pending actions.

• is_closed ()

  Checks if a stream is closed.

• set_pending ()

  Sets @stream to have actions pending. If the pending flag is already set or @stream is closed, it will return %FALSE and set @error.

class: IOStreamMeta

[237:14] static extends: object

Generated metadata helpers for IOStream class surfaces.

Methods

• properties ()

  Returns property metadata for IOStream.

  • @r A list.