Interface

GioPollableOutputStream

since: 2.28

Description [src]

interface Gio.PollableOutputStream : Gio.OutputStream

GPollableOutputStream is implemented by GOutputStreams that can be polled for readiness to write. This can be used when interfacing with a non-GIO API that expects UNIX-file-descriptor-style asynchronous I/O rather than GIO-style.

Some classes may implement GPollableOutputStream but have only certain instances of that class be pollable. If g_pollable_output_stream_can_poll() returns false, then the behavior of other GPollableOutputStream methods is undefined.

Available since: 2.28

Prerequisite

In order to implement PollableOutputStream, your type must inherit fromGOutputStream.

Implementations

Instance methods

g_pollable_output_stream_can_poll

Checks if stream is actually pollable. Some classes may implement GPollableOutputStream but have only certain instances of that class be pollable. If this method returns FALSE, then the behavior of other GPollableOutputStream methods is undefined.

since: 2.28

g_pollable_output_stream_create_source

Creates a GSource that triggers when stream can be written, or cancellable is triggered or an error occurs. The callback on the source is of the GPollableSourceFunc type.

since: 2.28

g_pollable_output_stream_is_writable

Checks if stream can be written.

since: 2.28

g_pollable_output_stream_write_nonblocking

Attempts to write up to count bytes from buffer to stream, as with g_output_stream_write(). If stream is not currently writable, this will immediately return G_IO_ERROR_WOULD_BLOCK, and you can use g_pollable_output_stream_create_source() to create a GSource that will be triggered when stream is writable.

g_pollable_output_stream_writev_nonblocking

Attempts to write the bytes contained in the n_vectors vectors to stream, as with g_output_stream_writev(). If stream is not currently writable, this will immediately return %G_POLLABLE_RETURN_WOULD_BLOCK, and you can use g_pollable_output_stream_create_source() to create a GSource that will be triggered when stream is writable. error will not be set in that case.

since: 2.60

Interface structure

struct GioPollableOutputStreamInterface {
  GTypeInterface g_iface;
  gboolean (* can_poll) (
    GPollableOutputStream* stream
  );
  gboolean (* is_writable) (
    GPollableOutputStream* stream
  );
  GSource* (* create_source) (
    GPollableOutputStream* stream,
    GCancellable* cancellable
  );
  gssize (* write_nonblocking) (
    GPollableOutputStream* stream,
    void* buffer,
    gsize count,
    GError** error
  );
  GPollableReturn (* writev_nonblocking) (
    GPollableOutputStream* stream,
    const GOutputVector* vectors,
    gsize n_vectors,
    gsize* bytes_written,
    GError** error
  );
  
}

The interface for pollable output streams.

The default implementation of can_poll always returns TRUE.

The default implementation of write_nonblocking calls g_pollable_output_stream_is_writable(), and then calls g_output_stream_write() if it returns TRUE. This means you only need to override it if it is possible that your is_writable implementation may return TRUE when the stream is not actually writable.

The default implementation of writev_nonblocking calls g_pollable_output_stream_write_nonblocking() for each vector, and converts its return value and error (if set) to a GPollableReturn. You should override this where possible to avoid having to allocate a GError to return G_IO_ERROR_WOULD_BLOCK.

Interface members

`g_iface`	`GTypeInterface`
	The parent interface.
`can_poll`	`gboolean (* can_poll) ( GPollableOutputStream* stream )`
	Checks if the `GPollableOutputStream` instance is actually pollable.
`is_writable`	`gboolean (* is_writable) ( GPollableOutputStream* stream )`
	Checks if the stream is writable.
`create_source`	`GSource* (* create_source) ( GPollableOutputStream* stream, GCancellable* cancellable )`
	Creates a `GSource` to poll the stream.
`write_nonblocking`	`gssize (* write_nonblocking) ( GPollableOutputStream* stream, void* buffer, gsize count, GError** error )`
	Does a non-blocking write or returns `G_IO_ERROR_WOULD_BLOCK`.
`writev_nonblocking`	`GPollableReturn (* writev_nonblocking) ( GPollableOutputStream* stream, const GOutputVector* vectors, gsize n_vectors, gsize* bytes_written, GError** error )`
	Does a vectored non-blocking write, or returns `G_POLLABLE_RETURN_WOULD_BLOCK`.

Virtual methods

Gio.PollableOutputStream.can_poll

Checks if stream is actually pollable. Some classes may implement GPollableOutputStream but have only certain instances of that class be pollable. If this method returns FALSE, then the behavior of other GPollableOutputStream methods is undefined.

since: 2.28

Gio.PollableOutputStream.create_source

Creates a GSource that triggers when stream can be written, or cancellable is triggered or an error occurs. The callback on the source is of the GPollableSourceFunc type.

since: 2.28

Gio.PollableOutputStream.is_writable

Checks if stream can be written.

since: 2.28

Gio.PollableOutputStream.write_nonblocking

Attempts to write up to count bytes from buffer to stream, as with g_output_stream_write(). If stream is not currently writable, this will immediately return G_IO_ERROR_WOULD_BLOCK, and you can use g_pollable_output_stream_create_source() to create a GSource that will be triggered when stream is writable.

Gio.PollableOutputStream.writev_nonblocking

Attempts to write the bytes contained in the n_vectors vectors to stream, as with g_output_stream_writev(). If stream is not currently writable, this will immediately return %G_POLLABLE_RETURN_WOULD_BLOCK, and you can use g_pollable_output_stream_create_source() to create a GSource that will be triggered when stream is writable. error will not be set in that case.

since: 2.60