GPollableInputStream
GPollableInputStream — Interface for pollable input streams
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Object Hierarchy
GInterface
╰── GPollableInputStream
Includes
#include <gio/gio.h>
Description
GPollableInputStream is implemented by GInputStreams that
can be polled for readiness to read. This can be used when
interfacing with a non-GIO API that expects
UNIX-file-descriptor-style asynchronous I/O rather than GIO-style.
Functions
g_pollable_input_stream_can_poll ()
gboolean
g_pollable_input_stream_can_poll (GPollableInputStream *stream);
Checks if stream
is actually pollable. Some classes may implement
GPollableInputStream but have only certain instances of that class
be pollable. If this method returns FALSE, then the behavior of
other GPollableInputStream methods is undefined.
For any given stream, the value returned by this method is constant;
a stream cannot switch from pollable to non-pollable or vice versa.
Returns
TRUE if stream
is pollable, FALSE if not.
Since: 2.28
g_pollable_input_stream_read_nonblocking ()
gssize
g_pollable_input_stream_read_nonblocking
(GPollableInputStream *stream,
void *buffer,
gsize count,
GCancellable *cancellable,
GError **error);
Attempts to read up to count
bytes from stream
into buffer
, as
with g_input_stream_read(). If stream
is not currently readable,
this will immediately return G_IO_ERROR_WOULD_BLOCK, and you can
use g_pollable_input_stream_create_source() to create a GSource
that will be triggered when stream
is readable.
Note that since this method never blocks, you cannot actually
use cancellable
to cancel it. However, it will return an error
if cancellable
has already been cancelled when you call, which
may happen if you call this method after a source triggers due
to having been cancelled.
Virtual: read_nonblocking
Types and Values
GPollableInputStream
typedef struct _GPollableInputStream GPollableInputStream;
An interface for a GInputStream that can be polled for readability.
Since: 2.28
struct GPollableInputStreamInterface
struct GPollableInputStreamInterface {
GTypeInterface g_iface;
/* Virtual Table */
gboolean (*can_poll) (GPollableInputStream *stream);
gboolean (*is_readable) (GPollableInputStream *stream);
GSource * (*create_source) (GPollableInputStream *stream,
GCancellable *cancellable);
gssize (*read_nonblocking) (GPollableInputStream *stream,
void *buffer,
gsize count,
GError **error);
};
The interface for pollable input streams.
The default implementation of can_poll
always returns TRUE.
The default implementation of read_nonblocking
calls
g_pollable_input_stream_is_readable(), and then calls
g_input_stream_read() if it returns TRUE. This means you only need
to override it if it is possible that your is_readable
implementation may return TRUE when the stream is not actually
readable.
Since: 2.28