Interface

GioDatagramBased

Description [src]

interface Gio.DatagramBased : GObject.Object

A GDatagramBased is a networking interface for representing datagram-based communications. It is a more or less direct mapping of the core parts of the BSD socket API in a portable GObject interface. It is implemented by GSocket, which wraps the UNIX socket API on UNIX and winsock2 on Windows.

GDatagramBased is entirely platform independent, and is intended to be used alongside higher-level networking APIs such as GIOStream.

It uses vectored scatter/gather I/O by default, allowing for many messages to be sent or received in a single call. Where possible, implementations of the interface should take advantage of vectored I/O to minimise processing or system calls. For example, GSocket uses recvmmsg() and sendmmsg() where possible. Callers should take advantage of scatter/gather I/O (the use of multiple buffers per message) to avoid unnecessary copying of data to assemble or disassemble a message.

Each GDatagramBased operation has a timeout parameter which may be negative for blocking behaviour, zero for non-blocking behaviour, or positive for timeout behaviour. A blocking operation blocks until finished or there is an error. A non-blocking operation will return immediately with a G_IO_ERROR_WOULD_BLOCK error if it cannot make progress. A timeout operation will block until the operation is complete or the timeout expires; if the timeout expires it will return what progress it made, or G_IO_ERROR_TIMED_OUT if no progress was made. To know when a call would successfully run you can call g_datagram_based_condition_check() or g_datagram_based_condition_wait(). You can also use g_datagram_based_create_source() and attach it to a GMainContext to get callbacks when I/O is possible.

When running a non-blocking operation applications should always be able to handle getting a G_IO_ERROR_WOULD_BLOCK error even when some other function said that I/O was possible. This can easily happen in case of a race condition in the application, but it can also happen for other reasons. For instance, on Windows a socket is always seen as writable until a write returns G_IO_ERROR_WOULD_BLOCK.

As with GSocket, GDatagramBaseds can be either connection oriented (for example, SCTP) or connectionless (for example, UDP). GDatagramBaseds must be datagram-based, not stream-based. The interface does not cover connection establishment — use methods on the underlying type to establish a connection before sending and receiving data through the GDatagramBased API. For connectionless socket types the target/source address is specified or received in each I/O operation.

Like most other APIs in GLib, GDatagramBased is not inherently thread safe. To use a GDatagramBased concurrently from multiple threads, you must implement your own locking.

Available since:2.48

Prerequisite

In order to implement DatagramBased, your type must inherit from GObject.

Instance methods

g_datagram_based_condition_check

Checks on the readiness of datagram_based to perform operations. The operations specified in condition are checked for and masked against the currently-satisfied conditions on datagram_based. The result is returned.

Available since: 2.48

g_datagram_based_condition_wait

Waits for up to timeout microseconds for condition to become true on datagram_based. If the condition is met, TRUE is returned.

Available since: 2.48

g_datagram_based_create_source

Creates a GSource that can be attached to a GMainContext to monitor for the availability of the specified condition on the GDatagramBased. The GSource keeps a reference to the datagram_based.

Available since: 2.48

g_datagram_based_receive_messages

Receive one or more data messages from datagram_based in one go.

Available since: 2.48

g_datagram_based_send_messages

Send one or more data messages from datagram_based in one go.

Available since: 2.48

Interface structure

struct GioDatagramBasedInterface {
  GTypeInterface g_iface;
  gint (* receive_messages) (
    GDatagramBased* datagram_based,
    GInputMessage* messages,
    guint num_messages,
    gint flags,
    gint64 timeout,
    GCancellable* cancellable,
    GError** error
  );
  gint (* send_messages) (
    GDatagramBased* datagram_based,
    GOutputMessage* messages,
    guint num_messages,
    gint flags,
    gint64 timeout,
    GCancellable* cancellable,
    GError** error
  );
  GSource* (* create_source) (
    GDatagramBased* datagram_based,
    GIOCondition condition,
    GCancellable* cancellable
  );
  GIOCondition (* condition_check) (
    GDatagramBased* datagram_based,
    GIOCondition condition
  );
  gboolean (* condition_wait) (
    GDatagramBased* datagram_based,
    GIOCondition condition,
    gint64 timeout,
    GCancellable* cancellable,
    GError** error
  );
  
}
Interface members
g_iface
GTypeInterface
 

The parent interface.

receive_messages
gint (* receive_messages) (
    GDatagramBased* datagram_based,
    GInputMessage* messages,
    guint num_messages,
    gint flags,
    gint64 timeout,
    GCancellable* cancellable,
    GError** error
  )
 No description available.
send_messages
gint (* send_messages) (
    GDatagramBased* datagram_based,
    GOutputMessage* messages,
    guint num_messages,
    gint flags,
    gint64 timeout,
    GCancellable* cancellable,
    GError** error
  )
 No description available.
create_source
GSource* (* create_source) (
    GDatagramBased* datagram_based,
    GIOCondition condition,
    GCancellable* cancellable
  )
 No description available.
condition_check
GIOCondition (* condition_check) (
    GDatagramBased* datagram_based,
    GIOCondition condition
  )
 No description available.
condition_wait
gboolean (* condition_wait) (
    GDatagramBased* datagram_based,
    GIOCondition condition,
    gint64 timeout,
    GCancellable* cancellable,
    GError** error
  )
 No description available.

Virtual methods

Gio.DatagramBased.condition_check

Checks on the readiness of datagram_based to perform operations. The operations specified in condition are checked for and masked against the currently-satisfied conditions on datagram_based. The result is returned.

Gio.DatagramBased.condition_wait

Waits for up to timeout microseconds for condition to become true on datagram_based. If the condition is met, TRUE is returned.

Gio.DatagramBased.create_source

Creates a GSource that can be attached to a GMainContext to monitor for the availability of the specified condition on the GDatagramBased. The GSource keeps a reference to the datagram_based.

Gio.DatagramBased.receive_messages

Receive one or more data messages from datagram_based in one go.

Gio.DatagramBased.send_messages

Send one or more data messages from datagram_based in one go.