DatagramBasedIF

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 or connectionless. 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.

Members

Functions

conditionCheck
GIOCondition conditionCheck(GIOCondition condition)

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.

conditionWait
bool conditionWait(GIOCondition condition, long timeout, Cancellable cancellable)

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

createSource
Source createSource(GIOCondition condition, Cancellable cancellable)

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.

getDatagramBasedStruct
GDatagramBased* getDatagramBasedStruct()

Get the main Gtk struct

getStruct
void* getStruct()

the main Gtk struct as a void*

receiveMessages
int receiveMessages(GInputMessage[] messages, int flags, long timeout, Cancellable cancellable)

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

sendMessages
int sendMessages(GOutputMessage[] messages, int flags, long timeout, Cancellable cancellable)

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

Meta

Since

2.48