Package org.gnome.gio

Interface DatagramBased

All Superinterfaces:

Proxy

All Known Subinterfaces:

DtlsClientConnection, DtlsConnection, DtlsServerConnection

All Known Implementing Classes:

DatagramBased.DatagramBased$Impl, DtlsClientConnection.DtlsClientConnection$Impl, DtlsConnection.DtlsConnection$Impl, DtlsServerConnection.DtlsServerConnection$Impl, Socket

@Generated("io.github.jwharm.JavaGI")
public interface DatagramBased
extends Proxy

Interface for socket-like objects with datagram semantics.

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 Socket, 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 IOStream.

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 conditionCheck(java.util.Set<org.gnome.glib.IOCondition>) or conditionWait(java.util.Set<org.gnome.glib.IOCondition>, long, org.gnome.gio.Cancellable). You can also use createSource(java.util.Set<org.gnome.glib.IOCondition>, org.gnome.gio.Cancellable) and attach it to a GLib.MainContext 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.

Since:

2.48

Nested Class Summary

Nested Classes

Modifier and Type	Interface	Description
static class	DatagramBased.DatagramBased$Impl	The DatagramBased$Impl type represents a native instance of the DatagramBased interface.
static class	DatagramBased.DatagramBasedInterface	Provides an interface for socket-like objects which have datagram semantics, following the Berkeley sockets API.

Method Summary

Modifier and Type	Method	Description
default Set<IOCondition>	conditionCheck(Set<IOCondition> condition)	Checks on the readiness of this DatagramBased to perform operations.
default Set<IOCondition>	conditionCheck(IOCondition... condition)	Checks on the readiness of this DatagramBased to perform operations.
default boolean	conditionWait(Set<IOCondition> condition, long timeout, @Nullable Cancellable cancellable)	Waits for up to timeout microseconds for condition to become true on datagramBased. If the condition is met, true is returned.
default boolean	conditionWait(IOCondition condition, long timeout, @Nullable Cancellable cancellable)	Waits for up to timeout microseconds for condition to become true on datagramBased. If the condition is met, true is returned.
default Source	createSource(Set<IOCondition> condition, @Nullable Cancellable cancellable)	Creates a GSource that can be attached to a GMainContext to monitor for the availability of the specified condition on the GDatagramBased.
default Source	createSource(IOCondition condition, @Nullable Cancellable cancellable)	Creates a GSource that can be attached to a GMainContext to monitor for the availability of the specified condition on the GDatagramBased.
static @Nullable Type	getType()	Get the GType of the DatagramBased class
default int	receiveMessages(@Nullable InputMessage @Nullable [] messages, int flags, long timeout, @Nullable Cancellable cancellable)	Receive one or more data messages from this DatagramBased in one go.
default int	sendMessages(@Nullable OutputMessage @Nullable [] messages, int flags, long timeout, @Nullable Cancellable cancellable)	Send one or more data messages from this DatagramBased in one go.

Methods inherited from interface org.javagi.base.Proxy

handle

Method Details

getType

static @Nullable Type getType()

Get the GType of the DatagramBased class

Returns:

the GType

conditionCheck

default Set<IOCondition> conditionCheck(Set<IOCondition> condition)

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

IOCondition.IN will be set in the return value if data is available to read with g_datagram_based_receive_messages(), or if the connection is closed remotely (EOS); and if the datagram_based has not been closed locally using some implementation-specific method (such as g_socket_close() or g_socket_shutdown() with shutdownRead set, if it’s a GSocket).

If the connection is shut down or closed (by calling g_socket_close() or g_socket_shutdown() with shutdownRead set, if it’s a GSocket, for example), all calls to this function will return IOErrorEnum.CLOSED.

IOCondition.OUT will be set if it is expected that at least one byte can be sent using g_datagram_based_send_messages() without blocking. It will not be set if the datagram_based has been closed locally.

IOCondition.HUP will be set if the connection has been closed locally.

IOCondition.ERR will be set if there was an asynchronous error in transmitting data previously enqueued using g_datagram_based_send_messages().

Note that on Windows, it is possible for an operation to return IOErrorEnum.WOULD_BLOCK even immediately after g_datagram_based_condition_check() has claimed that the GDatagramBased is ready for writing. Rather than calling g_datagram_based_condition_check() and then writing to the GDatagramBased if it succeeds, it is generally better to simply try writing right away, and try again later if the initial attempt returns IOErrorEnum.WOULD_BLOCK.

It is meaningless to specify IOCondition.ERR or IOCondition.HUP in condition; these conditions will always be set in the output if they are true. Apart from these flags, the output is guaranteed to be masked by condition.

This call never blocks.

Parameters:

condition - a GIOCondition mask to check

Returns:

the GIOCondition mask of the current state

Since:

2.48

conditionCheck

default Set<IOCondition> conditionCheck(IOCondition... condition)

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

IOCondition.IN will be set in the return value if data is available to read with g_datagram_based_receive_messages(), or if the connection is closed remotely (EOS); and if the datagram_based has not been closed locally using some implementation-specific method (such as g_socket_close() or g_socket_shutdown() with shutdownRead set, if it’s a GSocket).

If the connection is shut down or closed (by calling g_socket_close() or g_socket_shutdown() with shutdownRead set, if it’s a GSocket, for example), all calls to this function will return IOErrorEnum.CLOSED.

IOCondition.OUT will be set if it is expected that at least one byte can be sent using g_datagram_based_send_messages() without blocking. It will not be set if the datagram_based has been closed locally.

IOCondition.HUP will be set if the connection has been closed locally.

IOCondition.ERR will be set if there was an asynchronous error in transmitting data previously enqueued using g_datagram_based_send_messages().

Note that on Windows, it is possible for an operation to return IOErrorEnum.WOULD_BLOCK even immediately after g_datagram_based_condition_check() has claimed that the GDatagramBased is ready for writing. Rather than calling g_datagram_based_condition_check() and then writing to the GDatagramBased if it succeeds, it is generally better to simply try writing right away, and try again later if the initial attempt returns IOErrorEnum.WOULD_BLOCK.

It is meaningless to specify IOCondition.ERR or IOCondition.HUP in condition; these conditions will always be set in the output if they are true. Apart from these flags, the output is guaranteed to be masked by condition.

This call never blocks.

Parameters:

condition - a GIOCondition mask to check

Returns:

the GIOCondition mask of the current state

Since:

2.48

conditionWait

default boolean conditionWait(Set<IOCondition> condition,
 long timeout,
 @Nullable Cancellable cancellable)
                       throws GErrorException

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

If cancellable is cancelled before the condition is met, or if timeout is reached before the condition is met, then false is returned and error is set appropriately (IOErrorEnum.CANCELLED or IOErrorEnum.TIMED_OUT).

Parameters:

condition - a GIOCondition mask to wait for

timeout - the maximum time (in microseconds) to wait, 0 to not block, or -1 to block indefinitely

cancellable - a GCancellable

Returns:

true if the condition was met, false otherwise

Throws:

GErrorException - see GError

Since:

2.48

conditionWait

default boolean conditionWait(IOCondition condition,
 long timeout,
 @Nullable Cancellable cancellable)
                       throws GErrorException

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

If cancellable is cancelled before the condition is met, or if timeout is reached before the condition is met, then false is returned and error is set appropriately (IOErrorEnum.CANCELLED or IOErrorEnum.TIMED_OUT).

Parameters:

condition - a GIOCondition mask to wait for

timeout - the maximum time (in microseconds) to wait, 0 to not block, or -1 to block indefinitely

cancellable - a GCancellable

Returns:

true if the condition was met, false otherwise

Throws:

GErrorException - see GError

Since:

2.48

createSource

default Source createSource(Set<IOCondition> condition,
 @Nullable 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 datagramBased.

The callback on the source is of the GDatagramBasedSourceFunc type.

It is meaningless to specify IOCondition.ERR or IOCondition.HUP in condition; these conditions will always be reported in the callback if they are true.

If non-null, cancellable can be used to cancel the source, which will cause the source to trigger, reporting the current condition (which is likely 0 unless cancellation happened at the same time as a condition change). You can check for this in the callback using g_cancellable_is_cancelled().

Parameters:

condition - a GIOCondition mask to monitor

cancellable - a GCancellable

Returns:

a newly allocated GSource

Since:

2.48

createSource

default Source createSource(IOCondition condition,
 @Nullable 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 datagramBased.

The callback on the source is of the GDatagramBasedSourceFunc type.

It is meaningless to specify IOCondition.ERR or IOCondition.HUP in condition; these conditions will always be reported in the callback if they are true.

If non-null, cancellable can be used to cancel the source, which will cause the source to trigger, reporting the current condition (which is likely 0 unless cancellation happened at the same time as a condition change). You can check for this in the callback using g_cancellable_is_cancelled().

Parameters:

condition - a GIOCondition mask to monitor

cancellable - a GCancellable

Returns:

a newly allocated GSource

Since:

2.48

receiveMessages

default int receiveMessages(@Nullable InputMessage @Nullable [] messages,
 int flags,
 long timeout,
 @Nullable Cancellable cancellable)
                     throws GErrorException

Receive one or more data messages from this DatagramBased in one go.

messages must point to an array of GInputMessage structs and numMessages must be the length of this array. Each GInputMessage contains a pointer to an array of GInputVector structs describing the buffers that the data received in each message will be written to.

flags modify how all messages are received. The commonly available arguments for this are available in the GSocketMsgFlags enum, but the values there are the same as the system values, and the flags are passed in as-is, so you can pass in system-specific flags too. These flags affect the overall receive operation. Flags affecting individual messages are returned in GInputMessage.flags.

The other members of GInputMessage are treated as described in its documentation.

If timeout is negative the call will block until numMessages have been received, the connection is closed remotely (EOS), cancellable is cancelled, or an error occurs.

If timeout is 0 the call will return up to numMessages without blocking, or IOErrorEnum.WOULD_BLOCK if no messages are queued in the operating system to be received.

If timeout is positive the call will block on the same conditions as if timeout were negative. If the timeout is reached before any messages are received, IOErrorEnum.TIMED_OUT is returned, otherwise it will return the number of messages received before timing out. (Note: This is effectively the behaviour of MSG_WAITFORONE with recvmmsg().)

To be notified when messages are available, wait for the IOCondition.IN condition. Note though that you may still receive IOErrorEnum.WOULD_BLOCK from g_datagram_based_receive_messages() even if you were previously notified of a IOCondition.IN condition.

If the remote peer closes the connection, any messages queued in the underlying receive buffer will be returned, and subsequent calls to g_datagram_based_receive_messages() will return 0 (with no error set).

If the connection is shut down or closed (by calling g_socket_close() or g_socket_shutdown() with shutdownRead set, if it’s a GSocket, for example), all calls to this function will return IOErrorEnum.CLOSED.

On error -1 is returned and error is set accordingly. An error will only be returned if zero messages could be received; otherwise the number of messages successfully received before the error will be returned. If cancellable is cancelled, IOErrorEnum.CANCELLED is returned as with any other error.

Parameters:

messages - an array of GInputMessage structs

flags - an int containing GSocketMsgFlags flags for the overall operation

timeout - the maximum time (in microseconds) to wait, 0 to not block, or -1 to block indefinitely

cancellable - a GCancellable

Returns:

number of messages received, or -1 on error. Note that the number of messages received may be smaller than numMessages if timeout is zero or positive, if the peer closed the connection, or if numMessages was larger than UIO_MAXIOV (1024), in which case the caller may re-try to receive the remaining messages.

Throws:

GErrorException - see GError

Since:

2.48

sendMessages

default int sendMessages(@Nullable OutputMessage @Nullable [] messages,
 int flags,
 long timeout,
 @Nullable Cancellable cancellable)
                  throws GErrorException

Send one or more data messages from this DatagramBased in one go.

messages must point to an array of GOutputMessage structs and numMessages must be the length of this array. Each GOutputMessage contains an address to send the data to, and a pointer to an array of GOutputVector structs to describe the buffers that the data to be sent for each message will be gathered from.

flags modify how the message is sent. The commonly available arguments for this are available in the GSocketMsgFlags enum, but the values there are the same as the system values, and the flags are passed in as-is, so you can pass in system-specific flags too.

The other members of GOutputMessage are treated as described in its documentation.

If timeout is negative the call will block until numMessages have been sent, cancellable is cancelled, or an error occurs.

If timeout is 0 the call will send up to numMessages without blocking, or will return IOErrorEnum.WOULD_BLOCK if there is no space to send messages.

If timeout is positive the call will block on the same conditions as if timeout were negative. If the timeout is reached before any messages are sent, IOErrorEnum.TIMED_OUT is returned, otherwise it will return the number of messages sent before timing out.

To be notified when messages can be sent, wait for the IOCondition.OUT condition. Note though that you may still receive IOErrorEnum.WOULD_BLOCK from g_datagram_based_send_messages() even if you were previously notified of a IOCondition.OUT condition. (On Windows in particular, this is very common due to the way the underlying APIs work.)

If the connection is shut down or closed (by calling g_socket_close() or g_socket_shutdown() with shutdownWrite set, if it’s a GSocket, for example), all calls to this function will return IOErrorEnum.CLOSED.

On error -1 is returned and error is set accordingly. An error will only be returned if zero messages could be sent; otherwise the number of messages successfully sent before the error will be returned. If cancellable is cancelled, IOErrorEnum.CANCELLED is returned as with any other error.

Parameters:

messages - an array of GOutputMessage structs

flags - an int containing GSocketMsgFlags flags

timeout - the maximum time (in microseconds) to wait, 0 to not block, or -1 to block indefinitely

cancellable - a GCancellable

Returns:

number of messages sent, or -1 on error. Note that the number of messages sent may be smaller than numMessages if timeout is zero or positive, or if numMessages was larger than UIO_MAXIOV (1024), in which case the caller may re-try to send the remaining messages.

Throws:

GErrorException - see GError

Since:

2.48