IO::Async::Socket(3pm)User Contributed Perl DocumentatioIO::Async::Socket(3pm)
NAME
"IO::Async::Socket" - event callbacks and send buffering for a socket
filehandle
SYNOPSIS
use IO::Async::Socket;
use IO::Async::Loop;
my $loop = IO::Async::Loop->new;
my $socket = IO::Async::Socket->new(
on_recv => sub {
my ( $self, $dgram, $addr ) = @_;
print "Received reply: $dgram\n",
$loop->stop;
},
on_recv_error => sub {
my ( $self, $errno ) = @_;
die "Cannot recv - $errno\n";
},
);
$loop->add( $socket );
$socket->connect(
host => "some.host.here",
service => "echo",
socktype => 'dgram',
)->get;
$socket->send( "A TEST DATAGRAM" );
$loop->run;
DESCRIPTION
This subclass of IO::Async::Handle contains a socket filehandle. It
provides a queue of outgoing data. It invokes the "on_recv" handler
when new data is received from the filehandle. Data may be sent to the
filehandle by calling the "send" method.
It is primarily intended for "SOCK_DGRAM" or "SOCK_RAW" sockets (such
as UDP or packet-capture); for "SOCK_STREAM" sockets (such as TCP) an
instance of IO::Async::Stream is more appropriate.
EVENTS
The following events are invoked, either using subclass methods or CODE
references in parameters:
on_recv $data, $addr
Invoke on receipt of a packet, datagram, or stream segment.
The "on_recv" handler is invoked once for each packet, datagram, or
stream segment that is received. It is passed the data itself, and the
sender's address.
on_recv_error $errno
Optional. Invoked when the "recv" method on the receiving handle fails.
on_send_error $errno
Optional. Invoked when the "send" method on the sending handle fails.
The "on_recv_error" and "on_send_error" handlers are passed the value
of $! at the time the error occurred. (The $! variable itself, by its
nature, may have changed from the original error by the time this
handler runs so it should always use the value passed in).
If an error occurs when the corresponding error callback is not
supplied, and there is not a subclass method for it, then the "close"
method is called instead.
on_outgoing_empty
Optional. Invoked when the sending data buffer becomes empty.
PARAMETERS
The following named parameters may be passed to "new" or "configure":
read_handle => IO
The IO handle to receive from. Must implement "fileno" and "recv"
methods.
write_handle => IO
The IO handle to send to. Must implement "fileno" and "send" methods.
handle => IO
Shortcut to specifying the same IO handle for both of the above.
on_recv => CODE
on_recv_error => CODE
on_outgoing_empty => CODE
on_send_error => CODE
autoflush => BOOL
Optional. If true, the "send" method will atempt to send data to the
operating system immediately, without waiting for the loop to indicate
the filehandle is write-ready.
recv_len => INT
Optional. Sets the buffer size for "recv" calls. Defaults to 64 KiB.
recv_all => BOOL
Optional. If true, repeatedly call "recv" when the receiving handle
first becomes read-ready. By default this is turned off, meaning at
most one fixed-size buffer is received. If there is still more data in
the kernel's buffer, the handle will stil be readable, and will be
received from again.
This behaviour allows multiple streams and sockets to be multiplexed
simultaneously, meaning that a large bulk transfer on one cannot starve
other filehandles of processing time. Turning this option on may
improve bulk data transfer rate, at the risk of delaying or stalling
processing on other filehandles.
send_all => INT
Optional. Analogous to the "recv_all" option, but for sending. When
"autoflush" is enabled, this option only affects deferred sending if
the initial attempt failed.
The condition requiring an "on_recv" handler is checked at the time the
object is added to a Loop; it is allowed to create a
"IO::Async::Socket" object with a read handle but without a "on_recv"
handler, provided that one is later given using "configure" before the
stream is added to its containing Loop, either directly or by being a
child of another Notifier already in a Loop, or added to one.
METHODS
send
$socket->send( $data, $flags, $addr )
This method adds a segment of data to be sent, or sends it immediately,
according to the "autoflush" parameter. $flags and $addr are optional.
If the "autoflush" option is set, this method will try immediately to
send the data to the underlying filehandle, optionally using the given
flags and destination address. If this completes successfully then it
will have been sent by the time this method returns. If it fails to
send, then the data is queued as if "autoflush" were not set, and will
be flushed as normal.
EXAMPLES
Send-first on a UDP Socket
"UDP" is carried by the "SOCK_DGRAM" socket type, for which the string
'dgram' is a convenient shortcut:
$socket->connect(
host => $hostname,
service => $service,
socktype => 'dgram',
...
)
Receive-first on a UDP Socket
A typical server pattern with "UDP" involves binding a well-known port
number instead of connecting to one, and waiting on incoming packets.
$socket->bind(
service => 12345,
socktype => 'dgram',
)->get;
SEE ALSO
• IO::Handle - Supply object methods for I/O handles
AUTHOR
Paul Evans <leonerd@leonerd.org.uk>
perl v5.34.0 2022-08-19 IO::Async::Socket(3pm)
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