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.\" ========================================================================
.\"
.IX Title "IO::Socket::Timeout 3pm"
.TH IO::Socket::Timeout 3pm "2022-11-19" "perl v5.36.0" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
IO::Socket::Timeout \- IO::Socket with read/write timeout
.SH "VERSION"
.IX Header "VERSION"
version 0.32
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\&  use IO::Socket::Timeout;
\&
\&  # creates a standard IO::Socket::INET object, with a connection timeout
\&  my $socket = IO::Socket::INET\->new( Timeout => 2 );
\&  # enable read and write timeouts on the socket
\&  IO::Socket::Timeout\->enable_timeouts_on($socket);
\&  # setup the timeouts
\&  $socket\->read_timeout(0.5);
\&  $socket\->write_timeout(0.5);
\&
\&  # When using the socket:
\&  use Errno qw(ETIMEDOUT EWOULDBLOCK);
\&  print $socket "some request";
\&  my $response = <$socket>;
\&  if (! $response && ( 0+$! == ETIMEDOUT || 0+$! == EWOULDBLOCK )) {
\&    die "timeout reading on the socket";
\&  }
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
\&\f(CW\*(C`IO::Socket\*(C'\fR provides a way to set a timeout on the socket, but the timeout
will be used only for connection, not for reading / writing operations.
.PP
This module provides a way to set a timeout on read / write operations on an
\&\f(CW\*(C`IO::Socket\*(C'\fR instance, or any \f(CW\*(C`IO::Socket::*\*(C'\fR modules, like
\&\f(CW\*(C`IO::Socket::INET\*(C'\fR.
.SH "CLASS METHOD"
.IX Header "CLASS METHOD"
.SS "enable_timeouts_on"
.IX Subsection "enable_timeouts_on"
.Vb 1
\&  IO::Socket::Timeout\->enable_timeouts_on($socket);
.Ve
.PP
Given a socket, it'll return it, but will enable read and write timeouts on it.
You'll have to use \f(CW\*(C`read_timeout\*(C'\fR and \f(CW\*(C`write_timeout\*(C'\fR on it later on.
.PP
Returns the socket, so that you can chain this method with others.
.PP
If the argument is \f(CW\*(C`undef\*(C'\fR, the method simply returns empty list.
.SH "METHODS"
.IX Header "METHODS"
These methods are to be called on a socket that has been previously passed to
\&\f(CW\*(C`enable_timeouts_on()\*(C'\fR.
.SS "read_timeout"
.IX Subsection "read_timeout"
.Vb 2
\&  my $current_timeout = $socket\->read_timeout();
\&  $socket\->read_timeout($new_timeout);
.Ve
.PP
Get or set the read timeout value for a socket created with this module.
.SS "write_timeout"
.IX Subsection "write_timeout"
.Vb 2
\&  my $current_timeout = $socket\->write_timeout();
\&  $socket\->write_timeout($new_timeout);
.Ve
.PP
Get or set the write timeout value for a socket created with this module.
.SS "disable_timeout"
.IX Subsection "disable_timeout"
.Vb 1
\&  $socket\->disable_timeout;
.Ve
.PP
Disable the read and write timeouts for a socket created with this module.
.SS "enable_timeout"
.IX Subsection "enable_timeout"
.Vb 1
\&  $socket\->enable_timeout;
.Ve
.PP
Re-enable the read and write timeouts for a socket created with this module.
.SS "timeout_enabled"
.IX Subsection "timeout_enabled"
.Vb 2
\&  my $is_timeout_enabled = $socket\->timeout_enabled();
\&  $socket\->timeout_enabled(0);
.Ve
.PP
Get or Set the fact that a socket has timeouts enabled.
.SH "WHEN TIMEOUT IS HIT"
.IX Header "WHEN TIMEOUT IS HIT"
When a timeout (read, write) is hit on the socket, the function trying to be
performed will return \f(CW\*(C`undef\*(C'\fR or empty string, and \f(CW$!\fR will be set to
\&\f(CW\*(C`ETIMEOUT\*(C'\fR or \f(CW\*(C`EWOULDBLOCK\*(C'\fR. You should test for both.
.PP
You can import \f(CW\*(C`ETIMEOUT\*(C'\fR and \f(CW\*(C`EWOULDBLOCK\*(C'\fR by using \f(CW\*(C`POSIX\*(C'\fR:
.PP
.Vb 1
\&  use Errno qw(ETIMEDOUT EWOULDBLOCK);
.Ve
.SH "IF YOU NEED TO RETRY"
.IX Header "IF YOU NEED TO RETRY"
If you want to implement a try / wait / retry mechanism, I recommend using a
third-party module, like \f(CW\*(C`Action::Retry\*(C'\fR. Something like this:
.PP
.Vb 1
\&  my $socket;
\&
\&  my $action = Action::Retry\->new(
\&    attempt_code => sub {
\&        # (re\-)create the socket if needed
\&        if (! $socket) {
\&          $socket = IO::Socket\->new(...);
\&          IO::Socket::Timeout\->enable_timeouts_on($socket);
\&          $socket\->read_timeout(0.5);
\&        }
\&        # send the request, read the answer
\&        $socket\->print($_[0]);
\&        defined(my $answer = $socket\->getline)
\&          or $socket = undef, die $!;
\&        $answer;
\&    },
\&    on_failure_code => sub { die \*(Aqaborting, to many retries\*(Aq },
\&  );
\&
\&  my $reply = $action\->run(\*(AqGET mykey\*(Aq);
.Ve
.SH "IMPORT options"
.IX Header "IMPORT options"
You can give a list of socket modules names when use-ing this module, so that
internally, composed classes needed gets created and loaded at compile time.
.PP
.Vb 1
\&  use IO::Socket::Timeout qw(IO::Socket::INET);
.Ve
.SH "ENVIRONMENT VARIABLE"
.IX Header "ENVIRONMENT VARIABLE"
.SS "\s-1PERL_IO_SOCKET_TIMEOUT_FORCE_SELECT\s0"
.IX Subsection "PERL_IO_SOCKET_TIMEOUT_FORCE_SELECT"
This module implements timeouts using one of two strategies. If possible (if
the operating system is linux, freebsd or mac), it uses \f(CW\*(C`setsockopt()\*(C'\fR to set
read / write timeouts. Otherwise it uses \f(CW\*(C`select()\*(C'\fR before performing socket
operations.
.PP
To force the use of \f(CW\*(C`select()\*(C'\fR, you can set
\&\s-1PERL_IO_SOCKET_TIMEOUT_FORCE_SELECT\s0 to a true value at compile time (typically
in a \s-1BEGIN\s0 block)
.SH "SEE ALSO"
.IX Header "SEE ALSO"
Action::Retry, IO::Select, PerlIO::via::Timeout, Time::Out
.SH "THANKS"
.IX Header "THANKS"
Thanks to Vincent Pitt, Christian Hansen and Toby Inkster for various help and
useful remarks.
.SH "AUTHOR"
.IX Header "AUTHOR"
Damien \*(L"dams\*(R" Krotkine
.SH "COPYRIGHT AND LICENSE"
.IX Header "COPYRIGHT AND LICENSE"
This software is copyright (c) 2013 by Damien \*(L"dams\*(R" Krotkine.
.PP
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.