NAME

IO::FD - Faster accept, socket, listen with file descriptors, not handles

SYNOPSIS

Create and bind a STREAM socket (server):

use IO::FD;
use Socket ":all";

die "Error creating socket"
	unless defined IO::FD::socket(my $listen_fd, AF_INET, SOCK_STREAM, 0);

my ($err, @sockaddr)=addrinfo "0.0.0.0", 80, {
	family=>	AF_INET,
	socktype=>	SOCK_STREAM,
	flags=>		AI_NUMERICHOST|AI_PASSIVE
};

die "Error binding"
	unless defined FD::IO::bind($listen_fd, $sockaddr[0]{addr});	


die "Error accepting" 
	unless defined IO::FD::accept(my $client_fd, $listen_fd);

#read and write here

Create and connect a STREAM socket(client):

use IO::FD;
use Socket ":all";

die "Error creating socket"
	unless defined IO::FD::socket(my $fd, AF_INET,SOCK_STREAM,0);

my ($err,@sockaddr)=addrinfo "127.0.0.1", 80, {
	family=>	AF_INET,
	socktype=>	SOCK_STREAM,
	flags=>		AI_NUMERICHOST
};

die "Error connecting";
	unless defined FD::IO::connect($fd, $sockaddr[0]{addr});

#read and write here

Open a file

use IO::FD;
use Fcntl;
die "could not open file" 
	unless defined IO::FD::sysopen(my $fd, "path.txt", O_RDONLY);

Read/Write/Close an fd

use IO::FD;

my $fd; #From IO::FD::socket, IO::FD::accept IO::FD::sysopen, POSIX::open

die "Error writing"
	unless defined IO::FD::syswrite $fd, "This is some data"; #Length and optional offset

die "Error reading"
	unless defined IO::FD::sysread $fd, my $buffer, $length); 

die "Error closing" 
	unless defined IO::FD::close $fd;

Advanced:

	fcntl
  sendfile
  accept4
  accept_multiple

	#TODO:
	ioctl...

DESCRIPTION

IO::FD is an XS module implementing common core Perl system I/O functions to work with file descriptors instead of Perl file handles. Functions include but are not limited to accept, connect, socket, bind, sysopen, sysread, and syswrite.

Many non core system functions such as sendfile, dup and mkstemp, pread, pwrite, mkfifo which work with file descriptors are also implemented.

Additional support for streamlined connection accepting is included via accept_multiple.

This module can significantly lower memory usage per file descriptor and decrease file/socket opening and socket accepting times. accept performance is particularly improved with much higher connection handling rates for a given backlog.

Actual byte throughput (read/write) is basically unchanged compared to the core Perl sysread/syswrite. Please see the PERFORMANCE section later in this document

The supported interfaces mostly resemble the core Perl implementations of similarly named functions. The largest difference being you should check for defined values for error checks. For example:

#Perl:
sysopen(my $file_handle, ...) or die $!;
sysread($file_handle, ...) or die $!;

#IO::FD
defined IO::FD::sysopen(my $file_descriptor, ...) or die $!
defined IO::FD::sysread($file_descriptor, ...) or die $!;

This modules IS NOT intended to be a drop in replacement for core IO subroutines in existing code. If you want a 'drop in replacement' please look at IO::FD::DWIM which is part of the same distribution.

Currently this module is focused on UNIX/Linux systems, as this is the natural habitat of a file descriptor.

IMPORTANT VERSION DIFFERENCES

v0.3.0 and later

New functions:

pread, pwrite, mkfifo, mkfifoat, open, openat

v0.2.0 and later

New functions:

accept4, accept_multiple, sendfile

Changes:

All functions creating a new fd now behave more perlish and apply O_CLOEXEC if larger than $^F to prevent fd leakage. This may result in an extra system call you didn't need if your program never calls exec. To disable this, increase the value of $^F as per normal.

Functions now throw exceptions when output variables (fds) are read only when they need to be writable. This matches Perl behaviour in the same scenario for sysopen etc.

When function input fd variables doesn't look like an fd (an IV), a warning 'IO::FD::xxxx called with something other than a file descriptor' is generated, return value is undef and the $! variable is set to EBADF (bad file descriptor>). This is analogous to Perl behaviour when checking for valid GLOB/refs with sysread and friends.

WHERE SHOULD I USE THIS MODULE?

Networking ... Oh Yes

Socket centric programs will benefit greatly from this module. The process of socket creation/opening/accepting/listening, where it is INET/INET6 or UNIX families is much improved.

Slurp entire file ... Yes

If a file can be loaded completely into memory for processing, this module will provide improved opening and closing times. Any decoding and line processing will need to be done manually

Line Processing ... Hmmm, No

General text file line processing is best left to Perl file handles. File handles do the heavy lifting of line splitting, EOL handling, encodings, which this modules does not implement.

You can do it, but it is not in the scope of this module.

LIMITATIONS

Perl does a lot of nice things when working with files and handles. When using file descriptors directly you will loose:

Buffering for file small read/write performance (via print and <FH>)

Automatic close when out of scope

Special variables not supported (ie '_' in stat)

<FH> 'readline' support

IO::Handle inheritance

MOTIVATION

Perl makes working with text files easy, thanks to file handles. Line splitting, UTF-8, EOL processing etc. are awesome and make your life easier.

However, the benefits of file handles when working within a network or binary file context are not so clear cut. All the nice line ending and encoding support doesn't help in these scenarios.

In addition, the OS kernel does a lot of buffering for networking already. Do we really need to add more?

So if these features are not being fully utilised for binary/network programming, the hypothesis is that opening and accepting operations would be faster with file descriptors as less setup is required internally.

APIs

Each of the APIs mimic the Perl counterpart, if applicable, as much as possible. Unless explicitly mentioned, they should operate like built in routines. Consult perldoc -f FUNCTION for details. The general exception however is return values should be explicitly tested for definedness and not relying on a 'true' value

As none of these functions are exported, they must be called with full package name.

Socket Manipulation

IO::FD::socket

IO::FD::socketpair

IO::FD::bind

IO::FD::listen

IO::FD::accept

IO::FD::accept4

my $ok=defined IO::FD::accept4 $new, $listen, $flags;

Constants: IO::FD::SOCK_NONBLOCK, IO::FD::SOCK_CLOEXEC

Implements the linux accept4 syscall. On non linux systems this is emulated by calling fcntl to set the FD_CLOEXEC flag and O_NONBLOCK status. Returns undef on error, for the user to test $!.

The flags argument can be the bitwise or'ed value of SOCK_NONBLOCK and SOCK_CLOEXEC from the Socket module on linux and bsd. Darwin (macos) does not have these values. so please use IO::FD::SOCK_NONBLOCK, IO::FD::SOCK_CLOEXEC on that platform.

NOTE:Unlike other functions returning new file descriptors, this DOES NOT automatically apply the CLOEXEC flag. The $flags argument must be set accordingly to achieve this.

NOTE: On emulated systems, any errors reported are only from the accept call, not subsequent fcntl calls

IO::FD::accept_multiple

my @new_fds;
my @peers;
my $count=accept_multiple(@new_fds, @peers, $listen_sock);

NOTE: DO NOT use this function on a blocking socket!!

Accepts as many new connection sockets as available. The new sockets are stored in new_fds, which is an array, not a array ref. The corresponding peers to the connections are stored in @peers, also an array not a reference.

$listen_sock is the file descriptor from which the sockets are accepted from. It MUST be configured for non blocking operation, otherwise your program will just loop forever in this function

Because this function will only works for non blocking listening sockets, the sockets/fds returned are configured for non blocking mode also. On BSD type systems the socket will already be non blocking. On linux systems the accept4 call is used to set the SOCK_NONBLOCK flag.

Returns the number of sockets accepted until an error condition occurred. Returns undef if no sockets where accepted. Check the $! for normal non blocking error codes.

IO::FD::connect

IO::FD::getsockopt

IO::FD::setsockopt

Note: Implements the integer shorthand as per perldoc -f setsockopt

IO::FD::getpeername

IO::FD::getsockname

IO::FD::sendfile

sendfile $socket, $source_fd, $length, $offset

Calls system sendfile. Returns undef on error or the number of bytes transferred otherwise. The error might be an EAGAIN for non blocking sockets. Please reference the manual page for sendfile on your system, but be mindful the position of the arguments might not match.

Currently advanced header/trailer features of BSD sendfile are not supported.

File Maniupulation

IO::FD::sysopen

IO::FD::sysopen4

Same as IO::FD::sysopen, but expects all four arguments

IO::FD::open

Binding to open. Please see your system manual. If no mode is specified, the 'perlish' 0666, is used.

IO::FD::openat

Binding to openat. Please see your system manual. If no mode is specified, the 'perlish' 0666, is used.

IO::FD::mktemp

Behaves similar to File::Temp::mktemp

Requires at least six 'X' characters at the end of the template

The template string used as input is modified and is the same as the return value on success

NOTE: This function does not return a file descriptor. It might be included in future versions of this module

IO::FD::mkstemp

Behaves like File::Temp::mkstemp

Requires at least six 'X' characters at the end of the template

In list context returns ($fd,$path), where $fd is the already open file descriptor, and $path is the unique path generated from the template.

The template string used as input is modified and is the same as the $path return value on success

IO::FD::sysseek

Pipes

IO::FD::pipe

IO::FD::syspipe

A alias of IO::FD::pipe.

mkfifo

Binding to mkfifo. Please see your system manual. If no mode is specified, the 'perlish' 0666, is used.

mkfifoat

Binding to mkfifoat. Please see your system manual. If no mode is specified, the 'perlish' 0666, is used.

Common

IO::FD::dup

IO::FD::dup2

IO::FD::close

IO::FD::recv

IO::FD::send

IO::FD::sysread

NOTE: Versions prior to 0.1.4 would end up using fd = 0 (normally STDIN) when it was non numeric. This is fixed in 0.1.4. An fd which is not numeric will cause an immediate return of undefined.

IO::FD::sysread3

Same as IO::FD::sysread, but expects only 3 of 4 arguments

IO::FD::sysread4

Same as IO::FD::sysread, but expects all four arguments

IO::FD::syswrite

NOTE: Versions prior to 0.1.4 would end up using fd = 0 (normally STDIN) when it was non numeric. This is fixed in 0.1.4. An fd which is not numeric will cause an immediate return of undefined.

IO::FD::syswrite2

Same as IO::FD::syswrite, but expect 2 of 4 arguments.

IO::FD::syswrite3

Same as IO::FD::syswrite, but expect 3 of 4 arguments.

IO::FD::syswrite4

Same as IO::FD::syswrite, but expect 4 of 4 arguments.

IO::FD::fcntl

IO::FD::sysfcntl

Alias to IO::FD::fcntl

IO::FD::stat

Attempts to replicate string expansion of values for some stat values as CORE::stat does. Tests of equality should be done using the eq operator (just like CORE::stat results) if your Perl is not 64bit.

IO::FD::lstat

As above.

IO::FD::pread

Binding to pread. Please see your system manual.

IO::FD:pwrite

Binding to pwrite. Please see your system manual.

Experimental

These functions haven't really been tested, documented or finished. They exist none the less. You will need to Look at the code for documentation at the moment. Their behaviour and interface are LIKELY TO CHANGE without notice.

IO::FD::ioctl

Not complete

IO::FD::sysioctl

Alias to ioctl

IO::FD::clock_gettime_monotonic

IO::FD::select

Broken. Probably will be removed as core Perl has this already.

IO::FD::poll

Constants for use with poll are available via IO::FD:Constants

IO::FD::kqueue

IO::FD::kevent

This is broken ok 32 bit BSD at the moment. Constants for use with kevent are available via IO::FD:Constants

IO::FD::pack_kevent

IO::FD::sv_to_pointer

IO::FD::pointer_to_sv

IO::FD::SV

IO::FD::SV($size)

Allocates a string SV with the given size preallocated. The current string length is set to 0. For short string this is not the fastest way to allocate. For 4k and above, it is much faster, and doesn't use extra memory in compilation

IO::FD::readline

#SLURP A FILE
local $/=undef;
my $slurp=IO::FD::readline;

	#or
#SLURP ALL RECORDS OF KNOWN LENGTH
local $/=\1234;
my @records=IO::FD::readline;

A read line function is available, but is only operates in file slurp or record slurp mode (see perldoc -f readline). As no buffering is used, It does not attempt to split lines or read a line at a time like the normal Perl readline or <> operator

PERFORMANCE

Part of this distribution are benchmarking scripts. The following are typical outputs from my Intel 2020 Macbook Pro.

Listen Backlog

Results from benchmark/server-perl.pl benchmark/server.pl and benchmark/client.pl

Listen Backlog: 10
	Perl server:
	Connections before client refused: 18

	IO::FD server
	Connections before client refuse: 9285

Listen Backlog: 100
	Perl server:
	Connections before client refused: 190

	IO::FD server
	Connections before client refuse:  (none refused)

Listen Backlog: 1000

	Perl server:
	Connections before client refused: 245

	IO::FD server
	Connections before client refuse:  (none refused)

Accept

Results from benchmark/server-perl.pl benchmark/server.pl and benchmark/client.pl

Listen Backlog: 100

Perl accept rate:    73568.4857256754/s
IO::FD Accept rate: 150984.798776367/s

Memory Usage

Results from benchmark/file-memory.pl

Creating 2000 file handles/descriptors
Start maxrss (kB): 4500

Perl file handles
Bytes: 905216, per handle: 452.608

IO::FD
Bytes: 4096, per fd: 2.048

End maxrss (kB): 5692

Socket creation

Results from benchmark/socket-create.pl

		     Rate perl_socket_INET iofd_socket_INET
perl_socket_INET  81919/s               --             -56%
iofd_socket_INET 185679/s             127%               --
		      Rate perl_socket_INET6 iofd_socket_INET6
perl_socket_INET6  81498/s                --              -57%
iofd_socket_INET6 189253/s              132%                --
		     Rate perl_socket_UNIX iofd_socket_UNIX
perl_socket_UNIX 113778/s               --             -78%
iofd_socket_UNIX 508970/s             347%               --

File open and close

Results from benchmark/file-open-close.pl

		    Rate     file_handle file_desc_posix           io_fd
file_handle      91897/s              --            -35%            -37%
file_desc_posix 140549/s             53%              --             -4%
io_fd           146161/s             59%              4%              --

Read Performance

Result from benchmark/file-read-write.pl

Read performance:
Read (bytes): 1024 x 2^0
		     Rate file_desc_posix     file_handle           io_fd
file_desc_posix 1803743/s              --             -5%             -5%
file_handle     1889325/s              5%              --             -0%
io_fd           1890461/s              5%              0%              --
Read (bytes): 1024 x 2^1
		     Rate file_desc_posix           io_fd     file_handle
file_desc_posix 1799026/s              --             -1%             -2%
io_fd           1823610/s              1%              --             -1%
file_handle     1837458/s              2%              1%              --
Read (bytes): 1024 x 2^2
		     Rate file_desc_posix           io_fd     file_handle
file_desc_posix 1731140/s              --             -1%             -1%
io_fd           1747626/s              1%              --             -0%
file_handle     1747627/s              1%              0%              --
Read (bytes): 1024 x 2^3
		     Rate           io_fd file_desc_posix     file_handle
io_fd           1458670/s              --             -1%             -3%
file_desc_posix 1470359/s              1%              --             -2%
file_handle     1499189/s              3%              2%              --
Read (bytes): 1024 x 2^4
		     Rate file_desc_posix     file_handle           io_fd
file_desc_posix 1146879/s              --             -3%             -6%
file_handle     1180322/s              3%              --             -3%
io_fd           1214700/s              6%              3%              --

Write Performance

Result from benchmark/file-read-write.pl

Write performance:
Write (bytes): 1024 x 2^0
		     Rate file_desc_posix           io_fd     file_handle
file_desc_posix 1978800/s              --             -7%            -12%
io_fd           2117316/s              7%              --             -6%
file_handle     2244774/s             13%              6%              --
Write (bytes): 1024 x 2^1
		     Rate file_desc_posix           io_fd     file_handle
file_desc_posix 2007408/s              --             -6%             -9%
io_fd           2143700/s              7%              --             -3%
file_handle     2205537/s             10%              3%              --
Write (bytes): 1024 x 2^2
		     Rate file_desc_posix           io_fd     file_handle
file_desc_posix 1978800/s              --             -7%            -12%
io_fd           2123851/s              7%              --             -5%
file_handle     2244774/s             13%              6%              --
Write (bytes): 1024 x 2^3
		     Rate file_desc_posix           io_fd     file_handle
file_desc_posix 1960478/s              --             -7%             -9%
io_fd           2117316/s              8%              --             -2%
file_handle     2163924/s             10%              2%              --
Write (bytes): 1024 x 2^4
		     Rate file_desc_posix           io_fd     file_handle
file_desc_posix 1997468/s              --             -5%             -8%
io_fd           2104367/s              5%              --             -3%
file_handle     2163924/s              8%              3%              --

SEE ALSO

The POSIX module provides an open, close, read and write routines which return/work with file descriptors. If you are only concerned with working with files, this is a better option as it is a core module, and will give you the purported benefits of this module. However it does not provide any networking/socket support.

FUTURE WORK (IDEAS/TODO)

  Further emulate linux/bsd SOCK_NONBLOCK and SOCK_CLOEXEC on darwin
	Add more tests for stat and DWIM module
	Wider compatability for older Perls
	Add More system functions which work with fds
	Work with win32 sockets
	Maybe make an IO::Handle sub class

AUTHOR

Ruben Westerberg, <drclaw@mac.com>

REPOSITORTY and BUGS

Please report any bugs via git hub: http://github.com/drclaw1394/perl-io-fd

COPYRIGHT AND LICENSE

Copyright (C) 2023 by Ruben Westerberg

This library is free software; you can redistribute it and/or modify it under the same terms as Perl or the MIT license.

DISCLAIMER OF WARRANTIES

THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.

cpanm IO::FD

perl -MCPAN -e shell
install IO::FD