Provided by: libio-stream-perl_2.0.3-3_all 
NAME
IO::Stream - ease non-blocking I/O streams based on EV
VERSION
This document describes IO::Stream version v2.0.3
SYNOPSIS
use EV;
use IO::Stream;
IO::Stream->new({
host => 'google.com',
port => 80,
cb => \&client,
wait_for => SENT|EOF,
in_buf_limit=> 102400,
out_buf => "GET / HTTP/1.0\nHost: google.com\n\n",
});
$EV::DIED = sub { warn $@; EV::unloop };
EV::loop;
sub client {
my ($io, $e, $err) = @_;
if ($err) {
$io->close();
die $err;
}
if ($e & SENT) {
print "request sent, waiting for reply...\n";
}
if ($e & EOF) {
print "server reply:\n", $io->{in_buf};
$io->close();
EV::unloop; # ALL DONE
}
}
DESCRIPTION
Non-blocking event-based low-level I/O is hard to get right. Code usually error-prone and complex... and
it very similar in all applications. Things become much worse when you need to alter I/O stream in some
way - use proxies, encryption, SSL, etc.
This module designed to give user ability to work with I/O streams on higher level, using input/output
buffers (just scalars) and high-level events like CONNECTED, SENT or EOF. As same time it doesn't hide
low-level things, and user still able to work on low-level without any limitations.
PLUGINS
Architecture of this module make it ease to write plugins, which will alter I/O stream in any way - route
it through proxies, encrypt, log, etc.
Here are few available plugins, you may find more on CPAN: IO::Stream::Crypt::RC4,
IO::Stream::Proxy::HTTPS, IO::Stream::MatrixSSL::Client, IO::Stream::MatrixSSL::Server.
If you interested in writing own plugin, check source for "skeleton" plugins: IO::Stream::Noop and
IO::Stream::NoopAlias.
EXPORTS
This modules doesn't export any functions/methods/variables, but it exports a lot of constants. There two
groups of constants: events and errors (which can be imported using tags ':Event' and ':Error'). By
default all constants are exported.
Events:
RESOLVED CONNECTED IN OUT EOF SENT
Errors:
EINBUFLIMIT
ETORESOLVE ETOCONNECT ETOWRITE
EDNS EDNSNXDOMAIN EDNSNODATA
EREQINBUFLIMIT EREQINEOF
Errors are similar to $! - they're dualvars, having both textual and numeric values.
NOTE: Since v2.0.0 "ETORESOLVE", "EDNSNXDOMAIN" and "EDNSNODATA" are not used anymore ("EDNS" is used
instead), but they're still exported for compatibility.
OVERVIEW
You can create IO::Stream object using any "stream" fh (file, TTY, UNIX socket, TCP socket, pipe, FIFO).
Or, if you need TCP socket, you can create IO::Stream object using host+port instead of fh (in this case
IO::Stream will do non-blocking host resolving, create TCP socket and do non-blocking connect).
After you created IO::Stream object, it will handle read/write on this fh, and deliver only high-level
events you asked for into your callback, where you will be able to operate with in/out buffers instead of
doing sysread()/syswrite() manually.
There no limitations on what you can do with fh after you've created IO::Stream object - you can even do
sysread()/syswrite() (but there no reasons for you to do this anymore).
IMPORTANT! When you want to close this fh, you MUST use $io->close() method for closing fh instead of
doing close($fh). This is because IO::Stream doesn't require from you to keep object returned by new(),
and without call to $io->close() IO::Stream object will continue to exists and may receive/generate some
events, which is not what you expect after closing fh. Also, if you keep object returned by
IO::Stream->new() somewhere in your variables, you should either undef all such variables after you
called $io->close(), or you should use Scalar::Util::weaken() on these variables after storing IO::Stream
object. (The same is applicable for all plugin objects too.)
EVENTS
RESOLVED
If you created IO::Stream object using {host}+{port} instead of {fh}, this event will be generated
after resolving {host}. Resolved IP address will be stored in {ip}.
CONNECTED
If you created IO::Stream object using {host}+{port} instead of {fh}, this event will be generated
after connecting socket to {ip}:{port}.
IN Generated after each successful read. IO::Stream may execute several sysread() at once before
generating IN event for optimization. Read data will be stored in {in_buf}, and {in_bytes} counter
will be incremented by amount of bytes read.
EOF Generated only ONCE when EOF reached (sysread() return 0). Also will set {is_eof} to true.
OUT Generated when some data from {out_buf} was written. Written bytes either removed from {out_buf} or
just increment {out_pos} by amount of bytes written (see documentation about these fields below for
more details). Also increment {out_bytes} counter by amount of bytes written.
Here 'written' may be somewhat virtual, while {out_buf}/{out_pos} changes, the real data still can be
in plugin buffers (if you use plugins) and real syswrite() may not be called yet. To detect when all
data is really written you should use SENT event, not OUT.
SENT
Generated when all data from {out_buf} was written. It's usual and safe to call $io->close() on SENT
event.
TIMEOUTS
IO::Stream has 30-second timeouts for connect and write, to timeout DNS resolve it use default
AnyEvent::DNS timeout. If you need to timeout other operations, you have to create own timers using
EV::timer().
Current version doesn't allow you to change these timeouts.
SERVER
If you need to run TCP/UNIX-server socket, then you should handle that socket manually. But you can
create IO::Stream object for accept()'ed socket:
my ($host, $port) = ('0.0.0.0', 1234);
socket my $srv_sock, AF_INET, SOCK_STREAM, 0;
setsockopt $srv_sock, SOL_SOCKET, SO_REUSEADDR, 1;
bind $srv_sock, sockaddr_in($port, inet_aton($host));
listen $srv_sock, SOMAXCONN;
fcntl $srv_sock, F_SETFL, O_NONBLOCK;
$srv_w = EV::io($srv_sock, EV::READ, sub {
if (accept my $sock, $srv_sock) {
IO::Stream->new({
fh => $sock,
cb => \&server,
wait_for => IN,
});
}
elsif ($! != EAGAIN) {
die "accept: $!";
}
});
INTERFACE
IO::Stream provide only three public methods: new(), write() and close(). new() will create new object,
close() will destroy it and write() must be called when you want to modify (or just modified) output
buffer.
All other operations are done using IO::Stream object fields - for simplicity and performance reasons.
Moreover, you can keep your own data in it. There convention on field names, to avoid conflicts:
/^_/
Fields with names started with underscore are for internal use by IO::Stream, you shouldn't touch
them or create your own field with such names.
/^[a-z]/
Fields with names started with lower-case letter are part of IO::Stream public interface - you
allowed to read/write these fields, but you should not store incorrect values in these fields. Check
"PUBLIC FIELDS" below for description of available fields and their format.
/^[A-Z]/
You can store your own data in IO::Stream object using field names started with upper-case letter.
IO::Stream will not touch these fields.
When some event arise which you're waited for, your callback will be called with 3 parameters: IO::Stream
object, event mask, and error (if any):
sub callback {
my ($io, $e, $err) = @_;
}
METHODS
new
IO::Stream->new( \%opt );
Create and return IO::Stream object. You may not keep returned object - you will get it in your callback
(in first parameter) when some interesting for your event happens, and will exists until to call method
close(). See OVERVIEW for more details.
Fields of %opt become fields of created IO::Stream object. There only few fields required, but you can
set any other fields too, and can also set your custom fields (with names starting from upper-case
letter).
Only required fields in %opt are {cb} and either {fh} or {host}+{port}. The {wait_for} field also highly
recommended to set when creating object.
If {out_buf} will be set, then new() will automatically call write() after creating object.
IO::Stream->new({
fh => \*STDIN,
cb => \&console,
wait_for => IN,
});
write
$io->write();
$io->write($data);
Method write() MUST be called after any modifications of {out_buf} field, to ensure data in {out_buf}
will be written to {fh} as soon as it will be possible.
If {fh} available for writing when calling write(), then it will write (may be partially) {out_buf} and
may immediately call your callback function delivering OUT|SENT events there. So, if you call write()
from that callback (as it usually happens), keep in mind it may be called again while executing write(),
and object state may significantly change (it even may be close()'d) after it return from write() into
your callback.
The write($data) is just a shortcut for:
$io->{out_buf} .= $data;
$io->write();
close
$io->close()
Method close() will close {fh} and destroy IO::Stream object. See OVERVIEW for more details.
PUBLIC FIELDS
If field marked *RO* that mean field is read-only and shouldn't be changed.
Some field have default values (shown after equal sign).
Some field modified on events.
cb
method ='IO'
User callback which will be called when some listed in {wait_for} events arise or error happens.
Field {cb} should be either CODE ref or object or class name. In last two cases method named {method}
will be called. Field {method} should be string.
wait_for
Bitmask of events interesting for user. Can be changed at any time. For example:
$io->{wait_for} = RESOLVED|CONNECTED|IN|EOF|OUT|SENT;
When some data will be read from {fh}, {wait_for} must contain IN and/or EOF, or error EREQINEOF will
be generated. So, it's better to always have IN and/or EOF in {wait_for}.
If {wait_for} contain EOF and doesn't contain IN then {in_buf_limit} must be defined or error
EREQINBUFLIMIT will be generated.
fh *RO*
File handle for doing I/O. It's either provided by user to new(), or created by new() (when user
provided {host}+{port} instead).
host *RO*
port *RO*
If user doesn't provide {fh} to new(), he should provide {host} and {port} instead. This way new()
will create new TCP socket in {fh} and resolve {host} and connect this {fh} to resolved {ip} and
{port}. Both resolving and connecting happens in non-blocking way, and will result in delivering
RESOLVED and CONNECTED events into user callback (if user {wait_for} these events).
in_buf_limit =undef
Used to avoid DoS attach when user doesn't handle IN events and want his callback called only on EOF
event. Must be defined if user have EOF without IN in {wait_for}.
Any value >0 will defined amount of bytes which can be read into {in_buf} before EOF happens. When
size of {in_buf} become larger than {in_buf_limit}, error EINBUFLIMIT will be delivered to user
callback. In this case user can either remove some data from {in_buf} to make it smaller than
{in_buf_limit} or increase {in_buf_limit}, and continue reading data.
NOT RECOMMENDED! Value 0 will switch off DoS protection, so there will be no limit on amount of data
to read into {in_buf} until EOF happens.
out_buf =q{} # modified on: OUT
out_pos =undef # modified on: OUT
Data from {out_buf} will be written to {fh}.
If {out_pos} not defined, then data will be written from beginning of {out_buf}, and after successful
write written bytes will be removed from beginning of {out_buf}.
If {out_pos} defined, it should be >= 0. In this case data will be written from {out_pos} position in
{out_buf}, and after successful write {out_pos} will be incremented by amount of bytes written.
{out_buf} will not be changed!
out_bytes =0 # modified on: OUT
Each successful write will increment {out_bytes} by amount of written bytes. You can change
{out_bytes} in any way, but it should always be a number.
in_buf =q{} # modified on: IN
Each successful read will concatenate read bytes to {in_buf}. You can change {in_buf} in any way,
but it should always be a string.
in_bytes =0 # modified on: IN
Each successful read will increment {in_bytes} by amount of read bytes. You can change {in_bytes} in
any way, but it should always be a number.
ip *RO* =undef # modified on: RESOLVED
When you call new() with {host}+{port} instead of {fh} then IP address resolved from {host} will be
stored in {ip}, and event RESOLVED will be generated.
is_eof *RO* =undef # modified on: EOF
When EOF event happens {is_eof} will be set to true value. This allow you to detect is EOF already
happens at any time, even if you doesn't have EOF in {wait_for}.
plugin *RO* ={}
Allow you to set list of plugins when creating object with new(), and later access these plugins.
This field is somewhat special, because when you call new() you should set plugin to ARRAY ref, but
in IO::Stream object {plugin} is HASH ref:
my $io = IO::Stream->new({
host => 'www.google.com',
port => 443,
cb => \&google,
wait_for => EOF,
in_buf_limit=> 102400,
out_buf => "GET / HTTP/1.0\nHost: www.google.com\n\n",
plugin => [ # <------ it's ARRAY, but looks like HASH
ssl => IO::Stream::MatrixSSL::Client->new(),
proxy => IO::Stream::Proxy::HTTPS->new({
host => 'my.proxy.com',
port => 3218,
user => 'me',
pass => 'my pass',
}),
],
MyField1 => 'my data1',
MyField2 => \%mydata2,
});
# access the "proxy" plugin:
$io->{plugin}{proxy};
This is because when calling new() it's important to keep plugins in order, but later it's easier to
access them using names.
DIAGNOSTICS
Exceptions may be thrown only in new(). All other errors will be delivered to user's callback in last
parameter.
"usage: IO::Stream->new({ cb=>, wait_for=>, [fh=>, | host=>, port=>,] ... })"
You called new() with wrong parameters.
"socket: %s"
"fcntl: %s"
Error happens while creating new socket. Usually this happens because you run out of file
descriptors.
"can't get file descriptor"
Failed to get fileno() for your fh. Either fh doesn't open, or this fh type is not supported
(directory handle), or fh is not file handle at all.
"can't create second object for same fh"
You can't have more than one IO::Stream object for same fh.
IO::Stream keep all objects created by new() until $io->close() will be called. Probably you've
closed fh in some way without calling $io->close(), then new fh was created with same file descriptor
number, and you've tried to create IO::Stream object using new fh.
SEE ALSO
AnyEvent::Handle
SUPPORT
Bugs / Feature Requests
Please report any bugs or feature requests through the issue tracker at
<https://github.com/powerman/perl-IO-Stream/issues>. You will be notified automatically of any progress
on your issue.
Source Code
This is open source software. The code repository is available for public review and contribution under
the terms of the license. Feel free to fork the repository and submit pull requests.
<https://github.com/powerman/perl-IO-Stream>
git clone https://github.com/powerman/perl-IO-Stream.git
Resources
• MetaCPAN Search
<https://metacpan.org/search?q=IO-Stream>
• CPAN Ratings
<http://cpanratings.perl.org/dist/IO-Stream>
• AnnoCPAN: Annotated CPAN documentation
<http://annocpan.org/dist/IO-Stream>
• CPAN Testers Matrix
<http://matrix.cpantesters.org/?dist=IO-Stream>
• CPANTS: A CPAN Testing Service (Kwalitee)
<http://cpants.cpanauthors.org/dist/IO-Stream>
AUTHOR
Alex Efros <powerman@cpan.org>
COPYRIGHT AND LICENSE
This software is Copyright (c) 2008- by Alex Efros <powerman@cpan.org>.
This is free software, licensed under:
The MIT (X11) License
perl v5.36.0 2022-08-28 IO::Stream(3pm)