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# Copyright (C) all contributors <meta@public-inbox.org>
# License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
# RFC 8054 NNTP COMPRESS DEFLATE implementation
# RFC 4978 IMAP COMPRESS=DEFLATE extension
#
# RSS usage for 10K idle-but-did-something NNTP clients on 64-bit:
# TLS + DEFLATE[a] : 1.8 GB (MemLevel=9, 1.2 GB with MemLevel=8)
# TLS + DEFLATE[b] : ~300MB
# TLS only : <200MB
# plain : <50MB
#
# [a] - initial implementation using per-client Deflate contexts and buffer
#
# [b] - memory-optimized implementation using a global deflate context.
# It's less efficient in terms of compression, but way more
# efficient in terms of server memory usage.
package PublicInbox::DSdeflate;
use strict;
use v5.10.1;
use Compress::Raw::Zlib;
my %IN_OPT = (
-Bufsize => 1024,
-WindowBits => -15, # RFC 1951
-AppendOutput => 1,
);
# global deflate context and buffer
my ($zout, $zbuf);
{
my $err;
$zbuf = \(my $initial = ''); # replaced by $next in dflush/write
($zout, $err) = Compress::Raw::Zlib::Deflate->new(
# nnrpd (INN) and Compress::Raw::Zlib favor MemLevel=9,
# the zlib C library and git use MemLevel=8 as the default
# -MemLevel => 9,
-Bufsize => 65536, # same as nnrpd
-WindowBits => -15, # RFC 1951
-AppendOutput => 1,
);
$err == Z_OK or die "Failed to initialize zlib deflate stream: $err";
}
sub enable {
my ($class, $self) = @_;
my ($in, $err) = Compress::Raw::Zlib::Inflate->new(%IN_OPT);
if ($err != Z_OK) {
warn("Inflate->new failed: $err\n");
return;
}
bless $self, $class;
$self->{zin} = $in;
}
# overrides PublicInbox::DS::compressed
sub compressed { 1 }
sub do_read ($$$$) {
my ($self, $rbuf, $len, $off) = @_;
my $zin = $self->{zin} or return; # closed
my $doff;
my $dbuf = delete($self->{dbuf}) // '';
$doff = length($dbuf);
my $r = PublicInbox::DS::do_read($self, \$dbuf, $len, $doff) or return;
# Workaround inflate bug appending to OOK scalars:
# <https://rt.cpan.org/Ticket/Display.html?id=132734>
# We only have $off if the client is pipelining, and pipelining
# is where our substr() OOK optimization in event_step makes sense.
if ($off) {
my $copy = $$rbuf;
undef $$rbuf;
$$rbuf = $copy;
}
# assert(length($$rbuf) == $off) as far as NNTP.pm is concerned
# -ConsumeInput is true, so $dbuf is automatically emptied
my $err = $zin->inflate($dbuf, $rbuf);
if ($err == Z_OK) {
$self->{dbuf} = $dbuf if $dbuf ne '';
$r = length($$rbuf) and return $r;
# nothing ready, yet, get more, later
$self->requeue;
} else {
delete $self->{zin};
$self->close;
}
0;
}
# override PublicInbox::DS::msg_more
sub msg_more ($$) {
my $self = $_[0];
# $_[1] may be a reference or not for ->deflate
my $err = $zout->deflate($_[1], $zbuf);
$err == Z_OK or die "->deflate failed $err";
1;
}
sub dflush ($) {
my ($self) = @_;
my $deflated = $zbuf;
$zbuf = \(my $next = '');
my $err = $zout->flush($deflated, Z_FULL_FLUSH);
$err == Z_OK or die "->flush failed $err";
# We can still let the lower socket layer do buffering:
PublicInbox::DS::msg_more($self, $$deflated);
}
# compatible with PublicInbox::DS::write, so $_[1] may be a reference or not
sub write ($$) {
my $self = $_[0];
return PublicInbox::DS::write($self, $_[1]) if ref($_[1]) eq 'CODE';
my $deflated = $zbuf;
$zbuf = \(my $next = '');
# $_[1] may be a reference or not for ->deflate
my $err = $zout->deflate($_[1], $deflated);
$err == Z_OK or die "->deflate failed $err";
$err = $zout->flush($deflated, Z_FULL_FLUSH);
$err == Z_OK or die "->flush failed $err";
# We can still let the socket layer do buffering:
PublicInbox::DS::write($self, $deflated);
}
1;
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