diff options
Diffstat (limited to 'lib/PublicInbox/DSdeflate.pm')
-rw-r--r-- | lib/PublicInbox/DSdeflate.pm | 134 |
1 files changed, 134 insertions, 0 deletions
diff --git a/lib/PublicInbox/DSdeflate.pm b/lib/PublicInbox/DSdeflate.pm new file mode 100644 index 00000000..539adf0f --- /dev/null +++ b/lib/PublicInbox/DSdeflate.pm @@ -0,0 +1,134 @@ +# 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; |