1 files changed, 104 insertions, 0 deletions
diff --git a/lib/PublicInbox/NNTPdeflate.pm b/lib/PublicInbox/NNTPdeflate.pm
new file mode 100644
index 00000000..66210bfa
--- /dev/null
+++ b/lib/PublicInbox/NNTPdeflate.pm
@@ -0,0 +1,104 @@
+# Copyright (C) 2019 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
+# Warning, enabling compression for C10K NNTP clients is rather
+# expensive in terms of memory use.
+#
+# RSS usage for 10K idle-but-did-something NNTP clients on 64-bit:
+#   TLS + DEFLATE :  1.8 GB  (MemLevel=9, 1.2 GB with MemLevel=8)
+#   TLS only      :  <200MB
+#   plain         :   <50MB
+package PublicInbox::NNTPdeflate;
+use strict;
+use warnings;
+use 5.010_001;
+use base qw(PublicInbox::NNTP);
+use Compress::Raw::Zlib;
+use Hash::Util qw(unlock_hash); # dependency of fields for perl 5.10+, anyways
+
+my %IN_OPT = (
+        -Bufsize => PublicInbox::NNTP::LINE_MAX,
+        -WindowBits => -15, # RFC 1951
+        -AppendOutput => 1,
+);
+
+my %OUT_OPT = (
+        # nnrpd (INN) and Compress::Raw::Zlib favor MemLevel=9,
+        # but the zlib C library and git use MemLevel=8
+        # as the default.  Using 8 drops our memory use with 10K
+        # TLS clients from 1.8 GB to 1.2 GB, but...
+        # FIXME: sometimes clients fail with 8, so we use 9
+        # -MemLevel => 9,
+
+        # needs more testing, nothing obviously different in terms of memory
+        -Bufsize => 65536,
+
+        -WindowBits => -15, # RFC 1951
+        -AppendOutput => 1,
+);
+
+sub enable {
+        my ($class, $self) = @_;
+        unlock_hash(%$self);
+        bless $self, $class;
+        $self->{zin} = [ Compress::Raw::Zlib::Inflate->new(%IN_OPT), '' ];
+        $self->{zout} = [ Compress::Raw::Zlib::Deflate->new(%OUT_OPT), '' ];
+}
+
+# overrides PublicInbox::NNTP::compressed
+sub compressed { 1 }
+
+# SUPER is PublicInbox::DS::do_read, so $_[1] may be a reference or not
+sub do_read ($$$$) {
+        my ($self, $rbuf, $len, $off) = @_;
+
+        my $zin = $self->{zin} or return; # closed
+        my $deflated = \($zin->[1]);
+        my $r = $self->SUPER::do_read($deflated, $len) or return;
+
+        # assert(length($$rbuf) == $off) as far as NNTP.pm is concerned
+        # -ConsumeInput is true, so $deflated is automatically emptied
+        my $err = $zin->[0]->inflate($deflated, $rbuf);
+        if ($err == Z_OK) {
+                $r = length($$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 ($$) {
+        my $self = $_[0];
+        my $zout = $self->{zout};
+
+        # $_[1] may be a reference or not for ->deflate
+        my $err = $zout->[0]->deflate($_[1], $zout->[1]);
+        $err == Z_OK or die "->deflate failed $err";
+        1;
+}
+
+# SUPER is PublicInbox::DS::write, so $_[1] may be a reference or not
+sub write ($$) {
+        my $self = $_[0];
+        return $self->SUPER::write($_[1]) if ref($_[1]) eq 'CODE';
+        my $zout = $self->{zout};
+        my $deflated = pop @$zout;
+
+        # $_[1] may be a reference or not for ->deflate
+        my $err = $zout->[0]->deflate($_[1], $deflated);
+        $err == Z_OK or die "->deflate failed $err";
+        $err = $zout->[0]->flush($deflated, Z_PARTIAL_FLUSH);
+        $err == Z_OK or die "->flush failed $err";
+
+        # PublicInbox::DS::write puts partial writes into another buffer,
+        # so we can prepare the next deflate buffer:
+        $zout->[1] = '';
+        $self->SUPER::write(\$deflated);
+}
+
+1;