X-Git-Url: http://www.git.stargrave.org/?a=blobdiff_plain;f=lib%2FPublicInbox%2FGzipFilter.pm;h=d72ad3c88da55779e9f2c953a63f61040a90c123;hb=5afb24f06627641e3fed608e807b5ab628cda348;hp=99d43cf04cb93da78aedd362b9907b566c1041cf;hpb=20607bd628f4f8ea985661a8ce123ea482058144;p=public-inbox.git

diff --git a/lib/PublicInbox/GzipFilter.pm b/lib/PublicInbox/GzipFilter.pm
index 99d43cf0..d72ad3c8 100644
--- a/lib/PublicInbox/GzipFilter.pm
+++ b/lib/PublicInbox/GzipFilter.pm
@@ -1,11 +1,20 @@
 # Copyright (C) 2020 all contributors <meta@public-inbox.org>
 # License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
-
-# Qspawn filter
+#
+# In public-inbox <=1.5.0, public-inbox-httpd favored "getline"
+# response bodies to take a "pull"-based approach to feeding
+# slow clients (as opposed to a more common "push" model).
+#
+# In newer versions, public-inbox-httpd supports a backpressure-aware
+# pull/push model which also accounts for slow git blob storage.
+# {async_next} callbacks only run when the DS {wbuf} is drained
+# {async_eml} callbacks only run when a blob arrives from git.
+#
+# We continue to support getline+close for generic PSGI servers.
 package PublicInbox::GzipFilter;
 use strict;
 use parent qw(Exporter);
-use Compress::Raw::Zlib qw(Z_FINISH Z_OK);
+use Compress::Raw::Zlib qw(Z_OK);
 use PublicInbox::CompressNoop;
 use PublicInbox::Eml;
 use PublicInbox::GitAsyncCat;
@@ -14,12 +23,12 @@ our @EXPORT_OK = qw(gzf_maybe);
 my %OPT = (-WindowBits => 15 + 16, -AppendOutput => 1);
 my @GZIP_HDRS = qw(Vary Accept-Encoding Content-Encoding gzip);
 
-sub new { bless {}, shift }
+sub new { bless {}, shift } # qspawn filter
 
 # for Qspawn if using $env->{'pi-httpd.async'}
 sub attach {
 	my ($self, $http_out) = @_;
-	$self->{http_out} = $http_out;
+	$self->{http_out} = $http_out; # PublicInbox::HTTP::{Chunked,Identity}
 	$self
 }
 
@@ -95,7 +104,7 @@ sub translate ($$) {
 		$self->{zbuf} = $zbuf;
 		'';
 	} else { # undef == EOF
-		my $err = $gz->flush($zbuf, Z_FINISH);
+		my $err = $gz->flush($zbuf);
 		die "gzip->flush: $err" if $err != Z_OK;
 		$zbuf;
 	}
@@ -125,7 +134,7 @@ sub zflush ($;$) {
 		$err = $gz->deflate($_[1], $zbuf);
 		die "gzip->deflate: $err" if $err != Z_OK;
 	}
-	$err = $gz->flush($zbuf, Z_FINISH);
+	$err = $gz->flush($zbuf);
 	die "gzip->flush: $err" if $err != Z_OK;
 	$zbuf;
 }