httpd/async: improve naming and comments

Rename the {cleanup} field to {end}, since it's similar
to END {} and is consistent with the variable in Qspawn.pm

And document how certain subs get called, since we have
many subs named "new" and "close".

diff --git a/lib/PublicInbox/HTTPD/Async.pm b/lib/PublicInbox/HTTPD/Async.pm
index 8e8ece395de065d698b4df19d152cc10d96b93df..d5628ee8d7ca8b457f9999ef118b18553dab61fd 100644 (file)
--- a/lib/PublicInbox/HTTPD/Async.pm
+++ b/lib/PublicInbox/HTTPD/Async.pm
@@ -10,26 +10,29 @@ package PublicInbox::HTTPD::Async;
 use strict;
 use warnings;
 use base qw(PublicInbox::DS);
-use fields qw(cb cleanup);
+use fields qw(cb end);
 use Errno qw(EAGAIN);
 use PublicInbox::Syscall qw(EPOLLIN EPOLLET);
 
+# This is called via: $env->{'pi-httpd.async'}->()
+# $io is a read-only pipe ($rpipe) for now, but may be a
+# bidirectional socket in the future.
 sub new {
-       my ($class, $io, $cb, $cleanup) = @_;
+       my ($class, $io, $cb, $end) = @_;
 
        # no $io? call $cb at the top of the next event loop to
        # avoid recursion:
        unless (defined($io)) {
                PublicInbox::DS::requeue($cb);
-               die 'cleanup unsupported w/o $io' if $cleanup;
+               die '$end unsupported w/o $io' if $end;
                return;
        }
 
        my $self = fields::new($class);
        IO::Handle::blocking($io, 0);
        $self->SUPER::new($io, EPOLLIN | EPOLLET);
-       $self->{cb} = $cb;
-       $self->{cleanup} = $cleanup;
+       $self->{cb} = $cb; # initial read callback, later replaced by main_cb
+       $self->{end} = $end; # like END {}, but only for this object
        $self;
 }
 
@@ -37,6 +40,8 @@ sub main_cb ($$) {
        my ($http, $fh) = @_;
        sub {
                my ($self) = @_;
+               # $self->{sock} is a read pipe for git-http-backend or cgit
+               # and 65536 is the default Linux pipe size
                my $r = sysread($self->{sock}, my $buf, 65536);
                if ($r) {
                        $fh->write($buf); # may call $http->close
@@ -52,19 +57,28 @@ sub main_cb ($$) {
                }
 
                # Done! Error handling will happen in $fh->close
-               # called by the {cleanup} handler
+               # called by the {end} handler
                delete $http->{forward};
-               $self->close;
+               $self->close; # queues ->{end} to be called
        }
 }
 
+# once this is called, all data we read is passed to the
+# to the PublicInbox::HTTP instance ($http) via $fh->write
 sub async_pass {
        my ($self, $http, $fh, $bref) = @_;
        # In case the client HTTP connection ($http) dies, it
        # will automatically close this ($self) object.
        $http->{forward} = $self;
+
+       # write anything we overread when we were reading headers
        $fh->write($$bref); # PublicInbox:HTTP::{chunked,identity}_wcb
-       $$bref = undef; # we're done with this
+
+       # we're done with this, free this memory up ASAP since the
+       # calls after this may use much memory:
+       $$bref = undef;
+
+       # replace the header read callback with the main one
        my $cb = $self->{cb} = main_cb($http, $fh);
        $cb->($self); # either hit EAGAIN or ->requeue to keep EPOLLET happy
 }
@@ -75,14 +89,15 @@ sub event_step {
        $cb->(@_);
 }
 
+# may be called as $forward->close in PublicInbox::HTTP or EOF (main_cb)
 sub close {
        my $self = $_[0];
        delete $self->{cb};
-       $self->SUPER::close;
+       $self->SUPER::close; # DS::close
 
        # we defer this to the next timer loop since close is deferred
-       if (my $cleanup = delete $self->{cleanup}) {
-               PublicInbox::DS::requeue($cleanup);
+       if (my $end = delete $self->{end}) {
+               PublicInbox::DS::requeue($end);
        }
 }
 

diff --git a/lib/PublicInbox/Qspawn.pm b/lib/PublicInbox/Qspawn.pm
index 76e48e8126b912082166660c764d906993510b63..294bf0a4dde2a8446a3c1e14cce849e0260bda51 100644 (file)
--- a/lib/PublicInbox/Qspawn.pm
+++ b/lib/PublicInbox/Qspawn.pm
@@ -230,6 +230,7 @@ sub psgi_return {
 
        my $buf = '';
        my $rd_hdr = sub {
+               # typically used for reading CGI headers
                # we must loop until EAGAIN for EPOLLET in HTTPD/Async.pm
                # We also need to check EINTR for generic PSGI servers.
                my $ret;
@@ -250,7 +251,7 @@ sub psgi_return {
 
        my $cb = sub {
                my $r = $rd_hdr->() or return;
-               $rd_hdr = undef;
+               $rd_hdr = undef; # done reading headers
                my $filter = delete $env->{'qspawn.filter'};
                if (scalar(@$r) == 3) { # error
                        if ($async) {
@@ -261,6 +262,7 @@ sub psgi_return {
                        }
                        $wcb->($r);
                } elsif ($async) {
+                       # done reading headers, handoff to read body
                        $fh = $wcb->($r); # scalar @$r == 2
                        $fh = filter_fh($fh, $filter) if $filter;
                        $async->async_pass($env->{'psgix.io'}, $fh, \$buf);