imap: compile UID FETCH to opcodes

This is just a hair faster and cacheable in the future, if we
need it.  Most notably, this avoids doing PublicInbox::Eml->new
for simple "RFC822", "BODY[]", and "RFC822.SIZE" requests.

1 files changed, 118 insertions, 70 deletions

diff --git a/lib/PublicInbox/IMAP.pm b/lib/PublicInbox/IMAP.pm
index 8307343c..3fae8111 100644
--- a/lib/PublicInbox/IMAP.pm
+++ b/lib/PublicInbox/IMAP.pm
@@ -40,22 +40,26 @@ sub LINE_MAX () { 512 } # does RFC 3501 have a limit like RFC 977?
 # changing this will cause grief for clients which cache
 sub UID_BLOCK () { 50_000 }
 
-my %FETCH_NEED_BLOB = ( # for future optimization
-        'BODY[HEADER]' => 1,
-        'BODY[TEXT]' => 1,
-        'BODY[]' => 1,
-        'RFC822.HEADER' => 1,
-        'RFC822.SIZE' => 1, # needs CRLF conversion :<
-        'RFC822.TEXT' => 1,
-        BODY => 1,
-        BODYSTRUCTURE => 1,
-        ENVELOPE => 1,
-        FLAGS => 0,
-        INTERNALDATE => 0,
-        RFC822 => 1,
-        UID => 0,
+# these values area also used for sorting
+sub NEED_BLOB () { 1 }
+sub NEED_EML () { NEED_BLOB|2 }
+my $OP_EML_NEW = [ NEED_EML - 1, \&op_eml_new ];
+
+my %FETCH_NEED = ( # for future optimization
+        'BODY[HEADER]' => [ NEED_EML, \&emit_rfc822_header ],
+        'BODY[TEXT]' => [ NEED_EML, \&emit_rfc822_text ],
+        'BODY[]' => [ NEED_BLOB, \&emit_rfc822 ],
+        'RFC822.HEADER' => [ NEED_EML, \&emit_rfc822_header ],
+        'RFC822.TEXT' => [ NEED_EML, \&emit_rfc822_text ],
+        'RFC822.SIZE' => [ NEED_BLOB, \&emit_rfc822_size ],
+        RFC822 => [ NEED_BLOB, \&emit_rfc822 ],
+        BODY => [ NEED_EML, \&emit_body ],
+        BODYSTRUCTURE => [ NEED_EML, \&emit_bodystructure ],
+        ENVELOPE => [ NEED_EML, \&emit_envelope ],
+        FLAGS => [ 0, \&emit_flags ],
+        INTERNALDATE => [ 0, \&emit_internaldate ],
 );
-my %FETCH_ATT = map { $_ => [ $_ ] } keys %FETCH_NEED_BLOB;
+my %FETCH_ATT = map { $_ => [ $_ ] } keys %FETCH_NEED;
 
 # aliases (RFC 3501 section 6.4.5)
 $FETCH_ATT{FAST} = [ qw(FLAGS INTERNALDATE RFC822.SIZE) ];
@@ -63,9 +67,10 @@ $FETCH_ATT{ALL} = [ @{$FETCH_ATT{FAST}}, 'ENVELOPE' ];
 $FETCH_ATT{FULL} = [ @{$FETCH_ATT{ALL}}, 'BODY' ];
 
 for my $att (keys %FETCH_ATT) {
-        my %h = map { $_ => 1 } @{$FETCH_ATT{$att}};
+        my %h = map { $_ => $FETCH_NEED{$_} } @{$FETCH_ATT{$att}};
         $FETCH_ATT{$att} = \%h;
 }
+undef %FETCH_NEED;
 
 my $valid_range = '[0-9]+|[0-9]+:[0-9]+|[0-9]+:\*';
 $valid_range = qr/\A(?:$valid_range)(?:,(?:$valid_range))*\z/;
@@ -417,7 +422,7 @@ sub requeue_once ($) {
 
 sub uid_fetch_cb { # called by git->cat_async via git_async_cat
         my ($bref, $oid, $type, $size, $fetch_m_arg) = @_;
-        my ($self, undef, $msgs, undef, $want) = @$fetch_m_arg;
+        my ($self, undef, $msgs, undef, $ops, $partial) = @$fetch_m_arg;
         my $smsg = shift @$msgs or die 'BUG: no smsg';
         if (!defined($oid)) {
                 # it's possible to have TOCTOU if an admin runs
@@ -426,51 +431,72 @@ sub uid_fetch_cb { # called by git->cat_async via git_async_cat
         } else {
                 $smsg->{blob} eq $oid or die "BUG: $smsg->{blob} != $oid";
         }
-
         $$bref =~ s/(?<!\r)\n/\r\n/sg; # make strict clients happy
 
         # fixup old bug from import (pre-a0c07cba0e5d8b6a)
         $$bref =~ s/\A[\r\n]*From [^\r\n]*\r\n//s;
-
         $self->msg_more("* $smsg->{num} FETCH (UID $smsg->{num}");
-
-        $want->{'RFC822.SIZE'} and
-                $self->msg_more(' RFC822.SIZE '.length($$bref));
-        $want->{INTERNALDATE} and
-                $self->msg_more(' INTERNALDATE "'.$smsg->internaldate.'"');
-        $want->{FLAGS} and $self->msg_more(' FLAGS ()');
-        for ('RFC822', 'BODY[]') {
-                $want->{$_} or next;
-                $self->msg_more(" $_ {".length($$bref)."}\r\n");
-                $self->msg_more($$bref);
+        my $eml;
+        for (my $i = 0; $i < @$ops;) {
+                my $k = $ops->[$i++];
+                $ops->[$i++]->($self, $k, $smsg, $bref, $eml);
         }
+        partial_emit($self, $partial, $eml) if $partial;
+        $self->msg_more(")\r\n");
+        requeue_once($self);
+}
 
-        my $eml = PublicInbox::Eml->new($bref);
+sub emit_rfc822 {
+        my ($self, $k, undef, $bref) = @_;
+        $self->msg_more(" $k {" . length($$bref)."}\r\n");
+        $self->msg_more($$bref);
+}
 
-        $want->{ENVELOPE} and
-                $self->msg_more(' ENVELOPE '.eml_envelope($eml));
+# Mail::IMAPClient::message_string cares about this by default
+# (->Ignoresizeerrors attribute)
+sub emit_rfc822_size {
+        my ($self, $k, undef, $bref) = @_;
+        $self->msg_more(' RFC822.SIZE ' . length($$bref));
+}
 
-        for ('RFC822.HEADER', 'BODY[HEADER]') {
-                $want->{$_} or next;
-                $self->msg_more(" $_ {".length(${$eml->{hdr}})."}\r\n");
-                $self->msg_more(${$eml->{hdr}});
-        }
-        for ('RFC822.TEXT', 'BODY[TEXT]') {
-                $want->{$_} or next;
-                $self->msg_more(" $_ {".length($$bref)."}\r\n");
-                $self->msg_more($$bref);
-        }
-        $want->{BODYSTRUCTURE} and
-                $self->msg_more(' BODYSTRUCTURE '.fetch_body($eml, 1));
-        $want->{BODY} and
-                $self->msg_more(' BODY '.fetch_body($eml));
-        if (my $partial = $want->{-partial}) {
-                partial_emit($self, $partial, $eml);
-        }
-        $self->msg_more(")\r\n");
-        requeue_once($self);
+sub emit_internaldate {
+        my ($self, undef, $smsg) = @_;
+        $self->msg_more(' INTERNALDATE "'.$smsg->internaldate.'"');
+}
+
+sub emit_flags { $_[0]->msg_more(' FLAGS ()') }
+
+sub emit_envelope {
+        my ($self, undef, undef, undef, $eml) = @_;
+        $self->msg_more(' ENVELOPE '.eml_envelope($eml));
+}
+
+sub emit_rfc822_header {
+        my ($self, $k, undef, undef, $eml) = @_;
+        $self->msg_more(" $k {".length(${$eml->{hdr}})."}\r\n");
+        $self->msg_more(${$eml->{hdr}});
+}
+
+# n.b. this is sorted to be after any emit_eml_new ops
+sub emit_rfc822_text {
+        my ($self, $k, undef, $bref) = @_;
+        $self->msg_more(" $k {".length($$bref)."}\r\n");
+        $self->msg_more($$bref);
+}
+
+sub emit_bodystructure {
+        my ($self, undef, undef, undef, $eml) = @_;
+        $self->msg_more(' BODYSTRUCTURE '.fetch_body($eml, 1));
+}
+
+sub emit_body {
+        my ($self, undef, undef, undef, $eml) = @_;
+        $self->msg_more(' BODY '.fetch_body($eml));
 }
 
+# set $eml once ($_[4] == $eml, $_[3] == $bref)
+sub op_eml_new { $_[4] = PublicInbox::Eml->new($_[3]) }
+
 sub uid_clamp ($$$) {
         my ($self, $beg, $end) = @_;
         my $uid_min = $self->{uid_min} or return;
@@ -521,7 +547,7 @@ sub refill_range ($$$) {
 }
 
 sub uid_fetch_m { # long_response
-        my ($self, $tag, $msgs, $range_info, $want) = @_;
+        my ($self, $tag, $msgs, $range_info) = @_; # \@ops, \@partial
         while (!@$msgs) { # rare
                 if (my $end = refill_range($self, $msgs, $range_info)) {
                         $self->write(\"$tag $end\r\n");
@@ -710,42 +736,64 @@ sub partial_emit ($$$) {
         }
 }
 
-sub fetch_common ($$$$) {
-        my ($self, $tag, $range_csv, $want) = @_;
-        my $ibx = $self->{ibx} or return "$tag BAD No mailbox selected\r\n";
+sub fetch_compile ($) {
+        my ($want) = @_;
         if ($want->[0] =~ s/\A\(//s) {
-                $want->[-1] =~ s/\)\z//s or return "$tag BAD no rparen\r\n";
+                $want->[-1] =~ s/\)\z//s or return 'BAD no rparen';
         }
-        my (%partial, %want);
+        my (%partial, %seen, @op);
+        my $need = 0;
         while (defined(my $att = shift @$want)) {
                 $att = uc($att);
+                next if $att eq 'UID'; # always returned
                 $att =~ s/\ABODY\.PEEK\[/BODY\[/; # we're read-only
                 my $x = $FETCH_ATT{$att};
                 if ($x) {
-                        %want = (%want, %$x);
+                        while (my ($k, $fl_cb) = each %$x) {
+                                next if $seen{$k}++;
+                                $need |= $fl_cb->[0];
+
+                                # insert a special op to convert $bref to $eml
+                                # the first time we need it
+                                if ($need == NEED_EML && !$seen{$need}++) {
+                                        push @op, $OP_EML_NEW;
+                                }
+                                # $fl_cb = [ flags, \&emit_foo ]
+                                push @op, [ @$fl_cb , $k ];
+                        }
                 } elsif (!partial_prepare(\%partial, $want, $att)) {
-                        return "$tag BAD param: $att\r\n";
+                        return "BAD param: $att";
                 }
         }
+        my @r;
 
         # stabilize partial order for consistency and ease-of-debugging:
         if (scalar keys %partial) {
-                $want{-partial} = [ map {;
-                        [ $_, @{$partial{$_}} ]
-                } sort keys %partial ];
+                $need = NEED_EML;
+                push @op, $OP_EML_NEW if !$seen{$need}++;
+                $r[2] = [ map { [ $_, @{$partial{$_}} ] } sort keys %partial ];
         }
-        $range_csv = 'bad' if $range_csv !~ $valid_range;
-        my $range_info = range_step($self, \$range_csv);
-        return "$tag $range_info\r\n" if !ref($range_info);
-        [ $tag, [], $range_info, \%want ];
+
+        $r[0] = $need;
+
+        # r[1] = [ $key1, $cb1, $key2, $cb2, ... ]
+        use sort 'stable'; # makes output more consistent
+        $r[1] = [ map { ($_->[2], $_->[1]) } sort { $a->[0] <=> $b->[0] } @op ];
+        @r;
 }
 
 sub cmd_uid_fetch ($$$;@) {
         my ($self, $tag, $range_csv, @want) = @_;
-        my $args = fetch_common($self, $tag, $range_csv, \@want);
-        ref($args) eq 'ARRAY' ?
-                long_response($self, \&uid_fetch_m, @$args) :
-                $args; # error
+        my $ibx = $self->{ibx} or return "$tag BAD No mailbox selected\r\n";
+        my ($need, $ops, $partial) = fetch_compile(\@want);
+        return "$tag $need\r\n" unless $ops;
+
+        $range_csv = 'bad' if $range_csv !~ $valid_range;
+        my $range_info = range_step($self, \$range_csv);
+        return "$tag $range_info\r\n" if !ref($range_info);
+
+        long_response($self, \&uid_fetch_m,
+                        $tag, [], $range_info, $ops, $partial);
 }
 
 sub parse_date ($) { # 02-Oct-1993