From: Peter Rabbitson <ribasushi@cpan.org>
Date: Wed, 27 Feb 2013 10:01:12 +0000 (+0100)
Subject: MOAR optimization - tracking is_new_res is double work
X-Git-Tag: v0.08242~13
X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?p=dbsrgits%2FDBIx-Class.git;a=commitdiff_plain;h=aa1d8a8751baf1e4c06b43f38ff9e02cdea51e6a

MOAR optimization - tracking is_new_res is double work

We can get the root node assembler to do that for us instead

Also remove more of the superfluous ||= assignments
---

diff --git a/lib/DBIx/Class/ResultSource/RowParser/Util.pm b/lib/DBIx/Class/ResultSource/RowParser/Util.pm
index 22b4150..e89d723 100644
--- a/lib/DBIx/Class/ResultSource/RowParser/Util.pm
+++ b/lib/DBIx/Class/ResultSource/RowParser/Util.pm
@@ -146,7 +146,7 @@ sub assemble_collapsing_parser {
   my ($data_assemblers, $stats) = __visit_infmap_collapse ($args);
 
   my @idcol_args = $args->{hri_style} ? ('', '') : (
-    '%cur_row_ids, ', # only declare the variable if we'll use it
+    ', %cur_row_ids', # only declare the variable if we'll use it
 
     sprintf( <<'EOS', join ', ', sort { $a <=> $b } keys %{ $stats->{idcols_seen} } ),
   $cur_row_ids{$_} = defined($cur_row_data->[$_]) ? $cur_row_data->[$_] : "\0NULL\xFF$rows_pos\xFF$_\0"
@@ -156,7 +156,9 @@ EOS
 
   my $parser_src = sprintf (<<'EOS', @idcol_args, $top_node_key_assembler||'', $top_node_key, join( "\n", @{$data_assemblers||[]} ) );
 ### BEGIN LITERAL STRING EVAL
-  my ($rows_pos, $result_pos, $cur_row_data,%1$s @collapse_idx, $is_new_res) = (0,0);
+  my $rows_pos = 0;
+  my ($result_pos, @collapse_idx, $cur_row_data %1$s);
+
   # this loop is a bit arcane - the rationale is that the passed in
   # $_[0] will either have only one row (->next) or will have all
   # rows already pulled in (->all and/or unordered). Given that the
@@ -179,18 +181,18 @@ EOS
     # in the case of an underdefined root - calculate the virtual id (otherwise no code at all)
     %3$s
 
-    $is_new_res = ! $collapse_idx[0]%4$s and (
-      $_[1] and $result_pos and (unshift @{$_[2]}, $cur_row_data) and last
-    );
+    # if we were supplied a coderef - we are collapsing lazily (the set
+    # is ordered properly)
+    # as long as we have a result already and the next result is new we
+    # return the pre-read data and bail
+    $_[1] and $result_pos and ! $collapse_idx[0]%4$s and (unshift @{$_[2]}, $cur_row_data) and last;
 
     # the rel assemblers
 %5$s
 
-    $_[0][$result_pos++] = $collapse_idx[0]%4$s
-      if $is_new_res;
   }
 
-  splice @{$_[0]}, $result_pos; # truncate the passed in array for cases of collapsing ->all()
+  $#{$_[0]} = $result_pos - 1; # truncate the passed in array to where we filled it with results
 ### END LITERAL STRING EVAL
 EOS
 
@@ -241,10 +243,10 @@ sub __visit_infmap_collapse {
   my @src;
 
   if ($cur_node_idx == 0) {
-    push @src, sprintf( '%s ||= %s;',
+    push @src, sprintf( '%s ||= $_[0][$result_pos++] = %s;',
       $node_idx_slot,
-      $me_struct,
-    ) if $me_struct;
+      $me_struct || '{}',
+    );
   }
   else {
     my $parent_attach_slot = sprintf( '$collapse_idx[%d]%s%s{%s}',
@@ -257,7 +259,7 @@ sub __visit_infmap_collapse {
       push @src, sprintf ( '%s ||= %s%s;',
         $parent_attach_slot,
         $node_idx_slot,
-        $me_struct ? " ||= $me_struct" : '',
+        $me_struct ? " = $me_struct" : '',
       );
     }
     else {
diff --git a/t/prefetch/manual.t b/t/prefetch/manual.t
index 7ce13a7..222fe35 100644
--- a/t/prefetch/manual.t
+++ b/t/prefetch/manual.t
@@ -312,12 +312,29 @@ $schema->storage->debug($orig_debug);
 is ($queries, 2, "Only two queries for rwo prefetch calls total");
 
 # can't cmp_deeply a random set - need *some* order
-my @hris = sort { $a->{year} cmp $b->{year} } @{$rs->search({}, {
+my $ord_rs = $rs->search({}, {
   order_by => [ 'tracks_2.title', 'tracks.title', 'cds.cdid', \ 'RANDOM()' ],
-})->all_hri};
-is (@hris, 6, 'hri count matches' );
+  result_class => 'DBIx::Class::ResultClass::HashRefInflator',
+});
+my @hris_all = sort { $a->{year} cmp $b->{year} } $ord_rs->all;
+is (@hris_all, 6, 'hri count matches' );
+
+my $iter_rs = $rs->search({}, {
+  order_by => [ 'me.year', 'me.cdid', 'tracks_2.title', 'tracks.title', 'cds.cdid', \ 'RANDOM()' ],
+  result_class => 'DBIx::Class::ResultClass::HashRefInflator',
+});
+my @hris_iter;
+while (my $r = $iter_rs->next) {
+  push @hris_iter, $r;
+}
+
+cmp_deeply(
+  \@hris_iter,
+  \@hris_all,
+  'Iteration works correctly',
+);
 
-cmp_deeply (\@hris, [
+cmp_deeply (\@hris_all, [
   {
     single_track => undef,
     tracks => [
@@ -464,4 +481,46 @@ cmp_deeply (\@hris, [
   },
 ], 'W00T, multi-has_many manual underdefined root prefetch with collapse works');
 
+$rs = $rs->search({}, { order_by => [ 'me.year', 'me.cdid', \ 'RANDOM()' ] });
+my @objs_iter;
+while (my $r = $rs->next) {
+  push @objs_iter, $r;
+}
+
+for my $i (0 .. $#objs_iter) {
+  is ($objs_iter[$i]->year, $hris_all[$i]{year}, "Expected year on object $i" );
+  is (
+    (defined $objs_iter[$i]->single_track),
+    (defined $hris_all[$i]{single_track}),
+    "Expected single relation on object $i"
+  );
+}
+
+$rs = $schema->resultset('Artist')->search({}, {
+  join => 'cds',
+  columns => ['cds.title', 'cds.artist' ],
+  collapse => 1,
+  order_by => [qw( me.name cds.title )],
+});
+
+$rs->create({ name => "${_}_cdless" })
+  for (qw( Z A ));
+
+cmp_deeply (
+  $rs->all_hri,
+  [
+    { cds => [] },
+    { cds => [
+      { artist => 1, title => "Equinoxe" },
+      { artist => 1, title => "Magnetic Fields" },
+      { artist => 1, title => "Oxygene" },
+      { artist => 1, title => "fuzzy_1" },
+      { artist => 1, title => "fuzzy_2" },
+      { artist => 1, title => "fuzzy_3" },
+    ] },
+    { cds => [] },
+  ],
+  'Expected HRI of 1:M with empty root selection',
+);
+
 done_testing;
diff --git a/t/resultset/inflate_result_api.t b/t/resultset/inflate_result_api.t
index a6914d9..db7c874 100644
--- a/t/resultset/inflate_result_api.t
+++ b/t/resultset/inflate_result_api.t
@@ -419,6 +419,43 @@ cmp_structures (
   'Non-Collapsing chained has_many'
 );
 
+$schema->resultset('Artist')->create({ name => "${_}_cdless" })
+  for (qw( Z A ));
+
+cmp_structures (
+  [$schema->resultset ('Artist')->search ({}, {
+    result_class => 'DBICTest::_IRCapture',
+    collapse => 1,
+    join => 'cds',
+    columns => [qw( cds.title cds.artist )],
+    order_by => [qw( me.name cds.title )],
+  })->all],
+  [
+    [
+      undef,
+      { cds => bless( [
+        [ { artist => undef, title => undef } ]
+      ], 'DBIx::ResultParser::RelatedNullBranch' ) },
+    ],
+    [
+      undef,
+      { cds => [
+        [ { artist => 1, title => "Equinoxe" } ],
+        [ { artist => 1, title => "Magnetic Fields" } ],
+        [ { artist => 1, title => "Oxygene" } ],
+        [ { artist => 1, title => "fuzzy_1" } ],
+      ] }
+    ],
+    [
+      undef,
+      { cds => bless( [
+        [ { artist => undef, title => undef } ]
+      ], 'DBIx::ResultParser::RelatedNullBranch' ) },
+    ],
+  ],
+  'Expected output of collapsing 1:M with empty root selection',
+);
+
 sub cmp_structures {
   my ($left, $right, $msg) = @_;
 
diff --git a/t/resultset/rowparser_internals.t b/t/resultset/rowparser_internals.t
index ebeb150..c7d8ac8 100644
--- a/t/resultset/rowparser_internals.t
+++ b/t/resultset/rowparser_internals.t
@@ -210,7 +210,8 @@ is_same_src (
     inflate_map => $infmap,
     collapse => 1,
   }),
-  ' my($rows_pos, $result_pos, $cur_row_data, %cur_row_ids, @collapse_idx, $is_new_res) = (0, 0);
+  ' my $rows_pos = 0;
+    my ($result_pos, @collapse_idx, $cur_row_data, %cur_row_ids);
 
     while ($cur_row_data = (
       ( $rows_pos >= 0 and $_[0][$rows_pos++] ) or do { $rows_pos = -1; undef } )
@@ -222,21 +223,20 @@ is_same_src (
         for (0, 1, 3, 4, 5);
 
       # a present cref in $_[1] implies lazy prefetch, implies a supplied stash in $_[2]
-      $_[1] and $result_pos and unshift(@{$_[2]}, $cur_row_data) and last
-        if ( $is_new_res = ! $collapse_idx[0]{$cur_row_ids{4}}{$cur_row_ids{5}} );
+      $_[1] and $result_pos and ! $collapse_idx[0]{$cur_row_ids{4}}{$cur_row_ids{5}} and (unshift @{$_[2]}, $cur_row_data) and last;
 
       # the rowdata itself for root node
-      $collapse_idx[0]{$cur_row_ids{4}}{$cur_row_ids{5}} ||= [{ artist => $cur_row_data->[5], title => $cur_row_data->[4], year => $cur_row_data->[2] }];
+      $collapse_idx[0]{$cur_row_ids{4}}{$cur_row_ids{5}} ||= $_[0][$result_pos++] = [{ artist => $cur_row_data->[5], title => $cur_row_data->[4], year => $cur_row_data->[2] }];
 
       # prefetch data of single_track (placed in root)
-      $collapse_idx[0]{$cur_row_ids{4}}{$cur_row_ids{5}}[1]{single_track} ||= $collapse_idx[1]{$cur_row_ids{1}}{$cur_row_ids{4}}{$cur_row_ids{5}} ||= [];
+      $collapse_idx[0]{$cur_row_ids{4}}{$cur_row_ids{5}}[1]{single_track} ||= $collapse_idx[1]{$cur_row_ids{1}}{$cur_row_ids{4}}{$cur_row_ids{5}} = [];
       defined($cur_row_data->[1]) or bless( $collapse_idx[0]{$cur_row_ids{4}}{$cur_row_ids{5}}[1]{single_track}, __NBC__ );
 
       # prefetch data of cd (placed in single_track)
-      $collapse_idx[1]{$cur_row_ids{1}}{$cur_row_ids{4}}{$cur_row_ids{5}}[1]{cd} ||= $collapse_idx[2]{$cur_row_ids{1}}{$cur_row_ids{4}}{$cur_row_ids{5}} ||= [];
+      $collapse_idx[1]{$cur_row_ids{1}}{$cur_row_ids{4}}{$cur_row_ids{5}}[1]{cd} ||= $collapse_idx[2]{$cur_row_ids{1}}{$cur_row_ids{4}}{$cur_row_ids{5}} = [];
 
       # prefetch data of artist ( placed in single_track->cd)
-      $collapse_idx[2]{$cur_row_ids{1}}{$cur_row_ids{4}}{$cur_row_ids{5}}[1]{artist} ||= $collapse_idx[3]{$cur_row_ids{1}}{$cur_row_ids{4}}{$cur_row_ids{5}} ||= [{ artistid => $cur_row_data->[1] }];
+      $collapse_idx[2]{$cur_row_ids{1}}{$cur_row_ids{4}}{$cur_row_ids{5}}[1]{artist} ||= $collapse_idx[3]{$cur_row_ids{1}}{$cur_row_ids{4}}{$cur_row_ids{5}} = [{ artistid => $cur_row_data->[1] }];
 
       # prefetch data of cds (if available)
       (! $collapse_idx[4]{$cur_row_ids{1}}{$cur_row_ids{3}}{$cur_row_ids{4}}{$cur_row_ids{5}} )
@@ -254,10 +254,8 @@ is_same_src (
       );
       defined($cur_row_data->[0]) or bless( $collapse_idx[4]{$cur_row_ids{1}}{$cur_row_ids{3}}{$cur_row_ids{4}}{$cur_row_ids{5}}[1]{tracks}, __NBC__ );
 
-      $_[0][$result_pos++] = $collapse_idx[0]{$cur_row_ids{4}}{$cur_row_ids{5}}
-        if $is_new_res;
     }
-    splice @{$_[0]}, $result_pos;
+    $#{$_[0]} = $result_pos - 1;
   ',
   'Same 1:1 descending terminating with chained 1:M:M but with collapse',
 );
@@ -268,7 +266,8 @@ is_same_src (
     collapse => 1,
     hri_style => 1,
   }),
-  ' my($rows_pos, $result_pos, $cur_row_data, @collapse_idx, $is_new_res) = (0, 0);
+  ' my $rows_pos = 0;
+    my ($result_pos, @collapse_idx, $cur_row_data);
 
     while ($cur_row_data = (
       ( $rows_pos >= 0 and $_[0][$rows_pos++] ) or do { $rows_pos = -1; undef } )
@@ -277,11 +276,10 @@ is_same_src (
     ) {
 
       # a present cref in $_[1] implies lazy prefetch, implies a supplied stash in $_[2]
-      $_[1] and $result_pos and unshift(@{$_[2]}, $cur_row_data) and last
-        if ( $is_new_res = ! $collapse_idx[0]{$cur_row_data->[4]}{$cur_row_data->[5]} );
+      $_[1] and $result_pos and ! $collapse_idx[0]{$cur_row_data->[4]}{$cur_row_data->[5]} and (unshift @{$_[2]}, $cur_row_data) and last;
 
       # the rowdata itself for root node
-      $collapse_idx[0]{$cur_row_data->[4]}{$cur_row_data->[5]} ||= { artist => $cur_row_data->[5], title => $cur_row_data->[4], year => $cur_row_data->[2] };
+      $collapse_idx[0]{$cur_row_data->[4]}{$cur_row_data->[5]} ||= $_[0][$result_pos++] = { artist => $cur_row_data->[5], title => $cur_row_data->[4], year => $cur_row_data->[2] };
 
       # prefetch data of single_track (placed in root)
       (! defined($cur_row_data->[1]) ) ? $collapse_idx[0]{$cur_row_data->[4]}{$cur_row_data->[5]}{single_track} = undef : do {
@@ -291,7 +289,7 @@ is_same_src (
         $collapse_idx[1]{$cur_row_data->[1]}{$cur_row_data->[4]}{$cur_row_data->[5]}{cd} ||= $collapse_idx[2]{$cur_row_data->[1]}{$cur_row_data->[4]}{$cur_row_data->[5]};
 
         # prefetch data of artist ( placed in single_track->cd)
-        $collapse_idx[2]{$cur_row_data->[1]}{$cur_row_data->[4]}{$cur_row_data->[5]}{artist} ||= $collapse_idx[3]{$cur_row_data->[1]}{$cur_row_data->[4]}{$cur_row_data->[5]} ||= { artistid => $cur_row_data->[1] };
+        $collapse_idx[2]{$cur_row_data->[1]}{$cur_row_data->[4]}{$cur_row_data->[5]}{artist} ||= $collapse_idx[3]{$cur_row_data->[1]}{$cur_row_data->[4]}{$cur_row_data->[5]} = { artistid => $cur_row_data->[1] };
 
         # prefetch data of cds (if available)
         (! defined $cur_row_data->[3] ) ? $collapse_idx[3]{$cur_row_data->[1]}{$cur_row_data->[4]}{$cur_row_data->[5]}{cds} = [] : do {
@@ -313,11 +311,8 @@ is_same_src (
           };
         };
       };
-
-      $_[0][$result_pos++] = $collapse_idx[0]{$cur_row_data->[4]}{$cur_row_data->[5]}
-        if $is_new_res;
     }
-    splice @{$_[0]}, $result_pos;
+    $#{$_[0]} = $result_pos - 1;
   ',
   'Same 1:1 descending terminating with chained 1:M:M but with collapse, HRI-direct',
 );
@@ -388,7 +383,8 @@ is_same_src (
     inflate_map => $infmap,
     collapse => 1,
   }),
-  ' my ($rows_pos, $result_pos, $cur_row_data, %cur_row_ids, @collapse_idx, $is_new_res) = (0,0);
+  ' my $rows_pos = 0;
+    my ($result_pos, @collapse_idx, $cur_row_data, %cur_row_ids);
 
     while ($cur_row_data = (
       ( $rows_pos >= 0 and $_[0][$rows_pos++] ) or do { $rows_pos = -1; undef } )
@@ -400,14 +396,13 @@ is_same_src (
         for (0, 1, 5, 6, 8, 10);
 
       # a present cref in $_[1] implies lazy prefetch, implies a supplied stash in $_[2]
-      $_[1] and $result_pos and unshift(@{$_[2]}, $cur_row_data) and last
-        if ( $is_new_res = ! $collapse_idx[0]{$cur_row_ids{1}} );
+      $_[1] and $result_pos and ! $collapse_idx[0]{$cur_row_ids{1}} and (unshift @{$_[2]}, $cur_row_data) and last;
 
-      $collapse_idx[0]{$cur_row_ids{1}} ||= [{ genreid => $cur_row_data->[4], latest_cd => $cur_row_data->[7], year => $cur_row_data->[3] }];
+      $collapse_idx[0]{$cur_row_ids{1}} ||= $_[0][$result_pos++] = [{ genreid => $cur_row_data->[4], latest_cd => $cur_row_data->[7], year => $cur_row_data->[3] }];
 
-      $collapse_idx[0]{$cur_row_ids{1}}[1]{existing_single_track} ||= $collapse_idx[1]{$cur_row_ids{1}} ||= [];
-      $collapse_idx[1]{$cur_row_ids{1}}[1]{cd} ||= $collapse_idx[2]{$cur_row_ids{1}} ||= [];
-      $collapse_idx[2]{$cur_row_ids{1}}[1]{artist} ||= $collapse_idx[3]{$cur_row_ids{1}} ||= [{ artistid => $cur_row_data->[1] }];
+      $collapse_idx[0]{$cur_row_ids{1}}[1]{existing_single_track} ||= $collapse_idx[1]{$cur_row_ids{1}} = [];
+      $collapse_idx[1]{$cur_row_ids{1}}[1]{cd} ||= $collapse_idx[2]{$cur_row_ids{1}} = [];
+      $collapse_idx[2]{$cur_row_ids{1}}[1]{artist} ||= $collapse_idx[3]{$cur_row_ids{1}} = [{ artistid => $cur_row_data->[1] }];
 
       (! $collapse_idx[4]{$cur_row_ids{1}}{$cur_row_ids{6}} )
         and
@@ -430,7 +425,7 @@ is_same_src (
       );
       defined($cur_row_data->[5]) or bless( $collapse_idx[0]{$cur_row_ids{1}}[1]{tracks}, __NBC__ );
 
-      $collapse_idx[6]{$cur_row_ids{1}}{$cur_row_ids{5}}[1]{lyrics} ||= $collapse_idx[7]{$cur_row_ids{1}}{$cur_row_ids{5}}{$cur_row_ids{10}} ||= [];
+      $collapse_idx[6]{$cur_row_ids{1}}{$cur_row_ids{5}}[1]{lyrics} ||= $collapse_idx[7]{$cur_row_ids{1}}{$cur_row_ids{5}}{$cur_row_ids{10}} = [];
       defined($cur_row_data->[10]) or bless( $collapse_idx[6]{$cur_row_ids{1}}{$cur_row_ids{5}}[1]{lyrics}, __NBC__ );
 
       (! $collapse_idx[8]{$cur_row_ids{0}}{$cur_row_ids{1}}{$cur_row_ids{5}}{$cur_row_ids{10}} )
@@ -438,12 +433,9 @@ is_same_src (
       push @{ $collapse_idx[7]{$cur_row_ids{1}}{$cur_row_ids{5}}{$cur_row_ids{10}}[1]{existing_lyric_versions} }, (
         $collapse_idx[8]{$cur_row_ids{0}}{$cur_row_ids{1}}{$cur_row_ids{5}}{$cur_row_ids{10}} = [{ lyric_id => $cur_row_data->[10], text => $cur_row_data->[0] }]
       );
-
-      $_[0][$result_pos++] = $collapse_idx[0]{$cur_row_ids{1}}
-        if $is_new_res;
     }
 
-    splice @{$_[0]}, $result_pos;
+    $#{$_[0]} = $result_pos - 1;
   ',
   'Multiple has_many on multiple branches torture test',
 );
@@ -453,7 +445,8 @@ is_same_src (
     inflate_map => $infmap,
     collapse => 1,
   }),
-  ' my ($rows_pos, $result_pos, $cur_row_data, %cur_row_ids, @collapse_idx, $is_new_res) = (0,0);
+  ' my $rows_pos = 0;
+    my ($result_pos, @collapse_idx, $cur_row_data, %cur_row_ids);
 
     while ($cur_row_data = (
       ( $rows_pos >= 0 and $_[0][$rows_pos++] ) or do { $rows_pos = -1; undef } )
@@ -465,14 +458,13 @@ is_same_src (
         for (0, 1, 5, 6, 8, 10);
 
       # a present cref in $_[1] implies lazy prefetch, implies a supplied stash in $_[2]
-      $_[1] and $result_pos and unshift(@{$_[2]}, $cur_row_data) and last
-        if ( $is_new_res = ! $collapse_idx[0]{$cur_row_ids{1}} );
+      $_[1] and $result_pos and ! $collapse_idx[0]{$cur_row_ids{1}} and (unshift @{$_[2]}, $cur_row_data) and last;
 
-      $collapse_idx[0]{$cur_row_ids{1}} ||= [{ genreid => $cur_row_data->[4], latest_cd => $cur_row_data->[7], year => $cur_row_data->[3] }];
+      $collapse_idx[0]{$cur_row_ids{1}} ||= $_[0][$result_pos++] = [{ genreid => $cur_row_data->[4], latest_cd => $cur_row_data->[7], year => $cur_row_data->[3] }];
 
-      $collapse_idx[0]{$cur_row_ids{1}}[1]{existing_single_track} ||= $collapse_idx[1]{$cur_row_ids{1}} ||= [];
-      $collapse_idx[1]{$cur_row_ids{1}}[1]{cd} ||= $collapse_idx[2]{$cur_row_ids{1}} ||= [];
-      $collapse_idx[2]{$cur_row_ids{1}}[1]{artist} ||= $collapse_idx[3]{$cur_row_ids{1}} ||= [{ artistid => $cur_row_data->[1] }];
+      $collapse_idx[0]{$cur_row_ids{1}}[1]{existing_single_track} ||= $collapse_idx[1]{$cur_row_ids{1}} = [];
+      $collapse_idx[1]{$cur_row_ids{1}}[1]{cd} ||= $collapse_idx[2]{$cur_row_ids{1}} = [];
+      $collapse_idx[2]{$cur_row_ids{1}}[1]{artist} ||= $collapse_idx[3]{$cur_row_ids{1}} = [{ artistid => $cur_row_data->[1] }];
 
       (! $collapse_idx[4]{$cur_row_ids{1}}{$cur_row_ids{6}} )
         and
@@ -495,7 +487,7 @@ is_same_src (
       );
       defined($cur_row_data->[5]) or bless( $collapse_idx[0]{$cur_row_ids{1}}[1]{tracks}, __NBC__ );
 
-      $collapse_idx[6]{$cur_row_ids{1}}{$cur_row_ids{5}}[1]{lyrics} ||= $collapse_idx[7]{$cur_row_ids{1}}{$cur_row_ids{5}}{$cur_row_ids{10}} ||= [];
+      $collapse_idx[6]{$cur_row_ids{1}}{$cur_row_ids{5}}[1]{lyrics} ||= $collapse_idx[7]{$cur_row_ids{1}}{$cur_row_ids{5}}{$cur_row_ids{10}} = [];
       defined($cur_row_data->[10]) or bless( $collapse_idx[6]{$cur_row_ids{1}}{$cur_row_ids{5}}[1]{lyrics}, __NBC__ );
 
       (! $collapse_idx[8]{$cur_row_ids{0}}{$cur_row_ids{1}}{$cur_row_ids{5}}{$cur_row_ids{10}} )
@@ -503,12 +495,9 @@ is_same_src (
       push @{ $collapse_idx[7]{$cur_row_ids{1}}{$cur_row_ids{5}}{$cur_row_ids{10}}[1]{existing_lyric_versions} }, (
         $collapse_idx[8]{$cur_row_ids{0}}{$cur_row_ids{1}}{$cur_row_ids{5}}{$cur_row_ids{10}} = [{ lyric_id => $cur_row_data->[10], text => $cur_row_data->[0] }]
       );
-
-      $_[0][$result_pos++] = $collapse_idx[0]{$cur_row_ids{1}}
-        if $is_new_res;
     }
 
-    splice @{$_[0]}, $result_pos;
+    $#{$_[0]} = $result_pos - 1;
   ',
   'Multiple has_many on multiple branches with branch torture test',
 );
@@ -566,7 +555,8 @@ is_same_src (
     inflate_map => $infmap,
     collapse => 1,
   }),
-  ' my($rows_pos, $result_pos, $cur_row_data, %cur_row_ids, @collapse_idx, $is_new_res) = (0, 0);
+  ' my $rows_pos = 0;
+    my ($result_pos, @collapse_idx, $cur_row_data, %cur_row_ids);
 
     while ($cur_row_data = (
       ( $rows_pos >= 0 and $_[0][$rows_pos++] ) or do { $rows_pos = -1; undef } )
@@ -587,17 +577,16 @@ is_same_src (
       );
 
       # a present cref in $_[1] implies lazy prefetch, implies a supplied stash in $_[2]
-      $_[1] and $result_pos and unshift(@{$_[2]}, $cur_row_data) and last
-        if ( $is_new_res = ! $collapse_idx[0]{$cur_row_ids{10}} );
+      $_[1] and $result_pos and ! $collapse_idx[0]{$cur_row_ids{10}} and (unshift @{$_[2]}, $cur_row_data) and last;
 
-      $collapse_idx[0]{$cur_row_ids{10}} ||= [{ year => $$cur_row_data[1] }];
+      $collapse_idx[0]{$cur_row_ids{10}} ||= $_[0][$result_pos++] = [{ year => $$cur_row_data[1] }];
 
-      $collapse_idx[0]{$cur_row_ids{10}}[1]{single_track} ||= ($collapse_idx[1]{$cur_row_ids{0}} ||= [{ trackid => $cur_row_data->[0] }]);
+      $collapse_idx[0]{$cur_row_ids{10}}[1]{single_track} ||= ($collapse_idx[1]{$cur_row_ids{0}} = [{ trackid => $cur_row_data->[0] }]);
       defined($cur_row_data->[0]) or bless ( $collapse_idx[0]{$cur_row_ids{10}}[1]{single_track}, __NBC__ );
 
-      $collapse_idx[1]{$cur_row_ids{0}}[1]{cd} ||= $collapse_idx[2]{$cur_row_ids{0}} ||= [];
+      $collapse_idx[1]{$cur_row_ids{0}}[1]{cd} ||= $collapse_idx[2]{$cur_row_ids{0}} = [];
 
-      $collapse_idx[2]{$cur_row_ids{0}}[1]{artist} ||= ($collapse_idx[3]{$cur_row_ids{0}} ||= [{ artistid => $cur_row_data->[6] }]);
+      $collapse_idx[2]{$cur_row_ids{0}}[1]{artist} ||= ($collapse_idx[3]{$cur_row_ids{0}} = [{ artistid => $cur_row_data->[6] }]);
 
       (! $collapse_idx[4]{$cur_row_ids{0}}{$cur_row_ids{4}} )
         and
@@ -619,12 +608,9 @@ is_same_src (
           $collapse_idx[6]{$cur_row_ids{2}}{$cur_row_ids{3}} = [{ cd => $$cur_row_data[2], title => $cur_row_data->[3] }]
       );
       defined($cur_row_data->[2]) or bless ( $collapse_idx[0]{$cur_row_ids{10}}[1]{tracks}, __NBC__ );
-
-      $_[0][$result_pos++] = $collapse_idx[0]{$cur_row_ids{10}}
-        if $is_new_res;
     }
 
-    splice @{$_[0]}, $result_pos;
+    $#{$_[0]} = $result_pos - 1;
   ',
   'Multiple has_many on multiple branches with underdefined root torture test',
 );
@@ -635,7 +621,8 @@ is_same_src (
     collapse => 1,
     hri_style => 1,
   }),
-  ' my($rows_pos, $result_pos, $cur_row_data, @collapse_idx, $is_new_res) = (0, 0);
+  ' my $rows_pos = 0;
+    my ($result_pos, @collapse_idx, $cur_row_data);
 
     while ($cur_row_data = (
       ( $rows_pos >= 0 and $_[0][$rows_pos++] ) or do { $rows_pos = -1; undef } )
@@ -653,18 +640,17 @@ is_same_src (
       );
 
       # a present cref in $_[1] implies lazy prefetch, implies a supplied stash in $_[2]
-      $_[1] and $result_pos and unshift(@{$_[2]}, $cur_row_data) and last
-        if ( $is_new_res = ! $collapse_idx[0]{$cur_row_data->[10]} );
+      $_[1] and $result_pos and ! $collapse_idx[0]{$cur_row_data->[10]} and (unshift @{$_[2]}, $cur_row_data) and last;
 
-      $collapse_idx[0]{$cur_row_data->[10]} ||= { year => $$cur_row_data[1] };
+      $collapse_idx[0]{$cur_row_data->[10]} ||= $_[0][$result_pos++] = { year => $$cur_row_data[1] };
 
       (! defined $cur_row_data->[0] ) ? $collapse_idx[0]{$cur_row_data->[10]}{single_track} = undef : do {
 
-        $collapse_idx[0]{$cur_row_data->[10]}{single_track} ||= ($collapse_idx[1]{$cur_row_data->[0]} ||= { trackid => $$cur_row_data[0] });
+        $collapse_idx[0]{$cur_row_data->[10]}{single_track} ||= ($collapse_idx[1]{$cur_row_data->[0]} = { trackid => $$cur_row_data[0] });
 
         $collapse_idx[1]{$cur_row_data->[0]}{cd} ||= $collapse_idx[2]{$cur_row_data->[0]};
 
-        $collapse_idx[2]{$cur_row_data->[0]}{artist} ||= ($collapse_idx[3]{$cur_row_data->[0]} ||= { artistid => $$cur_row_data[6] });
+        $collapse_idx[2]{$cur_row_data->[0]}{artist} ||= ($collapse_idx[3]{$cur_row_data->[0]} = { artistid => $$cur_row_data[6] });
 
         (! defined $cur_row_data->[4] ) ? $collapse_idx[3]{$cur_row_data->[0]}{cds} = [] : do {
 
@@ -692,12 +678,9 @@ is_same_src (
             $collapse_idx[6]{$cur_row_data->[2]}{$cur_row_data->[3]} = { cd => $$cur_row_data[2], title => $$cur_row_data[3] }
         );
       };
-
-      $_[0][$result_pos++] = $collapse_idx[0]{$cur_row_data->[10]}
-        if $is_new_res;
     }
 
-    splice @{$_[0]}, $result_pos;
+    $#{$_[0]} = $result_pos - 1;
   ',
   'Multiple has_many on multiple branches with underdefined root, HRI-direct torture test',
 );