From: Peter Rabbitson <ribasushi@cpan.org>
Date: Mon, 14 Dec 2015 09:18:17 +0000 (+0100)
Subject: Microoptimize various "is this string empty" checks
X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=commitdiff_plain;h=d52c4a75538bd15d1fa531a63c6ec45b8943dfd0;p=dbsrgits%2FDBIx-Class-Historic.git

Microoptimize various "is this string empty" checks

Checking the truthiness of the separately tracked string length is vastly
faster than doing actual string comparison

Working set identified via: grep -nPr "\b(ne|eq)\b\s*(\"\"|''|q{}|q())" lib
---

diff --git a/lib/DBIx/Class/ResultSet.pm b/lib/DBIx/Class/ResultSet.pm
index e8b710c..be4a69e 100644
--- a/lib/DBIx/Class/ResultSet.pm
+++ b/lib/DBIx/Class/ResultSet.pm
@@ -442,7 +442,7 @@ sub search_rs {
     $call_cond = shift;
   }
   # fish out attrs in the ($condref, $attr) case
-  elsif (@_ == 2 and ( ! defined $_[0] or (ref $_[0]) ne '') ) {
+  elsif (@_ == 2 and ( ! defined $_[0] or length ref $_[0] ) ) {
     ($call_cond, $call_attrs) = @_;
   }
   elsif (@_ % 2) {
@@ -456,7 +456,7 @@ sub search_rs {
     for my $i (0 .. $#_) {
       next if $i % 2;
       $self->throw_exception ('All keys in condition key/value pairs must be plain scalars')
-        if (! defined $_[$i] or ref $_[$i] ne '');
+        if (! defined $_[$i] or length ref $_[$i] );
     }
 
     $call_cond = { @_ };
diff --git a/lib/DBIx/Class/Storage/DBI/Sybase/ASE.pm b/lib/DBIx/Class/Storage/DBI/Sybase/ASE.pm
index c471bf8..7756df7 100644
--- a/lib/DBIx/Class/Storage/DBI/Sybase/ASE.pm
+++ b/lib/DBIx/Class/Storage/DBI/Sybase/ASE.pm
@@ -683,7 +683,8 @@ sub _remove_blob_cols {
       }
       else {
         $fields->{$col} = \"''";
-        $blob_cols{$col} = $blob_val unless $blob_val eq '';
+        $blob_cols{$col} = $blob_val
+          if length $blob_val;
       }
     }
   }
@@ -709,7 +710,7 @@ sub _remove_blob_cols_array {
         else {
           $data->[$j][$i] = \"''";
           $blob_cols[$j][$i] = $blob_val
-            unless $blob_val eq '';
+            if length $blob_val;
         }
       }
     }
diff --git a/lib/DBIx/Class/Storage/DBIHacks.pm b/lib/DBIx/Class/Storage/DBIHacks.pm
index c129b1e..14410b7 100644
--- a/lib/DBIx/Class/Storage/DBIHacks.pm
+++ b/lib/DBIx/Class/Storage/DBIHacks.pm
@@ -1102,7 +1102,7 @@ sub _collapse_cond {
         for (sort keys %$chunk) {
 
           # Match SQLA 1.79 behavior
-          if ($_ eq '') {
+          unless( length $_ ) {
             is_literal_value($chunk->{$_})
               ? carp 'Hash-pairs consisting of an empty string with a literal are deprecated, use -and => [ $literal ] instead'
               : $self->throw_exception("Supplying an empty left hand side argument is not supported in hash-pairs")
@@ -1120,7 +1120,7 @@ sub _collapse_cond {
 
         # Match SQLA 1.79 behavior
         $self->throw_exception("Supplying an empty left hand side argument is not supported in array-pairs")
-          if $where_is_anded_array and (! defined $chunk or $chunk eq '');
+          if $where_is_anded_array and (! defined $chunk or ! length $chunk);
 
         push @pairs, $chunk, shift @pieces;
       }
@@ -1315,7 +1315,7 @@ sub _collapse_cond_unroll_pairs {
   while (@$pairs) {
     my ($lhs, $rhs) = splice @$pairs, 0, 2;
 
-    if ($lhs eq '') {
+    if (! length $lhs) {
       push @conds, $self->_collapse_cond($rhs);
     }
     elsif ( $lhs =~ /^\-and$/i ) {
diff --git a/lib/DBIx/Class/Storage/TxnScopeGuard.pm b/lib/DBIx/Class/Storage/TxnScopeGuard.pm
index 392e354..841337f 100644
--- a/lib/DBIx/Class/Storage/TxnScopeGuard.pm
+++ b/lib/DBIx/Class/Storage/TxnScopeGuard.pm
@@ -26,7 +26,7 @@ sub new {
   # There got to be a saner way of doing this...
   if (is_exception $@) {
     weaken(
-      $guard->{existing_exception_ref} = (ref($@) eq '') ? \$@ : $@
+      $guard->{existing_exception_ref} = (length ref $@) ? $@ : \$@
     );
   }
 
@@ -71,7 +71,7 @@ sub DESTROY {
     (
       ! defined $self->{existing_exception_ref}
         or
-      refaddr( ref($@) eq '' ? \$@ : $@ ) != refaddr($self->{existing_exception_ref})
+      refaddr( (length ref $@) ? $@ : \$@ ) != refaddr($self->{existing_exception_ref})
     )
   );
 
diff --git a/lib/DBIx/Class/_Util.pm b/lib/DBIx/Class/_Util.pm
index 98da93c..362bb35 100644
--- a/lib/DBIx/Class/_Util.pm
+++ b/lib/DBIx/Class/_Util.pm
@@ -158,7 +158,10 @@ sub is_exception ($) {
   {
     local $@;
     eval {
-      $not_blank = ($e ne '') ? 1 : 0;
+      # The ne() here is deliberate - a plain length($e), or worse "$e" ne
+      # will entirely obviate the need for the encolsing eval{}, as the
+      # condition we guard against is a missing fallback overload
+      $not_blank = ( $e ne '' );
       1;
     } or $suberror = $@;
   }
@@ -185,7 +188,7 @@ sub is_exception ($) {
       ));
 
       # workaround, keeps spice flowing
-      $not_blank = ("$e" ne '') ? 1 : 0;
+      $not_blank = !!( length $e );
     }
     else {
       # not blessed yet failed the 'ne'... this makes 0 sense...