From: Will Hawes <wdhawes@gmail.com>
Date: Wed, 15 Feb 2006 14:25:53 +0000 (+0000)
Subject: introduce row caching using related_resultset; has_many prefetch (single-level only... 
X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=commitdiff_plain;h=64acc2bc801dcc1c982b16fe45434e9b82edcef6;p=dbsrgits%2FDBIx-Class-Historic.git

introduce row caching using related_resultset; has_many prefetch (single-level only); **NOTE** breaks some tests in t/cdbi-t
---

diff --git a/lib/DBIx/Class/Relationship/Base.pm b/lib/DBIx/Class/Relationship/Base.pm
index 7e6542d..8925121 100644
--- a/lib/DBIx/Class/Relationship/Base.pm
+++ b/lib/DBIx/Class/Relationship/Base.pm
@@ -85,41 +85,15 @@ sub register_relationship { }
 
 sub search_related {
   my $self = shift;
-  die "Can't call *_related as class methods" unless ref $self;
   my $rel = shift;
-  my $attrs = { };
-  if (@_ > 1 && ref $_[$#_] eq 'HASH') {
-    $attrs = { %{ pop(@_) } };
+  my $rs = $self->related_resultset($rel);
+  if( @_ ) {
+    return $rs->search(@_);
   }
-  my $rel_obj = $self->relationship_info($rel);
-  $self->throw_exception( "No such relationship ${rel}" ) unless $rel_obj;
-  $attrs = { %{$rel_obj->{attrs} || {}}, %{$attrs || {}} };
-
-  $self->throw_exception( "Invalid query: @_" ) if (@_ > 1 && (@_ % 2 == 1));
-  my $query = ((@_ > 1) ? {@_} : shift);
-
-  my ($cond) = $self->result_source->resolve_condition($rel_obj->{cond}, $rel, $self);
-  if (ref $cond eq 'ARRAY') {
-    $cond = [ map { my %hash;
-      foreach my $key (keys %{$_}) {
-        unless ($key =~ m/\./) {
-          $hash{"me.$key"} = $_->{$key};
-        } else {
-          $hash{$key} = $_->{$key};
-        }
-      }; \%hash; } @$cond ];
-  } else {
-    foreach my $key (keys %$cond) {
-      unless ($key =~ m/\./) {
-        $cond->{"me.$key"} = delete $cond->{$key};
-      }
-    }
+  else {
+    # search() returns a new resultset, so related_resultsets would be lost
+    return wantarray ? $rs->all : $rs;
   }
-  $query = ($query ? { '-and' => [ $cond, $query ] } : $cond);
-  #use Data::Dumper; warn Dumper($cond);
-  #warn $rel_obj->{class}." $meth $cond ".join(', ', @{$attrs->{bind}||[]});
-  return $self->result_source->related_source($rel
-           )->resultset->search($query, $attrs);
 }
 
 =head2 count_related
@@ -142,7 +116,9 @@ sub count_related {
 sub create_related {
   my $self = shift;
   my $rel = shift;
-  return $self->search_related($rel)->create(@_);
+  my $obj = $self->search_related($rel)->create(@_);
+  delete $self->{related_resultsets}->{$rel};
+  return $obj;
 }
 
 =head2 new_related
@@ -222,11 +198,72 @@ sub update_from_related {
 
 sub delete_related {
   my $self = shift;
-  return $self->search_related(@_)->delete;
+  my $obj = $self->search_related(@_)->delete;
+  delete $self->{related_resultsets}->{$_[0]};
+  return $obj;
 }
 
 1;
 
+=head2 related_resultset($name)
+
+Returns a L<DBIx::Class::ResultSet> for the relationship named $name.
+
+  $rs = My::Table->related_resultset('related_table');
+
+=cut
+
+sub related_resultset {
+  my $self = shift;
+  $self->throw_exception("Can't call *_related as class methods") unless ref $self;
+  my $rel = shift;
+  $self->{related_resultsets} ||= {};
+  #use Data::Dumper; warn "related_resultsets: ", Dumper $self->{related_resultsets};
+  my $resultsets = $self->{related_resultsets};
+  if( !exists $resultsets->{$rel} ) {
+
+    #warn "creating related resultset for relation '$rel'", \$self;
+    my $source = $self->result_source;
+    # if relation exists but resultset doesn't, create the resultset
+
+    my $attrs = { };
+    if (@_ > 1 && ref $_[$#_] eq 'HASH') {
+      $attrs = { %{ pop(@_) } };
+    }
+  
+    my $rel_obj = $self->relationship_info($rel);
+    $self->throw_exception( "No such relationship ${rel}" ) unless $rel_obj;
+    $attrs = { %{$rel_obj->{attrs} || {}}, %{$attrs || {}} };
+
+    $self->throw_exception( "Invalid query: @_" ) if (@_ > 1 && (@_ % 2 == 1));
+    my $query = ((@_ > 1) ? {@_} : shift);
+
+    my ($cond) = $self->result_source->resolve_condition($rel_obj->{cond}, $rel, $self);
+    if (ref $cond eq 'ARRAY') {
+      $cond = [ map { my %hash;
+        foreach my $key (keys %{$_}) {
+          unless ($key =~ m/\./) {
+            $hash{"me.$key"} = $_->{$key};
+          } else {
+           $hash{$key} = $_->{$key};
+          }
+        }; \%hash; } @$cond ];
+      } else {
+      foreach my $key (keys %$cond) {
+        unless ($key =~ m/\./) {
+          $cond->{"me.$key"} = delete $cond->{$key};
+        }
+      }
+    }
+    $query = ($query ? { '-and' => [ $cond, $query ] } : $cond);
+    #use Data::Dumper; warn Dumper($cond);
+    #warn $rel_obj->{class}." $meth $cond ".join(', ', @{$attrs->{bind}||[]});
+    $resultsets->{$rel} = 
+      $self->result_source->related_source($rel)->resultset->search($query, $attrs);
+  }
+  return $resultsets->{$rel};
+}
+
 =head1 AUTHORS
 
 Matt S. Trout <mst@shadowcatsystems.co.uk>
diff --git a/lib/DBIx/Class/ResultSet.pm b/lib/DBIx/Class/ResultSet.pm
index e8c020a..e0e321a 100644
--- a/lib/DBIx/Class/ResultSet.pm
+++ b/lib/DBIx/Class/ResultSet.pm
@@ -255,22 +255,7 @@ records.
 =cut
 
 sub search_related {
-  my ($self, $rel, @rest) = @_;
-  my $rel_obj = $self->result_source->relationship_info($rel);
-  $self->throw_exception(
-    "No such relationship ${rel} in search_related")
-      unless $rel_obj;
-  my $rs = $self->search(undef, { join => $rel });
-  my $alias = ($rs->{attrs}{seen_join}{$rel} > 1
-                ? join('_', $rel, $rs->{attrs}{seen_join}{$rel})
-                : $rel);
-  return $self->result_source->schema->resultset($rel_obj->{class}
-           )->search( undef,
-             { %{$rs->{attrs}},
-               alias => $alias,
-               select => undef(),
-               as => undef() }
-           )->search(@rest);
+  return shift->related_resultset(shift)->search(@_);
 }
 
 =head2 cursor
@@ -368,6 +353,13 @@ Can be used to efficiently iterate over records in the resultset:
 
 sub next {
   my ($self) = @_;
+  my $cache = $self->get_cache;
+  if( @$cache ) {
+    $self->{all_cache_position} ||= 0;
+    my $obj = $cache->[$self->{all_cache_position}];
+    $self->{all_cache_position}++;
+    return $obj;
+  }
   my @row = $self->cursor->next;
 #  warn Dumper(\@row); use Data::Dumper;
   return unless (@row);
@@ -376,17 +368,71 @@ sub next {
 
 sub _construct_object {
   my ($self, @row) = @_;
+  my @row_orig = @row; # copy @row for key comparison later, because @row will change
   my @as = @{ $self->{attrs}{as} };
   #warn "@cols -> @row";
   my $info = [ {}, {} ];
   foreach my $as (@as) {
+    my $rs = $self;
     my $target = $info;
     my @parts = split(/\./, $as);
     my $col = pop(@parts);
     foreach my $p (@parts) {
       $target = $target->[1]->{$p} ||= [];
+      
+      # if cache is enabled, fetch inflated objs for prefetch
+      if( $rs->{attrs}->{cache} ) {
+        my $rel_info = $rs->result_source->relationship_info($p);
+        my $cond = $rel_info->{cond};
+        my $parent_rs = $rs;
+        $rs = $rs->related_resultset($p);
+        $rs->{attrs}->{cache} = 1;
+        my @objs = ();
+          
+        # populate related resultset's cache if empty
+        if( !@{ $rs->get_cache } ) {
+          $rs->all;
+        }
+
+        # get ordinals for pk columns in $row, so values can be compared
+        my $map = {};
+        keys %$cond;
+        my $re = qr/^\w+\./;
+        while( my( $rel_key, $pk ) = ( each %$cond ) ) {
+          $rel_key =~ s/$re//;
+          $pk =~ s/$re//;
+          $map->{$rel_key} = $pk;
+        } #die Dumper $map;
+          
+        keys %$map;
+        while( my( $rel_key, $pk ) = each( %$map ) ) {
+          my $i = 0;
+          foreach my $col ( $parent_rs->result_source->columns ) {
+            if( $col eq $pk ) {
+              $map->{$rel_key} = $i;
+            }
+            $i++;
+          }
+        } #die Dumper $map;
+
+        $rs->reset(); # reset cursor/cache position 
+          
+        # get matching objects for inflation
+        OBJ: while( my $rel_obj = $rs->next ) {
+          keys %$map;
+          KEYS: while( my( $rel_key, $ordinal ) = each %$map ) {
+            # use get_column to avoid auto inflation (want scalar value)
+            if( $rel_obj->get_column($rel_key) ne $row_orig[$ordinal] ) {
+              next OBJ;
+            }
+            push @objs, $rel_obj;
+          }
+        }
+        $target->[0] = \@objs;
+      }
     }
-    $target->[0]->{$col} = shift @row;
+    $target->[0]->{$col} = shift @row
+      if ref($target->[0]) ne 'ARRAY'; # arrayref is pre-inflated objects, do not overwrite
   }
   #use Data::Dumper; warn Dumper(\@as, $info);
   my $new = $self->result_source->result_class->inflate_result(
@@ -421,6 +467,8 @@ sub count {
   my $self = shift;
   return $self->search(@_)->count if @_ && defined $_[0];
   unless (defined $self->{count}) {
+    return scalar @{ $self->get_cache }
+      if @{ $self->get_cache };
     my $group_by;
     my $select = { 'count' => '*' };
     if( $group_by = delete $self->{attrs}{group_by} ) {
@@ -477,6 +525,14 @@ is returned in list context.
 
 sub all {
   my ($self) = @_;
+  return @{ $self->get_cache }
+    if @{ $self->get_cache };
+  if( $self->{attrs}->{cache} ) {
+    my @obj = map { $self->_construct_object(@$_); }
+            $self->cursor->all;
+    $self->set_cache( \@obj );
+    return @{ $self->get_cache };
+  }
   return map { $self->_construct_object(@$_); }
            $self->cursor->all;
 }
@@ -489,6 +545,7 @@ Resets the resultset's cursor, so you can iterate through the elements again.
 
 sub reset {
   my ($self) = @_;
+  $self->{all_cache_position} = 0;
   $self->cursor->reset;
   return $self;
 }
@@ -751,6 +808,90 @@ sub update_or_create {
   return $row;
 }
 
+=head2 get_cache
+
+Gets the contents of the cache for the resultset.
+
+=cut
+
+sub get_cache {
+  my $self = shift;
+  return $self->{all_cache} || [];
+}
+
+=head2 set_cache
+
+Sets the contents of the cache for the resultset. Expects an arrayref of objects of the same class as those produced by the resultset.
+
+=cut
+
+sub set_cache {
+  my ( $self, $data ) = @_;
+  $self->throw_exception("set_cache requires an arrayref")
+    if ref $data ne 'ARRAY';
+  my $result_class = $self->result_source->result_class;
+  foreach( @$data ) {
+    $self->throw_exception("cannot cache object of type '$_', expected '$result_class'")
+      if ref $_ ne $result_class;
+  }
+  $self->{all_cache} = $data;
+}
+
+=head2 clear_cache
+
+Clears the cache for the resultset.
+
+=cut
+
+sub clear_cache {
+  my $self = shift;
+  $self->set_cache([]);
+}
+
+=head2 related_resultset
+
+Returns a related resultset for the supplied relationship name.
+
+  $rs = $rs->related_resultset('foo');
+
+=cut
+
+sub related_resultset {
+  my ( $self, $rel, @rest ) = @_;
+  $self->{related_resultsets} ||= {};
+  my $resultsets = $self->{related_resultsets};
+  if( !exists $resultsets->{$rel} ) {
+    #warn "fetching related resultset for rel '$rel'";
+    my $rel_obj = $self->result_source->relationship_info($rel);
+    $self->throw_exception(
+      "search_related: result source '" . $self->result_source->name .
+      "' has no such relationship ${rel}")
+      unless $rel_obj; #die Dumper $self->{attrs};
+    my $rs;
+    if( $self->{attrs}->{cache} ) {
+      $rs = $self->search(undef);
+    }
+    else {
+      $rs = $self->search(undef, { join => $rel });
+    }
+    #use Data::Dumper; die Dumper $rs->{attrs};#$rs = $self->search( undef );
+    #use Data::Dumper; warn Dumper $self->{attrs}, Dumper $rs->{attrs};
+    my $alias = (defined $rs->{attrs}{seen_join}{$rel}
+                  && $rs->{attrs}{seen_join}{$rel} > 1
+                ? join('_', $rel, $rs->{attrs}{seen_join}{$rel})
+                : $rel);
+    $resultsets->{$rel} =
+      $self->result_source->schema->resultset($rel_obj->{class}
+           )->search( undef,
+             { %{$rs->{attrs}},
+               alias => $alias,
+               select => undef(),
+               as => undef() }
+           )->search(@rest);
+  }
+  return $resultsets->{$rel};
+}
+
 =head2 throw_exception
 
 See Schema's throw_exception
diff --git a/lib/DBIx/Class/Row.pm b/lib/DBIx/Class/Row.pm
index 0d4a8a4..85a70a8 100644
--- a/lib/DBIx/Class/Row.pm
+++ b/lib/DBIx/Class/Row.pm
@@ -66,6 +66,7 @@ sub insert {
   $source->storage->insert($source->from, { $self->get_columns });
   $self->in_storage(1);
   $self->{_dirty_columns} = {};
+  $self->{related_resultsets} = {};
   return $self;
 }
 
@@ -109,6 +110,7 @@ sub update {
     $self->throw_exception("Can't update ${self}: updated more than one row");
   }
   $self->{_dirty_columns} = {};
+  $self->{related_resultsets} = {};
   return $self;
 }
 
@@ -292,25 +294,35 @@ sub inflate_result {
                   },
                   ref $class || $class);
   my $schema;
-  PRE: foreach my $pre (keys %{$prefetch||{}}) {
-    my $pre_source = $source->related_source($pre);
-    $class->throw_exception("Can't prefetch non-existant relationship ${pre}") unless $pre_source;
-    my $fetched;
-    unless ($pre_source->primary_columns == grep { exists $prefetch->{$pre}[0]{$_} 
-       and !defined $prefetch->{$pre}[0]{$_} } $pre_source->primary_columns)
-    {
-      $fetched = $pre_source->result_class->inflate_result(
-                      $pre_source, @{$prefetch->{$pre}});      
+  foreach my $pre (keys %{$prefetch||{}}) {
+    my $pre_val = $prefetch->{$pre};
+    # if first prefetch item is arrayref, assume this is a has_many prefetch
+    # and that objects are pre inflated (TODO: check arrayref contents using "ref" to make sure)
+    if( ref $pre_val->[0] eq 'ARRAY' ) {
+      $new->related_resultset($pre)->set_cache( $pre_val->[0] );
     }
-    my $accessor = $source->relationship_info($pre)->{attrs}{accessor};
-    $class->throw_exception("No accessor for prefetched $pre")
-      unless defined $accessor;
-    if ($accessor eq 'single') {
-      $new->{_relationship_data}{$pre} = $fetched;
-    } elsif ($accessor eq 'filter') {
-      $new->{_inflated_column}{$pre} = $fetched;
-    } else {
-      $class->throw_exception("Don't know how to store prefetched $pre");
+    else {
+      my $pre_source = $source->related_source($pre);
+      $class->throw_exception("Can't prefetch non-existent relationship ${pre}") unless $pre_source;
+      my $fetched;
+      unless ($pre_source->primary_columns == grep { exists $prefetch->{$pre}[0]{$_} 
+         and !defined $prefetch->{$pre}[0]{$_} } $pre_source->primary_columns)
+      {
+        $fetched = $pre_source->result_class->inflate_result(
+                      $pre_source, @{$prefetch->{$pre}});      
+      }
+      my $accessor = $source->relationship_info($pre)->{attrs}{accessor};
+      $class->throw_exception("No accessor for prefetched $pre")
+       unless defined $accessor;
+      if ($accessor eq 'single') {
+        $new->{_relationship_data}{$pre} = $fetched;
+      } elsif ($accessor eq 'filter') {
+       $new->{_inflated_column}{$pre} = $fetched;
+      } elsif ($accessor eq 'multi') {
+       $class->throw_exception("Cache must be enabled for has_many prefetch '$pre'");
+      } else {
+       $class->throw_exception("Prefetch not supported with accessor '$accessor'");
+      }
     }
   }
   return $new;
diff --git a/t/basicrels/22cache.t b/t/basicrels/22cache.t
new file mode 100644
index 0000000..1f8672a
--- /dev/null
+++ b/t/basicrels/22cache.t
@@ -0,0 +1,7 @@
+use Test::More;
+use lib qw(t/lib);
+use DBICTest;
+use DBICTest::BasicRels;
+
+require "t/run/22cache.tl";
+run_tests(DBICTest->schema);
diff --git a/t/lib/DBICTest/Schema/BasicRels.pm b/t/lib/DBICTest/Schema/BasicRels.pm
index 2a4942c..fedeec9 100644
--- a/t/lib/DBICTest/Schema/BasicRels.pm
+++ b/t/lib/DBICTest/Schema/BasicRels.pm
@@ -5,7 +5,7 @@ use base 'DBIx::Class::Core';
 DBICTest::Schema::Artist->add_relationship(
     cds => 'DBICTest::Schema::CD',
     { 'foreign.artist' => 'self.artistid' },
-    { order_by => 'year', join_type => 'LEFT', cascade_delete => 1, cascade_copy => 1 }
+    { order_by => 'year', join_type => 'LEFT', cascade_delete => 1, cascade_copy => 1, accessor => 'multi' }
 );
 DBICTest::Schema::Artist->add_relationship(
     twokeys => 'DBICTest::Schema::TwoKeys',
diff --git a/t/run/22cache.tl b/t/run/22cache.tl
new file mode 100644
index 0000000..68d6a93
--- /dev/null
+++ b/t/run/22cache.tl
@@ -0,0 +1,79 @@
+sub run_tests {
+my $schema = shift;
+
+eval "use DBD::SQLite";
+plan skip_all => 'needs DBD::SQLite for testing' if $@;
+plan tests => 8;
+
+my $rs = $schema->resultset("Artist")->search(
+  { artistid => 1 }
+);
+
+my $artist = $rs->first;
+
+is( scalar @{ $rs->get_cache }, 0, 'cache is not populated without cache attribute' );
+
+$rs = $schema->resultset("Artist")->search(
+  { 'artistid' => 1 },
+  {
+    prefetch => [qw/ cds /],
+    cache => 1,
+  }
+);
+
+# use Data::Dumper; $Data::Dumper::Deparse = 1;
+
+# start test for prefetch SELECT count
+unlink 't/var/dbic.trace' if -e 't/var/dbic.trace';
+DBI->trace(1, 't/var/dbic.trace');
+
+$artist = $rs->first;
+$rs->reset();
+
+# make sure artist contains a related resultset for cds
+is( ref $artist->{related_resultsets}->{cds}, 'DBIx::Class::ResultSet', 'artist has a related_resultset for cds' );
+
+# check if $artist->cds->get_cache is populated
+is( scalar @{$artist->cds->get_cache}, 3, 'cache for artist->cds contains correct number of records');
+
+# ensure that $artist->cds returns correct number of objects
+is( scalar ($artist->cds), 3, 'artist->cds returns correct number of objects' );
+
+# ensure that $artist->cds->count returns correct value
+is( $artist->cds->count, 3, 'artist->cds->count returns correct value' );
+
+# ensure that $artist->count_related('cds') returns correct value
+is( $artist->count_related('cds'), 3, 'artist->count_related returns correct value' );
+
+# count the SELECTs
+DBI->trace(0, undef);
+my $selects = 0;
+my $trace = IO::File->new('t/var/dbic.trace', '<') 
+    or die "Unable to read trace file";
+while (<$trace>) {
+    $selects++ if /SELECT/;
+}
+$trace->close;
+unlink 't/var/dbic.trace';
+is($selects, 2, 'only one SQL statement for each cached table');
+
+# make sure related_resultset is deleted after object is updated
+$artist->set_column('name', 'New Name');
+$artist->update();
+
+is( scalar keys %{$artist->{related_resultsets}}, 0, 'related resultsets deleted after update' );
+
+# todo: make sure caching works with nested prefetch e.g. $artist->cds->tracks
+$rs = $schema->resultset("Artist")->search(
+  { artistid => 1 },
+  {
+    prefetch => {
+      cds => 'tags'
+    },
+    cache => 1
+  }
+);
+
+}
+
+1;