From: Gianni Ceccarelli <dakkar@thenautilus.net>
Date: Fri, 28 May 2010 21:03:51 +0000 (+0000)
Subject: cursor usage can now be switched on/off
X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=commitdiff_plain;h=590a6c438f5482f79051e433836c2981f98ee769;p=dbsrgits%2FDBIx-Class.git

cursor usage can now be switched on/off

default off, turn on via (increasing order of importance):
- package variable on DBIx::Class::Storage::DBI::Pg
- connection attributes
- RS attributes

also, "page" size used for each fetch from cursor can be tweaked in the
same way
---

diff --git a/lib/DBIx/Class/Storage/DBI/Pg.pm b/lib/DBIx/Class/Storage/DBI/Pg.pm
index 5854644..dae4094 100644
--- a/lib/DBIx/Class/Storage/DBI/Pg.pm
+++ b/lib/DBIx/Class/Storage/DBI/Pg.pm
@@ -20,6 +20,9 @@ __PACKAGE__->_use_multicolumn_in (1);
 __PACKAGE__->mk_group_accessors('simple' =>
                                     '_pg_cursor_number');
 
+our $DEFAULT_USE_PG_CURSORS=0;
+our $DEFAULT_PG_CURSORS_PAGE_SIZE=1000;
+
 sub _determine_supports_insert_returning {
   return shift->_server_info->{normalized_dbms_version} >= 8.002
     ? 1
@@ -247,14 +250,61 @@ sub _get_next_pg_cursor_number {
     return $ret;
 }
 
+sub __get_tweak_value {
+    my ($self,$attrs,$slot,$default,$extra_test)=@_;
+
+    $extra_test||=sub{1};
+
+    if (   exists $attrs->{$slot}
+        && defined $attrs->{$slot}
+        && $extra_test->($attrs->{$slot})
+    ) {
+        return $attrs->{$slot};
+    }
+    my @info=@{$self->_dbi_connect_info};
+    if (   @info
+        && ref($info[-1]) eq 'HASH'
+        && exists $info[-1]->{$slot}
+        && defined $info[-1]->{$slot}
+        && $extra_test->($info[-1]->{$slot})
+    ) {
+        return $info[-1]->{$slot};
+    }
+    return $default;
+}
+
+sub _should_use_pg_cursors {
+    my ($self,$attrs) = @_;
+
+    return $self->__get_tweak_value($attrs,'use_pg_cursors',$DEFAULT_USE_PG_CURSORS);
+}
+
+sub _get_pg_cursor_page_size {
+    my ($self,$attrs) = @_;
+
+    return $self->__get_tweak_value($attrs,'pg_cursors_page_size',$DEFAULT_PG_CURSORS_PAGE_SIZE,
+                                    sub { $_[0] =~ /^\d+$/ });
+}
+
+sub _select {
+    my $self = shift;
+    my ($ident, $select, $where, $attrs) = @_;
+
+    local $self->{_use_pg_cursors}=$self->_should_use_pg_cursors($attrs);
+    local $self->{_pg_cursor_page_size}=$self->_get_pg_cursor_page_size($attrs);
+
+    return $self->next::method(@_);
+}
+
 sub _dbh_sth {
     my ($self, $dbh, $sql) = @_;
 
-    if ($sql =~ /^SELECT\b/i) {
-        return DBIx::Class::Storage::DBI::Pg::Sth->new($self,$dbh,$sql);
+    if ($self->{_use_pg_cursors} && $sql =~ /^SELECT\b/i) {
+        return DBIx::Class::Storage::DBI::Pg::Sth
+            ->new($self,$dbh,$sql,$self->{_pg_cursor_page_size});
     }
     else { # short-circuit
-        return $self->SUPER::_dbh_sth($dbh,$sql);
+        return $self->next::method($dbh,$sql);
     }
 }
 
diff --git a/lib/DBIx/Class/Storage/DBI/Pg/Sth.pm b/lib/DBIx/Class/Storage/DBI/Pg/Sth.pm
index 8145135..d34f7e0 100644
--- a/lib/DBIx/Class/Storage/DBI/Pg/Sth.pm
+++ b/lib/DBIx/Class/Storage/DBI/Pg/Sth.pm
@@ -7,10 +7,11 @@ __PACKAGE__->mk_group_accessors('simple' =>
                                     'storage',
                                     'cursor_id', 'cursor_created',
                                     'cursor_sth', 'fetch_sth',
+                                    'page_size',
                             );
 
 sub new {
-    my ($class, $storage, $dbh, $sql) = @_;
+    my ($class, $storage, $dbh, $sql, $page_size) = @_;
 
     if ($sql =~ /^SELECT\b/i) {
         my $self=bless {},$class;
@@ -24,6 +25,7 @@ sub new {
         $self->cursor_id($csr_id);
         $self->cursor_sth($storage->_dbh_sth($dbh,$sql));
         $self->cursor_created(0);
+        $self->page_size($page_size);
         return $self;
     }
     else {
@@ -105,7 +107,11 @@ sub _run_fetch_sth {
     }
 
     $self->fetch_sth->finish if $self->fetch_sth;
-    $self->fetch_sth($self->storage->sth("fetch 1000 from ".$self->cursor_id));
+    $self->fetch_sth($self->storage->sth(
+        sprintf 'fetch %d from %s',
+        $self->page_size,
+        $self->cursor_id
+    ));
     $self->fetch_sth->execute;
 }
 
diff --git a/t/72pg_cursors.t b/t/72pg_cursors.t
index 17e01fd..1a933ea 100644
--- a/t/72pg_cursors.t
+++ b/t/72pg_cursors.t
@@ -5,14 +5,13 @@ use warnings;
 use Test::More;
 use lib qw(t/lib);
 use DBICTest;
-use Time::HiRes qw(gettimeofday tv_interval);
 
 my ($dsn, $dbuser, $dbpass) = @ENV{map { "DBICTEST_PG_${_}" } qw/DSN USER PASS/};
 
 plan skip_all => 'Set $ENV{DBICTEST_PG_DSN}, _USER and _PASS to run this test'
   unless ($dsn && $dbuser);
 
-plan tests => 3;
+plan tests => 10;
 
 sub create_test_schema {
     my ($schema)=@_;
@@ -43,11 +42,16 @@ sub drop_test_schema {
         });
 }
 
-# copied from 100populate.t
-
-my $schema = DBICTest::Schema->connection($dsn, $dbuser, $dbpass, { AutoCommit => 1 });
+my $schema = DBICTest::Schema->connection($dsn, $dbuser, $dbpass, { AutoCommit => 1, use_pg_cursors => 1 });
 drop_test_schema($schema);create_test_schema($schema);
 
+my ($called,$page_size)=(0,0);
+my $old_sth_new=\&DBIx::Class::Storage::DBI::Pg::Sth::new;
+*DBIx::Class::Storage::DBI::Pg::Sth::new=sub {
+    ++$called;$page_size=$_[4];
+    goto &$old_sth_new;
+};
+
 END {
     return unless $schema;
     drop_test_schema($schema);
@@ -57,7 +61,9 @@ my $start_id = 'populateXaaaaaa';
 my $rows=1e4;
 my $offset = 3;
 
+$called=0;
 $schema->populate('Artist', [ [ qw/artistid name/ ], map { [ ($_ + $offset) => $start_id++ ] } ( 1 .. $rows ) ] );
+is ($called,0,'Pg::Sth not created for insert');
 is (
     $schema->resultset ('Artist')->search ({ name => { -like => 'populateX%' } })->count,
     $rows,
@@ -65,25 +71,29 @@ is (
 );
 
 {
+    $called=0;
     my $rs=$schema->resultset('Artist')->search({});
     my $count=0;
-    my $t0=[gettimeofday];
     $count++ while $rs->next;
     is($count,$rows,'get all the rows (loop)');
-    diag('Time for all(loop): '.tv_interval($t0));
+    is($called,1,'Pg::Sth called once per rs');
+    is($page_size,$DBIx::Class::Storage::DBI::Pg::DEFAULT_PG_CURSORS_PAGE_SIZE,'default page size used');
 }
 
 {
-    my $rs=$schema->resultset('Artist')->search({});
-    my $t0=[gettimeofday];
+    $called=0;
+    my $rs=$schema->resultset('Artist')->search({},{pg_cursors_page_size=>10});
     $rs->first;
-    diag('Time for first: '.tv_interval($t0));
+    is($called,1,'Pg::Sth called again per rs');
+    is($page_size,10,'page size from attrs used');
 }
 
 {
+    $called=0;
     my $rs=$schema->resultset('Artist')->search({});
-    my $t0=[gettimeofday];
     my @rows=$rs->all;
     is(scalar(@rows),$rows,'get all the rows (all)');
-    diag('Time for all: '.tv_interval($t0));
+    is($called,1,'Pg::Sth called again per rs');
+    is($page_size,$DBIx::Class::Storage::DBI::Pg::DEFAULT_PG_CURSORS_PAGE_SIZE,'default page size used again');
 }
+