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lib/App/Repository.pm  view on Meta::CPAN

#############################################################################
# METHODS
#############################################################################

=head1 Methods: Locking (Concurrency Management)

=cut

# this is a write lock for the table
sub _lock_table {
    &App::sub_entry if ($App::trace);
    my ($self, $table) = @_;
    if (! $self->{locked}) {   # I have locked it myself, so I don't need to again
        my ($name, $dbname, $context, $rlock);
        $name = $self->{name};
        $dbname = $self->{dbname};
        $context = $self->{context};
        $rlock = $context->resource_locker($name);  # get the one that corresponds to this repository
        $rlock->lock("db.$dbname.$table");
        $self->{locked} = 1;
    }
    &App::sub_exit() if ($App::trace);
}

# unlocks the write lock for the table
sub _unlock_table {
    &App::sub_entry if ($App::trace);
    my ($self, $table) = @_;
    if ($self->{locked}) {
        my ($name, $dbname, $context, $rlock);
        $name = $self->{name};
        $dbname = $self->{dbname};
        $context = $self->{context};
        $rlock = $context->resource_locker($name);  # get the one that corresponds to this repository
        $rlock->unlock("db.$dbname.$table");
        delete $self->{locked};
    }
    &App::sub_exit() if ($App::trace);
}

#############################################################################
# METHODS
#############################################################################

=head1 Methods: Miscellaneous

=cut

#############################################################################
# summarize_rows()
#############################################################################

=head2 summarize_rows()

    * Signature: $summarized_rows = $rep->summarize_rows($table, $rows, $columns, $summary_keys, $options);
    * Param:     $table            string
    * Param:     $rows             [][]
    * Param:     $columns          []
    * Param:     $summary_keys       []
    * Param:     $formulas         {}
    * Return:    $summarized_rows  []
    * Throws:    App::Exception::Repository
    * Since:     0.01

    Sample Usage: 

    @rows = (
        [ 5, "Jim", "Green", 13.5, 320, ],
        [ 3, "Bob", "Green",  4.2, 230, ],
        [ 9, "Ken", "Green", 27.4, 170, ],
        [ 2, "Kim", "Blue",  11.7, 440, ],
        [ 7, "Jan", "Blue",  55.1,  90, ],
        [ 1, "Ben", "Blue",  22.6, 195, ],
    );
    @columns = ( "id", "name", "team", "rating", "score" );
    @summary_keys = ( "team" );

    $summarized_rows = $rep->summarize_rows(\@rows, \@columns, \@summary_keys, \%formulas);

    @rows = (
        { id=>5, name=>"Jim", team=>"Green", rating=>13.5, score=>320, },
        { id=>3, name=>"Bob", team=>"Green", rating=> 4.2, score=>230, },
        { id=>9, name=>"Ken", team=>"Green", rating=>27.4, score=>170, },
        { id=>2, name=>"Kim", team=>"Blue",  rating=>11.7, score=>440, },
        { id=>7, name=>"Jan", team=>"Blue",  rating=>55.1, score=> 90, },
        { id=>1, name=>"Ben", team=>"Blue",  rating=>22.6, score=>195, },
    );
    @columns = ( "rating", "score" );  # summarize a subset of the columns
    @summary_keys = ( "team" );
    %options = (
        ext_summaries => \%summaries,         # extended summaries
        ext_summary_columns => [ "rating", "score", "team", ],   # optional
        ext_summary_functions => {  # optional
            sum      => 1,
            count    => 1,
            sum_sq   => 1,
            distinct => 1,
            min      => 1,
            max      => 1,
            average  => 1,  # requires sum, count
            median   => 1,  # requires distinct
            mode     => 1,  # requires min, max
            stddev   => 1,  # requires sum, sum_sq, count
        },
    );

    # returns the "natural" summaries
    $summarized_rows = $rep->summarize_rows(\@rows, \@columns, \@summary_keys, \%options);

=cut

sub summarize_rows {
    &App::sub_entry if ($App::trace);
    my ($self, $table, $rows, $columns, $summary_keys, $options) = @_;

    #print STDERR "summarize_rows($table, ..., ..., [@$summary_keys], ...)\n";
    #foreach my $row (@$rows) {
    #    print STDERR "summarize_rows(IN)  {", join("|", %$row), "}\n";
    #}

    $summary_keys = [] if (!$summary_keys);

    my $table_def = $self->get_table_def($table);
    my $column_defs = $table_def->{column};

    my ($ext_summaries, $ext_column_summary, $ext_summary_columns, $ext_summary_functions);
    $ext_summaries = $options->{ext_summaries};
    if ($ext_summaries) {
        $ext_summary_columns = $options->{ext_summary_columns};
        $ext_summary_functions = $options->{ext_summary_functions} || {  # do all of them
            count    => 1,
            distinct => 1,
            sum      => 1,
            sum_sq   => 1,
            min      => 1,
            max      => 1,
            average  => 1,  # requires sum, count
            median   => 1,  # requires distinct