uses memory as cache

[webpac] / index_DBI_cache.pm

#
# this file implements index functions using DBI
# and huge amounts of memory for cache speedup
#

package index_DBI;
use strict qw(vars);
use vars qw($Count);
use HTML::Entities;

use DBI;

my %Table;      # index tables which where visited in this run
my %sth_cache;  # cache prepared statements

# cache var
my $c_table;
my $c_count;

sub new {
        my $class = shift;
        my $self = {};
        bless($self, $class);

        my $dbd = shift || die "need dbi_dbd= in [global] section of configuration file";
        my $dsn = shift || die "need dbi_dsn= in [global] section of configuration file";
        my $user = shift || die "need dbi_user= in [global] section of configuration file";
        my $passwd = shift || die "need dbi_passwd= in [global] section of configuration file";

        $self->{dbh} = DBI->connect("DBI:$dbd:$dsn",$user,$passwd) || die $DBI::errstr;
        # begin transaction
        $self->{dbh}->begin_work || die $self->{dbh}->errstr();

        $Count++;

        return $self;
}

sub delete_and_create {
        my $self = shift;

        my $field = shift;

#print "#### delete_and_create($field)\n";

        $self->{dbh}->commit;

        my $sql = "select count(*) from $field";
        my $sth = $self->{dbh}->prepare($sql) || die $self->{dbh}->errstr();
# FIX: this is not a good way to check if table exists!
        if ($sth->execute() && $sth->fetchrow_hashref) {
                my $sql = "drop table $field";
                $self->{dbh}->begin_work;
                my $sth = $self->{dbh}->do($sql) || die "SQL: $sql ".$self->{dbh}->errstr();
                $self->{dbh}->commit;
        }
        $sql = "create table $field (
                        item varchar(255),
                        ident varchar(255),
                        count int,
                        ord int,
                        primary key (item,ident)
                )";

        $self->{dbh}->begin_work;
        $sth = $self->{dbh}->do($sql); # || warn "SQL: $sql ".$self->{dbh}->errstr();
        $self->{dbh}->commit;

        $self->{dbh}->begin_work;
}

sub insert {
        my $self = shift;

        my $field = shift;
        my $index_data = shift || print STDERR "\$index->insert($field,NULL,...)";
        my $ident = shift || '';        # e.g. library id

        if (! $index_data) {
                print STDERR "\$index->insert() -- no value to insert\n";
                return;
        }

        if (! $Table{$field}) {
                $self->delete_and_create($field);

                my $sql = "select item from $field where upper(item)=upper(?)";
                $sth_cache{$field."select"} = $self->{dbh}->prepare($sql) || die $self->{dbh}->errstr();

                $sql = "insert into $field (item,ident,count) values (?,?,?)";
                $sth_cache{$field."insert"} = $self->{dbh}->prepare($sql) || die $self->{dbh}->errstr();

                $sql = "update $field set count = count + 1 where item = ? and ident = ?";
                $sth_cache{$field."update"} = $self->{dbh}->prepare($sql) || die $self->{dbh}->errstr();
        }
        $Table{$field}++;

        #$sth_cache{$field."select"}->execute($index_data) || die "cache: $field select; ".$self->{dbh}->errstr();
        $index_data = substr($index_data,0,255);
        my $uc = uc($index_data);
        if (! $c_table->{$field}->{$ident}->{$uc}) {
                $sth_cache{$field."insert"}->execute($index_data,$ident,0) || die "cache: $field insert; ".$self->{dbh}->errstr();
#print stderr "in index: $index_data\n";
                $c_table->{$field}->{$ident}->{$uc} = $index_data;
                $c_count->{$field}->{$ident}->{$uc} = 1;
        } else {
                $c_count->{$field}->{$ident}->{$uc}++;
        }
}

sub check {
        my $self = shift;

        my $field = shift;

        my $sql = "select count(*) from $field";

        my $sth = $self->{dbh}->prepare($sql) || die $self->{dbh}->errstr();
        $sth->execute() || die "sql: $sql; ".$self->{dbh}->errstr();

        my ($total) = $sth->fetchrow_array();

        return $total;
}


sub fetch {
        my $self = shift;

        my $field = shift;
        my $what = shift || 'item';     # 'item,ident'
        my $where = shift;

        my $from_ord = shift || 0;
        my $rows = shift || 10;

        my @sql_args;

        my $sql = "select $what,ord from $field";

        if ($where) {
                my $sql2 = " select ord from $field where upper($what) like upper(?)||'%'";
                my $sth = $self->{dbh}->prepare($sql2) || die "sql2: $sql2; ".$self->{dbh}->errstr();

                $sth->execute($where) || die "sql2: $sql2; ".$self->{dbh}->errstr();
                if (my $row = $sth->fetchrow_hashref) {
                        $from_ord += $row->{ord} - 1;
                }
        }
        $sql .= " order by ord limit $rows offset $from_ord";

        my $sth = $self->{dbh}->prepare($sql) || die "prepare: $sql; ".$self->{dbh}->errstr();
        $sth->execute() || die "execute: $sql; ".$self->{dbh}->errstr();
        my @arr;
        while (my $row = $sth->fetchrow_hashref) {
                $row->{item} = HTML::Entities::encode($row->{item},'<>&"');
                push @arr,$row;
        }
        return @arr;
}

sub close {
        my $self = shift;


        # re-create ord column (sorted order) in table
        sub create_ord {

                my $table = shift;

                $self->{dbh}->begin_work || die $self->{dbh}->errstr();

                my $sql = "select oid from $table order by upper(item)";
                my $sth = $self->{dbh}->prepare($sql) || die "sql: $sql; ".$self->{dbh}->errstr();
                $sql = "update $table set ord=? where oid=?";
                my $sth_update = $self->{dbh}->prepare($sql) || die "sql: $sql; ".$self->{dbh}->errstr();
                $sth->execute() || die "sql: $sql; ".$self->{dbh}->errstr();
                my $ord = 1;
                while (my $row = $sth->fetchrow_hashref) {
                        $sth_update->execute($ord++,$row->{oid});
                }

                $self->{dbh}->commit || die $self->{dbh}->errstr();
        }
        #--- end of sub

        if ($self->{dbh}) {

                # commit
                $self->{dbh}->commit || die $self->{dbh}->errstr();

                foreach my $table (keys %Table) {
# FIX
print STDERR "creating ord for $table...\n";
                        create_ord($table);
                        undef $sth_cache{$table."select"};
                        undef $sth_cache{$table."insert"};
                        undef $sth_cache{$table."update"};
# XXX
#               $sth_cache{$field."update"}->execute($index_data,$ident) || die "cache: $field update; ".$self->{dbh}->errstr();
                }

                $self->{dbh}->disconnect;
                undef $self->{dbh};
        }
}

END {
        $Count--;
        print STDERR "index_DBI fatal error: \$index->close() not called... $Count references left!\n" if ($Count > 0);
        # FIX: debug output
#       print STDERR "usage\ttable\n";
#       foreach (keys %Table) {
#               print STDERR $Table{$_},"\t$_\n";
#       }
}

1;