NAME
BDB::Wrapper Wrapper module for BerkeleyDB.pm
This will make it easy to use BerkeleyDB.pm.
You can protect bdb file from the concurrent access and you can use BerkeleyDB.pm with less difficulty.
This module is used on http://www.accessup.org/ and is developed based on the requirement.
Attention: If you use this module for the specified Berkeley DB file,
please use this module for all access to the bdb.
By it, you can control lock to the bdb file.
Lock files are created under /tmp/bdb_home.
If you set ram 1 in new option, lock files are created under /dev/shm/bdb_home.
Example
# Code Example
package test_bdb;
use BDB::Wrapper;my $pro=new test_bdb; $pro->run();
sub new(){ my $self={}; return bless $self; }
sub run(){ my $self=shift; $self->init_vars(); $self->demo(); }
sub init_vars(){ my $self=shift; $self->{'bdb'}='/tmp/test.bdb'; $self->{'bdbw'}=new BDB::Wrapper; }
sub demo(){ my $self=shift; # Open db handler for writing if(my $dbh=$self->{'bdbw'}->create_write_dbh($self->{'bdb'})){ # Ignore Ctr+C while putting to avoid to destruct bdb. local $SIG{'INT'}='IGNORE'; local $SIG{'TERM'}='IGNORE'; local $SIG{'QUIT'}='IGNORE'; # put if($dbh->db_put('name', 'value')==0){ } else{ die 'Failed to put to '.$self->{'bdb'}; } $dbh->db_close(); }
# Open db handler for reading
if(my $dbh=$self->{'bdbw'}->create_read_dbh($self->{'bdb'})){
my $value;
# read
if($dbh->db_get('name', $value)==0){
print 'Name='.$name.' value='.$value."\n";
}
$dbh->db_close();
}
}methods
new
Creates an object of BDB::Wrapper
If you set {'ram'=>1}, you can use /dev/shm/bdb_home for storing locking file for BDB instead of /tmp/bdb_home/.
If you set {'cache'=>$CACHE_SIZE}, you can allocate cache memory of the specified bytes for using bdb files.
If you set {'wait'=>wait_seconds}, you can specify the seconds in which dead lock will be removed.
create_env
Creates Environment for BerkeleyDB
create_dbh
Creates database handler for BerkeleyDB
This will be obsolete due to too much simplicity, so please don\'t use.
create_hash_ref
Creates database handler for BerkeleyDB
This will be obsolete due to too much simplicity, so please don\'t use.
create_write_dbh
This will creates database handler for writing.
$self->create_write_dbh($bdb, {'hash'=>0 or 1, 'dont_try'=>0 or 1, 'sort_code_ref'=>$sort_code_reference, 'sort' or 'sort_num'=>0 or 1, 'reverse_cmp'=>0 or 1, 'reverse' or 'reverse_num'=>0 or 1});
In the default mode, BDB file will be created as Btree;
If you set 'hash' 1, Hash BDB will be created.
If you set 'dont_try' 1, this module won\'t try to unlock BDB if it detects the situation in which deadlock may be occuring.
If you set sort_code_ref some code reference, you can set subroutine for sorting for Btree.
If you set sort or sort_num 1, you can use sub {$_[0] <=> $_[1]} for sort_code_ref.
If you set reverse or reverse_num 1, you can use sub {$_[1] <=> $_[0]} for sort_code_ref.
If you set reverse_cmp 1, you can use sub {$_[1] cmp $_[0]} for sort_code_ref.
create_read_dbh
This will creates database handler for reading.
$self->create_read_dbh($bdb, {'hash'=>0 or 1, 'dont_try'=>0 or 1, 'sort_code_ref'=>$sort_code_reference, 'sort' or 'sort_num'=>0 or 1, 'reverse_cmp'=>0 or 1, 'reverse' or 'reverse_num'=>0 or 1});
In the default mode, BDB file will be created as Btree;
If you set 'hash' 1, Hash BDB will be created.
If you set 'dont_try' 1, this module won\'t try to unlock BDB if it detects the situation in which deadlock may be occuring.
If you set sort_code_ref some code reference, you can set subroutine for sorting for Btree.
If you set sort or sort_num 1, you can use sub {$_[0] <=> $_[1]} for sort_code_ref.
If you set reverse or reverse_num 1, you can use sub {$_[1] <=> $_[0]} for sort_code_ref.
If you set reverse_cmp 1, you can use sub {$_[1] cmp $_[0]} for sort_code_ref.
create_write_hash_ref
This will creates hash for writing.
$self->create_write_hash_ref($bdb, {'hash'=>0 or 1, 'dont_try'=>0 or 1, 'sort_code_ref'=>$sort_code_reference, 'sort' or 'sort_num'=>0 or 1, 'reverse_cmp'=>0 or 1, 'reverse' or 'reverse_num'=>0 or 1});
In the default mode, BDB file will be created as Btree;
If you set 'hash' 1, Hash BDB will be created.
If you set 'dont_try' 1, this module won\'t try to unlock BDB if it detects the situation in which deadlock may be occuring.
If you set sort_code_ref some code reference, you can set subroutine for sorting for Btree.
If you set sort or sort_num 1, you can use sub {$_[0] <=> $_[1]} for sort_code_ref.
If you set reverse or reverse_num 1, you can use sub {$_[1] <=> $_[0]} for sort_code_ref.
If you set reverse_cmp 1, you can use sub {$_[1] cmp $_[0]} for sort_code_ref.
create_read_hash_ref
This will creates database handler for reading.
$self->create_read_hash_ref($bdb, 'hash'=>0 or 1, 'dont_try'=>0 or 1, 'sort_code_ref'=>$sort_code_reference, 'sort' or 'sort_num'=>0 or 1, 'reverse_cmp'=>0 or 1, 'reverse' or 'reverse_num'=>0 or 1});
In the default mode, BDB file will be created as Btree;
If you set 'hash' 1, Hash BDB will be created.
If you set 'dont_try' 1, this module won\'t try to unlock BDB if it detects the situation in which deadlock may be occuring.
If you set sort_code_ref some code reference, you can set subroutine for sorting for Btree.
If you set sort or sort_num 1, you can use sub {$_[0] <=> $_[1]} for sort_code_ref.
If you set reverse or reverse_num 1, you can use sub {$_[1] <=> $_[0]} for sort_code_ref.
If you set reverse_cmp 1, you can use sub {$_[1] cmp $_[0]} for sort_code_ref.