view release on metacpan or  search on metacpan

lib/DBIx/HA.pm  view on Meta::CPAN

			warn "$prefix Connecting to $dbname on init_child\n" if (DBIx_HA_DEBUG);
			DBIx::HA->connect($dbname);
		}
	};
}


sub _readsharedfile {
	# reads from file-based shared memory to get active database under Apache
	my $dbname = shift;
	if ($DATABASE::conf{$dbname}->{'failoverlevel'} eq 'application') {
		# do this only if we're doing application failover and not process failover
		if ($loaded_Apache && (-f "$logdir/DBIxHA_activedb_$dbname")) {
			open IN, "$logdir/DBIxHA_activedb_$dbname";
			my $dbidx = <IN>;
			chomp $dbidx;
			close IN;
			if ($dbidx == -1) {	# we're told that we're at the end of the stack. No db server is available.
				$DATABASE::conf{$dbname}->{'end_of_stack'} = 1;
				return 0;
			}
			$DATABASE::conf{$dbname}->{'end_of_stack'} = 0;
			if (($dbidx =~ /^\d+$/o) && $DATABASE::conf{$dbname}->{'db_stack'}->[$dbidx]) {
				$DATABASE::conf{$dbname}->{'active_db'} = $DATABASE::conf{$dbname}->{'db_stack'}->[$dbidx];
				$DBIx::HA::activeserver{$dbname}  = $dbidx;
				unless ($Apache::ServerStarting == 1) {
					my $r = Apache->request;
					$r->notes("activedb_$dbname", $dbidx) if (ref $r);
				}
			} else {
				warn "$prefix in _readsharedfile: $dbname shared file has erroneous content, overwriting.\n";
				_writesharedfile($dbname, $DBIx::HA::activeserver{$dbname});
				return 0;
			}
		}
	}
	return 1;
}

sub _writesharedfile {
	my $dbname = shift;
	my $dbidx = shift;
	# updates the active handle
	# and writes to file-based shared memory for active database under Apache
	warn "$prefix in _writesharedfile: activating index $dbidx for database $dbname\n" if (DBIx_HA_DEBUG);
	$DATABASE::conf{$dbname}->{'active_db'} = $DATABASE::conf{$dbname}->{'db_stack'}->[$dbidx];
	$DBIx::HA::activeserver{$dbname}  = $dbidx;

	if ($DATABASE::conf{$dbname}->{'failoverlevel'} eq 'application') {
	# do this only if we're doing application failover and not process failover
		if ($loaded_Apache) {
			unless ($Apache::ServerStarting == 1) {
				my $r = Apache->request;
				$r->notes("activedb_$dbname", $dbidx) if (ref $r);
			}
			$logdir = Apache::server_root_relative(undef,'logs');
			open IN, ">/$logdir/DBIxHA_activedb_$dbname" || return 0;
			print IN $DBIx::HA::activeserver{$dbname};
			close IN;
			if ($Apache::ServerStarting == 1) {
				chmod 0666, "$logdir/DBIxHA_activedb_$dbname";
			}
		}
	}
	return 1;
}

sub _getdbname {
	# returns the db server name when given the dsn string
	my $dsn = shift;
	warn "$prefix in _getdbname: $DBIx::HA::finddbserver{$dsn} \n" if (DBIx_HA_DEBUG > 2);
	return $DBIx::HA::finddbserver{$dsn};
}

sub _isactivedb {
	# returns true if the db server in use is the one that should be active
	my $dsn = shift;
	my $dbname = _getdbname ($dsn);
	_readsharedfile($dbname);
	if ($DATABASE::conf{$dbname}->{'end_of_stack'}) {
		# we're not in the active db, because there is no active database, the end of stack is reached.
		return 0;
	}
	if ($dsn eq $DATABASE::conf{$dbname}->{'active_db'}->[0]) {
		warn "$prefix in _isactivedb: ".$dsn." is the active one \n" if (DBIx_HA_DEBUG > 2);
		return 1;
	}
	warn "$prefix in _isactivedb: ".$dsn." is NOT active \n" if (DBIx_HA_DEBUG > 2);
	$DATABASE::retries{$DATABASE::conf{$dbname}->{'active_db'}->[0]} = 0;	# reset the active db's retries for this process
	return 0;
}

sub _getnextdb {
	# returns the proper db server arrayref to use if the current one is dead
	my $dsn = shift;
	my $dbname = _getdbname ($dsn);
	if (_isactivedb ($dsn)) {
		# do this only if we are the first to look for a good db server
		# otherwise just return the active db server
		my $foundmatch = 0;
		my $idxnextdb = 0;
		my $stackcount = scalar(@{$DATABASE::conf{$dbname}->{'db_stack'}});
		foreach (@{$DATABASE::conf{$dbname}->{'db_stack'}}) {
			$idxnextdb++;
			if ($dsn eq $_->[0]) {
				# we got to the current db server in the stack
				# next db server in the stack is the correct one
				$foundmatch = 1;
				last;
			}
		}
		if (! $foundmatch) {	# didn't find a match, current dsn is invalid
			warn "$prefix in _getnextdb: current dsn is invalid for $dbname: $dsn \n" if (DBIx_HA_DEBUG);
			$idxnextdb = 0;
		} elsif ($idxnextdb > ($stackcount - 1)) {
			warn "$prefix in _getnextdb: Reached end of db server stack for $dbname. Staying there.\n" if (DBIx_HA_DEBUG);
			$DATABASE::conf{$dbname}->{'end_of_stack'} = 1;
			_writesharedfile($dbname, -1);
			return undef;
		}
		_writesharedfile($dbname, $idxnextdb);