In the following code sample the database connection cannot be started until after Proc::Background::Init because DBI connections do not survive forks. The fork has to happen before the potentially fatal register_process() because you wouldn't want to write the wrong pid to the process list. This leaves you with no way to report a fatal exit to the console that just started the application.
exit main( @ARGV );
sub main
{
eval
{
Sys::Syslog::openlog( $SYSLOG_IDENT, '', $SYSLOG_FACILITY );
1;
}
or Carp::croak( $@ );
Proc::Background::Init();
db_start(); # <- The database connection cannot be established
...
}
sub db_start
{
return if $::DBH;
main::log_debug( "DBI->connect" ) if $::DEBUG;
$::DBH = DBI->connect
( $::DBI_DSN,
$::DBI_USER,
$::DBI_PASS,
{ RaiseError => 1,
PrintError => 0,
AutoCommit => 1 } )
or main::log_emerg( 'emerg', "Error connecting to database: $D
+BI::errstr" );
# Potentially fatal - if the process is already running that would
+ violate the table's constraint system.
$::DBH->do( "SELECT register_process( ?, ? )",
undef,
File::Basename::basename( $0 ),
$$ );
return 1;
}
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