#!/usr/bin/perl -w

use locale;
use DBI;
use POSIX;

use strict;             # Enforce declarations

# Declare cfg pkg so we can refer to it anywhere
{
    package cfg;

    # Database handle
    $cfg::dbh = '';
    $cfg::db_retry_cnt = 0;
    $cfg::db_cxn_msg_sent = 0;
}


# Connect to Database
db_connect();
if( !$cfg::dbh )
{
    print "startup connect failed\n";
    exit(1);
}


# Install SIG Handlers
$SIG{__DIE__} = \&do_sig_die; # trap & ignore
#local $SIG{__DIE__} = \&do_sig_die; # trap & ignore
#$SIG{__DIE__} = 'IGNORE'; # trap & ignore
#local $SIG{__DIE__} = 'IGNORE'; # trap & ignore

# Call main sub to process msgs
process_msgs();


#*********************************************************************
+*********
sub process_msgs
{
    my (
        $packet_interval,   # interval between keep alive
        $error_msg          # error msg (if any)
        );

    while(1)
    {
        # Check for DB errors as we go
        $error_msg = "";
        ($packet_interval, $error_msg) =
                        db_get_pkt_interval_type("xxx\@x.com.au");
        if( !$error_msg )
        {
            #DEBUG
            print "no error caught!\n";
        }
        sleep(5);
    }
}
#*********************************************************************
+*********
sub db_get_pkt_interval_type
{
    my (
        $sql,               # SQL code
        $sth,               # SQL statement handle
        $error_msg,         # sql error msg
        $userlogin,         # user's login eg xxx@x.com.au
        $username,
        $isp,
        $interval
        );

    # Get input params
    $userlogin = $_[0];

    # Extract ISP name
    ($username, $isp) = split(/@/, $userlogin);

    # Set SQL cmd
    $error_msg = "";
    $sql = "SELECT 1 ".
           "FROM   sometable ".
           "WHERE  somecol = ".$cfg::dbh->quote($isp);
print "here 1\n";
    # Run the select
    $sth = $cfg::dbh->prepare($sql);
print "here 2\n";

    $sth->execute();
print "here 3\n";
    if ( $sth->errstr )
    {
print "here 4\n";

        # SQL failure; set err msg from DB
        $error_msg = "db_get_pkt_interval(): ".localtime()." ".
                                                        $sth->errstr;

        # Check if real SQL error or DB gone away
        if( $sth->errstr =~ /MySQL server has gone away/ )
        {
print "here 5\n";

            # Try to re-connect for later
            # logging done in called sub
            db_connect();
        }
        else
        {
            # Other SQL error, so log
            print "$error_msg\n";
        }
    }
    else
    {
        # Collect values
        ( $interval ) = $sth->fetchrow_array;
    }
    # Finished txn
    $sth->finish;

    # Return user's interval value
    return($interval, $error_msg);
}
#*********************************************************************
+*********
#
# Function      : db_connect
#
# Description   : Connect to the Database, so we can insert the exchan
+ge info
#
#                 Some SQL calls specifically check for
#                 /MySQL server has gone away/ before checking for any
+ other
#                 SQL error. If found, call here, where a count is kep
+t of
#                 the num of times this happens. An email & sms is
#                 only sent if retry limit has been reached and no pre
+v msg
#                 has been sent. If a successful connection to the DB 
+is made,
#                 the err msg flag and retry cnt are reset.
#
# Params        : none
#
# Returns       : none      dbh stored as global
#
#*********************************************************************
+*********
sub db_connect
{
    my (
        $dsn,       # data source name
        $error_msg  # if any
        );

    # Set up connection string...
    $dsn = "DBI:mysql:database=somedb;host=somehost;port=nnnn";

    # ... and connect
    # NB: Set RaiseError => 0 so we can trap errors manually
    # without breaking the program
    $cfg::dbh = DBI->connect( $dsn, "user", "passwd",
                                {RaiseError => 0, AutoCommit => 1});

    if( $DBI::errstr)
    {
        # FAIL
        $error_msg = "db_connect(): $DBI::errstr";
        print "$error_msg\n";
        $cfg::db_retry_cnt++;
        if( !$cfg::db_cxn_msg_sent &&
            $cfg::db_retry_cnt > 3 )
        {
            print "would have sent email/sms\n";
            $cfg::db_cxn_msg_sent = 1;
        }
    }
    else
    {
        # SUCCESS
        $cfg::db_cxn_msg_sent = 0;
        $cfg::db_retry_cnt = 0;
    }
}
#*********************************************************************
+*********
#
# Function      : do_sig_die
#
# Description   : If we get SIGDIE, trap, log, ignore, re-install.
#                 Basically, some internal process keeps breaking this
#                 prog with SIGDIE. We are not using this signal ourse
+lves;
#                 sigh ...
#
# Params        : none
#
# Returns       : none
#
#*********************************************************************
+*********
sub do_sig_die
{
    # Log it for analysis
    print "SIGDIE caught\n";

    # Defensive programming ...
    $SIG{__DIE__} = \&do_sig_die;
}
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