Slave server DOWN management

gistfile1.aw

<?php
//1. Create a file that contains your constants or paths of locations of files
//2. Update your database classes before they make a connection to look for this $contants['slave_on'] path.  If file doesnt exist, only make a connection to your master server.  Tweak the settings of the seconds_behind_master if 120 seconds is too much for your reporting of slave data.
//3. Create a monitoring script to ping this URL to see if the connection is "OK".  Upon error it will unlink the file and recreate it once the slave's IO is back up

include('yourconstants.php');
$conn = mysql_connect('server','username','password');
$singleRow = mysql_query("SHOW SLAVE STATUS");
$row = mysql_fetch_array($singleRow);

$slaveInError = ((strtoupper($row['Slave_IO_Running']) == 'NO' || intval($row['Seconds_Behind_Master']) > 120) || is_null($row['Seconds_Behind_Master']));

if ($slaveInError && file_exists($contants['slave_on']))
{
   echo "ERROR";
   unlink($contants['slave_on']);
   mail("developers@yourwebsite.com","Slave Flag Turned off","A monitor detected that the slave went down for whatever reason.  The file that controls the slave being on '".$contants['slave_on']."' has taken the slave out of rotation");
}
else
{
   if ($slaveInError)
   {
      echo "ERROR";
   }
   else
   {
      if (!file_exists($contants['slave_on']) && intval($row['Seconds_Behind_Master']) < 5)
      {
         file_put_contents($contants['slave_on'],'on');
         mail("developers@yourwebsite.com","Slave Flag Turned On","Previously the slave was turned off, but now replication is back on and also between zero and 5 seconds.  We recreated the file '".$contants['slave_on']."'.");
      }
      echo "OK";
   }
}
?>