Active / Passive slightly diffrent recovery

Some experimenting later. I'm sure there is room for improvement, but it seems to do the job.

when CLIENT_ACCEPTED {
 Active/Passive iRule. IJdo Dijkstra 15-10-2015
 Pool A should be active, and failover to B. Pool B should remain active even if pool A returns.
 Failback occurs when pool B is down. 
 User table entry FailOver for failover state. 0 = normal, 1 = Failover
 Checked for FailOver!=1 to allow for non-set condition.


 Normal situation. Pool A is up, and FailOver != 1. Traffic to pool A
if { [table lookup -notouch FailOver]!=1  && [active_members /Test/pool-test-A]!=0  } {
    pool /Test/pool-test-A

 Normal failed-over situation. FailOver = 1 and pool B is up.
}elseif { [table lookup -notouch FailOver]==1  && [active_members /Test/pool-test-B]!=0  } {
    pool /Test/pool-test-B

 Actual failover trigger. Pool A is down, FailOver != 1 Traffic to Pool B
} elseif { [table lookup -notouch FailOver]!=1 && [active_members /Test/pool-test-A]==0 } {
    table set FailOver 1 indefinite
    pool /Test/pool-test-B

 Failback when pool B goes down and FailOver is 1. Traffic to pool A
 No strict need to check if pool A is up (with both pools down service is lost); but it seems neater.
} elseif { [table lookup -notouch FailOver]==1 && [active_members /Test/pool-test-A]!=0 && [active_members /Test/pool-test-B]== 0 } {
    table set FailOver 0 indefinite
    pool /Test/pool-test-A

 Happens is all the above conditions are not met. Optionally additional conditions could be used for sorryservers.
} else {
    pool /Test/pool-test-B
} 
}