@startuml

start
:Router sends request:
Version DB{TS10};

if (DSS has matching entry DB{TS10} AND\nCritical Section is not active) then (YES)
  #palegreen:Serve the request;
  stop
(NO) elseif (        Am I secondary?\n[!canAcceptNonLocalWrites(..)]) then (YES)
  :Wait until replication has
  applied until T10
  [waitUntilOpTimeForRead(..)];
else (NO)
endif

if (Critical Section taken?) then (YES)
  :Wait until critical section is released
  [waitForCriticalSectionToComplete(..)];
else (NO)
endif

switch (compare against DSS entry)
case (DSS has matching entry\nDB{TS10})
  #palegreen:Serve the request;
  stop
case (DSS has a newer entry.          \nDB{TS12})
  #yellow:Send Router stale;
  stop
case (DSS has no entry)
  #pink:Consider split brain handling\nfor primary;
  #yellow:Send Router stale;
  stop
case (DSS has older entry\nDB{TS7})
  #pink:Consider split brain handling\nfor primary;
  #red: ASSERT(Not Possible);
  end
@enduml