Example - Real Cache
 
 
- Unfortunately, a real cache is generally more complicated, requiring the ns_cond command as well:
  set lock [nsv_get cache lock]; set cond [nsv_get cache cond]
  if ![nsv_exists cache $key] {
    set value [… fetch data for $key …]
    nsv_set cache $key $value
    while {[set value [nsv_get cache $key]] == “”} {