Continuations are activated when they receive an event or by
INKContSchedule (which schedules a continuation to
receive an event). Continuations might receive an event because:
Your plugin calls INKContCall
The Traffic Server HTTP state machine sends an event corresponding to a particular HTTP hook
A Traffic Server IO processor (such as a cache processor or net
processor) is letting a continuation know there is data (cache or
network) available to read or write. These callbacks are a
result of using functions such
INKVConnRead/Write or INKCacheRead/Write