The idea is to filter the sources, replacing @<var>@ occurrences with
the mapping for <var> (which is currently hard-coded). @@ -> @. In order
to make this work, I had to move the doc sources one directory down
(into akka-docs/rst) so that the filtered result could be in a sibling
directory so that relative links (to _sphinx plugins or real code) would
continue to work.
While I was at it I also changed it so that WARNINGs and ERRORs are not
swallowed into the debug dump anymore but printed at [warn] level
(minimum).
One piece of fallout is that the (online) html build is now run after
the normal one, not in parallel.
This means tightening types from Duration to FiniteDuration in several
places; a good thing, since we replace runtime complaints by compile
time errors.
* Uses finite state machine for three states: Closed, Open, Half-Open
* Closed state allows calls through, and on sequential failures exceeding the max# set - transitions to Open state. Intervening successes cause the failure count to reset to 0
* Open state throws a CircuitOpenException on every call until the reset timeout is reached which causes a transition to Half-Open state
* Half-Open state will allow the next single call through, if it succeeds - transition to Closed state, if it fails - transition back to Open state, starting the reset timer again
* Allow configuration for the call and reset timeouts, as well as the maximum number of sequential failures before opening
* Supports async or synchronous call protection
* Callbacks are supported for state entry into Closed, Open, Half-Open. These are run in the supplied execution context
* Both thrown exceptions and calls exceeding max call time are considered failures
* Uses akka scheduler for timer events
* Integrated into File-Based durable mailbox
* Sample documented for other durable mailboxes
