Interface describing Observer wrappers
that are thread-safe (can receive concurrent events) and that
return an immediate Continue when receiving onNext
events. Meant to be used by data sources that cannot uphold the
no-concurrent events and the back-pressure related requirements
(i.e. data-sources that cannot wait on Future[Continue] for
sending the next event).
Implementations of this interface have the following contract:
onNext / onError / onComplete of this interface MAY be
called concurrently
onNext SHOULD return an immediate Continue, as long as the
buffer is not full and the underlying observer hasn't signaled
Stop (N.B. due to the asynchronous nature, Stop signaled
by the underlying observer may be noticed later, so
implementations of this interface make no guarantee about queued
events - which could be generated, queued and dropped on the
floor later)
onNext MUST return an immediate Stop result, after it
notices that the underlying observer signaled Stop (due to
the asynchronous nature of observers, this may happen later and
queued events might get dropped on the floor)
in general the contract for the underlying Observer is fully
respected (grammar, non-concurrent notifications, etc...)
when the underlying observer canceled (by returning Stop),
or when a concurrent upstream data source triggered an error,
this SHOULD eventually be noticed and acted upon
as long as the buffer isn't full and the underlying observer
isn't Stop, then implementations of this interface SHOULD
not lose events in the process
the buffer MAY BE either unbounded or bounded, in case of
bounded buffers, then an appropriate overflowStrategy needs to be set for
when the buffer overflows - either an onError triggered in the
underlying observer coupled with a Stop signaled to the
upstream data sources, or dropping events from the head or the
tail of the queue, or attempting to apply back-pressure, etc...
Interface describing Observer wrappers that are thread-safe (can receive concurrent events) and that return an immediate
Continuewhen receivingonNextevents. Meant to be used by data sources that cannot uphold the no-concurrent events and the back-pressure related requirements (i.e. data-sources that cannot wait onFuture[Continue]for sending the next event).Implementations of this interface have the following contract:
onNext/onError/onCompleteof this interface MAY be called concurrentlyonNextSHOULD return an immediateContinue, as long as the buffer is not full and the underlying observer hasn't signaledStop(N.B. due to the asynchronous nature,Stopsignaled by the underlying observer may be noticed later, so implementations of this interface make no guarantee about queued events - which could be generated, queued and dropped on the floor later)onNextMUST return an immediateStopresult, after it notices that the underlying observer signaledStop(due to the asynchronous nature of observers, this may happen later and queued events might get dropped on the floor)Stop), or when a concurrent upstream data source triggered an error, this SHOULD eventually be noticed and acted uponStop, then implementations of this interface SHOULD not lose events in the processonErrortriggered in the underlying observer coupled with aStopsignaled to the upstream data sources, or dropping events from the head or the tail of the queue, or attempting to apply back-pressure, etc...See OverflowStrategy for the buffer policies available.