true if the sink is full
true always even when full since those messages just get stored in a overflow list
Called for each value what is passed on to the down stream sink.
Called for each value what is passed on to the down stream sink.
Sets a refiller on the sink.
Sets a refiller on the sink. The refiller is executed when the sink is interested in receiving more deliveries.
Implements a delivery sink which buffers the overflow of deliveries that a 'down stream' sink cannot accept when it's full. An overflow sink always accepts offers even when it's full.