public Interface QueueFuseable<T>

Request any of the SYNC or ASYNC modes.

Request an asynchronous fusion mode and can be returned by requestFusion(int) for an accepted mode.

In asynchronous fusion, upstream values may become available to poll() eventually. Upstream signals onError() and onComplete() as usual but onNext may not actually contain the upstream value but have null instead. Downstream should treat such onNext as indication that poll() can be called. Note that poll() has to be called sequentially (from within a serializing drain-loop). In addition, callers of poll() should be prepared to catch exceptions.

Used in binary or combination with the other constants as an input to requestFusion(int) indicating that the poll() will be called behind an asynchronous boundary and thus may change the non-trivial computation locations attached to the poll() chain of fused operators.

For example, fusing map() and observeOn() may move the computation of the map's function over to the thread run after the observeOn(), which is generally unexpected.

Returned by the requestFusion(int) if the upstream doesn't support the requested mode.

Request a synchronous fusion mode and can be returned by requestFusion(int) for an accepted mode.

In synchronous fusion, all upstream values are either already available or is generated when poll() is called synchronously. When the poll() returns null, that is the indication if a terminated stream. In this mode, the upstream won't call the onXXX methods and callers of poll() should be prepared to catch exceptions. Note that poll() has to be called sequentially (from within a serializing drain-loop).

Request a fusion mode from the upstream.

This should be called before onSubscribe returns.

Calling this method multiple times or after onSubscribe finished is not allowed and may result in undefined behavior.

Parameters

mode:int

the requested fusion mode, allowed values are SYNC, ASYNC, ANY combined with BOUNDARY (e.g., requestFusion(SYNC | BOUNDARY)).

Returns:int

the established fusion mode: NONE, SYNC, ASYNC.