io.reactivex.rxjava3.operators

Interface QueueFuseable<T>

Type Parameters:

T - the value type returned by the SimpleQueue.poll()

All Superinterfaces:

SimpleQueue<T>

All Known Subinterfaces:

QueueDisposable<T>, QueueSubscription<T>

public interface QueueFuseable<T>
extends SimpleQueue<T>

Represents a SimpleQueue plus the means and constants for requesting a fusion mode.

Since:

3.1.1

Field Summary

Fields

Modifier and Type	Field and Description
static int	ANY Request any of the SYNC or ASYNC modes.
static int	ASYNC Request an asynchronous fusion mode and can be returned by requestFusion(int) for an accepted mode.
static int	BOUNDARY Used in binary or combination with the other constants as an input to requestFusion(int) indicating that the SimpleQueue.poll() will be called behind an asynchronous boundary and thus may change the non-trivial computation locations attached to the SimpleQueue.poll() chain of fused operators.
static int	NONE Returned by the requestFusion(int) if the upstream doesn't support the requested mode.
static int	SYNC Request a synchronous fusion mode and can be returned by requestFusion(int) for an accepted mode.

Method Summary

Modifier and Type	Method and Description
int	requestFusion(int mode) Request a fusion mode from the upstream.

Methods inherited from interface io.reactivex.rxjava3.operators.SimpleQueue

clear, isEmpty, offer, offer, poll

Field Detail

NONE

static final int NONE

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

See Also:

Constant Field Values

SYNC

static final int SYNC

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 SimpleQueue.poll() is called synchronously. When the SimpleQueue.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 SimpleQueue.poll() should be prepared to catch exceptions. Note that SimpleQueue.poll() has to be called sequentially (from within a serializing drain-loop).

See Also:

Constant Field Values

ASYNC

static final int ASYNC

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 SimpleQueue.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 SimpleQueue.poll() can be called. Note that SimpleQueue.poll() has to be called sequentially (from within a serializing drain-loop). In addition, callers of SimpleQueue.poll() should be prepared to catch exceptions.

See Also:

Constant Field Values

ANY

static final int ANY

Request any of the SYNC or ASYNC modes.

See Also:

Constant Field Values

BOUNDARY

static final int BOUNDARY

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

See Also:

Constant Field Values

Method Detail

requestFusion

int requestFusion(int mode)

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

Returns:

the established fusion mode: NONE, SYNC, ASYNC.