io.servicetalk.concurrent.internal

Class SubscriberUtils

java.lang.Object

io.servicetalk.concurrent.internal.SubscriberUtils

public final class SubscriberUtils
extends java.lang.Object

A set of utilities for common PublisherSource.Subscriber tasks.

Method Summary

Modifier and Type	Method and Description
static <T> int	calculateSourceRequested(java.util.concurrent.atomic.AtomicLongFieldUpdater<T> requestNUpdater, java.util.concurrent.atomic.AtomicLongFieldUpdater<T> sourceRequestedUpdater, java.util.concurrent.atomic.AtomicLongFieldUpdater<T> emittedUpdater, int limit, T owner) Attempts to increment sourceRequestedUpdater in order to make it the same as requestNUpdater while not exceeding the limit.
static boolean	checkDuplicateSubscription(PublisherSource.Subscription existing, PublisherSource.Subscription next) Checks for an already existing PublisherSource.Subscription and if one is given calls Cancellable.cancel() on next and returns false.
static void	deliverTerminalFromSource(CompletableSource.Subscriber subscriber, java.lang.Throwable cause) Deliver a terminal error to a CompletableSource.Subscriber that has not yet had CompletableSource.Subscriber#onSubscribe(Cancellable) called.
static <T> void	deliverTerminalFromSource(PublisherSource.Subscriber<T> subscriber) Deliver a terminal complete to a PublisherSource.Subscriber that has not yet had PublisherSource.Subscriber.onSubscribe(PublisherSource.Subscription) called.
static <T> void	deliverTerminalFromSource(PublisherSource.Subscriber<T> subscriber, java.lang.Throwable cause) Deliver a terminal error to a PublisherSource.Subscriber that has not yet had PublisherSource.Subscriber.onSubscribe(PublisherSource.Subscription) called.
static <T> void	deliverTerminalFromSource(SingleSource.Subscriber<T> subscriber, java.lang.Throwable cause) Deliver a terminal error to a SingleSource.Subscriber that has not yet had SingleSource.Subscriber#onSubscribe(Cancellable) called.
static void	handleExceptionFromOnSubscribe(CompletableSource.Subscriber subscriber, java.lang.Throwable cause) Handle the case when a call to CompletableSource.Subscriber#onSubscribe(Cancellable) throws from a source.
static <T> void	handleExceptionFromOnSubscribe(PublisherSource.Subscriber<T> subscriber, java.lang.Throwable cause) Handle the case when a call to PublisherSource.Subscriber.onSubscribe(PublisherSource.Subscription) throws from a source.
static <T> void	handleExceptionFromOnSubscribe(SingleSource.Subscriber<T> subscriber, java.lang.Throwable cause) Handle the case when a call to SingleSource.Subscriber#onSubscribe(Cancellable) throws from a source.
static boolean	isRequestNValid(long n) Returns false if the requested amount of elements n is not-positive, true otherwise.
static java.lang.IllegalArgumentException	newExceptionForInvalidRequestN(long n) Create a new exception for an invalid amount of PublisherSource.Subscription.request(long) according to Reactive Streams, Rule 3.9.
static <T> void	safeOnError(SingleSource.Subscriber<T> subscriber, java.lang.Throwable cause) Invokes SingleSource.Subscriber#onError(Throwable) ignoring an occurred exception if any.
static <R> boolean	trySetTerminal(TerminalNotification toSet, boolean overrideComplete, java.util.concurrent.atomic.AtomicReferenceFieldUpdater<R,TerminalNotification> terminalNotificationUpdater, R flagOwner) There are some scenarios where a completion TerminalNotification can be overridden with an error if errors are produced asynchronously.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

checkDuplicateSubscription

public static boolean checkDuplicateSubscription(@Nullable
                                                 PublisherSource.Subscription existing,
                                                 PublisherSource.Subscription next)

Checks for an already existing PublisherSource.Subscription and if one is given calls Cancellable.cancel() on next and returns false.

Parameters:

existing - the existing PublisherSource.Subscription or null if none exists.

next - the next PublisherSource.Subscription to use.

Returns:

true if no PublisherSource.Subscription exists, false otherwise.

isRequestNValid

public static boolean isRequestNValid(long n)

Returns false if the requested amount of elements n is not-positive, true otherwise.

Parameters:

n - the number of elements to request.

Returns:

false if the requested amount of elements n is not-positive, true otherwise.

newExceptionForInvalidRequestN

public static java.lang.IllegalArgumentException newExceptionForInvalidRequestN(long n)

Create a new exception for an invalid amount of PublisherSource.Subscription.request(long) according to Reactive Streams, Rule 3.9.

Parameters:

n - the invalid request count.

Returns:

The exception which clarifies the invalid behavior.

calculateSourceRequested

public static <T> int calculateSourceRequested(java.util.concurrent.atomic.AtomicLongFieldUpdater<T> requestNUpdater,
                                               java.util.concurrent.atomic.AtomicLongFieldUpdater<T> sourceRequestedUpdater,
                                               java.util.concurrent.atomic.AtomicLongFieldUpdater<T> emittedUpdater,
                                               int limit,
                                               T owner)

Attempts to increment sourceRequestedUpdater in order to make it the same as requestNUpdater while not exceeding the limit.

Type Parameters:

T - The type of object which owns the atomic updater parameters.

Parameters:

requestNUpdater - The total number which has been requested (typically from PublisherSource.Subscription.request(long)).

sourceRequestedUpdater - The total number which has actually been passed to PublisherSource.Subscription.request(long). This outstanding count sourceRequestedUpdater() - emittedUpdater.get() should never exceed limit.

emittedUpdater - The amount of data that has been emitted/delivered by the source.

limit - The maximum outstanding demand from the source at any given time.

owner - The object which all atomic updater parameters are associated with.

Returns:

The amount that sourceRequestedUpdater was increased by. This value is typically used to call PublisherSource.Subscription.request(long).

trySetTerminal

public static <R> boolean trySetTerminal(TerminalNotification toSet,
                                         boolean overrideComplete,
                                         java.util.concurrent.atomic.AtomicReferenceFieldUpdater<R,TerminalNotification> terminalNotificationUpdater,
                                         R flagOwner)

There are some scenarios where a completion TerminalNotification can be overridden with an error if errors are produced asynchronously.

This method helps set TerminalNotification atomically providing such an override.

Type Parameters:

R - Type of flagOwner.

Parameters:

toSet - TerminalNotification to set.

overrideComplete - Whether exisiting TerminalNotification.complete() should be overridden with the toSet.

terminalNotificationUpdater - AtomicReferenceFieldUpdater to access the current TerminalNotification.

flagOwner - instance of R that owns the current TerminalNotification field referenced by terminalNotificationUpdater.

Returns:

true if toSet is updated as the current TerminalNotification.

deliverTerminalFromSource

public static <T> void deliverTerminalFromSource(PublisherSource.Subscriber<T> subscriber,
                                                 java.lang.Throwable cause)

Deliver a terminal error to a PublisherSource.Subscriber that has not yet had PublisherSource.Subscriber.onSubscribe(PublisherSource.Subscription) called.

Type Parameters:

T - The type of PublisherSource.Subscriber.

Parameters:

subscriber - The PublisherSource.Subscriber to terminate.

cause - The terminal event.

deliverTerminalFromSource

public static <T> void deliverTerminalFromSource(PublisherSource.Subscriber<T> subscriber)

Deliver a terminal complete to a PublisherSource.Subscriber that has not yet had PublisherSource.Subscriber.onSubscribe(PublisherSource.Subscription) called.

Type Parameters:

T - The type of PublisherSource.Subscriber.

Parameters:

subscriber - The PublisherSource.Subscriber to terminate.

deliverTerminalFromSource

public static <T> void deliverTerminalFromSource(SingleSource.Subscriber<T> subscriber,
                                                 java.lang.Throwable cause)

Deliver a terminal error to a SingleSource.Subscriber that has not yet had SingleSource.Subscriber#onSubscribe(Cancellable) called.

Type Parameters:

T - The type of SingleSource.Subscriber.

Parameters:

subscriber - The SingleSource.Subscriber to terminate.

cause - The terminal event.

deliverTerminalFromSource

public static void deliverTerminalFromSource(CompletableSource.Subscriber subscriber,
                                             java.lang.Throwable cause)

Deliver a terminal error to a CompletableSource.Subscriber that has not yet had CompletableSource.Subscriber#onSubscribe(Cancellable) called.

Parameters:

subscriber - The CompletableSource.Subscriber to terminate.

cause - The terminal event.

handleExceptionFromOnSubscribe

public static <T> void handleExceptionFromOnSubscribe(PublisherSource.Subscriber<T> subscriber,
                                                      java.lang.Throwable cause)

Handle the case when a call to PublisherSource.Subscriber.onSubscribe(PublisherSource.Subscription) throws from a source.

Type Parameters:

T - The type of PublisherSource.Subscriber.

Parameters:

subscriber - The PublisherSource.Subscriber that threw an exception from PublisherSource.Subscriber.onSubscribe(PublisherSource.Subscription).

cause - The exception thrown by subscriber.

handleExceptionFromOnSubscribe

public static <T> void handleExceptionFromOnSubscribe(SingleSource.Subscriber<T> subscriber,
                                                      java.lang.Throwable cause)

Handle the case when a call to SingleSource.Subscriber#onSubscribe(Cancellable) throws from a source.

Type Parameters:

T - The type of SingleSource.Subscriber.

Parameters:

subscriber - The SingleSource.Subscriber that threw an exception from SingleSource.Subscriber#onSubscribe(Cancellable).

cause - The exception thrown by subscriber.

handleExceptionFromOnSubscribe

public static void handleExceptionFromOnSubscribe(CompletableSource.Subscriber subscriber,
                                                  java.lang.Throwable cause)

Handle the case when a call to CompletableSource.Subscriber#onSubscribe(Cancellable) throws from a source.

Parameters:

subscriber - The CompletableSource.Subscriber that threw an exception from CompletableSource.Subscriber#onSubscribe(Cancellable).

cause - The exception thrown by subscriber.

safeOnError

public static <T> void safeOnError(SingleSource.Subscriber<T> subscriber,
                                   java.lang.Throwable cause)

Invokes SingleSource.Subscriber#onError(Throwable) ignoring an occurred exception if any.

Type Parameters:

T - The type of SingleSource.Subscriber.

Parameters:

subscriber - The SingleSource.Subscriber that may threw an exception from SingleSource.Subscriber#onError(Throwable).

cause - The occurred Throwable for SingleSource.Subscriber#onError(Throwable).