reactor.core.publisher.FluxIterable Maven / Gradle / Ivy
/*
* Copyright (c) 2011-2017 Pivotal Software Inc, All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package reactor.core.publisher;
import java.util.Iterator;
import java.util.Objects;
import java.util.concurrent.atomic.AtomicLongFieldUpdater;
import org.reactivestreams.Subscriber;
import reactor.core.CoreSubscriber;
import reactor.core.Fuseable;
import reactor.util.annotation.Nullable;
/**
* Emits the contents of an Iterable source.
*
* @param the value type
*
* @see Reactive-Streams-Commons
*/
final class FluxIterable extends Flux implements Fuseable {
final Iterable iterable;
FluxIterable(Iterable iterable) {
this.iterable = Objects.requireNonNull(iterable, "iterable");
}
@Override
public void subscribe(CoreSubscriber actual) {
Iterator it;
try {
it = iterable.iterator();
}
catch (Throwable e) {
Operators.error(actual, Operators.onOperatorError(e, actual.currentContext()));
return;
}
subscribe(actual, it);
}
/**
* Common method to take an Iterator as a source of values.
*
* @param s the subscriber to feed this iterator to
* @param it the iterator to use as a source of values
*/
@SuppressWarnings("unchecked")
static void subscribe(CoreSubscriber s, Iterator it) {
//noinspection ConstantConditions
if (it == null) {
Operators.error(s, new NullPointerException("The iterator is null"));
return;
}
boolean b;
try {
b = it.hasNext();
}
catch (Throwable e) {
Operators.error(s, Operators.onOperatorError(e, s.currentContext()));
return;
}
if (!b) {
Operators.complete(s);
return;
}
if (s instanceof ConditionalSubscriber) {
s.onSubscribe(new IterableSubscriptionConditional<>((ConditionalSubscriber) s,
it));
}
else {
s.onSubscribe(new IterableSubscription<>(s, it));
}
}
static final class IterableSubscription
implements InnerProducer, SynchronousSubscription {
final CoreSubscriber actual;
final Iterator iterator;
volatile boolean cancelled;
volatile long requested;
@SuppressWarnings("rawtypes")
static final AtomicLongFieldUpdater REQUESTED =
AtomicLongFieldUpdater.newUpdater(IterableSubscription.class,
"requested");
int state;
/**
* Indicates that the iterator's hasNext returned true before but the value is not
* yet retrieved.
*/
static final int STATE_HAS_NEXT_NO_VALUE = 0;
/**
* Indicates that there is a value available in current.
*/
static final int STATE_HAS_NEXT_HAS_VALUE = 1;
/**
* Indicates that there are no more values available.
*/
static final int STATE_NO_NEXT = 2;
/**
* Indicates that the value has been consumed and a new value should be retrieved.
*/
static final int STATE_CALL_HAS_NEXT = 3;
T current;
IterableSubscription(CoreSubscriber actual,
Iterator iterator) {
this.actual = actual;
this.iterator = iterator;
}
@Override
public void request(long n) {
if (Operators.validate(n)) {
if (Operators.addCap(REQUESTED, this, n) == 0) {
if (n == Long.MAX_VALUE) {
fastPath();
}
else {
slowPath(n);
}
}
}
}
void slowPath(long n) {
final Iterator a = iterator;
final Subscriber s = actual;
long e = 0L;
for (; ; ) {
while (e != n) {
T t;
try {
t = Objects.requireNonNull(a.next(),
"The iterator returned a null value");
}
catch (Throwable ex) {
s.onError(ex);
return;
}
if (cancelled) {
return;
}
s.onNext(t);
if (cancelled) {
return;
}
boolean b;
try {
b = a.hasNext();
}
catch (Throwable ex) {
s.onError(ex);
return;
}
if (cancelled) {
return;
}
if (!b) {
s.onComplete();
return;
}
e++;
}
n = requested;
if (n == e) {
n = REQUESTED.addAndGet(this, -e);
if (n == 0L) {
return;
}
e = 0L;
}
}
}
void fastPath() {
final Iterator a = iterator;
final Subscriber s = actual;
for (; ; ) {
if (cancelled) {
return;
}
T t;
try {
t = Objects.requireNonNull(a.next(),
"The iterator returned a null value");
}
catch (Exception ex) {
s.onError(ex);
return;
}
if (cancelled) {
return;
}
s.onNext(t);
if (cancelled) {
return;
}
boolean b;
try {
b = a.hasNext();
}
catch (Exception ex) {
s.onError(ex);
return;
}
if (cancelled) {
return;
}
if (!b) {
s.onComplete();
return;
}
}
}
@Override
public void cancel() {
cancelled = true;
}
@Override
public CoreSubscriber actual() {
return actual;
}
@Override
@Nullable
public Object scanUnsafe(Attr key) {
if (key == Attr.CANCELLED) return cancelled;
if (key == Attr.REQUESTED_FROM_DOWNSTREAM) return requested;
if (key == Attr.TERMINATED) return state == STATE_NO_NEXT;
return InnerProducer.super.scanUnsafe(key);
}
@Override
public void clear() {
state = STATE_NO_NEXT;
}
@Override
public boolean isEmpty() {
int s = state;
if (s == STATE_NO_NEXT) {
return true;
}
else if (s == STATE_HAS_NEXT_HAS_VALUE || s == STATE_HAS_NEXT_NO_VALUE) {
return false;
}
else if (iterator.hasNext()) {
state = STATE_HAS_NEXT_NO_VALUE;
return false;
}
state = STATE_NO_NEXT;
return true;
}
@Override
@Nullable
public T poll() {
if (!isEmpty()) {
T c;
if (state == STATE_HAS_NEXT_NO_VALUE) {
c = iterator.next();
}
else {
c = current;
current = null;
}
state = STATE_CALL_HAS_NEXT;
return Objects.requireNonNull(c, "iterator returned a null value");
}
return null;
}
@Override
public int size() {
if (state == STATE_NO_NEXT) {
return 0;
}
return 1;
}
}
static final class IterableSubscriptionConditional
implements InnerProducer, SynchronousSubscription {
final ConditionalSubscriber actual;
final Iterator iterator;
volatile boolean cancelled;
volatile long requested;
@SuppressWarnings("rawtypes")
static final AtomicLongFieldUpdater REQUESTED =
AtomicLongFieldUpdater.newUpdater(IterableSubscriptionConditional.class,
"requested");
int state;
/**
* Indicates that the iterator's hasNext returned true before but the value is not
* yet retrieved.
*/
static final int STATE_HAS_NEXT_NO_VALUE = 0;
/**
* Indicates that there is a value available in current.
*/
static final int STATE_HAS_NEXT_HAS_VALUE = 1;
/**
* Indicates that there are no more values available.
*/
static final int STATE_NO_NEXT = 2;
/**
* Indicates that the value has been consumed and a new value should be retrieved.
*/
static final int STATE_CALL_HAS_NEXT = 3;
T current;
IterableSubscriptionConditional(ConditionalSubscriber actual,
Iterator iterator) {
this.actual = actual;
this.iterator = iterator;
}
@Override
public void request(long n) {
if (Operators.validate(n)) {
if (Operators.addCap(REQUESTED, this, n) == 0) {
if (n == Long.MAX_VALUE) {
fastPath();
}
else {
slowPath(n);
}
}
}
}
void slowPath(long n) {
final Iterator a = iterator;
final ConditionalSubscriber s = actual;
long e = 0L;
for (; ; ) {
while (e != n) {
T t;
try {
t = Objects.requireNonNull(a.next(),
"The iterator returned a null value");
}
catch (Throwable ex) {
s.onError(ex);
return;
}
if (cancelled) {
return;
}
boolean consumed = s.tryOnNext(t);
if (cancelled) {
return;
}
boolean b;
try {
b = a.hasNext();
}
catch (Throwable ex) {
s.onError(ex);
return;
}
if (cancelled) {
return;
}
if (!b) {
s.onComplete();
return;
}
if (consumed) {
e++;
}
}
n = requested;
if (n == e) {
n = REQUESTED.addAndGet(this, -e);
if (n == 0L) {
return;
}
e = 0L;
}
}
}
void fastPath() {
final Iterator a = iterator;
final ConditionalSubscriber s = actual;
for (; ; ) {
if (cancelled) {
return;
}
T t;
try {
t = Objects.requireNonNull(a.next(),
"The iterator returned a null value");
}
catch (Exception ex) {
s.onError(ex);
return;
}
if (cancelled) {
return;
}
s.tryOnNext(t);
if (cancelled) {
return;
}
boolean b;
try {
b = a.hasNext();
}
catch (Exception ex) {
s.onError(ex);
return;
}
if (cancelled) {
return;
}
if (!b) {
s.onComplete();
return;
}
}
}
@Override
public void cancel() {
cancelled = true;
}
@Override
public CoreSubscriber actual() {
return actual;
}
@Override
@Nullable
public Object scanUnsafe(Attr key) {
if (key == Attr.CANCELLED) return cancelled;
if (key == Attr.REQUESTED_FROM_DOWNSTREAM) return requested;
if (key == Attr.TERMINATED) return state == STATE_NO_NEXT;
return InnerProducer.super.scanUnsafe(key);
}
@Override
public void clear() {
state = STATE_NO_NEXT;
}
@Override
public boolean isEmpty() {
int s = state;
if (s == STATE_NO_NEXT) {
return true;
}
else if (s == STATE_HAS_NEXT_HAS_VALUE || s == STATE_HAS_NEXT_NO_VALUE) {
return false;
}
else if (iterator.hasNext()) {
state = STATE_HAS_NEXT_NO_VALUE;
return false;
}
state = STATE_NO_NEXT;
return true;
}
@Override
@Nullable
public T poll() {
if (!isEmpty()) {
T c;
if (state == STATE_HAS_NEXT_NO_VALUE) {
c = iterator.next();
}
else {
c = current;
current = null;
}
state = STATE_CALL_HAS_NEXT;
return c;
}
return null;
}
@Override
public int size() {
if (state == STATE_NO_NEXT) {
return 0;
}
return 1; // no way of knowing without enumerating first
}
}
}
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