/*
* 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.
Collection;
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;
import reactor.util.function.
Tuple2;
/**
* Emits the contents of an Iterable source.
*
* @param <T> the value type
*
* @see <a href="https://github.com/reactor/reactive-streams-commons">Reactive-Streams-Commons</a>
*/
final class
FluxIterable<T> extends
Flux<T> implements
Fuseable,
SourceProducer<T> {
final
Iterable<? extends T>
iterable;
private final
Runnable onClose;
FluxIterable(
Iterable<? extends T>
iterable,
Runnable onClose) {
this.
iterable =
Objects.
requireNonNull(
iterable, "iterable");
this.
onClose =
onClose;
}
FluxIterable(
Iterable<? extends T>
iterable) {
this(
iterable, null);
}
@
Override
public void
subscribe(
CoreSubscriber<? super T>
actual) {
Iterator<? extends T>
it;
try {
it =
iterable.
iterator();
}
catch (
Throwable e) {
Operators.
error(
actual,
Operators.
onOperatorError(
e,
actual.
currentContext()));
return;
}
subscribe(
actual,
it,
onClose);
}
@
Override
public
Object scanUnsafe(
Attr key) {
if (
key ==
Attr.
BUFFERED) {
if (
iterable instanceof
Collection) return ((
Collection)
iterable).
size();
if (
iterable instanceof
Tuple2) return ((
Tuple2)
iterable).
size();
}
return null;
}
/**
* 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 <T> void
subscribe(
CoreSubscriber<? super T>
s,
Iterator<? extends T>
it) {
subscribe(
s,
it, null);
}
/**
* 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
* @param onClose close handler to call once we're done with the iterator (provided it
* is not null, this includes when the iteration errors or complete or the subscriber
* is cancelled). Null to ignore.
*/
@
SuppressWarnings("unchecked")
static <T> void
subscribe(
CoreSubscriber<? super T>
s,
Iterator<? extends T>
it,
@
Nullable Runnable onClose) {
//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()));
if (
onClose != null) {
try {
onClose.
run();
}
catch (
Throwable t) {
Operators.
onErrorDropped(
t,
s.
currentContext());
}
}
return;
}
if (!
b) {
Operators.
complete(
s);
if (
onClose != null) {
try {
onClose.
run();
}
catch (
Throwable t) {
Operators.
onErrorDropped(
t,
s.
currentContext());
}
}
return;
}
if (
s instanceof
ConditionalSubscriber) {
s.
onSubscribe(new
IterableSubscriptionConditional<>((
ConditionalSubscriber<? super T>)
s,
it,
onClose));
}
else {
s.
onSubscribe(new
IterableSubscription<>(
s,
it,
onClose));
}
}
static final class
IterableSubscription<T>
implements
InnerProducer<T>,
SynchronousSubscription<T> {
final
CoreSubscriber<? super T>
actual;
final
Iterator<? extends T>
iterator;
final
Runnable onClose;
volatile boolean
cancelled;
volatile long
requested;
@
SuppressWarnings("rawtypes")
static final
AtomicLongFieldUpdater<
IterableSubscription>
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<? super T>
actual,
Iterator<? extends T>
iterator, @
Nullable Runnable onClose) {
this.
actual =
actual;
this.
iterator =
iterator;
this.
onClose =
onClose;
}
IterableSubscription(
CoreSubscriber<? super T>
actual,
Iterator<? extends T>
iterator) {
this(
actual,
iterator, null);
}
@
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);
}
}
}
}
private void
onCloseWithDropError() {
if (
onClose != null) {
try {
onClose.
run();
}
catch (
Throwable t) {
Operators.
onErrorDropped(
t,
actual.
currentContext());
}
}
}
void
slowPath(long
n) {
final
Iterator<? extends T>
a =
iterator;
final
Subscriber<? super T>
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);
onCloseWithDropError();
return;
}
if (
cancelled) {
return;
}
s.
onNext(
t);
if (
cancelled) {
return;
}
boolean
b;
try {
b =
a.
hasNext();
}
catch (
Throwable ex) {
s.
onError(
ex);
onCloseWithDropError();
return;
}
if (
cancelled) {
return;
}
if (!
b) {
s.
onComplete();
onCloseWithDropError();
return;
}
e++;
}
n =
requested;
if (
n ==
e) {
n =
REQUESTED.
addAndGet(this, -
e);
if (
n == 0L) {
return;
}
e = 0L;
}
}
}
void
fastPath() {
final
Iterator<? extends T>
a =
iterator;
final
Subscriber<? super T>
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);
onCloseWithDropError();
return;
}
if (
cancelled) {
return;
}
s.
onNext(
t);
if (
cancelled) {
return;
}
boolean
b;
try {
b =
a.
hasNext();
}
catch (
Exception ex) {
s.
onError(
ex);
onCloseWithDropError();
return;
}
if (
cancelled) {
return;
}
if (!
b) {
s.
onComplete();
onCloseWithDropError();
return;
}
}
}
@
Override
public void
cancel() {
onCloseWithDropError();
cancelled = true;
}
@
Override
public
CoreSubscriber<? super T>
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;
if (
c == null) {
onCloseWithDropError();
throw new
NullPointerException("iterator returned a null value");
}
return
c;
}
onCloseWithDropError();
return null;
}
@
Override
public int
size() {
if (
state ==
STATE_NO_NEXT) {
return 0;
}
return 1;
}
}
static final class
IterableSubscriptionConditional<T>
implements
InnerProducer<T>,
SynchronousSubscription<T> {
final
ConditionalSubscriber<? super T>
actual;
final
Iterator<? extends T>
iterator;
final
Runnable onClose;
volatile boolean
cancelled;
volatile long
requested;
@
SuppressWarnings("rawtypes")
static final
AtomicLongFieldUpdater<
IterableSubscriptionConditional>
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<? super T>
actual,
Iterator<? extends T>
iterator, @
Nullable Runnable onClose) {
this.
actual =
actual;
this.
iterator =
iterator;
this.
onClose =
onClose;
}
IterableSubscriptionConditional(
ConditionalSubscriber<? super T>
actual,
Iterator<? extends T>
iterator) {
this(
actual,
iterator, null);
}
@
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);
}
}
}
}
private void
onCloseWithDropError() {
if (
onClose != null) {
try {
onClose.
run();
}
catch (
Throwable t) {
Operators.
onErrorDropped(
t,
actual.
currentContext());
}
}
}
void
slowPath(long
n) {
final
Iterator<? extends T>
a =
iterator;
final
ConditionalSubscriber<? super T>
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);
onCloseWithDropError();
return;
}
if (
cancelled) {
return;
}
boolean
consumed =
s.
tryOnNext(
t);
if (
cancelled) {
return;
}
boolean
b;
try {
b =
a.
hasNext();
}
catch (
Throwable ex) {
s.
onError(
ex);
onCloseWithDropError();
return;
}
if (
cancelled) {
return;
}
if (!
b) {
s.
onComplete();
onCloseWithDropError();
return;
}
if (
consumed) {
e++;
}
}
n =
requested;
if (
n ==
e) {
n =
REQUESTED.
addAndGet(this, -
e);
if (
n == 0L) {
return;
}
e = 0L;
}
}
}
void
fastPath() {
final
Iterator<? extends T>
a =
iterator;
final
ConditionalSubscriber<? super T>
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);
onCloseWithDropError();
return;
}
if (
cancelled) {
return;
}
s.
tryOnNext(
t);
if (
cancelled) {
return;
}
boolean
b;
try {
b =
a.
hasNext();
}
catch (
Exception ex) {
s.
onError(
ex);
onCloseWithDropError();
return;
}
if (
cancelled) {
return;
}
if (!
b) {
s.
onComplete();
onCloseWithDropError();
return;
}
}
}
@
Override
public void
cancel() {
onCloseWithDropError();
cancelled = true;
}
@
Override
public
CoreSubscriber<? super T>
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;
}
onCloseWithDropError();
return null;
}
@
Override
public int
size() {
if (
state ==
STATE_NO_NEXT) {
return 0;
}
return 1; // no way of knowing without enumerating first
}
}
}